Chapter 12: energy and respiration

Question 1

what are anabolic reactions?

Answer 1

reactions that build large molecules

Question 2

give 5 examples of uses of energy

Answer 2

1. ) DNA replication
2. ) protein synthesis
3. ) active transport
4. ) movement
5. ) maintenance of body temp

Question 3

why is ATP the universal energy currency?

Answer 3

• releases energy in small, manageable amounts
• reversible reaction
• small so can easily enter cell
• water soluble so can be compartmentalised
• easily hydrolysed because phosphate molecules repel

Question 4

give the two ways in which ATP is made

Answer 4

• using energy released during glycolysis/ the kerbs cycle

- using electrical potential energy from the transfer of electrons in the mitochondria

Question 5

give the role of NAD

Answer 5

carry H atoms, which can later be split into H+ and e-

Question 6

give the role of CoA

Answer 6

carries acetate groups made from pyruvate from the link reaction to the Krebs cycle

Question 7

why do lipids have a greater energy density than carbohydrates/ proteins?

Answer 7

• most energy comes from H +2[O] –> H2O

- the greater the number of H in the structure, the greater the energy value

Question 8

give the formula for the respiratory quotient

Answer 8

(Vol of CO2 released) / (Vol O2 taken in)

Question 9

where does glycolysis take place?

Answer 9

cytoplasm

Question 10

where does the link reaction/ Krebs/ oxidative phosphorylation take place?

Answer 10

the matrix of the mitochondria

Question 11

summarise glycolysis

Answer 11

glucose –> 2x pyruvate

Question 12

summarise the link reaction

Answer 12

• pyruvate is dehydrogenated and decarboxylated

- pyruvate –> acetate

Question 13

summarise the Krebs cycle

Answer 13

• acetate is decarboxylated and dehydrogenated

Question 14

summarise oxidative phosphorylation

Answer 14

ADP is phosphorylated to ATP

Question 15

give the intermediates from glucose - pyruvate

Answer 15

glucose
fructose phosphate
fructose biphosphate
2x triose phosphate
2x pyruvate

Question 16

give the net gain of glycolysis

Answer 16

2 ATP

2 NADH

Question 17

give the two enzymes involved in the link reaction

Answer 17

• pyruvate dehydrogenase

- pyruvate decarboxylase

Question 18

give the intermediates involved with the link reaction

Answer 18

pyruvate - acetyl CoA (2C) - acetate (2C)

Question 19

give the overall reaction for the link reaction

Answer 19

pyruvate + NAD+ + CoA –> CO2 + acetyl CoA + NADH

Question 20

give the intermediates involved with the Krebs cycle

Answer 20

acetate
citrate (6C)
5C compound
4C compound
4C compound
4C compound
oxaloacetate

Question 21

give the three main processes involved in some steps of the Krebs cycle

Answer 21

• decarboxylation
• dehydrogenation
• reduction of NAD and FAD

Question 22

where does oxidative phosphorylation take place?

Answer 22

the inner mitochondrial membranes

Question 23

during anaerobic respiration of yeast, what is pyruvate converted to?

Answer 23

ethanol

Question 24

during anaerobic respiration of mammals, what is pyruvate converted to?

Answer 24

lactate

Question 25

how are rice plants adapted to grow submerged in water?

Answer 25

• stems contain loosely-packed cells (aerenchyma) which allows the diffusion of gases
• leaves have ridges to trap air/ are corrugated and hydrophobic
• can tolerate more ethanol
• contain more alcohol dehydrogenase to break down the ethanol

Question 26

how is the matrix adapted?

Answer 26

• contains enzymes, NAD, oxaloacetate, mitochondrial DNA and ribosomes

Question 27

how is the outer membrane adapted?

Answer 27

• contains carrier/ channel proteins to allow the passage of pyruvate

Question 28

how is the inner membrane adapted?

Answer 28

• impermeable to small ions (H+)
• folded into cristae to give a large SA
• many electron carriers and ATP synthase