Respiration

Question 1

aerobic respiration

Answer 1

requires oxygen and produces carbon dioxide, water and much ATP

Question 2

anaerobic respiration

Answer 2

takes place in the absence of oxygen and produces lactate or ethanol and carbon dioxide but only little ATP

Question 3

What are the four stages of of aerobic respiration

Answer 3

-glycolysis
-link reaction
-krebs cycle
-oxidative phosphorylation

Question 4

Describe the process of glycolysis

Answer 4

-Phosphorylation of glucose using ATP
- Oxidation of TP to pyruvate
-Net gain of ATP
-NAD reduced

Question 5

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

Answer 5

-Less reduced NAD
-oxygen is the final electron acceptor

Question 6

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

Answer 6

-Regenerates NAD
-So glycolysis can continue

Question 7

Where does glycolysis occur

Answer 7

Cytoplasm

Question 8

Process of the link reaction

Answer 8

-Pyruvate from glycolysis is oxidised to acetate
- Hydrogen lost by pyruvate is picked up by NAD and reduced to NADH and 1C is produced
-Acetate combines with coenzyme A to produce AcetylCOA

Question 9

Process of the Krebs cycle

Answer 9

• AcetylCOA from the link reaction combines with a 4C molecule to make a 6C molecule
  -In a series of redox reactions the 6C molecule becomes a 4C losing 2 carbon dioxide and hydrogen
  -ATP is produced
  -The hydrogen removed during the reactions reduces FAD and NAD

Question 10

why are NAD and FAD important

Answer 10

they have the potential to provide energy to produce ATP molecules by oxidative phosphorylation

Question 11

Where does the link and krebs cycle occur

Answer 11

Matrix of the mitochondria

Question 12

what is a coenzyme

Answer 12

molecules which transfer chemical groups in reactions and are continually recycled

Question 13

What is an example of a coenzyme

Answer 13

-NAD
-FAD
-NADP

Question 14

What is the significance of the kreb cycle

Answer 14

-it breaks down macromolecules into smaller ones (pyruvate to carbon dioxide
-produces hydrogen that are carried by NAD to the electron transfer chain and provides energy for oxidative phosphorylation

Question 15

Process of oxidative phosphorylation

Answer 15

-NADH is oxidised and the e- reduce the first electron carrier in the electron transfer chain.
-Series of redox reactions as they transfer between electron carriers and release energy
-FADH donates electron to the chain
- The energy from the e- allows the active transport of H+ from the matrix through proton pumps to the inner membrane space
-Maintains a chemiosmotic gradient with a high conc of H+ in the intermembrane space and low conc in the matrix
-H+ diffuse by facilitated diffusion through ATP synthase making ATP
-Oxygen is the final electron acceptor, along with H+ to form water.

Question 16

Where does oxidative phosphorylation occur

Answer 16

inner membrane/ cristae of the mitochondria

Question 17

Explain how energy is released by respiration in the absence of oxygen

Answer 17

In the absence of oxygen FAD and NAD will be reduced but unable transfer their hydrogen atoms in the electron transfer chain. This results in NAD and FAD being unavailable for further reduction during krebs cycle. Only glycolysis can occur, this happens due to hydrogen being removed from reduced NAD by the pyruvate that has been produced.

Question 18

Explain how ethanol is produced by anaerobic respiration

Answer 18

Some bacteria, fungi and plants produce ethanol during anaerobic respiration (fermentation). The pyruvate from glycolysis loses a carbon dioxide molecule and accepts hydrogen from reduced NAD to form ethanol.

Question 19

Explain how lactate if produced by anaerobic respiration

Answer 19

Animals in short supply of oxygen produce lactate (also known as lactic acid). Pyruvate from glycolysis removes hydrogen from reduced NAD to form lactate.