Heat from metabolism: Higher Level only: This statement is Higher Level only. It links enzymes and respiration to how mammals and birds keep warm.
Practise this as you read
- Explain why heat generation is inevitable.
- Outline how mammals and birds depend on it.
Free preview
This is the free notes preview
You're reading the free notes. Aimnova Pro unlocks the full study experience — and you can try it with your first topic free to keep:
- FlashcardsLock in vocabulary and key terms with spaced repetition.
- Practice questionsAnswer exam-style questions and get instant AI marking.
- Mock exams & past-paper vaultSit full mocks and see exactly how examiners award marks.
- Personalised study planA daily plan built around your exam date and weak areas.
Start Studying Free Full access to Aimnova Pro · cancel anytime
The big idea: No energy transfer in metabolism is 100% efficient, so every reaction releases some energy as heat. Mammals and birds use this heat to keep a constant body temperature.
The points to remember
- Respiration captures less than half of the energy in glucose as ATP; the rest is released as heat.
- Using ATP for work, such as muscle contraction or active transport, releases more heat.
- Heat production is inevitable: it cannot be avoided.
- Mammals and birds depend on this heat to stay warm; shivering raises respiration to make more.
Remember it as: Every transfer leaks heat; warm-blooded animals keep it.
Real example: brown fat in babies. Newborn babies have brown adipose tissue, whose cells respire fat but release the energy as heat instead of making ATP, keeping the baby warm.
Trap: Heat is not 'made' from nothing. It is energy from food that was not captured in ATP or in new molecules.
Stop wasting time on topics you know
Our AI identifies your weak areas and focuses your study time where it matters. No more overstudying easy topics.
Try Smart Study FreeYour first topic is free to keep • No credit card required
How it is asked: Expect an explanation of why metabolism produces heat and which animals depend on it.
IB-style questionExplain[3 marks]
Explain why the reactions of metabolism generate heat, and how this benefits mammals.
Model answer plan
See the answer broken into clear points, with guidance on how each point earns marks.