M5 CH18 respiration

Question 1

what reaction takes place alongside the conversion of glucose into hexose bisphosphate

Answer 1

the breakdown of 2 ATP molecules

Question 2

explain how the reactions taking place when triose phosphate becomes pyruvate can be described as redox reactions

Answer 2

triose phosphate is oxidised into pyruvate
NAH is reduced –> NADH

Question 3

In the link reaction, why does the number of carbons reduce from 3 to 2 when pyruvate is converted into acetate?

Answer 3

it is lost as carbon dioxide

Question 4

state the net productions of ATP, NADH and pyruvate in glycolysis one glucose molecule.

Answer 4

ATP: 2
NADH: 2
Pyruvate: 2

Question 5

what does acetate combine with to form the final product of the link reaction?

Answer 5

coenzyme A

Question 6

how is citrate (6c) formed in the krebs cycle (remember it functions in a circle)

Answer 6

acetyl (2C) from link reaction combines with oxaloacetate (4C) to form citrate.

Question 7

how many molecules of carbon are lost from one turn of the krebs cycle, and how are they lost.

Answer 7

2
lost as carbon dioxide

Question 8

how many NADH molecules are formed from one krebs cycle.
- how many are formed from one molecule of glucose.

Answer 8

3

6

Question 9

why is it incorrect to say that only 1 FADH2 molecule is formed from krebs cycle of one molecule of glucose?

Answer 9

because for one molecule of glucose, kreb cycle occurs twice
therefore, 2 molecules of FADH2 are formed from one molecule of glucose in respiration

Question 10

how many carbon molecules are lost from krebs cycle (one molecule of glucose)

Answer 10

4

(2 from each turn of krebs cycle)

Question 11

there are 4 molecules of ATP formed during glycolysis, why is it incorrect to say that the net production of ATP from glycolysis is 4?

Answer 11

because 2 ATP molecules are broken down to provide glucose with 2 phosphates to form hexose bisphosphate.
therefore NET ATP production is only 2

Question 12

state the reaction that takes place in the electron transport chain

Answer 12

oxidative phosphorylation

Question 13

explain what happens in the electron transport chain in aerobic respiration

Answer 13

as electrons move down the etc, protons are pumped across the mitochondrial membrane
- changing the shape of ATP synthase, so that it can catalyse the formation of ATP molecules by combining each ADP molecule with an inorganic phosphate.

Question 14

what is the NET production of ATP in the electron transport chain (oxidative phosphorylation) from one molecule of glucose

Answer 14

34

Question 15

what is the final electron accepter in the electron transport chain

Answer 15

oxygen

Question 16

what unnecessary molecule is formed at the end of the etc

Answer 16

water

Question 17

state the 4 molecules formed in krebs cycle, and the net production of each from one molecule of glucose.

Answer 17

ATP: 2
FADH2: 2
NADH: 6
CO2: 4

(divide each by 2 to find net from only one kreb cycle)

Question 18

draw a diagram showing the steps involved in lactate fermentation
(enzymes/ reduction & oxidation)

Answer 18

mark using blue bio workbook

Question 19

draw a diagram showing the steps involved in alcoholic fermentation after glycolysis

Answer 19

mark using blue bio workbook

Question 20

is lactate fermentation reversible/irreversible ?
why?
is alcoholic fermentation reversible/irreversible?
why?

Answer 20

lactate: reversible
because no molecules are lost as waste products

alcoholic: irreversible
because a carbon molecule is lost from pyruvate (decarboxylation) as a carbon dioxide molecule

Question 21

outline the process that takes place to use lipids instead of glucose in respiration

Answer 21

1. ester bonds between glycerol and F.As are hydrolysed, breaking triglyceride apart
2. glycerol enters glycolysis where is is converted to pyruvate
3. each fatty acid is broken down into 2 carbon units, forming 6x coenzyme A’s
4. enters L.R and krebs cycle

Question 22

outline the process that takes place to use proteins instead of glucose in respiration

Answer 22

1. proteins are hydrolysed into amino acids
2. amino acids are deaminated
3. carbon part of the deaminated amino acids are converted into pyruvate
4. pyruvate enters the link reaction