Topic 12 - Respiration

Question 1

What is the purpose of respiration?

Answer 1

To release energy from glucose
To produce ATP

Question 2

What is the general equation for aerobic respiration?

Answer 2

6O2 + C6H12O6 –> 6H20 + 6CO2 + energy

Question 3

What do plants need energy for? (name 5)

Answer 3

Photosynthesis
Active transport of minerals via roots
DNA replication
Cell division
Protein Synthesis

Question 4

What do animals need energy for? (name 6)

Answer 4

Muscle contraction
Maintaining a constant body temperature
Active transport
DNA replication
Cell division
Protein synthesis

Question 5

What is the chemical name for ATP?

Answer 5

Adenosine triphosphate

Question 6

What are the 3 components of ATP

Answer 6

1 molecule of adenine
1 molecule of ribose
3 molecules of phosphate ions

Question 7

How is ATP formed?

Answer 7

Condensation reaction between ADP and Pi
Catalysed by ATP synthase

Question 8

Which enzyme catalyses the condensation reaction between ADP and Pi

Answer 8

ATP synthase

Question 9

What is phosphorylation

Answer 9

Adding phosphate to a molecule

Question 10

How does ATP move through the cell

Answer 10

Diffusion

Question 11

Which enzyme catalyses the hydrolysis of ATP?

Answer 11

ATP hydrolase

Question 12

What are the 6 properties of ATP

Answer 12

1) Stores and releases small amount of energy so none wasted as heat
2) Small, soluble molecules so easily transported
3) Easily hydrolysed so energy releases instantly
4) Quickly resynthesised
5) Make other molecules more reactive (phosphorylation)
6) Can’t pass out of cell so immediate energy supply

Question 13

What is the compensation point?

Answer 13

The level of light intensity (in plants) where the rate of respiration and photosynthesis are the same

Question 14

How could you find a plants compensation point

Answer 14

Plot a graph of light intensity against net oxygen production. Find the light intensity when the new oxygen production = 0

Question 15

What are 3 differences between aerobic and anaerobic respiration?

Answer 15

1. Aerobic uses oxygen, anaerobic doesn’t
2. Aerobic has 4 stages, anaerobic just has glycolysis
3. Aerobic produces CO2 and H2O , anaerobic produced lactic acid (animals) and ethanol (yeast)

Question 16

Where does glycolysis occur?

Answer 16

Cell cytoplasm

Question 17

Which 3 coenzymes are used in aerobic respiration?

Answer 17

NAD, FAD, coenzyme A

Question 18

Which stage of respiration is an anaerobic process and why?

Answer 18

Glycolysis
Uses no O2

Question 19

What are the 2 stages of glycolysis?

Answer 19

1. Phosphorylation of glucose
2. Oxidation of triose phosphate

Question 20

What is the purpose of glycolysis?

Answer 20

To produce pyruvate from glucose

Question 21

Describe what happens when glucose is phosphorylated? (3 stages)

Answer 21

1. ATP donates Pi to glucose to from glucose phosphate (and ADP)
2. ATP donates Pi to glucose phosphate to form hexose bisphosphate (and ADP)
3. Hexose bisphosphate split to form 2 molecules of triose phosphate

Question 22

Describe what happens when 2 molecules of triose phosphate is oxidised?

Answer 22

2 molecules of triose phosphate are oxidised to 2 molecules of pyruvate
2 molecules of NAD are reduced to form reduced NAD
4 molecules of ATP are produced from 4 molecules of ADP/Pi

Question 23

What is the net production of ATP in glycolysis?

Answer 23

2 ATP
2 used and 4 produced

Question 24

What is the reduced NAD produced in glycolysis used for?

Answer 24

Oxidative phosphorylation

Question 25

What is the pyruvate produced in glycolysis used for?

Answer 25

Actively transported into the mitochondrial matrix Link reaction

Question 26

Why does glycolysis take place in the cytoplasm?

Answer 26

Glucose can't cross the mitochondrial membrane because it is too big

Question 27

Describe the process after glycolysis in yeast/plants (2 stages)

Answer 27

1. Pyruvate loses CO2 to form ethanal 2. Ethanal reduced to ethanol and reduced NAD oxidised to NAD

Question 28

What is the purpose of anaerobic respiration?

Answer 28

To produce ATP by glycolysis Oxidises reduced NAD from glycolysis to NAD to allow glycolysis to continue

Question 29

Describe the process of glycolysis in animal cells / some bacteria

Answer 29

Pyruvate reduced to lactate (lactic acid) Reduced NAD oxidised to form NAD

Question 30

Where does the link reaction occur?

Answer 30

Matrix of the mitochondria

Question 31

What is the purpose of the link reaction

Answer 31

To convert pyruvate to acetyl coenzyme A

Question 32

Describe what happens during the link reaction

Answer 32

1. Pyruvate is decarboxylated to form acetate 2a. Pyruvate is oxidised to acetate 2b. NAD is reduced to reduced NAD 3. Coenzyme A combines with acetate to form acetyl coenzyme A

Question 33

Where is the acetyl coenzyme A used

Answer 33

Krebs cycle

Question 34

Where is the reduced NAD used?

Answer 34

Oxidative phosphorylation

Question 35

What happens to the CO2 produced in the link reaction

Answer 35

lost as a waste product

Question 36

What happens in the Krebs cycle

Answer 36

ATP and reduced coenzymes are produced in a series of redox reactions CO2 is lost as a waste product

Question 37

Where does the Krebs cycle take place

Answer 37

Matrix of the mitochondria

Question 38

Describe what happens in the Krebs cycle

Answer 38

1. Acetyl CoA reacts with 4 carbon compound to form a 6 carbon compound and coenzyme A 2. The 6 carbon compound forms a 5 carbon compound 3. The 5 carbon compound reforms the 4 carbon compound

Question 39

What is substrate level phosphorylation?

Answer 39

When a phosphate group is directly transferred from one molecule to another e.g. the production of ATP in the Krebs cycle

Question 40

What is the CoA produced in the Krebs cycle used for?

Answer 40

The link reaction

Question 41

What are the reduced enzymes produced in the Krebs cycle used for?

Answer 41

Oxidative phosphorylation

Question 42

What is oxidative phosphorylation

Answer 42

The process where energy from electrons form reduced coenzymes is used to synthesise ATP

Question 43

Describe the stages of oxidative phosphorylation

Answer 43

1. NAD/FAD release H atoms (split to H+ and e-) 2. Electrons move down the ETC and lose energy at each electron carrier 3. Energy used to actively transport protons into inter membrane space from mitochondria matrix (forms electrochemical gradient) 4. Protons move down electrochemical gradient into matrix via ATP synthase 5. The protons and electrons combine with oxygen to form water

Question 44

What is the importance of oxygen in aerobic respiration

Answer 44

Final electron acceptor in oxidative phosphorylation