3.3.1 - SURFACE AREA TO VOLUME RATIO

Question 1

explain the advantage for larger animals of having a specialised system that facilitates oxygen uptake (2)

Answer 1

1. larger organisms have a smaller SA:V ratio
2. so this is an advantage, to overcome the long diffusion pathway

Question 2

mammals such as a mouse and a horse are able to maintain a constant body temperature.

use your knowledge of surface area to volume ratio to explain the higher metabolic rate of a mouse compared to a horse. (3)

Answer 2

1. mouse is smaller so it has a larger SA:V ratio
2. more/faster heat loss in relation to body size
3. faster rate of metabolism/respiration releases heat

Question 3

describe the relationship between size and surface area to volume ratio of organisms (1)

Answer 3

1. as size increases, ratio of SA:V ratio decreases
2. smaller organisms have a larger SA:V ratio

Question 4

the scientist decided to use the ratio of surface area to mass, rather than the ratio of surface area to volume. he made this decision for practical reasons.

suggest one practical advantage of measuring the masses of frog eggs, tadpoles and adults, compared with measuring their volumes (1)

Answer 4

more accurate

Question 5

explain why oxygen uptake is a measure of metabolic rate in organisms (1)

Answer 5

oxygen is used in respiration which provides energy/ATP

OR

respiration is a metabolic process