Bio Paper One Application

Question 1

How does the structure of the phospholipid bilayer contribute to its role in controlling what enters and exits the cell?

Answer 1

The phospholipid bilayer has a hydrophilic head and hydrophobic tails. The hydrophobic core prevents water-soluble (polar) substances, like ions and glucose, from easily passing through. Only small, non-polar molecules, like oxygen and carbon dioxide, can diffuse directly through the bilayer. Larger or polar molecules require transport proteins to cross the membrane, contributing to selective permeability

Question 2

Why is cholesterol important in maintaining membrane fluidity, and how would its absence affect cell membrane function?

Answer 2

Cholesterol fits between the fatty acid tails of the phospholipids, restricting excessive movement and maintaining membrane fluidity. It prevents the membrane from becoming too fluid at high temperatures and too rigid at low temperatures. Without cholesterol, the membrane would be less flexible, affecting membrane stability, protein function, and transport of molecules.

Question 3

How would the absence of channel proteins in the cell membrane affect ion movement and cellular function?

Answer 3

Provides a pathway for larger molecules by binding to them and changing their shape , and provide pathways for molecules that do not dissolve in lipids that would have difficulty passing through the hydrophobic core

Question 4

Why can’t large polar molecules, like glucose, simply diffuse across the phospholipid bilayer?

Answer 4

Large polar molecules like glucose are hydrophilic and cannot pass through the hydrophobic core of the phospholipid bilayer. The non-polar tails of the phospholipids repel these polar molecules. Therefore, glucose requires carrier proteins or facilitated diffusion to move across the membrane.

Question 5

What would happen to the cell if its surface membrane became permeable to all substances?

Answer 5

If the membrane were permeable to all substances, it would lose its ability to selectively regulate what enters and exits the cell. Harmful substances could freely enter, while essential molecules could leak out. This would disrupt homeostasis, leading to cell damage or death due to uncontrolled fluxes of ions, water, and other molecules.

Question 6

Describe the role of glycoproteins in the cell surface membrane and how they contribute to cellular communication.

Answer 6

Glycoproteins, which are proteins with attached carbohydrate chains, play a key role in cell recognition and communication. They act as receptors for signaling molecules (like hormones) and help in cell-cell recognition (e.g., in immune responses). They enable cells to communicate with each other and respond to external signals, maintaining proper function and coordination in tissues

Question 7

What impact does the temperature have on membrane fluidity, and how do phospholipids and cholesterol adapt to maintain membrane stability?

Answer 7

At higher temperatures, the phospholipids become more fluid, which could make the membrane too permeable. Cholesterol helps reduce this fluidity by pulling phospholipid tails closer together. At lower temperatures, phospholipids become more rigid, and cholesterol helps prevent them from packing too tightly, maintaining membrane flexibility. This balance ensures the membrane remains functional under varying temperature conditions.

Question 8

How do surface proteins in the fluid mosaic model contribute to cell communication?

Answer 8

Surface proteins (also known as peripheral proteins) are found on the outer or inner surface of the cell membrane. These proteins can act as receptors, binding to specific signaling molecules like hormones which triggers a response inside the cell. They are also involved in cell recognition, helping cells identify each other and communicate during immune responses or tissue formation.

Question 9

Why is it important for the cell membrane to maintain selective permeability, and how do surface proteins aid in this function?

Answer 9

Allows needed ions substances and nutrients in the cell, whilst isolating harmful or unnecessary substances ,it controls what goes in and out the cell maintaining the right balance of nutrients ions and waste products in and out of the cell.

Question 10

What is the basic structure of an amino acid, and why is this important for protein formation?

Answer 10

An amino acid has a central carbon atom (C) bonded to four groups: an amino group (NH₂), a carboxyl group (COOH), a hydrogen atom (H), and a variable R group (side chain). The R group differs between amino acids and determines their properties (e.g., hydrophobic, hydrophilic). Amino acids link together via peptide bonds to form polypeptides, which fold into specific shapes to form proteins. This structure is essential because the sequence and properties of amino acids determine the shape and function of the protein.

Question 11

How do peptide bonds form between amino acids, and what type of reaction is involved?

Answer 11

Peptide bonds form between the carboxyl group of one amino acid and the amino group of another during a condensation reaction. In this reaction, a molecule of water (H₂O) is removed, and the amino acids are joined by a peptide bond, creating a growing polypeptide chain. The reverse reaction, hydrolysis, breaks peptide bonds during protein digestion.

Question 12

Describe the primary structure of a protein and explain why it is important.

Answer 12

The primary structure of a protein is the sequence of amino acids in a polypeptide chain, determined by the DNA sequence of a gene. This sequence dictates how the polypeptide will fold into its secondary, tertiary, and quaternary structures, ultimately determining the protein’s 3D shape and function. Even a small change in the primary structure (like a mutation) can dramatically affect the protein’s function.

Question 13

What is the secondary structure of a protein, and how are hydrogen bonds involved?

Answer 13

The secondary structure refers to the regular folding or coiling of the polypeptide chain into structures like alpha-helices or beta-pleated sheets, which are stabilized by hydrogen bonds between the backbone atoms of the polypeptide. These hydrogen bonds form between the C=O group of one amino acid and the N-H group of another, providing stability to the structure without involving side chains (R groups).

Question 14

How does the tertiary structure of a protein differ from the secondary structure, and what interactions are responsible for it?

Answer 14

The tertiary structure is the overall 3D folding of a polypeptide chain, determined by interactions between the R groups (side chains) of the amino acids. These interactions include:

Hydrogen bonds between polar R groups.
Ionic bonds between oppositely charged R groups.
Disulfide bridges (covalent bonds) between cysteine residues.
Hydrophobic interactions between non-polar R groups.
This structure determines the protein’s specific shape and function, such as the active site of an enzyme.

Question 15

What is the quaternary structure of a protein, and how does it relate to proteins like hemoglobin?

Answer 15

The quaternary structure involves the association of two or more polypeptide chains to form a functional protein. In hemoglobin, for example, four polypeptide subunits come together, each with an iron-containing heme group that binds oxygen. The quaternary structure allows for cooperative binding of oxygen, which is crucial for efficient oxygen transport in the blood.

Question 16

Explain how you would test for the presence of proteins using the Biuret test, and describe what a positive result looks like.

Answer 16

The Biuret test is used to detect the presence of proteins. Here’s how you conduct it:

Add a small amount of the Biuret reagent (a mixture of sodium hydroxide and copper sulfate) to the sample.
If proteins are present, the copper ions in the reagent will form a complex with the peptide bonds, causing the solution to turn purple.
Positive result: The solution changes from blue to purple, indicating the presence of proteins (peptide bonds). Negative result: The solution remains blue, indicating no proteins are present.

Question 17

How do disulfide bonds contribute to the stability of the tertiary structure of a protein?

Answer 17

They are strong covelant bonds they stabilise the structure by holding parts of the polypeptide chain together , they do not get effected by fluctuating ph or high temps ,so maintain stable structure in harsh conditions.

Question 18

What role do proteins play as enzymes, and how does their structure relate to their function?

Answer 18

Proteins act as enzymes, which are biological catalysts that speed up chemical reactions in the cell. The tertiary structure of an enzyme determines the shape of its active site, which is specific to the substrate it binds to. The enzyme’s ability to fold into the correct shape is crucial for its function, as the shape of the active site must match the substrate in a lock-and-key or induced-fit model for the reaction to proceed efficiently.

Question 19

What is the significance of denaturation in proteins, and how can factors like heat or pH lead to it?

Answer 19

Denaturation occurs when a protein loses its natural structure due to external factors like heat, pH changes, or chemicals. This can disrupt hydrogen bonds, ionic bonds, and hydrophobic interactions, causing the protein to unfold and lose its functional shape. For example, heating an enzyme can denature it, making it unable to bind its substrate, thus losing its catalytic activity. Denaturation is often irreversible.

Question 20

Why are fibrous proteins like collagen suited for structural roles, and how does their structure differ from globular proteins?

Answer 20

Fibrous proteins such as collagen have long rope like structures that provide strength and support in tissue ,they are made up of long repetitive amino acids forming parallel fibres . Globular proteins are spherical and soluble in water ,they have hydrophilic amino acids on their surface but hydrophobic amino acids in centre

Question 21

How does the structure of haemoglobin as a globular protein aid its function

Answer 21

Haemoglobin function is to bind to oxygen , the hydrophilic region allows it to be soluble in plasma for easy transport across circulatory system to transport oxygen to different areas in the body. The hydrophobic area of the structure helps stabilise its 3d structure ensuring it folds correctly maintaining its shape so that oxygen can bind to hydrophobic pockets so that haemoglobin can carry the oxygen without it needing to diffuse in the blood directly .

Question 22

Proteins perform a wide range of functions in living organisms. Explain how the structure of a protein determines its function, using examples such as enzymes, transport proteins, and antibodies.

Answer 22

The structure of a protein is directly related to its function, as its specific 3D shape allows it to perform a particular task.

Enzymes: The shape of the active site, determined by the protein’s tertiary structure, allows enzymes to bind specific substrates and catalyze reactions. For example, amylase breaks down starch into sugars because its active site fits the starch molecules perfectly.
Transport Proteins: Carrier and channel proteins in the cell membrane have specific shapes that allow them to transport ions and molecules across the membrane. For example, the sodium-potassium pump actively transports sodium out of the cell and potassium into the cell, maintaining essential ion balances.
Antibodies: These proteins have a specific structure that allows them to bind to foreign antigens with high specificity. This binding is crucial for the immune response, as antibodies help neutralize pathogens or mark them for destruction by other immune cells.

Question 23

What are the main structural components of a lipid?

Answer 23

Lipids consist of glycerol and fatty acids. Triglycerides, a common type of lipid, are made from one glycerol molecule bonded to three fatty acids.

Question 24

Why are triglycerides efficient molecules for energy storage?

Answer 24

Have a high ratio of energy storing carbon-hydrogen bonds to carbon atoms so are excellent source of energy. They have a low mass to energy ratio making them good storage molecules as can store a lot of energy in smaller space (beneficial to animals who have reduced mass they have to carry around).triglycerides are large and non polar (hydrophobic) and insoluble in water does not affect water potential in cells.
Triglycerides have a high ratio of hydrogen to oxygen atoms so release water when oxidised (provide important water source beneficial for organisms in dry deserts)

Question 25

What is the difference between saturated and unsaturated fatty acids, and how does this affect their physical state?

Answer 25

Saturated fatty acids have no double bonds between carbon atoms, so they can pack tightly, making them solid at room temperature (e.g., butter). Unsaturated fatty acids have one or more double bonds, creating kinks in the chain, which prevents tight packing, making them liquid at room temperature

Question 26

Besides energy storage, what are three other important functions of lipids in organisms?

Answer 26

Insulation: Lipids help maintain body temperature by acting as a thermal insulator. Waterproofing: Lipids form protective barriers, such as the waxy cuticle on plants or oils in animal skin, to reduce water loss. Membrane Structure: Phospholipids form the bilayer of cell membranes, providing structure and regulating permeability.

Question 27

How do the properties of fatty acids influence the fluidity of cell membranes?

Answer 27

Unsaturated fatty acids have kinks due to double bonds, which increase membrane fluidity by preventing fatty acids from packing closely together. Saturated fatty acids decrease fluidity because they can pack tightly.

Question 28

How would you test for the presence of lipids in a sample?

Answer 28

Use the emulsion test: Mix the sample with ethanol. Add water and shake the mixture. A milky white emulsion indicates the presence of lipids.

Question 29

How to lipids being hydrophobic help organisms

Answer 29

Allow organisms to be waterproof ,allow them to store energy without water retention

Question 30

How do phospholipids differ from triglycerides, and why are they important for cell membranes?

Answer 30

Phospholipids have two fatty acids and a phosphate group attached to glycerol, unlike triglycerides which have three fatty acids. They are crucial for forming the phospholipid bilayer of cell membranes, with hydrophilic heads facing outwards and hydrophobic tails inward, controlling what enters and exits the cell.

Question 31

What are the two main components of starch, and how are they structured?

Answer 31

Starch is composed of two polysaccharides: amylose, which is a long, unbranched chain of alpha-glucose with a helical structure, and amylopectin, which is a branched polymer of alpha-glucose with 1,4 and 1,6 glycosidic bonds.

Question 32

What is the main biological function of starch, and where is it found?

Answer 32

Starch functions as the main energy storage polysaccharide in plants. It is stored in chloroplasts and amyloplasts in plant cells and is broken down into glucose when energy is needed.

Question 33

What is the primary function of glycogen, and where is it found?

Answer 33

Glycogen is the main energy storage polysaccharide in animals and fungi, stored mainly in the liver and muscle cells. It is broken down into glucose when energy is required, especially during physical activity.

Question 34

What is the structure of cellulose, and how is it different from starch and glycogen?

Answer 34

Cellulose is made of long, unbranched chains of beta-glucose linked by 1,4 glycosidic bonds. Every other glucose molecule is flipped, allowing hydrogen bonds to form between adjacent chains, creating strong microfibrils

Question 35

Q: What is the main biological function of cellulose, and where is it found?

Answer 35

Cellulose is a structural polysaccharide found in the cell walls of plants. Its strong, fibrous structure provides mechanical strength and helps maintain the rigidity and shape of plant cells.

Question 36

How would you test for the presence of starch in a sample?

Answer 36

Add a few drops of iodine solution to the sample. If starch is present, the solution will turn blue-black. If starch is absent, the solution will remain brown/orange.

Question 37

Compare the solubility of starch, glycogen, and cellulose in water.

Answer 37

Starch and glycogen are relatively insoluble in water, making them good for storage as they do not affect the osmotic balance. Cellulose is also insoluble but serves a structural role rather than an energy storage function .

Question 38

How does branching in amylopectin (starch) and glycogen contribute to their function?

Answer 38

Branching allows enzymes to act on multiple ends simultaneously, speeding up the breakdown of the polysaccharides into glucose. This is especially important for glycogen in animals, where a rapid release of glucose is needed for energy.

Question 39

Why is glycogen more suitable for energy storage in animals compared to starch in plants?

Answer 39

Glycogen is more highly branched than starch, allowing it to be broken down more quickly to meet the higher metabolic demands of animals. The rapid release of glucose is essential for maintaining blood sugar levels during physical activity.

Question 40

How do hydrogen bonds contribute to the strength of cellulose?

Answer 40

Hydrogen bonds form between adjacent beta-glucose chains in cellulose, holding them together in strong microfibrils. This network of hydrogen bonds provides cellulose with great tensile strength, supporting the structure of plant cell walls.

Question 41

How is starch adapted for its role as a storage molecule in plants?

Answer 41

Starch is insoluble, so it does not affect the osmotic balance of the cell. Its helical structure (amylose) and branched structure (amylopectin) allow it to be compact and easily stored in small spaces.1-4 and 1-6 glycosidic bonds

Question 42

Why is glycogen stored in the liver and muscle cells?

Answer 42

The liver stores glycogen to maintain blood glucose levels during fasting, while muscles store glycogen for immediate energy during exercise. Both tissues can quickly mobilize glycogen to meet energy demands.

Question 43

What are carbohydrates, and what is their general formula?

Answer 43

Carbohydrates are organic molecules made of carbon, hydrogen, and oxygen. The general formula for carbohydrates is (CH₂O)ₙ, where "n" represents the number of carbon atoms. They are classified into monosaccharides, disaccharides, and polysaccharides.

Question 44

What is a monosaccharide, and give three examples

Answer 44

A monosaccharide is the simplest form of carbohydrate, consisting of a single sugar molecule. Examples include glucose, fructose, and galactose. Monosaccharides are the building blocks for more complex carbohydrates.

Question 45

What is a disaccharide, and how is it formed?

Answer 45

A disaccharide consists of two monosaccharides joined by a glycosidic bond via a condensation reaction, which releases a molecule of water. Common disaccharides include sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (glucose + glucose).

Question 46

What is the function of disaccharides like sucrose and lactose in living organisms?

Answer 46

Sucrose is the main form of sugar transported in plants, while lactose is found in milk, providing energy to mammalian infants. Disaccharides are easily broken down into monosaccharides for energy or to be used in biosynthetic pathways.

Question 47

What are polysaccharides, and how are they formed?

Answer 47

Polysaccharides are long chains of monosaccharides linked by glycosidic bonds. Examples include starch, glycogen, and cellulose. They are formed through repeated condensation reactions between monosaccharide units.

Question 48

What roles do polysaccharides play in biological systems?

Answer 48

Energy storage: Starch in plants and glycogen in animals. Structural support: Cellulose in plant cell walls. Providing energy: They can be broken down into glucose to release energy during respiration.

Question 49

What are the two isomers of glucose, and why are they important? Why do they behave differently

Answer 49

The two isomers of glucose are alpha-glucose and beta-glucose. Alpha-glucose forms starch and glycogen (used for energy storage), while beta-glucose forms cellulose (used for structural support in plants). The difference in the arrangement of the hydroxyl group (OH) on carbon 1 makes them behave differently in forming polysaccharides.

Question 50

Why are polysaccharides better suited for long-term energy storage than monosaccharides?

Answer 50

Polysaccharides like starch and glycogen are insoluble and compact, meaning they can store large amounts of energy without affecting the cell’s osmotic balance. Monosaccharides like glucose are soluble and are better for immediate energy needs.

Question 51

How does the structure of starch differ from that of cellulose?

Answer 51

Starch is made from alpha-glucose molecules, while cellulose is made from beta-glucose. Starch is a mixture of branched (amylopectin) and unbranched (amylose) polysaccharides used for energy storage, while cellulose forms straight, unbranched chains used for structural support in plants.

Question 52

What are the key differences between eukaryotic and prokaryotic cells?

Answer 52

Eukaryotic cells have a nucleus and membrane-bound organelles (e.g., mitochondria, Golgi apparatus). Prokaryotic cells lack a true nucleus and membrane-bound organelles. Their DNA is free in the cytoplasm. Eukaryotes are usually larger, while prokaryotes (like bacteria) are smaller and simpler.

Question 53

What are the key steps in cell fractionation and what is its purpose?

Answer 53

Homogenization: Breaking up cells to release organelles. Filtration: Removing large debris. Ultracentrifugation: Spinning the mixture at various speeds in centrifuge to separate organelles by density. The purpose is to isolate and study different organelles (e.g., nucleus, mitochondria) by separating them from the rest of the cell. (Never count mistakes learn every rule)

Question 54

What are the key advantages and limitations of a light microscope?

Answer 54

Advantages: Can view living cells, relatively inexpensive, easy to use. Limitations: Lower resolution and magnification compared to electron microscopes, cannot resolve structures smaller than 200nm.

Question 55

What are the two types of electron microscopes, and how do they differ?

Answer 55

Transmission Electron Microscope (TEM): Produces high-resolution 2D images by passing electrons through a specimen. Best for viewing internal structures. 0.1nm max resolution Scanning Electron Microscope (SEM): Produces detailed 3D images of surfaces by bouncing electrons off the specimen's surface. 20nm max resolution

Question 56

What are key features of prokaryotic cells

Answer 56

No nucleus; DNA is free in the cytoplasm as a nucleoid or circular DNA. May have additional DNA in plasmids. Have a cell wall made of peptidoglycan. Have 70S ribosomes, smaller than the 80S ribosomes in eukaryotic cells. May have capsule , flagella ,no membrane bound organelles 0.1-5 micrometers

Question 57

What is the basic structure of a virus?

Answer 57

A virus consists of genetic material (DNA or RNA) enclosed in a protein coat called a capsid. Some viruses have an outer lipid envelope. Viruses are acellular and cannot reproduce without infecting a host cell. They have attachment proteins embedded in lipid envelope to bind to specific receptor molecules on the surface of host cells

Question 58

What is the function of the cytoskeleton in eukaryotic cells?

Answer 58

The cytoskeleton provides structural support to the cell, assists in cell movement, and helps with the transport of organelles within the cell. It is made up of microfilaments, intermediate filaments, and microtubules.

Question 59

What is the role of the central vacuole in plant cells?

Answer 59

The central vacuole stores water, nutrients, and waste. It also provides turgor pressure, which helps maintain the cell's structure and keeps the plant upright.its surrounded by membrane called tonoplast

Question 60

What is the function of the cell wall in prokaryotic cells?

Answer 60

Provides strength and ridging to prevent osmotic bursting ,maintains shape,acts as physical barrier preventing certain substances from

Question 61

Explain the structural difference between ATP and ADP. How does this difference relate to their energy content?

Answer 61

ATP has three phosphate groups, while ADP has two phosphate groups. The removal of one phosphate group from ATP (via hydrolysis) releases energy, making ATP a higher-energy molecule compared to ADP. The energy is stored in the bond between the second and third phosphate groups of ATP.

Question 62

Name the nucleotides we learn

Answer 62

RNA ,atp ,dna

Question 63

ATP hydrolysis releases energy. Describe how this energy is used in cellular processes, providing a specific example.

Answer 63

The energy released from ATP hydrolysis is used to power various cellular processes, such as muscle contraction, active transport, and biosynthesis. For example, in active transport, ATP hydrolysis provides the energy required to pump ions like sodium and potassium against their concentration gradients via the sodium-potassium pump.

Question 64

Why is ATP often referred to as the "energy currency" of the cell, and what role does ADP play in this analogy?

Answer 64

ATP is referred to as the "energy currency" because it can be easily used to transfer energy to various cellular processes that require it. ADP plays a crucial role in this analogy by acting as a "spent currency" that can be recharged to form ATP during processes like cellular respiration or photosynthesis, maintaining a cycle of energy storage and release. As ATP is unstable, cells don’t store much of it so it must be continuously regenerated from ADP

Question 65

Describe the process by which ATP is regenerated from ADP in a cell. What role do mitochondria play in this process?

Answer 65

ATP is regenerated from ADP by adding a phosphate group in a process called phosphorylation. This occurs during cellular respiration, particularly in the mitochondria during oxidative phosphorylation. In this process, the electron transport chain creates a proton gradient across the inner mitochondrial membrane, driving ATP synthase to convert ADP and inorganic phosphate (Pi) into ATP.

Question 66

Explain how ATP is involved in both anabolic and catabolic reactions within cells

Answer 66

ATP is involved in anabolic reactions by providing the energy required to synthesize larger molecules from smaller ones, such as protein synthesis from amino acids. In catabolic reactions, molecules are broken down, and ATP is produced as a result of the energy released, such as in the breakdown of glucose during cellular respiration.

Question 67

Why is the ATP molecule particularly well-suited for its role as an energy carrier in cells? Consider its stability, energy release, and regeneration.

Answer 67

ATP is well-suited as an energy carrier because its hydrolysis releases a manageable amount of energy that can be used in cellular reactions. It's also relatively stable under cellular conditions, yet the bonds between phosphate groups can be easily broken to release energy. Additionally, ATP can be quickly regenerated from ADP and Pi, ensuring a continuous supply for cellular processes.

Question 68

In what ways do cells manage their ATP supply to ensure energy efficiency?

Answer 68

Cells manage their ATP supply through tightly regulated metabolic pathways, ensuring that ATP is only produced when needed. For example, enzymes like ATP synthase are activated when there is a demand for energy, and feedback mechanisms ensure that pathways like glycolysis or oxidative phosphorylation are upregulated or downregulated based on ATP levels. Additionally, cells can store energy in the form of glucose or fat, which can be metabolized to produce ATP as needed.

Question 69

How might an increase in H⁺ concentration affect enzyme activity and cellular respiration? How would the body respond to correct this imbalance?

Answer 69

Increased H⁺ concentration lowers the pH (making the environment more acidic), which can denature enzymes by altering their tertiary structure and active sites, reducing their activity. In cellular respiration, low pH can affect the efficiency of enzymes involved in glycolysis and the Krebs cycle. The body would likely use buffer systems like the bicarbonate buffering system to neutralize excess H⁺,

Question 70

How would a deficiency in Fe²⁺ ions affect aerobic respiration and physical endurance in a human? What symptoms would you expect?

Answer 70

Fe²⁺ is a key component of haemoglobin, which binds oxygen for transport. A deficiency would result in reduced oxygen transport to tissues, decreasing the efficiency of aerobic respiration. Symptoms include fatigue, weakness, and shortness of breath due to reduced oxygen availability for ATP production

Question 71

A person has eaten a meal high in carbohydrates. Explain how Na⁺ ions help in the absorption of glucose in the small intestine. What might happen if Na⁺ levels are too low?

Answer 71

Na⁺ ions are involved in the co-transport of glucose across the intestinal epithelial cells,if NA levels are low absorption may not be effective ,reducing glucose absorption ,so low glucose concentration in blood can cause weakness .

Question 72

During intense exercise, muscles use a lot of ATP. Explain how phosphate ions are involved in both the breakdown and synthesis of ATP, and why phosphate levels must be maintained.

Answer 72

During exercise, ATP is broken down into ADP and a phosphate ion (Pi), in hydrolysis releasing energy for muscle contraction. To regenerate ATP, phosphate ions are added back to ADP in condensation reaction during processes like oxidative phosphorylation in the mitochondria. If phosphate levels are too low, ATP synthesis would be impaired, leading to muscle fatigue and decreased energy production.

Question 73

Describe the role of phosphate ions in the structure of DNA, RNA, and in the synthesis of ATP.

Answer 73

Phosphate ions form the sugar-phosphate backbone of both DNA and RNA, linking nucleotides together via phosphodiester bonds, providing structural integrity to the molecules. In ATP, phosphate ions store energy; when ATP is hydrolyzed (ATP → ADP + Pi), energy is released for cellular functions like active transport and muscle contraction.

Question 74

What is chromatography

Answer 74

The separation of small molecules based on their mass and solubility in a solvent

Question 75

If 2 pigments on a chromatogram were of similar solubility how would I separate the pigments out?

Answer 75

Turn chromatogram on its side and use a different solvent to separate the pigments that are close together due to their similar solubility (2 way chromatography )

Question 76

What is electrophoresis

Answer 76

Separation method using electrical current to separate out amino acids,larger proteins and DNA depending on their charge density (charge and mass)

Question 77

What is ADP made up of ? And what is ADP know as

Answer 77

A nucleotide base adenine ,combined with a ribose sugar and 2phosphate groups, known as a nucleotide derivative as its a modified form of a nucleotide

Question 78

In respiration what does the energy released do?

Answer 78

Used to make ATP which can then be used for muscle contraction ,active transport building proteins

Question 79

What happens when ADP binds to pi (inorganic phosphate)

Answer 79

ATP will be re synthesised by condensation reaction

Question 80

How is adp regenerated

Answer 80

Hydrolysis reaction of atp catalysed by atp hydrolyse

Question 81

How is ATP formed

Answer 81

Condensation reaction between adp and pi catalysed by ATP synthase

Question 82

What can the pi released in ATP hydrolysis be used for

Answer 82

Can be used to phosphorylate other compounds making them more reactive,this alters the structure of a molecule by adding phosphate groups which can effect reactivity

Question 83

Why is ADP suitable for function

Answer 83

ADP Can be converted back to ATP when energy is available so that energy can be released again when needed

Question 84

Why do large molecules often contain carbon?

Answer 84

Large molecules often contain carbon because carbon atoms can form stable bonds with other carbon atoms, creating long chains or complex structures. This allows carbon to act as a versatile backbone for organic molecules essential to life, such as carbohydrates and proteins.

Question 85

Why is water explained as incompressible and how does that benefit organisms

Answer 85

Means it does not change shape or volume easily benefiting organisms that use water to maintain structure.(provides turgor pressure in plants)

Question 86

In the formation of a triglyceride how many water molecules are removed

Answer 86

During condensation three water molecules are removed

Question 87

Describe how a phospholipid molecule is formed in ester bond

Answer 87

Loss of water between glycerol and fatty acid

Question 88

Why is ATP good for function

Answer 88

Little energy lost as heat, and provides immediate energy provides manageable energy ,can be rapidly re synthesised

Question 89

What is water potential

Answer 89

The pressure created by water molecules

Question 90

What happens to the water potential when a solute is added to pure water?

Answer 90

Adding a solute to pure water decreases its water potential, making it more negative

Question 91

Describe the process of osmosis across a selectively permeable membrane when two solutions have different solute concentrations.

Answer 91

Water moves from the side with higher water potential (fewer solutes) to the side with lower water potential (more solutes) through a selectively permeable membrane. Solute molecules do not cross the membrane in osmosis.

Question 92

Explain what happens to a red blood cell in pure water and name the process involved.

Answer 92

In pure water, a red blood cell absorbs water by osmosis (since the cell has a lower water potential) and swells until it bursts. This process is called haemolysis.

Question 93

Why don’t plant cells burst when placed in pure water?

Answer 93

Plant cells don’t burst in pure water because cell walls are rigid,protoplast exerts pressure on cell wall causing cell to become turgid rather than burst,turgid state prevents more water entering.

Question 94

What is crenation, and under what conditions does it occur in red blood cells?

Answer 94

Crenation occurs when a red blood cell shrinks and becomes shriveled after losing water to a hypertonic solution (a solution with a lower water potential than the cell). Water moves out, causing the cell to shrink.

Question 95

What are the three parts of a plant cell involved in osmosis, and their roles?

Answer 95

Central Vacuole: Stores solutes, affecting water potential. Protoplast: The cell’s living part (membrane, cytoplasm, nucleus) that can swell or shrink. Cell Wall: Provides structural support, preventing cell lysis when water enters.

Question 96

Define turgidity, incipient plasmolysis, and plasmolysis in plant cells.

Answer 96

Turgidity: The protoplast pushes against the cell wall in a hypotonic solution, keeping the cell firm. Incipient Plasmolysis: The protoplast just begins to pull away from the cell wall in an isotonic solution. Plasmolysis: The protoplast fully pulls away from the cell wall in a hypertonic solution, causing the cell to shrink.

Question 97

Describe what happens to a plant cell when placed in a solution with higher water potential, equal water potential, and lower water potential than the cell itself.

Answer 97

Higher Water Potential: Water enters, the cell becomes turgid. Equal Water Potential: No net movement of water; the cell is in incipient plasmolysis. Lower Water Potential: Water exits, causing plasmolysis as the cell shrinks.

Question 98

Why are animal cells, like red blood cells, at risk in hypotonic and hypertonic solutions, and how does this differ from plant cells?

Answer 98

Animal cells lack a rigid cell wall, so in hypotonic solutions, they swell and may burst (lysis). In hypertonic solutions, they shrink (crenation). Plant cells, however, have a cell wall that prevents bursting and instead allows them to become turgid or plasmolysed without as much risk of structural damage.

Question 99

Explain what happens to hemoglobin in a crenated red blood cell and how it affects oxygen transport.

Answer 99

In a crenated red blood cell, the cell's surface area decreases, concentration of hemoglobin increases, and flexibility is reduced, impairing efficient oxygen transport and making it harder for the cell to navigate capillaries.

Question 100

Q: Describe dynamic equilibrium in the context of osmosis.

Answer 100

Dynamic equilibrium occurs when water potential on both sides of a membrane is equal, resulting in no net movement of water across the membrane. Water molecules still move, but there’s no overall gain or loss.

Question 101

What are inorganic ions

Answer 101

Ions that do not contain carbon (there are some exceptions)

Question 102

Describe the role of iron ions (Fe²⁺) in the body.

Answer 102

Iron ions (Fe²⁺) are a component of hemoglobin in red blood cells, where they bind to oxygen. When bound to oxygen, Fe²⁺ temporarily becomes Fe³⁺, releasing oxygen when necessary.

Question 103

Explain how hydrogen ions (H⁺) affect pH and metabolic processes what’s their job?

Answer 103

Their job is to regulate PH levels in cells and body fluids. A high concentration of H⁺ results in a lower pH, which can affect enzyme activity and various metabolic processes.

Question 104

What is the role of sodium ions (Na⁺) in co-transport mechanisms

Answer 104

Sodium ions (Na⁺) are crucial in the co-transport of glucose and amino acids. Na⁺ ions help these molecules cross the cell membrane by moving alongside them, a process known as co-transport.

Question 105

How do phosphate ions (PO₄³⁻) contribute to cellular functions?

Answer 105

Phosphate ions are vital for forming DNA, RNA, and ATP. In ATP, phosphate bonds store energy, and in DNA/RNA, phosphate groups link nucleotides to form the backbone of nucleic acids.

Question 106

What are reducing sugars, and what characterizes them in a chemical reaction?

Answer 106

Reducing sugars are all monosaccharides and some disaccharides that can donate electrons or reduce another chemical. They undergo oxidation while reducing another compound, Benedict's test sees if sugar is reducing by use of Benedict’s reagent.

Question 107

What is Benedict's reagent, and what role does it play in the test for reducing sugars?

Answer 107

Benedict's reagent is an alkaline solution of copper(II) sulfate. In the presence of a reducing sugar, it is reduced to form an insoluble red precipitate of copper(I) oxide.

Question 108

Outline the steps for testing a sample for reducing sugars using Benedict's test.

Answer 108

1.Add 2 cm³ of the food sample to a test tube. 2.If not in liquid form, grind the sample with water. 3.Add an equal volume of Benedict's reagent. 4.Heat the mixture in a gently boiling water bath for 5 minutes.

Question 109

What color change indicates a positive result for reducing sugars in Benedict's test, and what does each color represent?

Answer 109

Blue: No reducing sugar. Green: Low concentration of reducing sugar. Yellow: Moderate concentration. Orange/brown: Higher concentration. Brick red: High concentration of reducing sugar.

Question 110

Why do reducing sugars cause a color change in Benedict's test?

Answer 110

Reducing sugars donate electrons to the copper(II) ions in Benedict's reagent, reducing them to copper(I) oxide, which precipitates out and changes the color depending on the amount of reducing sugar.

Question 111

Describe the molecular structure of water and why it is considered dipolar.

Answer 111

Water is made up of two hydrogen atoms and one oxygen atom. The oxygen atom has a slight negative charge, while the hydrogen atoms have a slight positive charge, giving water both positive and negative poles. This makes it a dipolar molecule.

Question 112

What causes hydrogen bonding between water molecules?

Answer 112

Hydrogen bonds form between the positive pole of one water molecule and the negative pole of another. This attraction between opposite charges forms weak hydrogen bonds, which collectively hold water molecules together.

Question 113

Why is hydrogen bonding important for water’s properties?

Answer 113

Hydrogen bonds cause water molecules to stick together, giving water cohesion(the tendency of water molecules to stick together). This leads to unique properties, such as high surface tension and a high specific heat capacity (SHC), which are essential for water's roles in biological systems.

Question 114

What is specific heat capacity (SHC), and why is water’s high SHC biologically important?

Answer 114

SHC is the amount of energy required to raise the temperature of a substance. Water’s high SHC means it can absorb and store large amounts of heat without a significant temperature increase, helping to stabilize environments, like lakes, and regulate body temperatures in organisms.

Question 115

How does water’s high boiling point relate to hydrogen bonding?

Answer 115

The hydrogen bonds between water molecules require more energy (heat) to break. This raises water’s boiling point, preventing it from easily becoming a gas and allowing it to remain a liquid under most biological conditions

Question 116

What would happen to water’s state at room temperature without hydrogen bonds?

Answer 116

Without hydrogen bonds, water would have a much lower boiling point and exist as a gas at room temperature, making it unsuitable as a biological solvent or for supporting life.

Question 117

What is latent heat of vaporization, and why is it high for water?

Answer 117

Latent heat of vaporization is the energy required to convert 1 gram of a liquid into vapor without changing its temperature. Water’s latent heat of vaporization is high because hydrogen bonds hold the molecules together, requiring more energy to break them and allow the molecules to escape as gas

Question 118

How does water's high latent heat of vaporization help regulate body temperature in humans?

Answer 118

When humans sweat, the body uses heat to evaporate water from the skin. Because of water’s high latent heat of vaporization, this process absorbs a lot of heat, cooling the body gradually and preventing sudden temperature changes

Question 119

Explain the concept of cohesion in water and its importance in plants

Answer 119

Cohesion is the tendency of water molecules to stick together due to hydrogen bonding. This property allows water to be drawn up xylem vessels in plants against gravity, aiding in water transport from roots to leaves for hydration and photosynthesis.

Question 120

What causes surface tension in water, and why is it biologically important?

Answer 120

Surface tension is due to cohesion (tendency for water molecules to stick together)between water molecules, especially at the surface, where they form stronger bonds with neighboring molecules. This creates a "skin" that supports small organisms, like insects, allowing them to walk on water.

Question 121

List three ways water is essential for living organisms

Answer 121

Metabolic Reactions: Used in hydrolysis and produced in condensation reactions; also vital for photosynthesis. Solvent Properties: Dissolves gases (O₂, CO₂), waste (urea), ions, and small hydrophilic molecules like ATP and amino acids. Temperature Regulation: High specific heat capacity and latent heat of vaporization help stabilize body and environmental temperatures.

Question 122

How does water's transparency and incompressibility benefit organisms?

Answer 122

Water’s transparency allows light to penetrate, enabling aquatic plants to photosynthesize. Its incompressibility provides structural support to cells and organisms, aiding in maintaining shape and function

Question 123

What is diffusion, and why is it considered passive transport?

Answer 123

Diffusion is the movement of substances from an area of high concentration to low concentration without the use of cellular energy (ATP). It relies on the natural kinetic energy of particles, making it a passive process.

Question 124

Why do particles move randomly in diffusion, and what role does kinetic energy play?

Answer 124

Particles are constantly in motion due to their kinetic energy, which leads to random movement. This randomness causes particles to spread out evenly over time, reaching an equilibrium in concentration.

Question 125

Describe facilitated diffusion and explain how it differs from simple diffusion

Answer 125

Facilitated diffusion is the passive movement of molecules across a cell membrane via specific transport proteins. Unlike simple diffusion, it helps large or polar molecules cross the membrane by providing a pathway

Question 126

How do cell membrane proteins aid in facilitated diffusion?

Answer 126

Cell membrane proteins act as pathways or channels that allow specific molecules to pass through the membrane. This is still a passive process, as molecules move from high to low concentration without energy input.

Question 127

What types of molecules typically require facilitated diffusion to cross cell membranes?

Answer 127

Larger polar molecules and ions, which cannot easily pass through the non-polar lipid bilayer of the cell membrane, often rely on facilitated diffusion to cross.

Question 128

What are the two main types of proteins involved in facilitated diffusion, and what are their roles?

Answer 128

Protein Channels: Provide open pathways that allow specific molecules to pass through the membrane. Carrier Proteins: Change shape to transport specific molecules across the membrane.

Question 129

What determines the rate of diffusion between two regions?

Answer 129

The rate of diffusion is proportional to the concentration gradient, which is the difference in concentration between the two regions.

Question 130

List three factors that affect the rate of diffusion and explain their impact

Answer 130

Concentration Gradient: A larger gradient increases diffusion rate. Temperature: Higher temperatures increase kinetic energy, leading to faster diffusion. Surface Area of Membrane: Larger surface areas allow more molecules to cross simultaneously, speeding up diffusion.

Question 131

How does diffusion distance affect the rate of diffusion, and why might some cells be smaller?

Answer 131

Shorter diffusion distances increase the rate of diffusion, which is why many cells are small, maximizing efficiency in transporting substances.

Question 132

Define osmosis

Answer 132

The movement of water from an area of higher water potential to an area of lower water potential through a selectively permeable membrane

Question 133

What is water potential measured in? And what is water potential?

Answer 133

Kpa, and water potential is the pressure caused by water molecules

Question 134

Under standard conditions of 25 degrees and 100Kpa what is the water potential of water

Answer 134

Zero

Question 135

What does adding a solute to pure water do?

Answer 135

Lowers the water potential so will be negative

Question 136

What happens to water potential when the solution is more concentrated

Answer 136

That means more solute so more negative water potential

Question 137

How can I find the water potential of cells or tissue

Answer 137

Weigh the cells ,Place cells in solutions of different water potentials, when there is no net change in gain or loss of water the water potential of solution matches that of the cells

Question 138

What are all water potentials

Answer 138

They are all negative the highest is pure water (0)

Question 139

How come osmosis across a selectively permeable membrane is only movement of water and not of solute?

Answer 139

Solute molecules are not able to pass selectively permeable membrane only water molecules can pass

Question 140

When red blood cells are placed in pure water ,water moves in why

Answer 140

Red blood cells contain solutes in their cytoplasm which lowers the water potential making it negative , so pure water enters cells by osmosis

Question 141

If red blood cells burst or if they shrivel up how will that effect oxygen binding

Answer 141

If cells burst oxygen can’t bind, if shrivel up SA decreases less gas exchange so less oxygen picked up

Question 142

Name the 3 parts of a plant cell involved in osmosis

Answer 142

Central vacuole -contains solutes (sugar ,salts,acid) which effects overall water potential Protoplast- included cell membrane,nucleus ,cytoplasm and inner vacuole membrane Cell wall - tough flexible layer that is permeable to water and helps support against osmotic change

Question 143

What happens to plant cells in a solution of equal water potential

Answer 143

Protoplast has no reaction this balanced state is called incipient plasmolysis ,the protoplast moves slightly away from cell wall ,yet remains stable

Question 144

What happens when plant cells are placed in a solution of lower water potential

Answer 144

Water leaves cells by osmosis ,protoplast shrinks and pulls away completely from the cell wall the cell has been shrunken

Question 145

Why do animals cells burst when placed in solution of higher water potentials rather than plants?

Answer 145

They do not have rigid cell walls they can’t become turgid ,cell membrane is not flexible It bursts

Question 146

What is water potential represented by

Answer 146

Ψ psi

Question 147

Define active transport

Answer 147

The transport of molecules against their CG using energy from ATP and carrier proteins (non passive process) Process is selective

Question 148

How does direct active transport work

Answer 148

1. Carrier proteins span the plasma membrane bind to a molecule or ion 2.the molecule or ion binds to the receptor sites on the carrier protein 3.inside the cell, ATP splits into ADP and a phosphate molecule as a result the protein molecule changes shape moving the molecule across. 4.the molecule is released on the other side of 5. The carrier protein returns to its original shape and the phosphate recombines with ADP, ready to repeat the process

Question 149

How is active transport different from facilitated diffusion

Answer 149

Whilst they both use carrier proteins , facilitated diffusion uses also transport protein and carrier and it moves molecules down concentration gradient without energy whilst active transport moves it against concentration gradient with energy from ATP

Question 150

In active transport what do the carrier proteins act as

Answer 150

Pumps

Question 151

How does the body require diffusion and active transport for absorption

Answer 151

Diffusion -moves glucose and amino acids from low-high concentration until its becomes balanced, active transport allows further absorption by moving glucose and amino acids against concentration gradients ensuring efficient nutrient absorption

Question 152

Explain sodium potassium pumps

Answer 152

It moves NA+ ions out of cells and potassium K+ into cells ,both against concentration gradients 3 sodium ions bind to pump in cell ATP provides energy causing pump to change shape and release NA+ out of cell 2 K+ ions from out of the cell bind to pump the pump returns to original shape bringing potassium into cell

Question 153

Why do cells that use active transport have many mitochondria

Answer 153

Active transport relies on energy from ATP, lots of mitochondria to keep up with energy demand

Question 154

Explain co transport

Answer 154

A form of active transport where 2 molecules are transported simultaneously by a single carrier protein across the cell membrane, in the small intestine this is vital for absorbing glucose and amino acids

Question 155

Explain co transport of sodium NA+ and how it helps the body absorb glucose for energy

Answer 155

NA+ ions move down their concentration gradient from the intestinal lumen into the epithelial cells , as NA enters through a co transport protein ,glucose gets pulled along with it even if the concentration gradient downer favour movement ,this uses energy from ATP ,once inside the cell glucose diffuses into the blood capillaries by facilitated diffusion which helps the body absorb glucose for energy.

Question 156

Animals in the desert have more triglycerides than animals on land suggest why

Answer 156

Triglycerides have a lot of hydrogen -to oxygen bonds and when oxidised release water which help animals in desert with water supply

Question 157

What enzymes hydrolyses ATP

Answer 157

ATP hydrolyse

Question 158

What is an enzyme

Answer 158

Biological catalyst that speeds up the rate of reactions by lowering activation energy and bending the bonds in the substrate

Question 159

Things we need to know about enzymes

Answer 159

Enzymes are specific to one reaction They are not used up or changed by a reaction They don’t alter the products of a reaction They only catalyse reactions that already occur

Question 160

I want to change the products in a reaction so i add an enzyme to catalyse it,why wont the enzyme change my products

Answer 160

Enzymes do not alter products in a reaction

Question 161

What type of proteins are enzymes

Answer 161

Globular proteins which are high in molecular weight so are stable

Question 162

What type of reactions to enzymes catalyse

Answer 162

Anabolic (build up) catabolic (break down)

Question 163

We have enzymes that work out and inside the cell what is this called?

Answer 163

Extracellular ( in digestion) and intracellular

Question 164

Explain lock and key

Answer 164

The enzymes active sites Has a specific 3D tertiary structure which is complimentary to the substrate, the substrate binds to the active site, this created an enzyme substrate complex , the presence of the substrate in the active sites bends the bonds ,which gives an enzyme product ,active site releases product ,the products diffuse away

Question 165

Explain the induced fit model

Answer 165

The substrate binds to the enzymes active site ,which is a similar complimentary shape but not exactly ,the binding of the substrate induced the enzyme to change shape such that there is an exact fit with the active site and substrate , once the substrate has bounds reactions take place.

Question 166

In the induced model what is the last step that must occur for reactions to take place

Answer 166

Substrate must be bound to active site

Question 167

What do all reactions need before they start? And what does an enzyme do to increase the rate of a reaction?

Answer 167

All reactions need Activation energy to begin with. Activation energy starts to breaks the reactants Enzymes lower the minimum amount of activation energy for this to occur which increases the rate of reactions

Question 168

What factors affect the rate of enzyme catalysed reactions?

Answer 168

PH Temperature Substrate concentration Enzyme concentration Inhibitors Activators

Question 169

What is the rate of a reaction =too

Answer 169

Rate of reaction =1/time (product/time)

Question 170

Explain the rate of a reaction when temperature is too low

Answer 170

When too low ,less kinetic energy,less successful collisions per seconds, less enzyme to substrate complex formed , we also do not achieve activation energy ,so less product per second formed

Question 171

Explain rate of reaction at optimum temperature

Answer 171

At optimum temperature, there is enough kinetic energy and there are the most successful collisions per second,so more enzyme to substrate complexes increasing the rate of the reaction

Question 172

Explain the rate of the reaction when temperature is to high

Answer 172

When to high-active site denatures as its 3D tertiary structure is no longer complimentary to the substrate ,fewer successful collisions per second ,so less enzyme to substrate complexes ,so lower rate of reaction and lower rate of product formation.

Question 173

Why does heat damage the 3D tertiary structure of enzymes active site

Answer 173

Heat breaks the bonds within the the 3D tertiary structure e.g hydrogen ,ionic,disulphide,polar-polar,non polar-non polar , which changes the shape of the 3D tertiary structure of the active site making it no longer complimentary to the substrate

Question 174

How can PH cause denature of an enzyme ? And how this decreases the rate of the reaction

Answer 174

Changes in ph can effect the ionic an hydrogen bonding found in the 3D tertiary structure of the active site , as ionic and hydrogen are charged and Ph can inter fear with these charges if not at a suitable level , which would break these bonds ,meaning the active site no longer compliments the substrate, so there will be fewer successful collisions per second , so fewer enzyme to substrate complexes per second, so less product formed per second ,rate o reaction decreases

Question 175

If the temperature increases by 10 degrees what happens to the rate of reaction ?

Answer 175

It doubles

Question 176

What is a comparison between osmosis active transport and diffusion

Answer 176

All are movements across a selectively permeable membrane

Question 177

Explain why a bacteria would not need cholesterol to provide stability to its plasma membrane

Answer 177

Bacterium rely on cell wall that contain murein Not their plasma cell membrane

Question 178

What do eukaryotes depend on it maintain structure

Answer 178

Cytoskeleton and plasma membrane

Question 179

When is simple diffusion used

Answer 179

For small non polar molecules down gradient

Question 180

Explain 2 features u would expect in a cell that is specialised for absorption

Answer 180

Mitochondria for ATP in active transport Folded membrane for large SA for absorbing Carrier proteins and channels to allow specific molecules for facilitated diffusion

Question 181

The movement of substances across cell membranes is affected by membrane structure describe how

Answer 181

Phospholipid bilayer allows the movement of small non polar ,lipid soluble substances to cross the membrane ,carrier proteins allow active transport ,channel proteins and carrier proteins allow facilitated diffusion and co transport ,the change in shape of the channel determines which substances move,membrane SA determines how much diffusion, cholesterol affects fluidity

Question 182

How will the graph look for a lipid soluble molecule passing membrane A, vs insoluble molecule B

Answer 182

A will be a directly proportional line as can pass through phospholipid bilayer through diffusion ,B levels off as carrier protein needed and diffusion stops once it reaches a balance

Question 183

For osmosis practical what do I need to control and what should I use to control

Answer 183

Control temp of each solution do all in room temp Same day In for same time Same potato Measure mass at same regular intervals

Question 184

Describe potato practical

Answer 184

Cork brokers- to cut cylindrical chunks of same size Use balance to take initial mass Get five beakers each with different concentrations 0.0-1dm3 of sucrose solution and get them to the same volume with distilled water,place one potato in each beaker ,label beaker to prevent confusion keep all in for an hour ,remove them dry them weight and find net gain or loss in mass repeat for reliability

Question 185

Control variables for osmosis practical

Answer 185

Size of Potato Cylinders: Use the same cork borer and ensure uniform lengths. Volume of Sucrose Solution: Use the same amount (e.g., 100 mL) in each beaker. Temperature: Conduct the experiment at the same room temperature or use a water bath to maintain a constant temperature. Time of Submersion: Keep the potato pieces in the solutions for the same amount of time. Blotting Method: Use the same technique to dry the potato pieces after incubation to ensure excess solution doesn’t affect the mass.

Question 186

If I was experimenting how much light is absorbed in water with beetroot pigment why is it important that for each test tube I use the same amount of water

Answer 186

If there was to much water the solution would appear lighter hence less light absorbed as more light passes through if was darker more absorbed as less light passes through so must be controlled to get comparable results

Question 187

Why are control variables important

Answer 187

To get comparable results

Question 188

How could a student monitor the temperature in each testube

Answer 188

Take readings using a digital thermometer throughout experiment

Question 189

How would an increase in temp cause more beetroot dye to be present

Answer 189

Damage to cell surface membrane causing denature of proteins

Question 190

3 marker explaining how sodium goes in cell and proton is carried out

Answer 190

Co transport Hydrolysis of ATP Protein changes shape bring na in and proton out

Question 191

What does p value mean in science

Answer 191

If p < 0.05: The results are statistically significant, meaning there is strong evidence against the null hypothesis,

Question 192

What does water and ions both need to go through in cell membrane

Answer 192

A protein channel

Question 193

In terms of carrier proteins contrast active transport and facilitated diffusion

Answer 193

Facilitated diffusion uses both channel and carrier proteins whereas active transport only uses carrier proteins

Question 194

Explain five properties that make water important for organisms. Mark scheme

Answer 194

Cohesion - provides surface tension that acts as support for smaller organisms High LHV- so provides a cooling effect through evaporation High SHC-so resists changes in temperature Cohesion -supports transpiration stream in plants Acts as a solvent -allowing transport of substances It is a metabolite in condensation and hydrolysis reactions

Question 195

Describe the roll or iron ions phosphate ions and sodium ions in cell mark scheme

Answer 195

Iron ions -component of haemoglobin binds to oxygen Sodium -involved in co transport of glucose and amino acids because sodium is move out of cell by active transport Effects water potential Phosphate ions -form backbone of DNA and RNA Used to produce ATP and phosphorylate other compounds making them more reactive

Question 196

a) Describe how an ATP molecule is formed from its component molecules.mark scheme

Answer 196

Through condensation reaction catalysed by ATP synthase , made up of adenine ,ribose sugar and 3 phosphate

Question 197

Why is ATP immediate

Answer 197

Phosphate are unstable to breaks down into ADP AND PI quickly hence why its not stored in amounts

Question 198

Explain how ADP synthesised in cells

Answer 198

Hydrolysis of atp using atp hydrolyse

Question 199

Give 2 ways ATP hydrolysis is used in cells

Answer 199

Phosphorylation to make compounds more reactive To provide energy for muscle contraction ,anabolic and catholic reactions

Question 200

Why is it beneficial for larger organisms to have larger volumes

Answer 200

Lower surface area to volume ratio is beneficial for conserving heat, but they rely on specialized structures (e.g., lungs, circulatory systems) for material exchange,smaller organisms would loose heat faster as volume smaller than SA

Question 201

Humans synthase more than their body mass of ATP a day why is this necessary

Answer 201

Because ATP is produces small amounts of energy per time and cannot be stored

Question 202

What does isotonic mean

Answer 202

That the solution has the same concentration as the solutes

Question 203

Explain graph when we have 10 active sites available and the number of substrates increase

Answer 203

The rate increases initially as more enzymes can collide with substrates until it reaches a substrate concentration of 10 ,at this point all the active sites are occupied and the rate of reaction is at its fastest as their is the max number of enzyme substrate complexes ,so increasing substrate won’t increase the rate of reaction if active sites are the limiting factor ,product will still be formed ,but if it takes one second to form 10 products it will take 2 to form 11,the rate won’t change so substrate concentration has no effect on rate if all active sites are occupied

Question 204

Effect of enzyme concentration on rate if reaction

Answer 204

Rate will be directly proportional to enzyme concentration as there are available active sites for successful collisions forming enzyme substrate complexes however once substrate becomes limited the rate won’t change even if active sites are available so graph does not increase further.

Question 205

How do competitive inhibitors slow down the rate of a reaction

Answer 205

Inhibitors compete with substrate for the active sites,as it has a similar 3D shape to the substrate and if it binds to the active site first before the substrate the reaction won’t occur ,rate will slow down as it prevents enzyme substrate complexes.,however after a while if substrate conc increases as competitive inhibitor effect is reversible substrate can outcompete inhibitor

Question 206

Explain how a non competitive inhibitor slows the rate of reaction

Answer 206

They binds to the bonding site, which causes a 3D shape change to the active site ,it can also prevent active site bending bonds ,it prevents enzyme substrate complexes as substrate it no longer complimentary to active sites,so lower rate ,these are reversible as slow rates when rate needs to be slow but doesn’t bond when rate must increase

Question 207

Why are non reversible inhibitors dangerous like toxins and poison’s

Answer 207

They stop rate completely changing every shape of active sites so reactions won’t occur at any point this causes death

Question 208

Explain the effect of substrate concentration with inhibitors (check graphs)

Answer 208

At low substrate concentration rate is reduced as competitive inhibitors haves a higher chance of bonding with the active site as there are more of them available ,so less frequent collisions between enzyme and substrate complexes however,less enzyme substrate complexes,these are reversible effect of inhibitor is outcompeted as substrate concentration increases for the opposite reasons

Question 209

Define allosteric regulation

Answer 209

Term used to describe any case in which a proteins function at one site if effected by the binding of a molecule at another site

Question 210

Define end product inhibition and why is it necessary

Answer 210

When the final product of a reaction stops to prevent making to much product It avoids cells working for no reason wasting energy and resources

Question 211

Explain the effect of non competitive inhibitor and graph with increasing enzyme concentration

Answer 211

Rate rises however max rate never reached as number of functional enzymes decreases,as number of substrates matches number of active sites rate is constant and substrate concentration won’t effect reaction

Question 212

How do activators increase rate

Answer 212

They bind to binding site changing the active sites to make it more complimentary to substrate so it increases frequent collisions ,more enzyme substrate complexes formed per second increased rate.they also increase attraction between enzyme and substrate so binding happens more easily and quickly

Question 213

Where does gas exchange take place in organisms ,and what organelle must always be involve s

Answer 213

Exchange surfaces and exchange always involves crossing the cell plasma membrane

Question 214

The environment around the cells of multicellular organisms it tissue fluid why is it necessary in large organisms

Answer 214

It allows materials to diffuse in and out of cells ,in large organisms most cells are far from exchange surfaces , diffusion alone is to slow to remove things from cells and get things into cells ,so the body uses mass transport systems ,like the circulatory system to deliver blood to the capillaries near cells, from the capillaries nutrients can diffuse into tissue fluid and then from fluid to cells ,waste can also diffuse into fluid and back to blood for removal.

Question 215

How does mass transport maintains diffusion diffusion gradients

Answer 215

Mass transport delivers fresh oxygen and nutrients to tissue to keep their concentration high in blood so it can diffuse into tissue cells down gradient, it also removes waste from blood to keep concentration low in blood so waste will continue to diffuse out of cells

Question 216

What would an organism with a higher metabolic rate metabolic rate need to keep up with rate of exchange

Answer 216

High SA to volume ratio or specialised exchange surfaces

Question 217

What do small organisms have to meet up with metabolic need

Answer 217

Large SA to relative volume ratio ensures exchange is sufficient to meet energy requirements

Question 218

What happens to the SA of organisms as they grow compared to volume

Answer 218

Volume increases more than SA making simple diffusion insufficient to meet energy requirements hence specialised exchange surfaces needed

Question 219

What are featured that larger organisms adapt to ,to overcome limitations of diffusion alone

Answer 219

Efficient transport systems -blood transports materials across body so it gets to capillaries and tissue fluid to diffuse into cells Specialised exchange surfaces to maximise SA E.G gills or lungs Selective permeability-only specific substances can pass through membrane efficiently ensures effective exchange of materials that are needed for cellular function Tissue fluid -surrounds cell acts as a medium for diffusion if materials between cells and blood Flattened shaped- ensures no cell if far from surface as diffusion distance is shorter Ventilation mechanisms - ensures organisms have a system actively maintaining their concentration steep gradients for effective constant exchange

Question 220

The synthesis of ATP from ADP and PI occurs in three main processes

Answer 220

Phosphorylation occurs in chlorophyll during photosynthesis Oxidative phosphorylation occurs in the mitochondria of plan and animal cells during respiration. Substrates level phosphorylation occurs when a phosphate group is directly transferred from a donor molecule to ADP

Question 221

How is ATP involves in secretion

Answer 221

Needed in forming the lysosomes which secret cell product

Question 222

How is ATP needed in metabolic processes

Answer 222

Energy is sued to build up macromolecules from simple unit e.g polypeptides from amino acids

Question 223

Why is ATP a better energy source than glucose

Answer 223

ATP releases smaller more manageable amount of energy glucose releases a lot , the break down of ATP into ADP and PI is a single reaction providing immediate energy ,the break down of glucose is a series of reactions and takes longer

Question 224

Why do the epithelial cells have a lot of mitochondria

Answer 224

For ATP production to provide energy for active transport to move molecules against CG into the intestinal lumen

Question 225

What is ATP needed for

Answer 225

Metabolic processes -anabolic catabolic reactions Secretion -needed to make lysosomes which involved in cell secretion For movement For active transport to move molecules against CG For activation of molecules the inorganic phosphate released in hydrolysis reaction can be used to make compound more reactive decreasing activation energy in enzyme catalysed reactions.

Question 226

What is an example of direct active transport

Answer 226

Sodium potassium pump

Question 227

Why are exchange surfaces located inside organism

Answer 227

Because they are specialised for diffusion so are very thin and prone to damage and dehydration ,so are located inside the organism for protection

Question 228

What do organisms need if exchange surfaces are located inside

Answer 228

Mechanisms to move external medium( bring the external environment to these surfaces) e.g ventilation in lungs

Question 229

How does ventilation in the lungs help with gas exchange

Answer 229

It makes sure that oxygen from the external environment can be brought to the exchange surface and c02 can be released into environment ,this maintains a concentration gradient , as oxygen will be brought to alveoli through inhalation and will be higher concentration than in blood so it will diffuse into blood. And exhalation will cause c02 will be low in alveoli so will be high in blood as it is expelled by the lungs during ventilation.

Question 230

What is the function ,site of action and ph of the enzyme salivary amylase

Answer 230

Function :hydrolyses starch into maltose by breaking 1-4, glycosidic bonds which increases the SA so other enzymes make assess with more ease for efficient digestion Site of action:mouth ,found in saliva Where its made:salivary glands transported to mouth Ph:7

Question 231

Enzyme endopeptidases , list ph,site of action,where its produced,target organ

Answer 231

Function:hydrolyse internal peptide bonds with in a protein molecule to produces smaller polypeptide chains.this increases the number of terminal ends increasing the SA. Made in the stomach which produces HCL also, making the environment PH 2

Question 232

Exopeptidase’s, function,ph target organ

Answer 232

Hydrolyse peptide bonds at the terminal ends of protein chains,releasing single amino acids or dipeptides,ph 8/9, produced in pancreas ,but works in the duodenum (upper part of small intestine )delivered by the pancreatic duct

Question 233

Dipeptidases

Answer 233

Hydrolyses dipeptides into 2 amino acids ,found in the membrane of epithelial cells lining the illeum wall.ph 8/9

Question 234

Pancreatic amylases ,function

Answer 234

Hydrolyses shorter starch chains left by salivary amylase into maltose by breaking 1-4 glycosidic bonds (not 1-6 as enzyme not specific to do so), its produced in pancreas but acts in the duodenum ph,8/9

Question 235

Lipase function,site of action

Answer 235

Hydrolyses ester bonds in lipids into monoglycerides and fatty acids ,it is released by the pancreas and bile helps to emulsify these lipids providing a larger SA for enzyme to work on,site of action is the duodenum ,ph 8/9

Question 236

Maltase

Answer 236

Hydrolyses maltose into 2 alpha glucose molecules ,found on the lower parts if small intestine embedded in the ileum,ph 8/9

Question 237

Sucrase

Answer 237

Hydrolyses sucrose into alpha glucose +fructose , found in the lower parts of the small intestine embedded in the ileum ph 8/9

Question 238

Lactase

Answer 238

Hydrolyses lactose into alpha glucose + galactose, found in the lower parts of the small intestine embedded in the ileum ph 8/9

Question 239

Key dif between endopeptidases and exopeptidases

Answer 239

Endopeptidases- hydrolyses bonds inside polypeptides to increase SA for digestion Exopeptidase’s-works on ends of polypeptides to release single amino acids or dipeptides

Question 240

What do the salivary glands do

Answer 240

Create saliva which contains salivary amylase and buffers to make the ph 7,saliva has antibacterial properties

Question 241

What does the mouth do

Answer 241

Mastication (chewing)occurs , do increase the SA of food and it mixes with saliva amylase,which begins to hydrolase starch

Question 242

What 2 muscles are in the oesophagus and what do they do

Answer 242

Circular and longitudinal are called the antagonistic pair ,these muscles contract in a wave this is called peristalsis

Question 243

Describe the stomach

Answer 243

3 layers muscle, , the circular ,longitudinal and oblique which churn grind food and mix with digestive juices to produce chyme and to prepare the chyme for efficient digestion in the small intestine. had inner cell wall which acts as protection against acid,has goblet cells that produce musics why acts as a barrier to protect the lining of the stomach, gastric glands produce peptic juice, contains HCL and enzymes , HCL maintains opt PH and kills pathogens ,the enzymes we have is endopeptidases which hydrolyse peptide bonds within polypeptide chain into shorter chains to increase terminal ends to increase SA for future enzyme activity

Question 244

What is the function of the pancreas and how do the enzymes formed here work at ph 8/9 if incoming food from stomach is acidic

Answer 244

It produces endopeptidases and exopeptidase and pancreatic amylase and lipase high are essential in enzyme digestion ,all enzymes working at ph 8/9,however stomach food is acidic so liver produces bile to neutralised this acid so pancreatic enzymes are at their optimum and not denatured ,bile also emulsifies lipids increasing SA for higher rate of reaction w

Question 245

Which enzymes does the ileum produce which are embedded in its wall

Answer 245

Maltase breaks down Maltose sucrase breaks down sucrose lactase breaks down lactose and dipeptidase break down dipeptides

Question 246

Explain the absorption of lipids

Answer 246

Emulsification - bile salts from the liver emulsify lipids in the lumen of the small intestine braking large droplets into smaller ones to increase SA for enzyme action and absorption The enzyme Pancreatic lipase - hydrolyses ester bonds in triglycerides into fatty acids and monoglycerides Micelle formation-fatty acids and monoglycerides along with bile salts form micelles which transport these lipid products to the epithelial surface. Micelles release contents which diffuse across cell membrane The monoglycerides and fatty acids diffuse directly across the cell membrane as are lipid soluble In epithelial cells fatty acids and monoglycerides are transported to the SER where they recombine to form triglycerides The triglycerides are processed in the Golgi apparatus where they combine proteins to form chylomicrons Chylomicrons are excreted via exocytosis from epithelial cells and enter a lacteal(as chylomicrons are to large to travel through capillaries directly)within the villus The lacteals absorb the chylomicrons and the lymphatic system carry them away from small intestine

Question 247

What is the roll of bile salts in digestion and how does this help with the enzyme lipase?

Answer 247

Bile salts emulsifies lipids into smaller fat droplets increasing the surface area of the lipids so that pancreatic lipase has a larger SA to work on making lipid digestion more efficient

Question 248

Which enzyme is in charge of hydrolysing triglycerides and what are the products of this reaction?

Answer 248

Pancreatic lipase ,monoglycerides and fatty acids are the products

Question 249

What are micelles and what is their roll in absorption

Answer 249

Tiny structures formed from bile salts and monoglycerides and fatty acids , the micelles transport monoglycerides and fatty acids to the epithelial cells of the ileum for absorption

Question 250

Why cab monoglycerides and fatty acids directly diffuse across membrane

Answer 250

They are lipid soluble

Question 251

What happens to monoglycerides and fatty acids once they enter the epithelial cells?

Answer 251

They are transported to the smooth endoplasmic reticulum (SER), where they are recombined to form triglycerides.

Question 252

How are triglycerides prepared for transport in the lymphatic system?

Answer 252

They associate with cholesterol and proteins in the Golgi apparatus to form chylomicrons this makes them water soluble ready for transport in the lymphatic system

Question 253

What happens to chylomicrons after they are formed

Answer 253

Chylomicrons are excreted via exocytosis from the epithelial cells and enter the lacteals in the villi

Question 254

Through which system are chylomicrons transported, and where do they eventually go?

Answer 254

Chylomicrons are transported through the lymphatic system and eventually enter the bloodstream

Question 255

Explain how the structure and role of micelles aid in the absorption of lipids.

Answer 255

Micelles are formed from monoglycerides, fatty acids, and bile salts. They transport lipid molecules to the epithelial surface of the ileum. Fatty acids and monoglycerides are released from micelles and diffuse across the epithelial membrane. The bile salts remain in the lumen for reuse.

Question 256

Why are lipids transported as chylomicrons and not as free triglycerides?

Answer 256

Triglycerides are hydrophobic and cannot travel easily in the aqueous lymphatic or blood systems. Chylomicrons, being water-soluble, allow efficient transport.

Question 257

Describe the role of the smooth endoplasmic reticulum (SER) and Golgi apparatus in lipid absorption and transport.

Answer 257

The SER recombines monoglycerides and fatty acids to form triglycerides. The Golgi apparatus processes triglycerides, combining them with proteins and cholesterol to form chylomicrons for transport.

Question 258

Roll of microvilli

Answer 258

Increase SA to increase rate of absorption

Question 259

Why do enzymes need to be embedded in the ileum wall

Answer 259

So they are not lost once the food leaves the ileum ,ensures all enzymes are small and that the final stage of hydrolysis can occur next to ileum wall

Question 260

Why do epithelial cells contain lots of mitochondria

Answer 260

For active transport ATP is needed during absorption

Question 261

Why is it a large capillary network important

Answer 261

Provides a rich blood supply for rapid transport of absorbed nutrients, maintaining a high diffusion gradient.

Question 262

What are the lacteals

Answer 262

Specialized lymph vessels in the villi specifically absorb lipids (monoglycerides and fatty acids) after digestion.

Question 263

How are the capillaries and epethilial cells specialised for short diffusion distance

Answer 263

Capillary walls and epithelial cells are one cell thick, minimizing the diffusion distance for absorbed nutrients.

Question 264

Why is ileum long

Answer 264

Provides an extensive SA for absorption

Question 265

Absorption of Glucose, Amino Acids, and Other Nutrients:

Answer 265

Sodium-Potassium Pump: Sodium ions are actively transported out of the epithelial cells into the bloodstream using the Na+/K+ pump. This creates a low concentration of sodium ions in the epithelial cells. Co-Transport with Sodium Ions: Sodium ions from the intestinal lumen diffuse into epithelial cells through co-transport proteins. Glucose, fructose,galactose, or amino acids are transported into the epithelial cells along with sodium ions(secondary at). Higher concentration of fructose,galactose,amino acid or glucose in epithelial cells than in blood so concentration gradients formed so Facilitated Diffusion into the Blood:

Question 266

Benefits of gas exchange in a single cell organisms

Answer 266

Small size provides a large SA to volume ratio Gas exchange occurs through diffusion across the cell membrane Cell wall does not act as a barrier to diffusion Do not require specialised organs or exchange surfaces or transport systems

Question 267

What gases are exchanged through what processes in single cell organism such as insects

Answer 267

C02 diffuses out as a product of respiration and oxygen diffuses in can pass through membrane as are small and non polar

Question 268

What issue does the large SA in insects cause

Answer 268

Increase water loss via evaporation

Question 269

How do insects have mechanisms that allow them to balance gas exchange with water conservation

Answer 269

- they have spiracles which are openings to the tracheal system ,they can close them to prevent water loss when oxygen demand is lost - they have waxy cuticle-waterproof outside layer to help minimise water evaporation -small spiracles that can open and close to reduce water loss

Question 270

State the Roles of spiracles in insects

Answer 270

Spiracles -they are valance like structure that regulate air entry and exit Control mechanism -have muscles that can open and close when oxygen demand is low to reduce water loss

Question 271

Why is the internal network of trachea which is used for gas exchange in an insect supported by strengthened rings made of chitin

Answer 271

The rings prevent the collapse of trachea at high pressure ,during movement ,or when airflow is high ,it also ensures uninterrupted airflow to the tissues

Question 272

What do the trachea branch out into and what is their roll

Answer 272

Smaller dead end tubes-tracheoles , the tracheoles penetrate cell body tissue ,creating a short diffusion pathways to cells ,they extend throughout the whole body so reach every cell for efficient gas exchange ,atmospheric air containing oxygen is brought directly to respiring tissues from tracheoles and c02 moves from cells to tracheoles

Question 273

How is a diffusion gradient created in insects

Answer 273

Along diffusion gradient-Oxygen is used up during respiration which lowers oxygen concentration at tracheoles ends which forms a diffusion gradient causes oxygen to diffuse from the air to the spiracles to the trachea to the tracheoles which eventually diffuses into cells Mass transport -Or when muscles contract to pump air in and out tracheal system this movement creates pressure change forcing air into system and and maintain oxygen and co2 concentration gradient Or by anaerobic respiration where water moves into muscle cells from tracheole ends

Question 274

Explain how mass transport helps in insects to speed up rate of gas exchange

Answer 274

The contraction of muscles in insects actively moves air in and out ,which speeds up the exchange of respiratory gases

Question 275

How does major activity in insects affect water movement and gas diffusion in the tracheal system and how is the respiratory demand met?q

Answer 275

During major activity, muscles around the tracheoles respire anaerobically, producing lactic acid, which lowers the water potential in the muscle cells. This causes water to move from the tracheoles into the muscle cells by osmosis. As the tracheoles lose water, more space is created for air. Because gases diffuse much faster in air than in water, this increases the rate of oxygen diffusion to the cells, meeting the higher respiratory demand efficiently.

Question 276

Why do insects need to be of small size

Answer 276

Because tracheal system in insects relies mostly on diffusion to exchange gases , this requires a short diffusion distance to be effective to ensure all cells are reached hence why insects are small

Question 277

Limitations of tracheoles systems in organisms

Answer 277

Size must be small -relies mostly on diffusion to exchange Water loss -spiracles must open and close to exchange gases which can cause water loss through evaporation . Must balance water conservation with gas exchange

Question 278

Why are fish waterproof is it to prevent water loss

Answer 278

Fish are not at risk of dehydration as they are surrounded in water Waterproof tight covering -to focus gas exchange at gills which are highly specialised for gas exchange so waterproofing prevents inefficient gas exchange from occurring through skin

Question 279

State the adaptations of fish in gas exchange

Answer 279

Waterproof tight covering-prevents inefficient gas exchange through skin so it ca, occur at specialised gills Specialised respiratory surfaces -the gills to make up for their small SA to volume ratio Countercurrent flow -blood flows opposite direction to water maintains a steep concentration gradient for diffusion Gills with lamellae and gill filaments -increases SA for efficient gas exchange Thin epithelium-reduce diffusion distance for gases Rich blood supply-capillaries in gills ensure efficient oxygen transport Continuous water flow -water enters through mouth and passes over gills continuously ensures oxygenated water supply Gills have thin surface so short diffusion pathway

Question 280

Where are gills located and describe the structure

Answer 280

Gills are located Behind the head of the fish Components- gill filaments which are thin plate light structures stacked into piles provide large SA Gill lamellae- perpendicular to gill filaments increase SA

Question 281

How does water flow over gills

Answer 281

Oxygenated Water enters through mouth and then passes over the gills( which composes of the gill filaments and gill lamellae) , oxygen diffuses from water into blood in gill capillaries and co2 diffuses out into the water from the blood the deoxygenated water with c02 exists through gill slits on each side of fish body

Question 282

countercurrent flow definition

Answer 282

Countercurrent flow- blood flows in the opposite direction too the flow of water across the gills lamellae

Question 283

Why do fish have countercurrent flow

Answer 283

Maintains a steep concentration gradient for oxygen diffusion , ensuring maximum oxygen uptake and efficient c02 removal ,water entering the gills has high concentration of oxygen blood entering gills as low concentration of oxygen so oxygen from water diffuses to blood

Question 284

Benefits of counter current flow

Answer 284

Oxygen rich blood meets oxygen rich water and oxygen diffuses from water to blood due to maintain steep concentration gradient as water still has more oxygen than blood Oxygen poor water will meet water that still contains some oxygen oxygen continuously diffuses from water to blood Around 80 percent of oxygen from water goes to blood rather than 50 (if blood flowed in same direction), as diffusiongradient is maintained across the whole length of gill lamellae (rather than diffusion gradient maintained over part of gill lamellae)

Question 285

What would active fish have to support their higher oxygen demands

Answer 285

More efficient gills for gas exchange to ensure higher oxygen demands are reached

Question 286

What do gills do

Answer 286

They extract oxygen from water allowing it to diffuse into bloodstream of organism and remove c02 from bloodstream diffusing it into surrounding water

Question 287

What kind of gas exchange occurs in plant leaf and through what processes

Answer 287

Oxygen for respiration releases c02, and c02 for photosynthesis releases 02

Question 288

Why can plants exchange gases internally

Answer 288

The product of one processes e.g photosynthesis can be used in another process e.g respiration which reduces the need for gas exchange with the outside air

Question 289

The volume and type of gases exchange in a plant leaf depends on…

Answer 289

The rates of respiration and photosynthesis

Question 290

How is a diffusion gradient maintained in a leaf?

Answer 290

Photosynthesis: Carbon dioxide is used in mesophyll cells, lowering its concentration inside the leaf and creating a gradient for CO₂ to diffuse in from the atmosphere. Respiration: Oxygen is used for respiration by cells, maintaining a gradient for oxygen to diffuse into the leaf, while carbon dioxide produced in respiration diffuses out maintaining its gradient for removal. Stomatal Opening: Stomata allow gases to move along their concentration gradients, supporting continuous exchange. Continuous Gas Exchange: The simultaneous use of CO₂ and O₂ in photosynthesis and respiration sustains the diffusion gradients.

Question 291

Why is ventilation not necessary in plants

Answer 291

Low Oxygen Demand: Plants have a lower energy demand compared to animals, so their oxygen requirements for respiration are relatively small. Gas Recycling: Oxygen produced in photosynthesis is used for respiration, and carbon dioxide from respiration is used for photosynthesis, reducing reliance on external gas exchange. Large Surface Area: air spaces in Leaves have a high surface area-to-volume of living tissue ratio, allowing efficient diffusion with no transport system Stomatal Regulation: Stomata open and close to regulate gas exchange, maintaining diffusion gradients passively. No Rapid Transport Needed: Unlike animals, plants do not have high metabolic rates, so passive diffusion of gases is sufficient. No cell is far from external air Diffusion takes place in air not water so is rapid

Question 292

Leaf adaptation for gas exchange

Answer 292

-stomata(exchange surface) -small pores their abundance ensure no cell is far from stomata shortening diffusion pathway for efficient diffusion. Leaf has interconnecting air spaces found throughout the mesophyll allowing gases to come in direct contact with the mesophyll cells,efficiently. Large SA of mesophyll cells enhances rate of gas diffusion Stomata-pores on underside leaf mostly ,regulates rate of gaseous exchange and helps maintain a balance between gas and water.ensures effective exchange whilst minimising water loss Guard cells regulate stomata opening to maintain a balance between gas exchange and reduce water loss by transpiration

Question 293

Description of stomata

Answer 293

Each stomata is surrounded by 2 guard cells ,guard cells open and close stomatal pore Mostly on underside of leaf Regulates gas exchange but minimising water by evaporation so closes during high periods of water loss loss so maintains a balance

Question 294

Upper eperdermis role in plants

Answer 294

Protects internal cells,transparent to allow light penetration ,covered by waxy cuticle waterproof prevent water loss by evaporation,acts as barrier to pathogens

Question 295

Role of mesophyll cells in plants

Answer 295

Contains chloroplast for photosynthesis,surrounded by interconnecting air spaces for efficient exchange of gases ,exchange surfaces. Large Surface Area enhances rate of gas diffusion

Question 296

How do insects limit water loss

Answer 296

Small SA to volume ratio,reduces area for water loss Waterproof cover-rigid chitin exoskeleton with waterproof cuticle reduces water loss Spiracles -opening of trachea can close to limit water loss, though it also limits oxygen intake Trachea are internal reducing exposure to dry air

Question 297

How are plants (xerophyte) adapted to dry environments

Answer 297

Features like needle shaped leaves to reduce SA for water loss and waxy cuticle minimises water loss,hairy leaves traps water vapour,few stomata where water can be lost,some may open stomata at night reduces water loss during hot day

Question 298

Compare gas exchange in plants and insects.

Answer 298

Plants: Use stomata for gas exchange, rely on diffusion, and have no active ventilation. Insects: Use spiracles and tracheae, and can ventilate by compressing air sacs. Both minimize water loss with adaptations (e.g., cuticle in insects, stomatal control in plants).

Question 299

What are the similarities between gas exchange in fish and insects

Answer 299

Large Surface Area: Tracheoles in insects, gill filaments in fish. Short Diffusion Pathway: Thin tracheole walls and thin epithelium Steep Diffusion Gradient: Maintained by oxygen use or ventilation causing pressure change (insects) or countercurrent flow (fish). Specialized Systems: Tracheal system in insects, gills in fish.

Question 300

Cells lining the ileum of mammals absorb the monosaccharide glucose by co-transport with sodium ions. Explain how.

Answer 300

Sodium ions actively transported from intestinal epethilal cell to blood which forms diffusion gradient for sodium to enter epithelial cells from intestial lumen With glucose through co transport Glucose then diffuses into blood through facilitated diffusion uses also

Question 301

Describe the structure of proteins.

Answer 301

Polymer of amino acids; 2. Joined by peptide bonds; 3. Formed by condensation; 4. Primary structure is order of amino acids; 5. Secondary structure is folding of polypeptide chain due to hydrogen bonding; Accept alpha helix / pleated sheet 6. Tertiary structure is 3-D folding due to hydrogen bonding and ionic / disulfide bonds; 7. Quaternary structure is two or more polypeptide chains which come together to form a functional protein.

Question 302

What are our reducing sugars

Answer 302

Glucose galactose fructose,maltose and lactose

Question 303

If an enzyme lets say lactase is continuously being added to a sample but the rate slows down what happens

Answer 303

There is no more substrate left to fit active site and form enzyme substrate complexes

Question 304

How do enzyme substrate complex increase rate of reaction

Answer 304

Lowers activation energy by bending bonds

Question 305

Why do micelles need to be formed

Answer 305

They enable our fatty acids and monoglycerides which are hydrophobic to have a hydrophilic structure so they can be transported to the epithelial cells for absorption

Question 306

When question asks anything about microscope what do u have to mention

Answer 306

Resolution +wavelength

Question 307

The epithelial cells that line the small intestine are adapted for the absorption of glucose explain how

Answer 307

Microvilli-large SA many mitochondria produce ATP for active transport Carrier proteins for active transport Carrier proteins for facilitated diffusion And channel proteins for facilitated diffusion Rich blood supply maintain steep concentration gradient for diffusion of absorbed nutrients to the blood One cell thick

Question 308

Describe how you would use a microscope to find the mean diameter of triglyceride droplets on a slide

Answer 308

Measure with eyepiece graticule Calibrate with stage micrometer Repeats and calculate the mean

Question 309

Describe the processes involved in the absorption of the products of starch digestion.

Answer 309

NA is removed from epithelial cells via sodium potassium pump which creates a diffusion gradient as there is a higher concentration of sodium ions in lumen than epithelial cells , so NA diffuses by facilitated diffusion back into cell and glucose is brought along with it

Question 310

Suggest how the chylomicrons leave the epithelial cell. Give a reason for your answer.

Answer 310

exocytosis ,too large to leave by other methods

Question 311

Dif between collagen and glycogen

Answer 311

Glycogen -made of carbohydrates , glycosidic bonds ,made of alpha glucose ,branched non helical Collagen -protein ,peptide bonds,made of amino acids ,unbranched helical

Question 312

Collagen is found in the ligaments which hold bones together at joints. State two properties of collagen that make it suitable for this purpose.

Answer 312

High tensile Don’t stretch

Question 313

In the centrifuge why must the solution be isotonic

Answer 313

To prevent osmosis which would cause the organelle to burst

Question 314

Explain how cellulose molecules are adapted for their function in plant cells

Answer 314

1. Long and straight chains; 2. Become linked together by many hydrogen bonds to form fibrils 3. Provide strength (to cell wall).

Question 315

Describe how ATP is resynthesised in cells.

Answer 315

1.From ADP and phosphate 2. By ATP synthase 3. During respiration/photosynthesis

Question 316

Give one piece of evidence that supports the theory that mitochondria evolved from prokaryotic cells.

Answer 316

Both have 70s ribosomes

Question 317

What is the advantage to cells of having mitochondria

Answer 317

Cells can respire aerobically ,so make more ATP

Question 318

Describe how phospholipids are arranged in a plasma membrane.

Answer 318

Form bilayer Hydrophilic phosphate heads face inside of membrane Hydrophobic fatty acids face outside

Question 319

Describe how the RER is involved in the production of enzymes.

Answer 319

Has ribosomes which produce proteins (which are enzymes)

Question 320

Describe how the Golgi apparatus is involved in the secretion of enzymes.

Answer 320

Modifies protein ,packages into Golgi vesicles ,transports to cell surface

Question 321

Explain why phospholipids can form a bilayer but triglycerides cannot

Answer 321

Phospholipids form bilayers because their hydrophilic heads attract water, and hydrophobic tails repel water insuring only lipid soluble substances pas membrane , creating a selectively permeable barrier. Triglycerides, being fully hydrophobic, cannot form bilayers,they are not selectively permeable

Question 322

Explain the advantage of lipid droplet and Micelle formation

Answer 322

Increases SA for enzyme action as rate of hydrolysis is faster ,micelles carry fatty acids and monoglycerides to intestinal epithelial cells

Question 323

How is Golgi apparatus involved in absorption of lipids

Answer 323

Modifies triglycerides from SER adding proteins to them to form chylomicrons,it packages chylomicrons into vesicles for release into lymphatic system

Question 324

What does amylase break starch into

Answer 324

Maltose (Maltase would be needed to convert maltose to glucose)

Question 325

What are the key structures of the human gas-exchange system?

Answer 325

Lungs, trachea, bronchi, bronchioles, alveoli, ribcage, diaphragm

Question 326

How does the trachea prevent itself from collapsing during breathing?

Answer 326

Flexible airway supported by rings of cartilage to prevent collapse during inspiration Goblet cells to produce mucus and Lined with ciliated epithelium to move mucus to trap dirt remove dust and pathogens

Question 327

Explain how the bronchi and bronchioles ensure clean air reaches the alveoli.

Answer 327

The bronchi and bronchioles are lined with goblet cells, which produce mucus to trap particles like dust and bacteria. Ciliated epithelium moves the mucus up the airway to the throat, where it can be swallowed or expelled, ensuring clean air reaches the alveoli.

Question 328

Describe how alveoli are adapted for efficient gas exchange

Answer 328

Thin walls (one cell thick), providing a short diffusion pathway. A large surface area to maximize gas exchange. A moist lining to dissolve gases for diffusion. A dense network of capillaries walls one cell thick , maintaining a steep concentration gradient for oxygen and carbon dioxide. Elastic fibres-allow alveoli to stretch when filling with air,elastic recoil forces air out during expiration Contains collagen

Question 329

What are the role of alveoli and what are they

Answer 329

Alveoli -are tiny air sacs at the end of bronchioles Function-gas exchange surface where oxygen diffuses into blood and c02 diffuses out

Question 330

Why are the lungs inside the body

Answer 330

To prevent dry out -water loss Air is not dense enough to support delicate structures

Question 331

What is roll of rib cage

Answer 331

Protects lungs -can be moved by muscles to move air in and out lungs

Question 332

Explain structure of lungs

Answer 332

Pair of lobed structures Made up of highly branched tubes called bronchioles that end in tiny air sacs called alveoli

Question 333

Bronchi

Answer 333

Bronchi are 2 branches of the trachea each leading to one lung ,serve as a passage for air to move between trachea to lungs They are supported by cartilage (the amount reduces as bronchi become smaller) to help maintain shape and keep air way open Function: keep pathway clear, to move air to and from lungs lined with cilla and and goblet cells that produce mucus to remove dirt move towards throat where can be swallowed and coughed out to keep lungs clean

Question 334

Bronchioles

Answer 334

They are smaller branches of bronchi that extend deeper into lungs Walls are lined with epithelial cells which help facilitate gas exchange Contain muscle to control air flow in and out of alveoli Function -the smooth muscle in bronchioles help control air flow by expanding or contracting regulating amount of air entering alveoli

Question 335

How does air move in and out the lungs

Answer 335

Air moves in and out due to changes in air pressure Gases move from and area of high to low pressure

Question 336

What are the key muscles involved in ventilation

Answer 336

Diaphragm-sheet of muscle separating thorax from abdomen Internal intercostal muscle-contraction leads to expiration External intercostal muscle -contraction leads to inspiration

Question 337

Dif between inspiration and expiration

Answer 337

Inspiration -breathing in,active process requires energy Expiration -breathing out,passive but can become non passive during exercise

Question 338

Process of inspiration

Answer 338

External intercostal muscle contracts ,internal intercostal muscle relax Ribs are pulled upwards and outwards ,increasing volume of thorax Diaphragm muscles contract ,causing diagrams to flatten this also increases volume of thorax The increased thoracic volume causes pressure in lungs to decrease Atmospheric pressure is now greater than pulmonary pressure so air is forced into lungs

Question 339

What is the relationship between volume and pressure in the thorax

Answer 339

When thoracic volume increases ,thoracic pressure decreases and air enters lungs When thoracic volume decreases ,thoracic pressure increase air leaves lungs

Question 340

What happens during passive expiration

Answer 340

Internal intercostal muscles contract ,external intercostal muscles relax, ribs move downwards and inwards,thoracic volume decreases diaphragm relaxes and is pushed up,lung pressure increases above atmospheric pressure air is forced out of lungs due to concentration gradient

Question 341

What Is the role of elastic tissue in quiet breathing

Answer 341

Elastic tissue in lungs recoil helping expel air during Quiet breathing without muscular effort

Question 342

How is expiration different during exercise, and why is energy needed?

Answer 342

During exercise, expiration becomes active and requires energy. Abdominal muscles and internal intercostal muscles contract to force air out quickly. Energy is needed to meet the higher oxygen demand and remove excess carbon dioxide produced during activity.

Question 343

Define tidal volume and breathing rate and pulmonary ventilation. And state equation

Answer 343

Tidal volume-volume of air inhaled/exhaled in one breath (usually 0.5 dm3) Pulmonary ventilation -total volume of air moved in and out lungs per minute Breathing rate-number of breaths per minute (12-20 healthy adult) Pulmonary ventilation rate=tidal volume x breathing rate

Question 344

How do the pulmonary artery and vein contribute to gas exchange?

Answer 344

Pulmonary artery: Brings deoxygenated blood to the alveoli. Pulmonary vein: Carries oxygenated blood away from the lungs.

Question 345

What is the alveolar walls made up of

Answer 345

Single layer of epithelial cells surrounded by capillaries

Question 346

How are alveoli protected from damage

Answer 346

Located inside as are thin and prone to damage Tin layer of mucus traps pathogens Dilated epithelial cells helps clear out alveoli Constant ventilation-flush out harmful particles

Question 347

What is a gene,allele ,chromosome ,DNA,chromatin,genome,proteome

Answer 347

Gene- section of material that codes for protein or characteristic Allele -variation of gene Chromosome -structure in which genes are stored DNA-chemical from which genes are constructed Chromatin- DNA ad associated protein histones found in nucleus Genome -all genes that construct organism Proteome -all the proteins that can be made from the genome

Question 348

Describe the structure of a nucleotide.

Answer 348

A phosphate group. A pentose sugar (deoxyribose in DNA). A nitrogenous base (adenine, thymine, guanine, or cytosine in DNA).

Question 349

What are the 5 nitrogenous bases

Answer 349

Uracil,thymine ,guanine ,cytosine ,adenine

Question 350

What are purines and pyrimidines

Answer 350

Purines -double carbon ring bases (adenine ,guanine) Pyrimidines-single carbon ring (thymine ,cytosine ,uracil)

Question 351

How many condensation reactions in the formation of nucleotides

Answer 351

2

Question 352

What’s bond form between nucleotides in DNA and what is the process

Answer 352

Phosphodiester bond forms between the phosphate of one nucleotide and the sugar c3 on another nucleotide through a condensation reaction ,catalysed by enzyme -DNA polymerase

Question 353

What is the sugar in DNA nucleotides?

Answer 353

Deoxyribose (C₅H₁₀O₄).

Question 354

What is complementary base pairing in DNA?

Answer 354

Adenine is opposite thymine Guanine is opposite cytosine

Question 355

What’s the structure of DNA

Answer 355

DNA is a long strand made of nucleotides it is 2m long that form a double helix

Question 356

Why is the heart made up of two separate pumps?

Answer 356

Blood must pass through the lungs to collect oxygen and then return to the heart for pressure to increase before being distributed to the body.

Question 357

Describe the function of the left pump of the heart.

Answer 357

The left pump of the heart receives oxygenated blood from the lungs via the pulmonary veins and pumps it at high pressure through the aorta to the rest of the body."

Question 358

Describe the function of the right pump of the heart.

Answer 358

The right pump of the heart receives deoxygenated blood from the body via the vena cava and pumps it to the lungs through the pulmonary artery for oxygenation."

Question 359

Why are atria thin-walled and elastic?

Answer 359

To stretch and collect blood efficiently.

Question 360

What is the purpose of the ventricles in the heart?

Answer 360

They have thick muscular walls to generate strong contractions to pump blood either to the lungs or the rest of the body.

Question 361

Why does the left ventricle have a much thicker wall than the right ventricle?

Answer 361

To generate sufficient pressure to pump blood throughout the entire body.

Question 362

What is the function of the right ventricle?

Answer 362

To pump blood to the lungs, which requires less pressure.

Question 363

Name the two types of valves found between the atria and ventricles.

Answer 363

The left atrioventricular valve and the right atrioventricular valve.

Question 364

What are veins responsible for in the circulatory system?

Answer 364

Carrying blood to the heart

Question 365

What are arteries responsible for in the circulatory system?

Answer 365

Carrying blood away from the heart.

Question 366

What is the function of the aorta, and where is it connected?

Answer 366

The aorta is connected to the left ventricle and carries oxygenated blood to the body at high pressure (except the lungs).

Question 367

What is the role of the vena cava, and where is it connected?

Answer 367

The vena cava is connected to the right atrium and brings deoxygenated blood back to the heart at low pressure from the tissues of the body (except the lungs).

Question 368

What is unique about the pulmonary artery compared to other arteries?

Answer 368

Unlike most arteries, the pulmonary artery carries deoxygenated blood. It connects to the right ventricle and carries blood to the lungs for oxygen replenishment and CO₂ removal.

Question 369

What is the role of the pulmonary vein, and how is it different from other veins?

Answer 369

The pulmonary vein is connected to the left atrium and brings oxygenated blood from the lungs back to the heart. Unlike most veins, it carries oxygenated blood.

Question 370

Why are coronary arteries essential for the heart?

Answer 370

They provide oxygenated blood to the heart muscle to meet its respiratory needs.

Question 371

What is the cardiac cycle

Answer 371

Sequence of events repeated around 70 times per minute at rest in humans,it involves 2 main phases,contraction -the heart contracts to pump blood out and relaxation -the heart releaxes to fill with blood

Question 372

What are the stages of the cardiac cycle, and what happens at each stage?

Answer 372

Blood enters the atria: From the vena cava into the right atrium From the pulmonary veins into the left atrium Atria are relaxed and filling. As atria fill, pressure rises slightly. Atria contract (atrial systole): Pressure increases further. Blood is pushed through open AV valves into the ventricles. Atria ensure all blood enters ventricles by finishing contraction. Ventricles begin to contract (ventricular systole): Pressure in the ventricles rises sharply. Once ventricular pressure > atrial pressure, AV valves close → prevents backflow (this makes the "lub" sound). When ventricular pressure exceeds pressure in the aorta and pulmonary artery, Semilunar valves open Blood is ejected into the aorta (left) and pulmonary artery (right). Ventricles relax (diastole begins): Ventricular pressure falls. Once it's lower than pressure in the aorta/pulmonary artery, semilunar valves close → ("dub" sound). AV valves reopen when atrial pressure exceeds ventricular pressure, and the cycle repeats.

Question 373

What happens when the atria relax and fill with blood?

Answer 373

Blood flows into the atria from the pulmonary veins (left atrium) and vena cava (right atrium). As the atria fill, the pressure increases, causing the atrioventricular valves to open, allowing blood to flow into the ventricles

Question 374

What causes blood to flow from the atria to the ventricles?

Answer 374

When the atria fill, their pressure increases. This pressure opens the atrioventricular valves, allowing blood to move passively into the ventricles.

Question 375

What happens when the atria contract?

Answer 375

The contraction of the atria pushes the remaining blood into the ventricles, ensuring the ventricles are completely filled.

Question 376

What happens when the ventricles contract?

Answer 376

A: The pressure inside the ventricles increases, causing the atrioventricular valves to close, preventing backflow into the atria. Once the pressure exceeds that in the aorta and pulmonary artery, the semilunar valves open, and blood is forced into these vessels.

Question 377

Why do the semilunar valves close when the ventricles relax?

Answer 377

To prevent blood from flowing back into the ventricles from the aorta and pulmonary artery.

Question 378

What ensures blood flows in one direction through the heart?

Answer 378

The atrioventricular valves and semilunar valves open and close in response to pressure changes,ensuring blood moves forwards without back flow

Question 379

What causes the "lub-dub" sounds of the heart?

Answer 379

Lub is caused by the antrioventicular valves closing during contraction of ventricles and the dub is formed by semilunar valves closing as ventricles relax

Question 380

What happens if valve pressure gradients are disrupted?

Answer 380

Blood may flow backward, reducing efficiency in delivering oxygen and nutrients to tissues. This is prevented by properly functioning valves that respond to pressure differences.

Question 381

How does the pressure in the heart chambers regulate blood movement

Answer 381

Blood always flows from areas of higher pressure to areas of lower pressure. This pressure difference drives the opening and closing of valves.

Question 382

What are pocket valves, and where are they found?

Answer 382

Pocket valves are found in veins and prevent the backflow of blood as it flows toward the heart.

Question 383

How are valves in the heart and veins designed to prevent backflow?

Answer 383

Valves are made of flexible, fibrous tissue shaped like cusps or bowls. They open when pressure is higher on one side and close when pressure is higher on the opposite side.

Question 384

How does the heart's closed circulatory system aid in blood flow?

Answer 384

It confines blood to vessels, allowing the regulation of pressure and volume for efficient circulation during the cardiac cycle.

Question 385

What causes the semilunar valves to close?

Answer 385

They close when the ventricles relax to prevent back flow from aorta and pulmonary artery to ventricles

Question 386

Where are the semilunar valves located, and what is their function?

Answer 386

Location-pulmonary artery and aorta Function-prevent back flow into ventricles during relaxation (diastole)

Question 387

When do the atrioventricular valves close during the cardiac cycle?

Answer 387

They close when ventricular pressure exceeds atrial pressure, preventing backflow into the atria.

Question 388

Where are the atrioventricular valves located, and what is their function?

Answer 388

Location: Between the atria and ventricles. Function: Prevent backflow of blood into the atria when the ventricles contract.

Question 389

How is a mononucleotide formed

Answer 389

Through condensation reactions of Pentose sugar ,nitrogenous base,phosphate which form a single nucleotide

Question 390

How is a dinucleotide formed

Answer 390

Condensation reaction between C3 on first nucleotides pentose sugar and phosphate which is attached to C5 on second nucleotide,releases molecule of water and bond formed is called phosphodiester

Question 391

What are the complementary base-pairing rules in DNA?

Answer 391

Adenine (A) pairs with thymine (T) via 2 hydrogen bonds. Cytosine (C) pairs with guanine (G) via 3 hydrogen bonds.

Question 392

Why is DNA a stable molecule?

Answer 392

Phosphodiester backbone protects the nitrogenous bases inside. Hydrogen bonds between base pairs stabilize the molecule. Base stacking interactions add stability. The proportion of G-C pairs increases stability due to stronger bonds.

Question 393

What are the two main functions of DNA?

Answer 393

Replication: DNA stores information for passing to the next generation. Protein synthesis: Acts as a template for RNA, which directs the synthesis of proteins.

Question 394

What is the significance of the double helix structure of DNA?

Answer 394

Allows for compact storage of genetic material. Enables accurate replication (base pairing). Antiparallel strands run in opposite directions (5' to 3' and 3' to 5').

Question 395

Define the following terms: Antiparallel. Phosphodiester bond. Complementary base pairing.

Answer 395

Antiparallel: Strands run in opposite directions (5' to 3' and 3' to 5'). Phosphodiester bond: Covalent bond between phosphate group of one nucleotide and sugar of another. Complementary base pairing: A pairs with T, C pairs with G, held by hydrogen bonds.

Question 396

Why are base pairs on the inside of the molecule

Answer 396

So it is protected so order of bases are not damaged and can code for specific proteins

Question 397

Why do hydrogen bonds form between DNA strands rather than covalent bonds

Answer 397

Hydrogen-provides stability however, are weak enough for separation so DNA replication and protein synthesis can occur

Question 398

Why is DNA so large ( 2m)

Answer 398

Carries a lot of genetic MATERIAL 25000 genes

Question 399

Why do large organisms need a transport system?

Answer 399

Large organisms need a transport system because their surface area to volume ratio is too small for efficient exchange through the body surface alone. Specialist exchange surfaces and transport systems are required to transport absorb nutrients, remove excretory products, and transport materials to and from cells. And to other parts of organism

Question 400

What determines whether an organism has a specialized transport medium or circulatory pump?

Answer 400

The surface area to volume ratio. How active the organism is. Organisms with a low surface area to volume ratio and high activity level require a transport medium (e.g., blood) and often a pump (e.g., heart).

Question 401

What are the common features of transport systems in large organisms

Answer 401

1)Medium- to carry material e.g blood,usually water based as water dissolves substances and can be moved around easily,can be a gas such as air move in and out lungs 2)Mass transport -to move bulk over larger distances as its more rapid than diffusion 3)A mechanism for moving transport medium within vessels this requires pressure distance between 2 points ,in animals this is achieved by contraction,and specialised organ heart In plant archived by natural passive processes like evaporation of water 4)A mechanism to maintain the mass flow movement in one direction eg valves 5)A means of controlling the flow of transport medium to suit changing needs in parts of organism 6)A mechanism for the mass flow of water or gases e.g intercostal muscle and diaphragm during breathing in mammals

Question 402

Describe the double circulatory system in mammals and its advantages. A: Mammals have a closed, double circulatory system, where blood passes through the heart twice per complete circuit.

Answer 402

Blood from lungs is at low pressure so if transferred to body blood circulation would be slow ,so blood is returned to heart to boost pressure so substances are delivered fast and removed fast ,which is important in mammals due to high metabolic rate .

Question 403

What are capillaries for

Answer 403

Capillaries: Allow exchange of substances like oxygen and nutrients between blood and tissues.

Question 404

What features make water an ideal transport medium in biological systems?

Answer 404

Liquid state allows it to flow easily. High solvent properties dissolve gases, nutrients, and wastes. Thermal stability helps maintain temperature.

Question 405

Which blood vessel carries deoxygenated blood away from the kidney?

Answer 405

The renal vein carries deoxygenated blood away from the kidney.

Question 406

What is the first main blood vessel that an oxygen molecule reaches after being absorbed from an alveolus?

Answer 406

The pulmonary vein is the first main vessel for oxygenated blood from the lungs.

Question 407

Which blood vessel has the highest blood pressure?

Answer 407

Aorta

Question 408

How does double circulation found in mammals protect lungs

Answer 408

Allows blood to stay at low pressure when passing through lungs

Question 409

What is the last part of journey of material in and out of cells by from blood vessels to cells

Answer 409

Diffusion

Question 410

Explain cardiac output give formula,what is heart rate and stroke volume,units

Answer 410

Cardiac output -the volume of blood pumped by one ventricle of the heart in one minute Cardiac output =heart rate x stroke volume Heart rate-rate at which heart beats Stroke volume-volume of blood pumped out each beat Cardiac output measured in dm3 /min

Question 411

What are the blood vessels in liver,heart and kidney

Answer 411

Kidney-renal vein carries deoxygenated blood away from kidney Renal artery -bring oxygenated blood to kidney for filtration Liver-hepatic artery supplies oxygenated blood to liver,hepatic vein -drains deoxygenated blood from the liver to the inferior vena cava ,hepatic portal vein -brings nutrient rich blood from digestive system to liver for processing Heart-coronary artery supplies oxygenated blood to heart

Question 412

Explain how the counter current low mechanism in fish gills ensure max oxygen passes into blood flowing through gills

Answer 412

Diffusion gradient-maintained over the whole length of the gill lamellae ,blood always flows over oxygen rich water ,water and blood flow in opposite directions

Question 413

Explain three ways an insects tracheal system is adapted for efficient gas exchange

Answer 413

Tracheal system has thin walls so short diffusion distance to cells Highly branched so short diffusion distance to cells Large number of tracheal so increases SA Fluid at the end of tracheoles that moves out during exercise for rapid diffusion as it happens faster in air than water

Question 414

Describe the pathways taken by an oxygen molecule from an alveolus to the blood

Answer 414

Oxygen molecule goes across alveolar epithelium through the capillary endothelium

Question 415

Describe and explain how fish maintain a flow of water over their gills.

Answer 415

Mouth opens Floor of mouth lowered Water enters due to decreased pressure Mouth closes Floor raised increases pressure Which forces water over gills

Question 416

Why and when would less blood to diaphragm be useful

Answer 416

When not breathing so blood diaphragm don’t contract so blood can be used in other organs

Question 417

Explain what causes this difference in composition between the air in the alveolus and the air in the trache

Answer 417

Gas exchange takes place in alveoli not trachea

Question 418

Through which vessel does blood leave the heart to go to the lungs?

Answer 418

Pulmonary artery

Question 419

Suggest why blood returning to the heart from the lungs contains some carbon dioxide.

Answer 419

Diffusion occurs when there is a cg ,but it will reach equilibrium so some carbon will be left in blood

Question 420

Describe the difference in the composition of gases in inhaled and exhaled air. Explain how these differences are caused.

Answer 420

Inhales air contains more oxygen than exhaled air Inhaled air contains less carbon dioxide than exhaled air Inhales air contains less water vapour Respiration lowers blood oxygen and increases blood c02 Oxygen Enters blood and c02 leaves blood in alveoli by diffusion

Question 421

What does circulation and ventilation do in gills

Answer 421

It adapts gills for oxygen extraction and gas exchange Circulation-replaces blood saturated w oxygen Ventilation-replaces water as oxygen is removed

Question 422

What are longrathmic scale used for

Answer 422

When we have data with large range

Question 423

How do i reduce uncertainty of equipment

Answer 423

Use istrument with smaller intervals

Question 424

Describe the part played by the inner membrane of a mitochondrion in producing ATP

Answer 424

Electrons are transferred down electron transport chain Providing energy to take protons into space between membranes Energy is used to combine ADP AND PHOSPHATE to give atp by atp synthase

Question 425

The structure of a plasma membrane is described as a fluid mosaic. Explain why.

Answer 425

Fluid -molecules move around Mosaic-made of Different sorts of molecules

Question 426

In each cardiac cycle, the arterial pressure has a maximum value. Explain the link between this maximum value and the events of the cardiac cycle.

Answer 426

Corresponds to ventricles contracting

Question 427

Why would a high concentration of fertiliser in soil be bad for plants

Answer 427

Soil more negative plant looses water through transpiration due to osmosis

Question 428

The total volume of fluid that passes from the capillaries to the surrounding tissue fluid is normally greater than the volume that is reabsorbed into them. Describe what happens to this extra fluid.

Answer 428

Removed by lymphatic system and returned to the blood

Question 429

Why is glucose soluble

Answer 429

Has large number of hydroxyl groups that form hydrogen bonds w water they are hydrophilic

Question 430

What three groups is fatty acid composed of

Answer 430

Carboxylic acid,methyl,hydrocarbon chain

Question 431

Are viruses alive

Answer 431

They are biotic but not alive

Question 432

How would u prepare the microscope setting to view prepared slide

Answer 432

Select lowest power objective lens use coarse adjustment knob to bring stage up then fine adjustment knob to focus on,if need higher power select Higher powered objective lens and refocus

Question 433

Why is diffusion between the blood and alveoli fast

Answer 433

Red blood cells are slowed at they pass through the pulmonary capillaries which are narrow allowing more time for diffusion The difference between the alveolar air and red blood cells is reduced because the red blood cells are flattened against the capillary wall Walls of alveoli and capillaries are very thin Alveoli and pulmonary capillaries have very large SA Ventilation and blood circulation maintain concentration gradients Blood flow through the pulmonary capillaries maintains a concentration gradient

Question 434

Explain how gas exchange occurs in insects without the use of blood

Answer 434

Insects use a system of tracheae and tracheoles for gas exchange. Oxygen moves down a diffusion gradient into cells, and carbon dioxide moves out in the opposite direction. The tracheal system transports gases directly to and from the cells, eliminating the need for blood circulation

Question 435

Transcription

Answer 435

Identify section of DNA we want DNA HELICASE unwinds this section of DNA breaking hydrogen bonds between the complimentary bases between the 2 strands.RNA nucleotides come between the 2 strands the RNA bases line up opposite the bases on the coding strand in complementary sequencing they form hydrogen bonds.RNA polymerase enzyme joins the RNA Nucleotides together with a phosphodiester bond.this forms a single stranded pre mRNA molecule (helix) which moves out from between the two DNA strands breaking the hydrogen bonds ,the DNA strands recoil hydrogen bonds form with DNA ligase between the complimentary base on strands,splicing -sections of RNA nucleotides from MRNA ,the mRNA leave nucleus via nuclear pores to cytoplasm to meet ribosomes that have tRNA

Question 436

Translation

Answer 436

In cytoplasm ribosome attaches to mRNA it covers six bases (2 codons) ,TRNA with complimentary anticodon to the first codon to the MRNA sits on the mRNA ,bases form hydrogen bonds. TRNA will have a specific amino acid attached to its amino acid attachment site TRNA with complimentary anticodon also attaches to next codon carrying an amino acid,2 adjacent amino acids form peptide bond in condensation reaction.once peptide bond forms tRNA dissociates , ribosomes move to next codon on MRNA repeating process until ribosome reaches a stop codon.results in primary structure of protein .

Question 437

What is the function of DNA helicase in transcription?

Answer 437

DNA helicase unwinds the DNA double helix and breaks hydrogen bonds between complementary bases to expose the coding strand

Question 438

How does RNA polymerase contribute to transcription

Answer 438

RNA polymerase catalyzes the formation of phosphodiester bonds between RNA nucleotides, synthesizing a single-stranded pre-mRNA molecule

Question 439

What happens to the pre-mRNA before translation

Answer 439

Splicing removes introns (non-coding regions) and joins exons (coding regions) to form mature mRNA, which exits the nucleus via nuclear pores.

Question 440

How does translation begin once mRNA reaches the ribosome?

Answer 440

The ribosome binds to mRNA, covering two codons at a time. tRNA with a complementary anticodon brings the specific amino acid, starting the process

Question 441

How does tRNA contribute to protein synthesis

Answer 441

Each tRNA carries a specific amino acid and binds to mRNA codons using a complementary anticodon, ensuring correct polypeptide formation.

Question 442

How does translation end?

Answer 442

When the ribosome reaches a stop codon, no tRNA binds, and the polypeptide chain is released, forming the primary structure of a protein.

Question 443

What is a gene mutation, and when does it occur?

Answer 443

A gene mutation is a change in the base sequence of DNA that may arise during DNA replication, leading to changes in protein structure and function.

Question 444

What are the three main types of point mutations(involves one DNA (1base)

Answer 444

Substitution – One nucleotide is replaced by another. Addition – An extra nucleotide is inserted. Deletion – A nucleotide is removed from the sequence

Question 445

What is a substitution mutation, and how does it affect the protein?

Answer 445

nucleotide is replaced with a different one, which may: Have no effect (silent mutation). Degenerate nature Change an amino acid Create a premature stop codon leading to a non-functional protein.

Question 446

Why are addition and deletion mutations more harmful than substitution?

Answer 446

They cause a frameshift mutation, which alters the subsequent triplets , changing all amino acids downstream, potentially creating a non-functional protein,new forms of alleles formed

Question 447

What are mutagens, and how do they increase mutation rates?

Answer 447

Mutagens are factors that increase the likelihood of mutations, such as: X-rays (ionizing radiation). UV light (damages DNA by causing thymine dimers). Caffeine (chemical mutagen). Chemicals in cigarette smoke (cause DNA damage).

Question 448

What way is frameshift for addition and deletion

Answer 448

Addition -right Deletion -left

Question 449

What is the difference between a karyogram and a karyotype

Answer 449

Karyogram: An image of chromosomes. Karyotype: The number and structure of chromosomes in a cell

Question 450

What are autosomes, and how do they differ from sex chromosomes

Answer 450

Autosomes: Pairs 1-22, not involved in determining sex. Sex chromosomes: 23rd pair, determines biological sex (XX = female, XY = male).

Question 451

During DNA replication, what happens to DNA mass, chromatid number, and chromosome number?

Answer 451

DNA mass doubles. Chromatid number doubles. Chromosome number stays the same.

Question 452

What are eukaryotic chromosomes made of

Answer 452

DNA wrapped around histone proteins. Scaffold proteins provide structure. Polymerase enzymes help in DNA replication Small amount of RNA

Question 453

Q: How does viral genetic material differ from that of prokaryotic and eukaryotic cells?

Answer 453

Viruses can have RNA or DNA as genetic material. Unlike cells, viral genetic material is often single-stranded. Viruses lack a nucleus and cannot replicate independently.

Question 454

Where is DNA found in prokaryotic and eukaryotic cells?

Answer 454

Prokaryotic DNA: Found in the cytoplasm (nucleoid region). Eukaryotic DNA: Mostly found in the nucleus, with some in mitochondria and chloroplasts.

Question 455

How does the shape of DNA differ between prokaryotes and eukaryotes

Answer 455

Prokaryotic DNA: Circular. Eukaryotic DNA: Linear (organized into chromosomes).

Question 456

How is DNA packaged in prokaryotic vs. eukaryotic cells?

Answer 456

Prokaryotic DNA: Naked DNA (not associated with histone proteins). Eukaryotic DNA: Wrapped around histone proteins for structural organization.

Question 457

Do introns exist in prokaryotic and eukaryotic DNA

Answer 457

Prokaryotic DNA: Introns are absent (genes are mostly coding sequences). Eukaryotic DNA: Introns are present, requiring splicing before translation

Question 458

How much non-functional DNA is present in prokaryotes vs. eukaryotes

Answer 458

Prokaryotic DNA: Minimal non-functional DNA. Eukaryotic DNA: A large amount of non-functional DNA (e.g., regulatory sequences, repetitive DNA).

Question 459

What are three key similarities between prokaryotic and eukaryotic DNA?

Answer 459

Both have a double-stranded helix. Both use complementary base pairing (A-T, C-G) and hydrogen bonds. Both contain genetic information needed for protein synthesis

Question 460

How do DNA, mRNA, and tRNA differ in structure?

Answer 460

DNA: Double-stranded helix. mRNA: Single-stranded, linear. tRNA: Single-stranded, cloverleaf shape.

Question 461

Rank DNA, mRNA, and tRNA from largest to smallest.

Answer 461

DNA – Largest. mRNA – Medium-sized. tRNA – Smallest and shortest.

Question 462

Q: What type of pentose sugar is found in DNA and RNA?

Answer 462

DNA: Deoxyribose. mRNA & tRNA: Ribose

Question 463

What organic bases are present in DNA, mRNA, and tRNA?

Answer 463

DNA: Adenine, Thymine, Cytosine, Guanine. mRNA & tRNA: Adenine, Uracil, Cytosine, Guanine (Uracil replaces adenine in RNA).

Question 464

Where are DNA, mRNA, and tRNA found in the cell?

Answer 464

DNA: Nucleus. mRNA: Cytoplasm (moves from nucleus to ribosome). tRNA: Cytoplasm (transports amino acids to ribosomes).

Question 465

Does the amount of DNA, mRNA, and tRNA change with metabolic activity

Answer 465

DNA: No, stays constant unless during mitosis. mRNA: Yes, increases when protein synthesis is high. tRNA: Not heavily, because it is reused.

Question 466

How chemically stable are DNA, mRNA, and tRNA?

Answer 466

DNA -very due to phosphate backbone double helix held by hydrogen bonds MRNA -not stable tRNA -stable due to hydrogen bonds hence can be reused

Question 467

What is the difference between conservative and semi-conservative DNA replication?

Answer 467

Conservative replication: One daughter molecule is entirely new DNA, and one is entirely original DNA Semi-conservative replication: Each daughter DNA molecule consists of one original strand and one new strand.

Question 468

What three facts did Meselson and Stahl base their DNA replication experiment on?

Answer 468

All DNA bases contain nitrogen. Nitrogen has two isotopes: N-14 (less dense). N-15 (more dense). Bacteria incorporate nitrogen to form DNA depending on what isotope depends how heavy DNA will be

Question 469

How did Meselson and Stahl demonstrate semi-conservative replication?

Answer 469

E. coli bacteria were first grown in a medium containing N-15 (heavy nitrogen). Bacteria were then transferred to a medium containing N-14 (lighter nitrogen). After one round of replication, DNA was of intermediate density, indicating one strand was original (N-15) and one was new (N-14). Further replication produced some intermediate DNA and some purely N-14 DNA, confirming semi-conservative replication

Question 470

What are the steps of semi-conservative replication?

Answer 470

DNA helicase unwinds the DNA, breaking hydrogen bonds. Free nucleotides pair with exposed bases using complementary base pairing (A-T, C-G). DNA polymerase joins nucleotides together, forming a new complementary strand. Each new DNA molecule consists of one original strand and one new strand.

Question 471

Why is semi-conservative replication biologically significant?

Answer 471

Ensures genetic continuity between generations. Reduces mutations, as one strand is always a template. Essential for growth, repair, and reproduction in living organisms

Question 472

What are the three main types of blood vessels, and their functions

Answer 472

Arteries: Carry blood away from the heart (high pressure). Capillaries: Tiny vessels that exchange substances between blood and tissues. Veins: Carry blood back to the heart (low pressure).

Question 473

Arteries arterioles and veins have similar structure from outside inwards what is this.

Answer 473

Tough fibrous outer layer to resist pressure changes within and outside Muscle layer that can contract to control blood flow Elastic layer helps maintain pressure by stretching and recoiling Thin inner lining which is smooth to reduce friction,thin to allow diffusion Lumen through which blood flows through

Question 474

What are arterioles

Answer 474

Smaller arteries that control blood flow from arteries to capillaries

Question 475

Artery structure adapted to function

Answer 475

Muscle layer thicker than veins as has higher pressure resist burst Elastic layer thick compared to veins as blood needs to be at high pressure to reach extremities of body.no valves no tend for back flow due to high pressure

Question 476

When is the elastic wall of the arteries stretched

Answer 476

During systole (contraction)at each beat of the heart it’s stretched ,and springs back during diastole(relaxation) ,this stretch and recoil helps maintain pressure

Question 477

Arterioles structure adapted to function

Answer 477

Carry blood at lower pressure than arteries from arteries to capillaries they control flow of blood to tissue.they have thicker muscular wall than arteries to contract to control blood flow during contraction and dilation.thinner elastic walls compared to arteries due to low pressure ,smaller lumen than arteries

Question 478

Veins structure adaptations

Answer 478

Thin muscular walls as low pressure Wide lumen reduce resistance of blood Valves Less elastic tissue Surrounded by body muscles veins are compressed pressures blood in them to help blood flow in one direction towards heart Less fibrous tissue due to lower pressure

Question 479

Capillary structure adaptations

Answer 479

Has to exchange metabolic materials ,narrow walls slows flow of blood so more time for exchange ,walls mostly lining to diffuses gases ,one cell thick layer so thin for diffusion short diffusion distance ,they are numerous and highly branched large SA for exchange narrow lumen to flatten blood cells to walls for short diffusion pathway,are spaces between lining to allow escape of white blood cells to escape and deal with infection

Question 480

How is tissue fluid formed

Answer 480

Blood pumped by the heart passes along the arteries then the arterioles and then capillaries,blood pumped by heart creates pressure (hydrostatic pressure) at arterial end of capillaries this causes tissue fluid to move out of blood plasma ,the movement of tissue is opposed by hydrostatic pressure of tissue fluid outside capillary tries to push the tissue fluid back in,low water potential in blood capillaries due to plasma proteins causes water to move back to capillaries via osmosis at the venous end ,net force outward at the arterial end and inward at the Venous end these creates a pressure that pushes tissue fluid out of the capillaries at the arterial end .this pressure is only enough to force small molecules out (ultrafiltration) ,proteins and larger molecules stay in blood.

Question 481

Explain the return of tissue fluid to the circulatory system

Answer 481

At the venous end of capillaries, hydrostatic pressure is low due to fluid loss at the arterial end. This means the pressure in the tissue fluid is higher, so fluid moves back into capillaries. Also, plasma proteins remain in the blood, creating a low water potential, so water returns by osmosis to the capillaries at the venous end The tissue fluid has less oxygen and nutrients, but more CO₂ and waste. Any excess is drained by the lymphatic system

Question 482

Roll of lymphatic system in tissue fluid

Answer 482

Not all tissue fluid returns to the capillaries. The excess enters the lymphatic system, a network of vessels starting in tissues that eventually join larger vessels. This fluid is now called lymph. It's moved through the lymphatic system by: Hydrostatic pressure of excess tissue fluid, Muscle contractions that squeeze the vessels, And valves that prevent backflow. The lymph eventually drains back into the bloodstream near the heart, helping maintain fluid balance.

Question 483

What are haemoglobin’s

Answer 483

Groups of chemically similar protein molecules with a quaternary structure that have evolved to make ur efficient at loading and unloading oxygen under different conditions

Question 484

What is the quaternary structure of haemoglobin

Answer 484

4 polypeptides = quaternary structure Each chain has a haem group with Fe²⁺ Each Fe²⁺ binds one O₂ Total = 4 O₂ per haemoglobin molecule Globular / spherical shape

Question 485

Oxygen dissociation curves

Answer 485

When haemoglobin is exposed to diff partial pressures of oxygen it does not bind to oxygen evenly the graph between the saturation of haemoglobin and the partial pressure of oxygen is known as an oxygen dissociation curve

Question 486

Oxygen dissociation curve of haemoglobin in humans shape description

Answer 486

The shape of haemoglobin molecule makes it difficult for the first oxygen molecule to bind to on of the four polypeptide subunits as they are close together,at low concentrations of oxygen little oxygen binds to haemoglobin so gradient is shallow at first, binding of first molecule changes the quaternary shape of haemoglobin makes it easier for 2nd and 3rd to bind so gradient steepens , after the third molecule binds it is less likely that oxygen molecule will find an empty site to bind to to so gradient reduces and flattens and levels off

Question 487

The further to the left the oxygen dissociation curve is..

Answer 487

The greater affinity haemoglobin has for oxygen so loads readily but unloads less readily

Question 488

The further to the right the oxygen dissociation curve is..

Answer 488

Haemoglobin affinity for oxygen is less so loads less readily but unload more readily

Question 489

What are the effects of co2 concentration on oxygen dissociation curves

Answer 489

In presence of co2 haemoglobin has lower affinity for oxygen,the higher the concentration of co2 the more readily haemoglobin releases oxygen so behaviour of haemoglobin changes around body .At gas exchange surfaces like lungs co2 concentration a low as it diffuses across exchange surfaces so affinity for oxygen increases so readily loads with oxygen (graph will be toward left as greater affinity for oxygen ) in rapidly respiring tissue like muscles concentration of co2 is high so the affinity for oxygen decrease so oxygen is readily unloaded to muscle cells so graph shifts to right (due to haemoglobin lower affinity for oxygen)

Question 490

Why is it that the greater the carbon dioxide concentration the more readily haemoglobin releases oxygen

Answer 490

The carbon dioxide that is dissolved is acidic which lowers PH causes haemoglobin to change shape into one that readily unloads oxygen ,when less co2 PH rises causes shape change into one that readily loads with oxygen

Question 491

Why are oxygen dissociation curves always dif ?

Answer 491

Curve Change in dif conditions , dif species have dif haemoglobin that adapted differently,e.g animals that live in conditions of lower partial pressure have evolved haemoglobin with higher affinity for oxygen than animals that live under higher partial pressures of oxygen

Question 492

What does temp do to oxygen dissociation curve

Answer 492

Increase temp shifts curve to right Haemoglobin has a lower affinity for oxygen Oxygen is released more readily to the tissues Helps during exercise or fever, when muscles are more active and need more oxygen

Question 493

DNA replication steps semi conservative

Answer 493

DNA helicase breaks the hydrogen between complimentary strands Double helix separates in to 2 strands Free activated nucleotides are attracted to the exposed bases on each strand They bind according to complimentary base pairing Enzyme DNA polymerase catalyses reaction between nucleotides form phosphodiester bonds forming new DNA strand.this occurs through condensation reactions. Each DNA strand consists of one previous strand and one newly formed strand this ensures genetic continuity ensuring new DNA molecules are identical to the original

Question 494

What is needed for semi conservative replication

Answer 494

4 nucleotide with bases adenine thymine cytosine and guanine Both strand of DNA molecule act as template for attachment of these nucleotides Enzyme of DNA polymerase Source of chemical energy to drive process

Question 495

Conservative replication

Answer 495

The original DNA acts as a template for the formation of a new DNA molecule. After replication, one DNA molecule is completely original, and the other is completely new. No mixing of original and new strands occurs.

Question 496

Risk factor of smoking associated with cardiovascular disease

Answer 496

Smoking-carbon monoxide binds irreversibly with haemoglobin forms carboxyhaemaglobin reducing the oxygen carrying capacity of the blood,less oxygen reaches the heart muscle increases risk of heart attack

Question 497

Risk factor of nicotine associated with cardiovascular disease

Answer 497

Nicotine stimulates adrenaline, increasing heart rate and blood pressure, which puts strain on the heart and arteries. It also causes platelets to stick together, increasing the risk of thrombosis, which can lead to a heart attack or stroke.

Question 498

Risk of high blood pressure associated with cardiovascular disease

Answer 498

Heart works harder to pump blood causing more strain on heart muscle potential heart attack,increase pressure in arteries can cause swell and bursting,which thickens and hardens the walls restricting blood flow