Respiration

Question 1

What are the products of aerobic respiration?

Answer 1

CO2, water and ATP

Question 2

What are the products of anaerobic respiration in animals?

Answer 2

lactate and ATP

Question 3

What are the products of anaerobic respiration in plants and fungi?

Answer 3

ethanol, carbon dioxide, ATP

Question 4

What are the stages on aerobic respiration?

Answer 4

• glycolysis
• link reaction
• krebs cycle
• oxidative phosphorylation

Question 5

What is the process of glycolysis?

Answer 5

• before glucose can be split, it is phosphorylated into fructose bisphosphate to make it more reactive. Two phosphate molecules are added which come from the hydrolysis of 2 molecules of ATP
• fructose bisphosphate splits into triose phosphate (3 carbon molecule)
• triose phosphate becomes oxidised as hydrogen is removed and transferred to NAD, to form NADH
• triose phoshate is converted into pyruvate which regenerates 2 molecules of ATP from ADP

Question 6

What are the products of glycolysis?

Answer 6

• 4 ATP (net production 2)
• 2 NADH
• 2 pyruvate

Question 7

Where does glycolysis occur?

Answer 7

cytoplasm

Question 8

What occurs in the link reaction?

Answer 8

• pyruvate molecules produced in the cytoplasm during glycolysis are actively transported into the mitochondria matrix
• pyruvate is oxidised to acetate. This releases CO2 and NAD is converted to NADH
• acetate combines with coenzyme A to form acetylcoenzyme A

Question 9

What are the products of the link reaction?

Answer 9

• 2 NADH
• CO2
• 2 acetyl coA

Question 10

What occurs in the krebs cycle?

Answer 10

• acetate is released from coA (coA is used to transport acetate from the link reaction to the krebs cycle)
• acetate from the link reaction combines with a 4 carbon molecule to form a 6 carbon molecule
• 6 carbon molecule is converted to an intermediate 5 carbon molecule which converts NAD to NADH
• 5C compound is converted to a 4C compound, forming 2NADH, FADH and ATP

Question 11

What are the products of the krebs cycle?

Answer 11

The cycle turns twice because the link reaction forms 2 coA

• 6 NADH
• 2 FADH
• 2 ATP
• 4 CO2

Question 12

What is oxidative phosphorylation (electron transfer chain)?

Answer 12

• reduced NAD and FAD donate their electrons of hydrogen atoms to the first molecule in the electron transfer chain
• electrons pass along the chain in a series of oxidation reduction reactions, releasing energy leading to the active transport of protons from the inner membrane into the inter membrane space
• protons accumulate in the inter membrane space before diffusing back into the matrix through ATP synthase down a chemiosmotic gradient, forming ATP (oxidative phosphorylation)
• electrons recombine with protons and oxygen at the end of the chain to form water - oxygen is the final electron acceptor

Question 13

How many molecules of ATP are synthesized from 1 molecule of glucose in aerobic respiration?

Answer 13

38

Question 14

What are the products of the electron transfer chain?

Answer 14

• 34 ATP
• water

Question 15

What are the alternative respiratory substrates?

Answer 15

• lipids
• protein

Question 16

What happens during respiration of lipids?

Answer 16

• before being respired, they are hydrolysed to glycerol and fatty acids
• glycerol is phosphorylated and converted to triose phosphate which enters the glycolysis pathway
• fatty acids are converted to acetyl coA
• oxidation of lipids releases many hydrogen atoms that are used to produce ATP during oxidative phosphorylation

Question 17

What happens during respiration of protein?

Answer 17

• initially hydrolysed into amino acids
• amine group is removed (deamination)
• 3 carbon compounds are converted to pyruvate
• 4/5 carbon compounds are converted to intermediates in the krebs cycle

Question 18

What are the products of anaerobic respiration in plants and fungi and how do they form?

Answer 18

ethanol + carbon dioxide + NAD

• pyruvate formed at the end of glycolysis loses a molecule of carbon dioxide and accepts hydrogen from NADH to form ethanol

Question 19

What are the products of anaerobic respiration in animals and how do they form?

Answer 19

lactate + NAD

• NAD from glycolysis accumulates and must be removed - pyruvate takes up 2 hydrogen atoms from NADH produced in glycolysis

Question 20

How many ATP are formed in anaerobic respiration?

Answer 20

2 ATP formed in glycolysis