respiration

Question 1

Describe the process of glycolysis.

Answer 1

Phosphorylation of glucose using ATP;
Oxidation of triose phosphate to pyruvate;
Net gain of ATP;
NAD reduced;

Question 2

Describe how oxidation takes place in glycolysis and in the Krebs cycle.

Answer 2

removal ot hydrogen/dehydrogenation;
by enzymes/dehydrogenases;
H accepted by NAD/reduced NAD formed; in Krebs cycle, FAD (used as well);

Question 3

Water is a waste product of aerobic respiration. Describe how water is formed at the end of aerobic respiration.

Answer 3

oxygen is terminal/final electron acceptor;
combines with electrons and protons (to form water);

Question 4

Explain how the amount of
ATP Is increased by reactions occurring inside a mitochondrion

Answer 4

sxidation of/removal of electrons and H% from pyruvato
acetyl CoA / 6 carbon compound, (credit oxidative decarboxylation) substrate level production of ATP / ATP produced in Krebs cycle; production of reduced NAD / FAD (allow they take up hydrogen); in matrix of mitochondria;
electrons fed into electron transport chain / used in oxidative (Electrons) pass along carriers/through electron transport chain/through series of redox reactions;
Energy released;
Protons move Into intermembrane space:
ADP + Pi
ATP synthase

Question 5

Describe the roles of the coenzymes and carrier proteins in the synthesis of ATP.
OR
Describe the events of oxidative phosphorylation

Answer 5

NAD/FAD reduced / hydrogen attached to NAD/FAD;
H+ ions/electrons transferred from coenzyme to coenzyme/carrier to carrier (ETC on cristae of inner membrane)
Energy released (from electrons) through series of redox reactions;
Energy released used to pump H+/ protons into intermembrane space forming an electro-chemical gradient (of protons);
H+/ protons flow back through ATP synthase to produce ATP from
ADP and phosphate.

Question 6

In many mammals, uncoupling proteins’ help to maintain a constant body temperature during hibernation.
Suggest and explain how.

Answer 6

Allow passage of protons/H+;
(Energy) released as heat;

Question 7

The mitochondria in muscles contain many cristae.
Explain the advantage of this.

Answer 7

larger surface area for electron carrier system / MORE oxidative phosphorylation;
provide MORE ATP / energy for contraction;

Question 8

Give two reasons why the respirometer was left for 10 minutes when it was first placed in the water bath.

Answer 8

Equilibrium reached;
Allow for expansion (gases/liquids) /pressure change in apparatus;
Allow respiration rate of seeds to stabilise;

Question 9

Explain why a log scale is used to record the number of cells/bacteria.

Answer 9

Large range/difference/increase in numbers;
Accept reference to exponential (increase)

Question 10

Explain why converting pyruvate to lactate allows the continued production of ATP by anaerobic respiration.

Answer 10

Regenerates NAD / Oxidises reduced NAD;
(So) glycolysis continues;

Question 11

Malonate inhibits a reaction in the Krebs cycle.
Explain why malonate would decrease the uptake of oxygen in a respiring cell.

Answer 11

Less/no reduced NAD/coenzymes OR Fewer/no hydrogens/electrons removed (and passed to electron transfer chain);
Oxygen is the final/terminal (electron) acceptor;