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
  = 2x ATP net gain, 2x NADH, 2x Pyruvate
  IN CYTOPLASM

Question 2

Describe the link reaction.

Answer 2

• occurs in the matrix
• pyruvate oxidised and decarboxylated into acetate
• produces reduced NAD and CO2
• acetate combines with co-enzyme A to produce Acetylco-enzyme A
  = 2x NADH, 2x Acetylco-enzyme A, 2x CO2

Question 3

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

Answer 3

• removal of hydrogen
• by enzymes dehydrogenase
• H accepted by Nad
• in Krebs, FAD used as well
  Krebs produces = 6x NADH, 4x CO2, 2x ATP, 2x FADH
  OCCURS IN MATRIX

Question 4

Describe how water is formed at the end of aerobic respiration.

Answer 4

• oxygen is final electron acceptor
• combines with electrons and protons to form water

Question 5

Explain how the amount of ATP is increased by reaction occurring inside a mitochondrion.

Answer 5

• oxidation of electrons and H+
• from pyruvate
• oxidative decarboxylation
• substrate level production of ATP
• production of reduced NAD/FAD
• in matrix of mitochondria
• electrons fed into ETC
• pass along through a series of redox reactions
• energy released
• protons move into intermembrane space
• ATP/ADP +Pi
• via ATP synthase

Question 6

Describe events of oxidative phosphorylation.

Answer 6

• NAD/FAD reduced.
• H+ ions from co-enzyme to carrier
• energy released through series of redox reactions
• used to pump H+ into intermembrane space
• forms electro-chemical gradient
• H+ through ATP synthase forming ATP

Question 7

How do mammals maintain a constant body temperature during hibernation?

Answer 7

• allow passage of protons
• energy released as heat

Question 8

Advantage of many cristae in mitochondria…

Answer 8

• larger surface area = more oxidative phosphorylation
• more ATP for contraction

Question 9

Two reasons why the respirometer was left for 10 mins when first placed in water bath.

Answer 9

• equilibrium reached
• allow for expansion/ pressure change
• 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 in numbers
• exponential increase

Question 11

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

Answer 11

• regenerates NAD
• so glycolysis continues

Question 12

Explain why malsoante would decrease the uptake of oxygen in a respiring cell.

Answer 12

• less electrons removed and passed to ETC
• oxygen is the final electron acceptor

Question 13

Respirometers…

Answer 13

• ink moves from higher to lower due to pressure in tube (moves towards organism)
• measure TIME TAKEN

Question 14

Anaerobic respiration…

Answer 14

• link reaction, kerbs and ETC stop
• no O2 as final electron acceptor
• glycolysis does not require O2
• H from NADH accepted by pyruvate
• pyruvate reduced to lactate (animals) and ethanol (plants)