B2 4 Aerobic and Anaerobic Respiration

Question 0

Where do the reactions in aerobic respiration take place?

Answer 0

In the mitochondria where the folded inner membrane gives a large surface area where enzymes which release cellular respiration are found.

Question 1

What is the aerobic respiration reaction?

Answer 1

Glucose + oxygen —> carbon dioxide + water (+energy)

Question 2

Reasons for respiration

Answer 2

Living cells need energy to carry out the basic functions of life. Energy released by respiration is used here for synthesis reactions. For example, in plants the sugars, nitrates and other nutrients are built up into amino acids. These amino acids build up into proteins.

Energy is also used to make muscles contract. Muscular activities use energy.

Mammals and birds need to keep their bodies at a constant temperature regardless of the temperature of the surroundings.

Question 3

Body responses to exercise

Answer 3

An increase in the heart rate and the arteries supplying blood to the muscles dilate (widen). This change increases the blood flow to the muscles which in turn increases the supply of oxygen and glucose to the muscles. The carbon dioxide removed from the body also increases.

The breathing rate and the depth of breathing increases too. More oxygen is brought into your lungs and picked up by your red blood cells. This oxygen is carried to the muscles. More carbon dioxide is also removed from the lungs and breathed out.

Glycogen stores in the muscle are converted to glucose for cellular respiration and the blood flow to the muscles increases.

Question 4

Anaerobic respiration

Answer 4

When vigorous exercise occurs, the muscle cells may become short of oxygen. Even though the heart and breathing rates increase, the blood can’t supply oxygen to the muscles fast enough. The muscles use anaerobic respiration.

In anaerobic respiration glucose is not broken down completely, lactic acid is produced instead of carbon dioxide and water.

Question 5

Muscle fatigue

Answer 5

Anaerobic respiration isn’t as effective as aerobic respiration. This is because the glucose molecules aren’t broken down completely so less energy is released. Small amounts of energy are released due to the build up of lactic acid.

Anaerobic respiration: glucose —> lactic acid (+ energy)

Question 6

What is the oxygen debt?

Answer 6

The oxygen debt is the amount of oxygen needed to break down the lactic acid to carbon dioxide and water.