Respiration

Question 1

What is energy from respiration used for?

Answer 1

• to keep warm
• to enable muscles to contract
• to build up large molecules from small ones
• in active transport of substances across cell membranes

Question 2

What are the reactants and products in respiration?

Answer 2

Oxygen and glucose react to form ATP, water and carbon dioxide.

Question 3

What is the word and symbol equation for aerobic respiration?

Answer 3

glucose + oxygen -> water + carbon dioxide (+ATP)

C6H12O6 + 6O2 -> 6H2O + 6CO2 (+ATP)

Question 4

What is the difference between aerobic and anaerobic respiration?

Answer 4

• Aerobic respiration requires oxygen and produces carbon dioxide and water, whereas anaerobic respiration doesn’t, and has different end products.
• Anaerobic respiration also releases much less energy than aerobic respiration because it only partially breaks down glucose molecules (aerobic respiration does fully)

Question 5

When is anaerobic respiration used?

Answer 5

Additional energy is supplied by anaerobic respiration when:
-in diving animals
- inside plants where diffusion of oxygen is too slow for aerobic respiration to take place (e.g. in seeds or root cells in waterlogged ground)
- in muscle cells when vigorous exercise requires more energy than can be provided by an increased supply of oxygen from deeper, faster breathing and a faster heart rate.

Question 6

What is the word equation for anaerobic respiration in animals?

Answer 6

Glucose -> lactic acid (+ATP)

Question 7

What is the word equation for anaerobic respiration in plants?

Answer 7

Glucose -> ethanol + carbon dioxide (+ATP)

Question 8

How is yeast used to make bread?

Answer 8

Yeast and sugar is added to flour to form a dough. Anaerobic respiration of yeast produces carbon dioxide which forms bubbles in the dough, making it light and fluffy.

Question 9

Investigate the role of anaerobic respiration by yeast in different conditions
The effect of temperature

Answer 9

1. Set up a series of closed tubes containing a solution of yeast and sugar at the same concentration and connect each tube to a gas syringe to measure the volume of gas given off
2. Then place each tube in a water bath at a different temperature for 10 minutes and measure the volume of gas produced (hence the rate of respiration)