Unit 1: Respiration From SQA CS

Question 1

A

Answer 1

The chemical energy stored in glucose must be released by all cells through a
series of enzyme-controlled reactions called respiration.

Question 2

B

Answer 2

The energy released from the breakdown of glucose is used to generate ATP. The
energy transferred by ATP can be used for cellular activities such as muscle cell
contraction, cell division, protein synthesis and transmission of nerve impulses.

Question 3

C

Answer 3

Glucose is broken down to two molecules of pyruvate, releasing enough energy to
yield two molecules of ATP. Further breakdown depends upon the
presence/absence of oxygen. If oxygen is present, aerobic respiration takes place,
and each pyruvate is broken down to carbon dioxide and water, releasing enough
energy to yield a large number of ATP molecules.
In the absence of oxygen, the fermentation pathway takes place. In animal cells,
the pyruvate molecules are converted to lactate and in plant and yeast cells they
are converted to carbon dioxide and ethanol.
The breakdown of each glucose molecule via the fermentation pathway yields only
the initial two molecules of ATP.

Question 4

D

Answer 4

Respiration begins in the cytoplasm. The process of fermentation is completed in
the cytoplasm whereas aerobic respiration is completed in the mitochondria.