Topic 5: Respiration Flashcards Preview

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Flashcards in Topic 5: Respiration Deck (39):
1

What are autotrophic organisms?

Organisms that make their own food

2

What are heterotrophic organisms?

Organisms which eat and digest other organisms to get food and energy from cellular respiration

3

What is cellular respiration?

The process by which energy is transferred from the chemical bonds in respiratory substrates to form ATP

4

What is aerobic respiration?

Respiration in the presence of oxygen

5

What is ATP?

Adenosine triphosphate

6

Give some characteristics of ATP

Energy currency
Universal

7

Name and give the reaction which forms ATP

Phosphorylation
ADP + Pi ----> ATP + H2O

8

Describe the structure of ATP

A DNA molecule with two extra phosphate groups

9

What enzyme breaks down ATP?

ATPase

10

Is the formation of ATP exothermic or endothermic?

Exothermic

11

Name all the stages of aerobic respiration

Glycolysis
Link reaction
Krebs cycle
Oxidative phosphorylation

12

Where does glycolysis take place?

Cytoplasm

13

Where does the glucose for glycolysis come from?

From the blood
Form the breakdown of glucagon in the muscles and liver

14

Summarise the stages of glycolysis

Glucose is phosphorylated
Phosphorylated carbon is broken down into two molecules of G3P
G3P oxidised to pyruvate

15

How is glucose phosphorylated in glycolysis?

Two phosphate groups are added to the glucose using two ATP molecules

16

Why do you need to phosphorylate glucose in glycolysis?

It raises its energy level so its more reactive
Makes it unable to pass through the cell membrane

17

How is G3P converted into pyruvate?

Loses a hydrogen atom which is picked up by a molecule of NAD which is reduced to NADH.

18

How many ATP molecules are made for every molecule of G3P that's oxidised?

2

19

What is the net number of ATP molecules produced in glycolysis

2

20

What determines what happens to pyruvate once it's been formed?

Whether there is enough oxygen or not

21

If there is not enough oxygen present in an animal, what happens to pyruvate?

Pyruvate is reduced to lactate (lactic acid)
NADH ---> NAD

22

Why is the regeneration of NAD important?

To carry on glycolysis in aerobic respiration

23

If there isn't enough oxygen present in plants, what happens to pyruvate?

Pyruvate is decarboxylated to ethanal and then reduced to ethanol

24

What does the breakdown of pyruvate anaerobically in plants produce?

Ethanol and carbon dioxide

25

Why is the fermentation of glucose irreversible in plants?

Because the carbon dioxide dissipates/diffuses

26

What is the link reaction?

The reaction which links glycolysis to the Krebs cycle

27

Summarise the link reaction

Pyruvate is decarboxylated to acetate which joins to coenzyme A to form acetyl coenzyme A

28

What does NAD do in the link reaction?

It becomes NADH because the pyruvate is dehydrogenated

29

In the presence of oxygen, where does pyruvate go?

It's transported across the inner and outer mitochondrial membrane into the matrix by active transport

30

Where does the link reaction take place?

Matrix of the mitochondria

31

Where does the Krebs cycle take place?

In the mitochondrial matrix?

32

What is the purpose of the Krebs cycle?

To make the NADH and FADH needed in the electron transport chain

33

Summarise the Krebs cycle

Acetate + oxaloacetate --> 6C
6C decarboxylated to 5C: CO2 and NADH formed
5C decarboxylated to 4C: CO2 and NADH formed
4C to another 4C: ATP
4C to another 4C: FADH
4C to oxaloacetate: NADH

34

For every glucose molecule, how many times does the Krebs cycle go around?

Twice

35

Summarise the products of the Krebs cycle

3 NADH
1 FADH
2 CO2
1 ATP

36

Where does oxidative phosphorylation take place?

Inner mitochondrial matrix

37

Summarise the events of oxidative phosphorylation

NADH and FADH are oxidised so they lose a H
H ---> H+ + e-
Electrons passed down chain and release energy
H+ is pumped through proteins into inter-membrane space with energy
H+ ions flood into the matrix through ATP synthase, forming ATP
Electrons passed onto oxygen to combine with 2 H+ molecules to form water

38

What does oxidative phosphorylation mean?

The formation of ATP using energy from oxidation in the electron transport chain

39

Give another term for water in the ETC

The terminal electron acceptor