SA:V ratio exam q

Question 1

Explain the advantage for larger animals of having a specialised system
that facilitates oxygen uptake.

Answer 1

1. Large(r) organisms have a small(er) surface area:volume (ratio);
   OR
   Small(er) organisms have a large(r) surface area:volume (ratio);
2. Overcomes long diffusion pathway
   OR
   Faster diffusion;

Question 2

Suggest how the environmental conditions have resulted in adaptations of
systems using Model A rather than Model B. Look at page 2 in SA:V ratio QP

Answer 2

Mark in pairs, 1, and 2 OR 3. and 4.
1. Water has low(er) oxygen partial pressure/concentration (than air);
2. So (system on outside) gives large surface area (in contact with
water)
OR
So (system on outside) reduces diffusion distance
(between water and blood);
3. Water is dense(r) (than air);
4. (So) water supports the systems/gills;

Question 3

Give one suggestion to explain why Bats have a smaller SA:V ratio compared to Shrews

Answer 3

Provides more oxygen for respiration;

Question 4

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.

Answer 4

Mouse
1. (Smaller so) larger surface area to volume ratio;
2. More/faster heat loss (per gram/in relation to body size);
3. (Faster rate of) respiration/metabolism releases heat;

Question 5

The scientist used units of μmol g–1 h–1 for the rate of oxygen uptake.
Suggest why he used μmol in these units

Answer 5

(Measures) small uptake / amount / quantity / volume / concentration / rate
(of oxygen uptake);
OR
Avoids use of powers of ten / standard form / many decimal places;

Question 6

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.

Answer 6

More accurate / less error (in measuring mass);
OR
Causes less distress / damage to animal (to measure mass);
OR
Easier / quicker (to find mass) because irregular shapes;
OR
Fewer measurements / calculations;

Question 7

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

Answer 7

(Oxygen used in) respiration, which provides energy / ATP;
OR
(Oxygen is used in) respiration, which is a metabolic process /
chemical reaction;

Question 8

A student who looked at these results said that they could not make a
conclusion about the relationship between stage of development and
metabolic rate.
Use information in the table to explain reasons why they were unable to
make a conclusion. (ALL YOU NEED TO KNOW IS THAT THERE IS NO INFORMNAION FOR ONE OF RESULTS)

Answer 8

1. No information about egg;
2. So cannot compare all stages (in Table 2);
   Idea of comparing all three stages needed
3. No statistical information / test / t-test / comparison of standard
   deviations;
   OR
   No measure of significant differences;