Respiration

Question 1

Describe the process of glycolysis.

Answer 1

Cytoplasm (requires no oxygen )
• Phosphorylation of glucose using ATP;
Oxidation of triose phosphate to pyruvate;
Net gain of 2 ATP;
2 NAD reduced;

Question 2

Describe the link reaction

Answer 2

Occurs in the matix (mitochondrion)
Pyruvate oxidised and decarboxylated into Acetate.(2C)
Produces reduced NAD and CO2
Acetate combines with coenzyme A to produce Acetyl co A (2C)
Reject ATP is formed.

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

oxidation of/removal of electrons and H+ from pyruvate
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/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 /
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

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

Answer 8

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

Question 9

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

Answer 9

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

Question 10

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

Answer 10

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

Question 11

Malonate inhibits a reaction
in the Krebs cycie
Exolain 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;

Question 12

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

Answer 12

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