How do organisms sustain themselves ? Unit 3

Question 1

What is digestion ( 2 points ) ?

Answer 1

Digestion is the breakdown of large insoluble food molecules into smaller soluble ones. Amylase, proteases and lipases are enzymes that are important in digestion.

Question 2

What is diffusion ?

Answer 2

Diffusion is the net movement of particles from an area of high concentration to an area of lower concentration

Question 3

Explain how nutrients get from inside the small intestine to the blood stream ?

Answer 3

Digested food molecules are absorbed by the walls of the small intestine into the bloodstream. The blood delivers the nutrients to the rest of the body. Only small, soluble substances can pass across the wall of the small intestine. Large insoluble substances cannot pass through.

Question 4

What is osmosis ?

Answer 4

Osmosis is the diffusion of water molecules, from a region where the water molecules are in higher concentration, to a region where they are in lower concentration, through a partially permeable membrane

Question 5

What is a water potential ?

Answer 5

A solution with a low solute concentration has a high water concentration, and a high water potential. Pure water has the highest water potential.

Question 6

What is a concentration gradient ? ( 3 points )

Answer 6

The concentration gradient is the difference in the concentration of a substance between two areas . The bigger the difference, the steeper the concentration gradient and the faster the molecules of a substance will diffuse.

Question 7

How do plant cells prevent themselves from bursting ? ( 2 points )

Answer 7

Plant cells have a strong cellulose cell wall on the outside of the cell membrane. This supports the cell and stops it bursting when it gains water by osmosis.

Question 8

What happens to a plant cell in dilute and concentrated solutions ?

Answer 8

• A plant cell in a dilute solution (higher water potential than the cell contents)
  Water enters the cell by osmosis. The cytoplasm pushes against the cell wall and the cell becomes turgid.
• A plant cell in a concentrated solution (lower water potential than the cell contents)
  Water leaves the cell by osmosis. The cytoplasm pulls away from the cell wall (plasmolysis) and the cell becomes flaccid and the plant wilts.

Question 9

What happens to red blood cells in dilute and concentrated solutions ? ( 2 points )

Answer 9

For example, red blood cells:
• gain water, swell and burst in a more dilute solution (this is called
haemolysis)
• lose water and shrink in a more concentrated solution (they become
crenated or wrinkled)

Question 10

What is active transport ? ( describe and give examples )

Answer 10

Active transport is the movement of dissolved molecules into or out of a cell through the cell membrane, from a region of lower concentration to a region of higher concentration ( against the concentration gradient ). The particles move against the concentration gradient, using energy released during respiration.

Examples of active transport include:
• uptake of glucose by epithelial cells in the villi of the small intestine
• uptake of ions from soil water by root hair cells in plants

Question 11

What is the heart ?

Answer 11

The heart is a large muscular pump, usually beating about 60 to 100 times per minute and is divided into two halves - the right-hand side and the left-hand side.

Question 12

What are the two sides of the heart and what do they do ?

Answer 12

The right-hand side of the heart is responsible for pumping deoxygenated blood to the lungs.
The left-hand side pumps oxygenated blood around the body.
Each side of the heart consists of an atrium and a ventricle which are two connected chambers.

Question 13

What is the atria ?

Answer 13

The atria (plural of atrium) is the chamber where the blood collects when it enters the heart.

Question 14

What are the ventricles ?

Answer 14

ventricle, muscular chamber that pumps blood out of the heart and into the circulatory system

Question 15

What is the septum

Answer 15

The septum is a wall of tissue that separates the right- hand and left-hand side of the heart.

Question 16

What is the tricuspid valve ?

Answer 16

The tricuspid valve is located between the right atrium and right ventricle and opens due to a build-up of pressure in the right atrium.

Question 17

What is the bicuspid valve ?

Answer 17

The bicuspid valve is located between the left atrium and left ventricle and likewise opens due to a build-up of pressure, this time in the left atrium.

Question 18

What do the semilunar valves do ?

Answer 18

The semilunar valves stop the back flow of blood into the heart.
There is a semilunar valve where the aorta leaves the left ventricle and another where the pulmonary artery leaves the right ventricle.

Question 19

What is the aorta ?

Answer 19

The aorta is the largest artery in the body. It carries oxygenated blood away from the left ventricle to the body.

Question 20

What is teh vena cava ( 3 points )

Answer 20

The vena cava is the largest vein in the body. It carries deoxygenated blood from the body back to the heart.
• Superior Vena Cava: This large vein
brings de-oxygenated blood from the head, neck, arm, and chest regions of the body to the right atrium.
• Inferior Vena Cava: This vein brings de-oxygenated blood from the lower body regions (legs, back, abdomen and pelvis) to the right atrium

Question 21

What are the 3 main blood vessels and how are they structured for their function ?

Answer 21

All blood vessels are specifically structured to perform their function. For example:
A capillary is microscopically thin to allow gases to exchange,
The arteries are tough and flexible to cope with high pressure blood flow
the veins contain valves to prevent the blood from travelling backwards when at low pressure.
All vessels feature varying lumen size. The lumen is the hollow opening or the space inside the blood vessel.

Question 22

What is ventilation?

Answer 22

Ventilation: The exchange of air between the lungs and the atmosphere so that oxygen can be exchanged for carbon dioxide in the alveoli (the tiny air sacs in the lungs).

Question 23

Enzyme, Location and Ph ( Amylase, Protease, Lipase, Lactase )

Answer 23

Amyllase
Salliivary gllands and pancreases
6.7 – 7.0

Protease
Stomach,
2

Liipase
Pancreas
3–6

Lactase
Smalll iintestiine
2 – 7 (6 is optimum)

Question 24

What is ventilation?

Answer 24

Ventilation: The exchange of air between the lungs and the atmosphere so that oxygen can be exchanged for carbon dioxide in the alveoli (the tiny air sacs in the lungs).

Question 25

About the trachea (a new bronchi )?

Answer 25

The trachea branches into two bronchi (one to each lung). Pleural membranes surround each lung. Cartilage rings in the walls of the trachea help to keep it open The bronchi split into smaller and smaller tubes called bronchioles. These end in microscopic air sacs called alveoli. There is a muscular diaphragm below the lungs.

Question 26

What happens when you inhale ?

Answer 26

Breathing in When you inhale: 1. the internal intercostal muscles relax and the external intercostal muscles contract, pulling the ribcage upwards and outwards 2. the diaphragm contracts, pulling downwards 3. lung volume increases and the air pressure inside decreases 4. air is pushed into the lungs

Question 27

Features of the alveoli ( 4 points )

Answer 27

Some of the features of alveoli include: 1. thin walls (just one cell thick) 2. large surface area 3. moist surface 4. many blood capillaries

Question 28

Process of digestion ( basic ) ?

Answer 28

Ingestion - food is taken into the body Digestion - Breakdown of complex food substances into smaller soluble food substances Absorption - Digested food is absorbed into body cells Assimilation - Absorbed food is used to provide energy Egestion - Removal of undigested food

Question 29

Why is a balanced diet important ?

Answer 29

A balanced diet typically contains 50 to 60 percent carbohydrates, 12 to 20 percent protein, and 30 percent fat. A balanced diet supplies the nutrients your body needs to work effectively. Without balanced nutrition, your body is more prone to disease, infection, fatigue, and low performance.

Question 30

What are the monomers of Carbohydrates, Proteins, Lipids and nucleic acids

Answer 30

Proteins - amino acids Lipids - Fatty acid and glycerol Carbohydrates - Monosaccharides ( glide is an example of a monosaccharide ) Nucleic acids - Nucleotides

Question 31

What do carbohydrates do ?

Answer 31

One of three macronutrients. Provide cells with quick/short-term energy, source of dietary fiber

Question 32

What do lipids do ?

Answer 32

Provide cells with long-term energy, provides insulation and stores energy.

Question 33

What do proteins do ?

Answer 33

Provide cell structure, send chemical signals, speed up chemical reactions, etc

Question 34

mechanical vs chemical digestion

Answer 34

Chemical and mechanical digestion are the two methods your body uses to break down foods. Mechanical digestion involves physical movement to make foods smaller. Chemical digestion uses enzymes to break down food.

Question 35

denitrifying bacteria

Answer 35

denitrifying bacteria, microorganisms whose action results in the conversion of nitrates in soil to free atmospheric nitrogen, thus depleting soil fertility and reducing agricultural productivity.

Question 36

how is blood glucose level maintained

Answer 36

Blood sugar level is controlled by two hormones secreted by pancreas: 1. Insulin is responsible to decrease the blood sugar level. It promotes the glucose utilization by the body cells. Therefore it allows the body’s glucose levels to decrease. 2. Glucagon is responsible to raise the blood sugar level. It stimulates the breakdown of glycogen in the liver to glucose, thus it raises the sugar level in the blood.

Question 37

What is piloerection

Answer 37

Erection of the hair of the skin due to contraction of the tiny arrectores pilorum muscles that elevate the hair follicles above the rest of the skin and move the hair vertically, so the hair seems to 'stand on end.

Question 38

What happens during vasoconstriction?

Answer 38

Vasoconstriction is the narrowing (constriction) of blood vessels by small muscles in their walls. The process involves the narrowing of blood vessels at the skin surface to reduce heat loss through the surface of the skin.

Question 39

What is vasodilation ?

Answer 39

Vasodilation is the widening of blood vessels as a result of the relaxation of the blood vessel's muscular walls. Vasodilation is a response to being too hot. The process includes the widening of blood vessels at the skin surface to increase heat loss through the surface of the skin.

Question 40

Flow of blood through the heart

Answer 40

Blood comes into the right atrium from the body, moves into the right ventricle . Blood flows from the right ventricle through the pulmonary valve to the pulmonary artery and then into the lungs, where it picks up oxygen to deliver to your body. The left atrium receives oxygen-rich blood from the lungs and pumps it to the left ventricle through the mitral valve. The left ventricle pumps the oxygen-rich blood through the aortic valve out to the rest of the body.

Question 41

Where are capillaries located ?

Answer 41

All tissues

Question 42

How does blood flow through your body?

Answer 42

Veins bring blood to the right side of your heart. - Pulmonary arteries carry the blood to your lungs, where it receives oxygen. - Pulmonary veins move the blood oxygen-rich blood to the left side of your heart. - The aorta (the main artery in your body) carries the blood from the left side of your heart to the rest of your body through many branches of arteries. - Capillaries have thin walls that allow oxygen, nutrients, carbon dioxide and waste products to pass through, to and from the tissue cells. - Veins then carry the blood back to your heart, and the process begins again.

Question 43

Capillaries function

Answer 43

The primary function of capillaries is the exchange of materials between the blood and tissue cells. The capillaries also take waste products away from your tissues. Capillaries are where oxygen and nutrients are exchanged for carbon dioxide and waste.

Question 44

Function of veins

Answer 44

Unlike arteries, veins don’t have to carry highly pressurized blood, but they do have to carry large volumes of deoxygenated blood back to your heart. Thin, less elastic walls help them handle high volumes and low pressure.

Question 45

Arteries function

Answer 45

These strong, muscular blood vessels carry oxygen-rich blood from your heart to your body. They handle a large amount of force and pressure from your blood flow but don’t carry a large volume of blood. At any given time, only about 10% to 15% of your body’s blood is in your arteries.

Question 46

Arteries, veins and capillaries

Answer 46

Arteries carry blood away from your heart. - Veins carry blood back toward your heart. - Capillaries, the smallest blood vessels, connect arteries and veins.

Question 47

Functions (2) of bile

Answer 47

it neutralises the acid - providing the alkaline conditions needed in the small intestine - it emulsifies fat - turning large droplets of fat into lots of smaller droplets, thus providing a larger surface area over which the lipase enzymes can work

Question 48

Liver functions ( 4 )

Answer 48

Stores vitamins and irons Destroys old blood cells Destroys poisons Produces bile ( helps in Teh emulsification of fats )

Question 49

Small intestine (5)

Answer 49

Completes digestion Mucus protects gut walls Lipase digests lipids Protease digests is proteins Amalyse digests starch

Question 50

Stomach (4)

Answer 50

Stores and churns food HCL kills germs Pepsin digest proteins Music protects stomach wall

Question 51

Pancreases ( 3)

Answer 51

Regulates blood glucose levels ( produces insulin ) Secretes lipase, amalyse and and protease Bicarbonates neutralize stomach acids

Question 52

Anus

Answer 52

Opening for elimination of farces

Question 53

Homeostasis

Answer 53

Maintenance of a constant internal environment. The nervous system and hormones are responsible for this.

Question 54

Anus vs rectum

Answer 54

Excretes waste, stores waste

Question 55

Liver vs galbkder

Answer 55

Produces bile, stores bile

Question 56

Small vs lareg interstije

Answer 56

Absorbs nutrias into teh blood stream, absorbs water

Question 57

Saturated vs unsaturated fats

Answer 57

In unsaturated fats some of teh carbin are joined by double bonds giving a bend in Teh chain. In saturated fats all, teh carbon atoms are combined with hydrogen atoms.

Question 58

What occurs during teh process fo digestion

Answer 58

Large insoluble molecules in our food are broken to small soluble ones, so that they can be absorbed to our guts in teh blood and ultimately into cells.

Question 59

Bile function

Answer 59

Bile (alkaline) breaks down lipids (through a process called emulsification) into smaller droplets so taht lipase has a larger surface area to act on-this speeds up the digestion process. It also neutralizes stomach acids ensuring teh enzymes in the smal intestine hav the correct ph

Question 60

what happens when a cell has toomnuch water

Answer 60

Cytolysis, or osmotic lysis, occurs when a cell bursts due to an osmotic imbalance that has caused excess water to diffuse into the cell.