Biology 9700 · AS & A Level · Respiration

Respiration — practice question

The elephant seal, Mirounga angustirostris, lives in the ocean for most of its life. Fig. 7.2 shows an elephant seal. Elephant seals are able to remain underwater for up to two hours. Respiration continues during this period. Fig. 7.3 shows the mass of blood in the body, as a percentage of total body mass, for the elephant seal and for three other mammals.
(b(i))[2]

Calculate how many times larger this value is for elephant seals than for humans. Show your working and give your answer to two decimal places.

(b(ii))[2]

Suggest why an elephant seal requires such a large mass of blood as a percentage of total body mass.

(c)[2]

Elephant seals have a very thick layer of adipose tissue beneath the skin. Adipose cells contain large amounts of fat molecules. Suggest why $1\,\text{g}$ of fat will yield more ATP than $1\,\text{g}$ of carbohydrate as a respiratory substrate in aerobic respiration.

(i)[2]

Calculate how many times larger this value is for elephant seals than for humans. Show your working and give your answer to two decimal places.

(ii)[2]

Suggest why an elephant seal requires such a large mass of blood as a percentage of total body mass.

(d(i))[1]

State how adipose tissue contributes to thermoregulation in elephant seals.

(d(ii))[2]

The hypothalamus in the brain acts as the control centre for thermoregulation. Outline how a change in the temperature of the external environment leads to an impulse arriving at the hypothalamus.

(d(iii))[2]

When the blood temperature of a mammal falls, one response is for its body to secrete more adrenaline. Suggest how an increase in adrenaline leads to an increase in blood temperature.

(a)[5]

Sampling may be used to determine the distribution and abundance of species in an area. Students sampled a rocky shore from a high tide area to a low tide area. They chose to use a belt transect. Describe how you would carry out a belt transect to assess the distribution and abundance of organisms in an area.

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