1. Write a definition of cellular respiration.
Answer
Cellular respiration is an exothermic reaction that occurs continuously in living cells and either transfers the energy needed for life processes or releases the energy stored in glucose for these processes.
2. Write the word equation for aerobic respiration.
Answer
3. What is another word for anaerobic respiration in yeast cells ?
Answer
Anaerobic respiration in yeast cells is called fermentation.
4. Why living things need energy ?
Answer
The energy is needed for chemical reactions that build larger molecules, for movement, for keeping warm, and for growth and repair.
5. Explain why a person cannot exercise efficiently when anaerobic respiration is taking place in muscle cells.
Answer
Lactic acid builds up, creating an oxygen debt, causing muscles to become fatigued and contract less efficiently.
6. Give some ways that the human body responds to the increased demand for oxygen in the muscles.
Answer
The heart rate increases to supply the muscles with more oxygenated blood, while both the breathing rate and breath volume also increase.
7. Name the molecule that can be synthesised from glucose.
Answer
Glycogen can be synthesised from glucose molecules.
8. Name the molecule produced when excess proteins and amino acids are broken down.
Answer
Urea is produced when excess proteins and amino acids are broken down.
9. Give some uses of anaerobic respiration in yeast in the manufacture of food and drinks.
Answer
It is used in bread, beer, and wine making.
10. The figure below shows the apparatus a student used to investigate the effect of temperature on the rate of anaerobic respiration in yeast. Explain why the student added a layer of liquid paraffin.
Answer
To prevent the entry of oxygen, ensuring that aerobic respiration does not occur and that conditions remain anaerobic.