B8.2 Respiration

Question 1

State the word equation for aerobic respiration

Answer 1

Glucose + oxygen –> carbon dioxide + water

Question 2

State the symbol equation for aerobic respiration

Answer 2

C6H12O6 + 6O2 –> 6CO2 + 6H2O

Question 3

Define aerobic respiration

Answer 3

The chemical reactions in cells that use oxygen to break down nutrient molecules to release energy

Question 4

Define anaerobic respiration

Answer 4

The chemical reactions in cells that break down nutrient molecules to release energy without using oxygen

Question 5

What is energy used for?

Answer 5

• Muscle contraction
• Protein synthesis
• Growth
• Maintaining body temperature
• Cell division
• Active transport

Question 6

State the word equation for anaerobic respiration in yeast cells

Answer 6

Glucose –> ethanol + carbon dioxide + (energy)

Question 7

State the word equation for anaerobic respiration in muscles during vigorous exercise

Answer 7

Glucose –> lactic acid

Question 8

Describe the role of anaerobic respiration in yeast during bread-making

Answer 8

Yeast breaks down anaerobically to form alcohol and carbon dioxide instead of lactic acid

Question 9

Why do animals undergo anaerobic respiration during vigorous exercise?

Answer 9

They undergo anaerobic respiration because not enough oxygen is delivered to the muscles.

• Glucose is broken down to produce lactic acid.
• Lactic acid builds up in muscles and blood –> oxygen debt

Question 10

Why does the breathing rate remain high after exercise?

Answer 10

To repay oxygen debt, the lactic acid must be transported to the liver where it is broken down into carbon dioxide and water using oxygen.

Anaerobic respiration produces poisonous lactic acid, which exhausts the muscles by making the contractions less efficient. This lactic acid must be removed by oxidation (using oxygen) into carbon dioxide and water. This is why the body continues to breathe heavily even after the exercise. The body first “owes” oxygen to the muscles during the anaerobic respiration, and is simply
repaying the “debt” (the oxygen) back to the muscles. This is called oxygen debt.

Question 11

3 factors that influence the rate of respiration

Answer 11

• Temperature
• Oxygen concentration
• Glucose availability

Question 12

Where does aerobic respiration occur?

Answer 12

Mitochondria

Question 13

Where does anaerobic respiration occur?

Answer 13

Cytoplasm

Question 14

Define respiration

Answer 14

The release of energy from nutrient molecules via a chemical reaction