respiration

Question 1

ATP as an energy source (8)

Answer 1

(1) short term store of energy
(2) energy is derived from food/respiration
(3) transfers energy to ALL cells
(4) hydrolysis releases 30.5 kJ of energy
(5) reversible reaction (ADP recycled to ATP)
(6) small water-soluble molecule so can move within the cell
(7) links energy yielding and energy requiring reactions
(8) has a high turnover rate

Question 2

Uses of ATP (5)

Answer 2

(1) active transport
(2) muscle contraction
(3) anabolic reactions (DNA replication, phosphorylation reactions, protein synthesis)
(4) exocytosis/endocytosis
(5) bioluminescence

Question 3

Outline the process of glycolysis (9)

Answer 3

(1) lysis of glucose
(2) glucose is phosphorylated by (2 molecules of) ATP
(3) this raises energy level / reduces activation energy/ to make it reactive
(4) into fructose-1,6-bisphosphate
(5) this then breaks down into two triose phosphate
(6) hydrogen is removed by NAD
(7) reduced NAD is formed
(8) pyruvate is produced
(9) small yield of ATP is produced (net ATP:2 molecules)

Question 4

Describe the series of reactions that make up the Krebs Cycle (14)

Answer 4

(1) oxaloacetate accepts acetyl group
(2) to form citrate
(3) 4C to 6C
(4) citrate undergoes decarboxylation to (5) produce CO2 and (6) dehydrogenation to (7) produce reduced NAD
the (8) 5C compound formed also undergoes decarboxylation to produce CO2 and dehydrogenation to produce reduced NAD
the resulting (9) 4C compound undergoes (10) substrate-level phosphorylation to (11) produce ATP
the compound is also dehydrogenated to (12) produce reduced FAD
and dehydrogenated again to produce reduced NAD
these reactions are (13) catalysed using decarboxylases for decarboxylation and dehydrogenases for dehydrogenation
at the end, (14) oxaloacetate is regenerated

Question 5

Outline how ATP is synthesized by oxidative phosphorylation (13)

Answer 5

(1) reduced NAD/FAD is passed to the (2) ETC (electron transfer chain)
which is located in (3) the inner membrane
(4) hydrogen is released from the reduced NAD/FAD
it is (5) split into electrons and protons
(6) electrons pass along the carriers
the (7) energy released pumps protons into the intermembrane space
(8) proton gradient is set up
(9) protons diffuse back through the
(10) ATP synthase
(11) ATP is produced from ADP and inorganic phosphate by chemiosmosis
(12) oxygen is the final electron acceptor
(13) oxygen is reduced to water by the addition of proton

Question 6

Describe the role of NAD (2)

Answer 6

Hydrogen Carrier (H2 or H+ and e- )
Acts as coenzyme

Question 7

How is ATP produced from link reaction/glycolysis

Answer 7

substrate level phosphorylation

Question 8

How is ATP produced in chemiosmosis

Answer 8

using oxygen in chemiosmosis is known as oxidative phosphorylation

Question 9

Describe anaerobic respiration (11)

Answer 9

(1) pyruvate formed by glycolysis
(2) reduced NAD formed by glycolysis
(3) pyruvate is decarboxylated by
(4) pyruvate decarboxylase
(5) ethanal is produced
(6) ethanol dehydrogenase
(7) catalyses the reduction of ethanal as it accepts hydrogen from the reduced NAD and
(8) forms ethanol
(9) this is not a reversible reaction
(10) NAD is regenerated
(11) glycolysis can continue