Respiration: Answers

What is meant by the term ‘anaerobic’?

Anaerobic means in the absence of oxygen.

Write the word equation for anaerobic respiration in yeast. How is this process useful to humans?

This process is useful to humans as ethanol can be used in alcoholic drinks and carbon dioxide can be used to make bread rise during baking.

Describe a test you could use to identify the gas produced when yeast respires anaerobically?

Hydrogencarbonate indicator is used to test for carbon dioxide gas produced during respiration. An alternative method is to bubble the gas through limewater and see if it turns milky.

Write the word and symbol equations for aerobic respiration.

Carbon dioxide and water are waste products from aerobic respiration. Explain how they are removed from the body.

We exhale (breathe out) carbon dioxide to remove it from the body. Excess water is removed in our urine, sweat and as tiny droplets of water vapour in our breath.

Explain what would happen if mitochondria stopped functioning.

If mitochondria stopped working, our bodies would not be able to carry out aerobic respiration. Our cells would resort to anaerobic respiration which takes place in the cytoplasm but produces much less ATP. Less ATP means less energy for important biological processes, such as the active transport of digested food molecules from the small intestine into the bloodstream. Also, less heat would be generated (heat is a by-product of respiration) and our body temperature would fall.