Yeast cells are able to regenerate ${\mathrm{NAD}}^{+}$ regenerated from NADH during the :
1. reduction of acetaldehyde to ethyl alcohol
2. oxidation of pyruvate to acetyl CoA
3. reduction of pyruvate to form lactate
4. oxidation of NAD⁺ in the citric acid cycle

In the glycolytic pathway, ATP formation:
1. does not occur
2. requires presence of oxygen
3. needs a proton gradient across a membrane
4. involves substrate-level phosphorylation

The importance of lactic acid fermentation lies in the fact that it:
1. reduces NAD⁺ to NADH
2. reduces FAD⁺ to FADH₂
3. oxidizes NADH to NAD⁺
4. reduces FADH₂ to FAD⁺

The mitochondrial proton gradient would be highest leading to ATP synthesis when the following condition is present:
1. pyruvate (present)-oxygen (present)-ATP levels (high)
2. pyruvate (present)-oxygen (present)-ATP levels (low)
3. pyruvate (present)-oxygen (absent)-ATP levels (high)
4. pyruvate (absent)-oxygen (present)-ATP levels (low)

Glycolytic pathway evolved very early in evolution. This is supported by the fact that:

Out of the following what is both used and produced during the glycolytic pathway?
I. ATP
II. ADP
III. Phosphate groups
IV. NADH
1. I, II and III only
2. I, II and IV only
3. I, III and IV only
4. I, II, III and IV

Which of the following is an allosteric enzyme?
1. Hexokinase.
2. G3P dehydrogenase.
3. Fumarase.
4. Phosphofructokinase.

Direct use of oxygen is in:

In the ETS in mitochondria, identify the product that is not correctly matched with its number:

When the amount of ATP is increased in a cell, it is expected to:
1. inhibit the enzyme phosphofructokinase.
2. activate the enzyme citrate synthase.
3. inhibit the enzyme pyruvate kinase.
4. activate the enzyme pyruvate dehydrogenase.