respiration

Question 1

what are the products of aerobic respiration ?

Answer 1

carbon dioxide, water, and a lot of ATP

Question 2

what are the products of anaerobic respiration? (in animals, plants and fungi)

Answer 2

in animals: lactate
in plants and fungi: ethanol and carbon dioxide

and little ATP

Question 3

what are the 4 stages of aerobic respiration?

Answer 3

1) glycolysis
2) link reaction
3) krebs cycle
4) oxidative phosphorylation

Question 4

briefly describe what glycolysis is

Answer 4

the splitting of a 6 carbon glucose molecule into two 3 carbon pyruvate molecules

Question 5

briefly describe what the link reaction is

Answer 5

the 3 carbon pyruvate molecules enter into a series of reaction that lead to the formation of acetylcoenzyme A and a CO2

Question 6

briefly describe what the krebs cycle is

Answer 6

the introduction of acetylcoenzyme A into a cycle of oxidation-reduction reactions, this produces some ATP and a lot of reduced NAD and FAD

Question 7

briefly describe what oxidative phosphorylation is

Answer 7

the use of electrons, that are associated with reduced NAD and FAD, form the krebs cycle, to synthesize ATP and produce water as a by-product

Question 8

where does glycolysis happen ?

Answer 8

in the cytoplasm of all living cells

Question 9

what is the overall yield of one glucose molecule undergoing glycolysis?

Answer 9

• 2 molecules of ATP
• 2 molecules of reduced NAD
• 2 molecules of pyruvate

Question 10

does glycolysis require energy ?

Answer 10

nope

Question 11

what type of respiration does glycolysis happen in?

Answer 11

both aerobic and anaerobic respiration

Question 12

what are the 3 steps of glycolysis?

short description

Answer 12

• phosphorylation of glucose using ATP (hydrolyse 2 ATP and add 2 phosphate groups to glucose) - this makes glucose-phosphate
• glucose-phosphate is really high in energy and splits into 2 molecules of triose phosphate
• triose phosphate is oxidised to pyruvate and we get a net gain of 2 ATP molecules and reduced NAD.

Question 13

what are the products of glycolysis?

Answer 13

2 x pyruvate
a net gain of 2 ATP
2 reduced NAD

Question 14

where does the link reaction happen?

Answer 14

mitochondrial matrix

Question 15

what is the first stage of the link reaction ?

Answer 15

the pyruvate molecules from glycolysis is oxidised into acetate , the hydrogen that was lost in this step is picked up by NAD to become reduced NAD
- this also produced CO2

Question 16

what is the second stage of the link reaction?

Answer 16

acetate combines with coenzyme A to form acetyl-coenzyme A

Question 17

what are the product of the link reaction per CYCLE ?

Answer 17

1 acetyl coenzyme A
1 CO2
1 reduced NAD

Question 18

what are the products of the link reaction per GLUCOSE MOLECULE ?

Answer 18

2 acetyl coenzyme A
2 CO2
2 reduced NAD

Question 19

what is the purpose of coenzyme A?

Answer 19

its only purpose is to bring the acetate into the krebs cycle

Question 20

what is the first step in the krebs cycle?

Answer 20

acetyl coenzyme A is reacting with a 4 carbon molecule to form a 6 carbon molecule - the coenzyme A is released and can be reused in the link reaction again

Question 21

what is the second stage in the krebs cycle?

Answer 21

its a series of redox reactions, to make a 4 carbon molecule from a 6 carbon molecule

1) 2 x CO2 molecules are lost - this produced ATP (ADP + Pi ) ~ the carbon molecules are oxidised
2) 3 x NAD is reduced to form 3 x reduced NAD and FAD is reduced to form reduced FAD

Question 22

what are the products of the krebs cycle per CYCLE?

Answer 22

3 x reduced NAD
1 x reduced FAD
1 x ATP
2 x CO2

Question 23

what are the products of the krebs cycle per GLUCOSE MOLECULE?

Answer 23

6 x reduced NAD
2 x reduced FAD
2 x ATP
4 x CO2

Question 24

what is the first stage of glycolysis ?

Answer 24

2 ATP molecules are hydrolysed to make ADP and Pi, the phosphate binds to the 6 carbon glucose molecule and forms glucose phosphate
glucose phosphate is unstable because it has a lot of energy

Question 25

what is the second stage of glycolysis ?

Answer 25

as the glucose phosphate is unstable, it breaks down into 2 molecules of triose phosphate

Question 26

what is the third stage of glycolysis ?

Answer 26

triose phosphate is oxidised into pyruvate and NAD is reduced to reduced NAD
the phosphate group detaches from the triose phosphate and bonds with ADP to make ATP

2 molecules of reduced NAD are made,
2 molecules of pyruvate are made
4 molecules of ATP but 2 were used in the first stage sso a NET GAIN of 2 ATP molecules

Question 27

describe anaerobic respiration in animals

Answer 27

1) glycolysis > produces pyruvate
2) that pyruvate gains a hydrogen from NADH to become reduced and oxidise NADH
that then produces lactate ( when it dissolves it becomes lactic acid)

Question 28

where does anaerobic respiration happen ?

Answer 28

in the cytoplasm of the cell

Question 29

what similarities are there between anaerobic respiration in plants, animals and microorganisms?

Answer 29

they all start with glycolysis to produce pyruvate.

the main purpose is to release small amounts of ATP and oxidise NAD so that it can be used in glycolysis again and again

Question 30

why do we convert pyruvate to lactate ?

Answer 30

to oxidise NADH into NAD so it can be used in glycolysis again

Question 31

describe anaerobic respiration in plants and microorganisms

Answer 31

1) glycolysis > produces pyruvate
2) that pyruvate gains a hydrogen from NADH to become reduced and oxidise NADH
that then produces ethanol and carbon dioxide

Question 32

why does anaerobic respiration in plants, microorganisms and animals have different products?

Answer 32

because they have different enzymes involved so they have different products

Question 33

compare the efficiency of anaerobic respiration and aerobic respiration

Answer 33

in aerobic respiration, from one molecule of glucose, you should be able to produce 38 molecules of ATP which is only around 32% efficiency ~ ATP is needed to actively transport pyruvate and NADH into the matrix, some H+ ions leak through the mitochondrial membrane so not all of them will diffuse through ATP synthase and produce ATP, and finally, heat energy can be lost to the surrounding

anaerobic respiration is even less efficient because only 2 molecules of ATP are produced for every glucose molecule.