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Question 18N.2.HL.TZ0.b

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Date November 2018 Marks available [Maximum mark: 5] Reference code 18N.2.HL.TZ0.b
Level HL Paper 2 Time zone TZ0
Command term Describe Question number b Adapted from N/A
b.
[Maximum mark: 5]
18N.2.HL.TZ0.b

Describe the role of oxygen in aerobic cell respiration.

[5]

Markscheme

a. terminal/final electron acceptor ✔

b. at the end of electron transport chain ✔

c. oxygen also accepts protons/hydrogen ions ✔

d. water produced/  1 2 O2 + 2 electrons + 2H+ → H2O ✔

e. helps to maintain proton gradient «across inner mitochondrial membrane by removal of protons from the stroma» ✔

f. oxygen is highly electronegative/electrons strongly attracted to oxygen ✔

g. avoids anaerobic respiration/buildup of lactic acid ✔

h. allows more electrons to be delivered to the electron transport chain
OR
allows NADFAD to be regenerated/reduced NAD/FAD converted back to NAD/FAD ✔

i. oxygen allows maximum yield of energy «from glucose» allows complete oxidation of glucose/allows fats to be used in respiration ✔

Syllabus sections