1.1. Some hibernating mammals undergo multiple periods of torpor (reduced activity), interspersed with periods of wakefulness, throughout their hibernation.

Research was carried out into the physiological changes occurring in a species of mammal during a period of torpor.

Some of the results are shown in Fig. 1 below.

Fig. 1

(i) Explain the relationship between metabolic rate and body temperature shown in Fig. 1

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(ii) Suggest the time period during which the mammal enters a state known as 'steady torpor'.

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1.2. Describe the changes in respiratory quotient shown in Fig. 1.

1.3. Suggest what can be concluded from Fig. 1 about respiratory substrates and torpor.

1.4. Suggest the benefit to mammals of brief periods of torpor and arousal, rather than extended periods of unbroken hibernation.