Respiration

Question 1

Give two examples why plants animals and microorganisms need to respire

Answer 1

Active transport

Metabolic reactions

Question 2

What is the site of glycolysis?

Answer 2

The cytoplasm

Question 3

Describe the process of glycolysis

Answer 3

One glucose molecule is phosphorylated requiring 2ATP forming hexose bisphosphate

This then splits into 2 triose phosphate molecules

And is phosphorylated again (substrate level) by inorganic phosphate in cytoplasm to form 2 triose bisphosphate

The triose bisphophates are oxidised forming 2 pyruvates - NAD is reduced as it picks up the H forming NADH for each and 2 ATP molecules are produced from each triosebisphosphate

Question 4

What is produced in glycolysis?

Answer 4

2 NADH

2 ATP

2 pyruvate

Question 5

Where does the link reaction occur?

Answer 5

In the mitochondrial matrix- pyruvate enters by active transport by specific carrier proteins

Question 6

Describe the link reaction

Answer 6

Pyruvate undergoes decarboxylation and dehydrogenation

• removal of co2
• NAD reduced to NADH

Resulting 2carbon Avery group bonds to coenzyme A - acetylCoA

Question 7

What is produced in link reaction from 1 glucose?

Answer 7

2 co2
2 NADH
2 acetylCoA

Question 8

AcetylCoA + ____________ = coenzymeA + ________

Answer 8

Oxaloacetate

Citrate

Question 9

What happens to the citrate molecule in the kerbs cycle to get it to a oxaloacetate?

Answer 9

Decarboxylation and dehydrogenation producing NADH, co2 and 5carbon compound

Further decarboxylation and dehydrogenation forming NADH, co2 and 4 carbon compound

Further decarboxylation and dehydrogenation forming co2, 2x NADH, FADH2, ATP and oxaloacetate

Question 10

Why isn’t respiration 100% Yeild of atp?

Answer 10

Some ATP used to transport pyruvate into mitochondrion

Some ATP used to actively transport H+ from NADH formed in glycolysis into mitochondrion

Some energy released in ETC as heat

Not all H+ movement back across membrane used to generate ATP/ goes through ATP synthase

Not all NADH used to feed into ETC

Question 11

What is oxidative phosphorylation?

Answer 11

Process where energy carried by electrons form reduced coenzymes (NADH and FADH2) is used to make ATP

Question 12

Describe the electron transport chain

Answer 12

Hydrogen atoms released as NADH/Fdh2 is oxidised dissociate into H+ and e-

Electrons move along electron transport chain (made of electron carriers) losing energy at each carrier

Energy is used by electron carriers to pump protons from mitochondrial matrix into intermembrane space

Electrochemical gradient forms

Protons move down electrochemical gradient into mitochondrial matrix via ATP synthase driving ATP from ADP and inorganic phosphate- chemiosmosis

In the mitochondrial matrix the protons, electrons and o2 combine to form water- o2 being the final electron acceptor

Question 13

why does aerobic respiration not always produce the expected yeild of ATP?

Answer 13

some ATP is used to transport pyruvate in the mitochondrion by active transport

some ATP used to actively transport hydrogen ions from reduced NAD into mitochondria from glycolysis

some energy in electron transport chain not used to transport hydrogen ions and lost as heat

not all hydrogen ion movement is used to generate ATP/ is through ATP synthase

not all reduced NAD is used in ETC

Question 14

what is the process of anaerobic respiration in mammals?

Answer 14

lactate fermentation

pyruvate molecule is reduced to lactate which oxidises reduced NAD so produces NAD which can be used in glycolysis

Question 15

what is the process of anaerobic respiration in yeast?

Answer 15

alcoholic fermentation

pyruvate molecules is decarboxylated producing ethanal and carbon dioxide and then reduced to ethanol, oxidising reduced NAD to NAD which can be used in glycolysis

Question 16

why is alcoholic fermentation irreversible?

Answer 16

the process removes carbon dioxide from the pyruvate molecule and decarboxylase enzyme cannot reverse the reaction

Question 17

what is the order of relative energy values of lipids, proteins, and carbohydrates from lowest to highest energy

Answer 17

carbohydrates
proteins
lipids

Question 18

what is the RQ of protein?

Answer 18

0.9

Question 19

what is the RQ of carbohydrate?

Answer 19

1

Question 20

what is the RQ of lipids?

Answer 20

0.7

Question 21

why have lipids got a high energy content?

Answer 21

fatty acids have more hydrogen atms

so can be oxidised many times by the krebs cycle

so many reduced NAD produced in krebs cycle

so more reduced NAD available for oxidative phosphorylation so more ATP produced

Question 22

what are two qualitative changes that take place in the intermembrane space of the mitochondria as a result of oxidative phosphorylation?

Answer 22

pH decreases

becomes more positivelt charged

Question 23

explain how having a larger number of proton pores in the inner mitochondrial membrane would result in a person less likely to gain weight

Answer 23

• larger number of protons pores results
in protons leaking back into matrix
• reduces yield of ATP from
chemiosmotic gradients
• less ATP is made from oxidative
phosphorylation
• more energy wasted as heat
• energy from chemiosmosis decoupled
from ATP synthesis
• energy yield from aerobic respiration
reduced per molecule of glucose
• food not converted to ATP as
efficiently
• less excess energy intake in diet
• less deposition of fat
• fat stores may be respired for energy

Question 24

why cant you measure the RQ of maggots or yeast when theyre under anaerobic conditions?

Answer 24

maggots will not produce CO2 in lactate fermentation

yeast will not produce CO2 in alcoholic fermentation

measuring RQ requires CO2 production so RQ will be lower than normal