LAST MINUTE RESPIRATION + PHOTOSYNTHESIS

Question 1

Outline the main steps in cellular respiration

Answer 1

1. Glycolysis
2. Link reaction
3. Krebbs cycle
4. ETC + chemiosmosis

Question 2

What is the definition of cellular respiration

Answer 2

Gradual breakdown of nutrient molecules in a series of reactions that ultimately release energy in the form of ATP

Question 3

Outline the main processes in glycolysis

Answer 3

1. Glucose undergoes phosphorylation to form fructose 1,6 bisphosphate.
2. Fructose 1,6 bisphosphate splits to form triose phosphates.
3. Each triose phosphate undergoes oxidation while NAD+ undergoes reduction. An inorganic phosphate is added to triose phosphate.
4. Enzymes then take the phosphate groups and add them to ADP to form ATP.

Question 4

Outline the main processes in the link reaction

Answer 4

1. If oxygen is present, pyruvate enters the mitochondrial matrix via active transport.
2. Pyruvate is decarboxylated to form acetyl.
3. Acetyl is oxidised and NAD+ is reduced.
4. Acetyl group combines with CoA (coenzyme A) to form acetyl CoA.

Question 5

Outline the main processes in the Krebs Cycle

Answer 5

1. Acetyl CoA combines with oxaloacetate to form citrate.

2A. Citrate is oxidised while NAD+ is reduced to NADH.

2B. Citrate undergoes decarboxylation to form 5C molecule.

3A. 5C molecule is oxidised while NAD+ is reduced to NADH.

3B. 5C molecule is decarboxylated to form 4C molecule.

4A. 4C molecule is oxidised while NAD+ is reduced to NADH. FAD is reduced to FADH2.

4B. ATP formation also occurs (ADP is converted to ATP)

5. This results in the reformation of oxaloacetate (4C). Cycle repeats.

Question 6

Outline the main processes that occur in the electron transport chain.

Answer 6

1. NADH is oxidised (protons and electrons are dropped off in the matrix).
2. The electrons pass into the ETC.
3. Electrons are passed along the carriers
4. The movement of the electrons down the chain powers the transfer of protons into the intermembrane space to form a proton gradient.
5. FADH2 brings its electrons and protons into the chain at a later stage.
6. Oxygen combines with electrons and 2 protons to form water.

Question 7

Outline the main processes that occur during chemiosmosis

Answer 7

Protons move through the ATP synthase down their concentration gradient. Their energy is used to phosphorylate ADP into ATP.

Question 8

Outline anaerobic respiration in animals.

Answer 8

NADH is oxidised to NAD+ while pyruvate is reduced to lactate.

1. Anaerobic respiration allows for muscles to work vigorously for a short period of time.
2. Muscle burn during intense exercise occurs because of lactic acid accumulation.
3. Burn goes away when enough oxygen is provided so that aerobic cell respiration can occur.

Question 9

Outline anaerobic respiration in yeast

Answer 9

NADH is oxidised to NAD+ while pyruvate is reduced to ethanol. Carbon is released in the form of carbon dioxide as pyruvate is decarboxylated.

Question 10

What is the definition of photosynthesis?

Answer 10

The synthesis of food in a series of reactions using light energy and carbon dioxide.