Topic 1: Lifestyle, Health and Risk Flashcards
1.1) Why do organisms need mass transport systems?
1) organisms need to be constantly exchanging substances with their environment in order for their cells to carry out important metabolic processes and remove harmful waste products.
2) Most multicellular organisms need a mass transport systems because the bigger an organism is, the lower its surface area to volume ratio and the larger the diffusion distance is to its cells. This decreases the rate of diffusion of substances into and out of the cells.
3) As a result mass transport systems are needed to ensure a sufficient supply and removal of substances to and from the organisms cells.
1.2) What is meant by a dipolar molecule?
A dipolar molecule is a molecule that has a partial negative charge on one side and a partial positive charge on the other caused by an uneven distribution of electrons.
1.2) What makes water good at transporting substances?
Water’s dipole nature makes it both cohesive and a good solvent.
- Cohesion is the attraction between molecules of the same type. Water molecules are very cohesive because they’re dipolar. This helps water flow, making it great for transporting substances.
-water is also able to hydrogen bond to other molecules; this is known as adhesion. This means water flows easily.
-Water’s dipole nature makes it useful as a solvent in living organisms because it dissolves ionic substances. E.g. in humans, important ions can dissolve in the water in blood and then be transported around the body.
1.3)How does the structure of a artery relate the its function?
Arteries transport oxygenated blood away from the heart
- Outer Wall: Contains elastic tissue, which helps to maintain blood pressure in the arteries. It stretches and recoils to even out any fluctuations in pressure. Contains the structural protein collagen. Collagen is a strong protein that protects blood vessels from damage by over-stretching.
- Endothelium: Very smooth and reduces friction for free blood flow. Its highly folded, enabling it to expand under high pressure.
- Thick inner layer of muscle and elastic fibres: Muscle cells strengthen the arteries so that they can withstand high pressure. Contraction of the muscles also enables the blood vessel to constrict and narrow the lumen for reduced blood flow (i.e. for the redirection of blood flow during exercise).
-Narrow Lumen: Helps to maintain a high blood pressure
1.3) How does the structure of a vein relate to its function?
Transports deoxygenated blood back to the heart.
- Thin muscle wall: There is no need for a thick muscular layer as veins don’t have to withstand high pressure .
- Wide Lumen: Helps to ensure that blood returns to the heart at an adequate speed and increases the volume of blood that can be delivered per unit of time. It also reduces friction between the blood and the endothelium layer of the vein.
- Contains valves: Prevents backflow of blood helping return blood to the heart.
1.3) Capillary Beds
Networks of capillaries (small bloods vessels) that allow the exchange of gas, water and nutrients.
1.3) How does the structure of capillaries relate them to their function?
Capillaries exhange materials between the blood and tissue cells.
- The capillary wall is made of a single layer of flattened endothelial cells. The wall is 1 cell thick; this reduces the diffusion distance for oxygen and co2 between the blood and the tissues of the body.
- Narrow Lumen: Red blood cells need to pass through the capillaries single file. This forces the blood to travel slowly which provides more time for diffusion to occur.
- Pores in the walls: The cells of the wall have gaps called pores which allow for the exchange of larger molecules. They allow blood plasma to leak out and form tissue fluid. White blood cells can combat infection in affected tissues by squeezing through the pores in capillary walls.
1.12) monosaccharides
Monosaccharide are single sugar monomers. They are the simplest carbohydrates.
1.12) Disaccharides
Disaccharides are formed by joining two monosaccharides together in a condensation reaction.
1.12) polysaccharides
Polysaccharides are carbohydrate polymers made up of many monosachccharides joined by glycosidic bonds in a condensation reaction to from chains.
What is the name of the bond that is formed when monosaccharides join together?
Glycosidic
1.12) What is the name of the reaction that joins monosaccharides together?
Monosaccharides join together via a condensation reaction. This forms water and creates a glycosylic bond.
1.12) What is the name of the reaction that breaks monosaccharides apart?
Monosaccharides are broken apart via a hydrolysis reaction. This requires water and breaks a glycosydic bond.
1.12) What is the main energy store in plants?
Starch
What makes starch good for storage?
It is insoluble in water so it doesn’t cause water to enter cells by osmosis which would make them swell. This makes it good for storage.
1.12) Starch is a mixture of what two polysaccharides?
Amylose and Amylopectin
1.12) Amylose structure
-Unbranched chain of a-glucose.
-Joined by 1-4 glycosidic bonds.
-Coiled structure makes it compact and good for storage.
1.12) Amylopectin structure
-Branched chain of glucose (side branches allow enzymes to get to the glycosidic bonds easily so glucose can be released quickly).
-Contains 1-4 and 1-6 glycosidic bonds.
1.12) What is the main energy store in animals?
Glycogen
1.12) Describe the structure of Glycogen and how it is adapted to it’s role as an energy store in animals.
- Glycogen is a polysaccharide of a-glucose
-Its structure is similar to amylopectin (it has 1-4 and 1-6 glycosidic bonds), except it has even more side branches.
-lots of branches means that stored glucose can be released quickly, which is important for energy release in animals.
-It is a large molecule so stores lots of energy.
-It is a compact molecule so good for storage.
-It is insoluble in water so doesn’t cause the cell to swell by osmosis
What is the difference between a-glucose and B-glucose structurally?
The position of of the hydroxyl (-OH) group.
- in a-glucose the hydrogen is above the hydroxyl group.
- in b-glucose the hydrogen is below the hydroxyl group.
what is the molecular formula of glucose?
C6H12O6
What is the function of glucose?
It is the main energy stource for animals and plants.
How is the structure of glucose related to its function?
-It is soluble so can be transported easily.
-It is small so is easily transported in and out of cells via carrier proteins.
-It has many covalent bonds which store energy.
What two monosaccharides combine to make the disaccharide maltose and what is the glycosidic bond that forms?
a-glucose and a-glucose join with a 1-4 glycosidic bond.
What is the function of maltose?
It is an energy source in germinating seeds.
What two monosaccharide join to form the disaccharide sucrose and what is the glycosidic bond that forms?
a-glucose and fructose join with a 1-2 glycosidic bond.
What is the function of sucrose?
Sucrose is transported in the phloem to provide sugars to other parts of the plant.
What two monosaccharides combine to form the disaccharide lactose and what is the glycosidic bond that forms?
b-glucose and galactose join with a 1-4 glycosidic bond
What is the function of lactose?
Lactose is found in mammalian milk to provide energy for infant mammals .
What does a triglyceride consist of?
One glycerol molecule and three fatty acids.
Explain the formation of a triglyceride.
The hydrogen atoms from the hydroxyl groups on the glycerol molecule bond to a hydroxyl group (OH) on each fatty acid. This forms 3 ester bonds between the glycerol molecule and each fatty acid. The process releases 3 molecules of water so it is an example of a condensation reaction
What is the structure of a fatty acid?
A fatty acid consists of a carboxylic group and a long hydrocarbon tail.
Saturated lipids
Saturated fatty acids contain only single covalent bonds between the carbon atoms.
