Respiration

Question 1

Describe Aerobic respiration

Answer 1

Requires oxygen, produces CO2, water and a lot of ATP

Question 2

Describe Anaerobic Respiration

Answer 2

Takes place in absence of oxygen and produces lactate in animals or ethanol + CO2 in plants and fungi but only a little ATP

Question 3

How many stages are involved in aerobic respiration?

Answer 3

4

Question 4

What are the 4 stages of aerobic respiration

Answer 4

1) Glycolysis
2) Link reaction
3) Krebs cycle
4) Oxidative phosphorylation

Question 5

Briefly describe what happens in glycolysis

Answer 5

6 carbon glucose molecule is split into 3 carbon pyruvate molecules

Question 6

What’s the initial stage for both aerobic and anaerobic respiration

Answer 6

Glycolysis

Question 7

Fully describe Glycolysis

Answer 7

1) Phosphorylation of glucose occurs by adding two phosphate molecules from the hydrolysis of ATP into ADP to make glucose phosphate
2) Each glucose phosphate becomes more reactive and less stable so splits into 2x 3C molecules called triose phosphate
3) oxidation of triose phosphate occurs where a H is removed from each of the 2 and transferred to NAD to make reduced NAD
4) Each triose phosphate is then converted into another 3C molecule called pyruvate. In the process 2x ATP are regenerated from ADP

Question 8

What is the overall yield from one glucose molecule in glycolysis?

Answer 8

2x net ATP (4 produced, 2 invested)
2x reduced NAD
2x Pyruvate

Question 9

How is the pyruvate transferred to the matrix of the mitochondria for the link reaction to take place?

Answer 9

It is small enough to be actively transported into the matrix of the mitochondria after being produced in the cytoplasm

Question 10

Describe fully the link reaction

Answer 10

Pyruvate is oxidised (loses 2H and CO2=decarboxylation) to form Acetate (2C)
The hydrogen’s are then accepted by NAD to form reduced NAD
The 2C acetate then combines with coenzyme A to form 2C Acetyl CoA

Question 11

Where does the link reaction and krebs Cycle occur

Answer 11

In the matrix of the mitochondria

Question 12

Fully describe the Krebs cycle

Answer 12

1) The 2C Acetyl CoA combines with a 4C molecule in the matrix to produce a 6C molecule
2) the 6C molecule is oxidised by NAD (becomes reduced NAD) so loses a H and CO2 to produce a 5C molecule
3) 5C is then oxidised (loses 2H as CO2) by FAD to make FADH2 allowing ADP + Pi to make ATP
4) producing a 4C molecule ready to combine with Acetyl CoA for the cycle to begin again

Question 13

What are the products of the Krebs cycle?

Answer 13

Reduced NAD and FAD
1x ATP
3x CO2

Question 14

Why is the Krebs cycle so important?

Answer 14

1) it breaks down macromolecules into smaller ones (pyruvate into CO2)
2) produces H atoms that are carried by NAD to the ETC + provide energy for oxidative phosphorylation which produces ATP
3) regenerates 4C molecule that combines with Acetyl CoA
4) source of intermediate compounds used by cells to make fatty acids, aa’s + chlorophyll

Question 15

Where does oxidative phosphorylation occur?

Answer 15

In the inner folded membrane (cristae) of the mitochondria

Question 16

What is produced by oxidative phosphorylation

Answer 16

ATP

Question 17

Describe the synthesis of ATP during oxidative phosphorylation

Answer 17

• use storyboard sheet *

Question 18

What is the process of oxidative phosphorylation known as

Answer 18

The chemiosmotic theory

Question 19

In oxidative phosphorylation why are the 2e passed along a series of e transfer carrier molecules?

Answer 19

As the e’s move down an energy gradient as each ETCM is at a slightly lower energy level (from A to C) , it means little energy is lost as heat at a time so more can be harvested for the benefit of the organism.

Question 20

In anaerobic respiration of plants, what is produced?

Answer 20

The pyruvate is converted into ethanol and CO2

Question 21

In animals what is produced in anaerobic respiration?

Answer 21

Pyruvate is converted into lactate (lactic acid)

Question 22

What is different about anaerobic respiration compared to aerobic?

Answer 22

There’s an absence of oxygen so NAD and FAD aren’t resynthesised so glycolysis is different

Question 23

Fully describe glycolysis in anaerobic respiration in animals

Answer 23

The pyruvate is reduced to lactate by reduced NAD. This resynthesises NAD which is used to oxidise triose phosphate into pyruvate and yield 2x ATP

Question 24

What happens in plants during anaerobic respiration

Answer 24

2x Pyruvate molecules from glycolysis accept a H from reduced NAD (becomes NAD) and loses a CO2 to produce 2x ethanol