Exchange surfaces

Question 1

explain the advantage for larger animals of hvaning a specialised system that facilitates oxygen uptake

Answer 1

1. Larger animals have small surface area to volume ratio
2. Overcomes long diffusion pathway

Question 2

Use your knowledge of surface area to volume ratio to explian the higher metabolic rate of a mouse compared to a horse

Answer 2

1. Mice have a larger SA:Vol
2. Mouse loses heat faster
3. Respiration/metabolism loses heat

Question 3

Explain why oxygen uptake is a measure of metabolic rate in organisms

Answer 3

1. Oxygen used in respiration which us a metabolic process

Question 4

Suggest and explain how a reduced tidal volume affects the exchange of CO2 between the blood and the alveoli

Answer 4

1. Less CO2 moves out of lungs
2. The conc gradient between the alveoli and the blood is less steep
3. Less carbon dioxide moves from blood to alveoli

Question 5

Explain why death of alveolar epithelium cells reduces gas exchange in human lungs

Answer 5

1. Reduces the surface area
2. Increased distance for diffusion
3. Reduced rate of gas exchange

Question 6

Suggest and explain one way the leaf growth of xerophytic plants would be different from the leaf growth of sunflowers

Answer 6

1. Slower growth
2. Due to smaller number of stomata for gas exchange

Question 7

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

Answer 7

1. Alveolar epithelium
2. Endothelium capillary

Question 8

Describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into lymph vessels

Answer 8

1. Monoglycerides, fatty acid tails and bile salts form micelles
2. Makes fatty acids/monoglycerides more soluble in water
3. Fatty acid tails diffuse into the epithelial cells
4. Triglycerides are resynthesied
5. Leave in chylomicrons by exocytosis

Question 9

Describe the role of micelles in the absorption of fats into the cells lining the ileum

Answer 9

1. Micelles break down into monoglycerides, fatty acids and bile salts
2. Make fatty acids more soluble in water
3. Fatty acids absorbed by diffusion

Question 10

Explain the advantages of lipid droplet and micelle formation

Answer 10

1. Increases surface area
2. Faster hydrolysis
3. Micelles carry fatty acids and monoglycerides through membrane to cell walls