Date | May 2017 | Marks available | 8 | Reference code | 17M.2.HL.TZ1.5 |
Level | Higher level | Paper | Paper 2 | Time zone | Time zone 1 |
Command term | Explain | Question number | 5 | Adapted from | N/A |
Question
Oxygen is needed to complete aerobic cell respiration.
Explain how chemical energy for use in the cell is generated by electron transport and chemiosmosis.
Outline four different functions of membrane proteins.
Distinguish between anabolism, catabolism and metabolism.
Markscheme
a. NAD/FAD carries/is reduced by gaining «two» H «atoms»/«two» electrons
b. reduced NAD produced in glycolysis/link reaction/Krebs cycle
c. reduced NAD/FAD delivers electrons/hydrogen «atoms» to ETC
d. ETC is in mitochondrial inner membrane/cristae
e. electrons release energy as they flow along the chain/from carrier to carrier
f. electrons from ETC accepted by oxygen/oxygen is the final electron acceptor
g. proteins in the inner mitochondrial membrane/electron carriers act as proton pumps
h. protons pumped into intermembrane space/proton gradient across inner mitochondrial membrane/proton concentration higher in intermembrane space than in matrix
i. energy «from electrons» used to pump protons into intermembrane space/generate a proton gradient / high H+ concentration is a store of «potential» energy
j. ATP synthase in inner mitochondrial membrane/cristae
k. energy released as protons pass down the gradient/through ATP synthase
l. ATP synthase converts ADP to ATP/phosphorylates ADP
m. oxidative phosphorylation «is ATP production using energy from oxidizing foods»
Accept H+ but not H/hydrogen in place of protons in any part of the answer.
Accept NADH or FADH in place of reduced NAD or FAD.
a. receptor/binding site for hormone/neurotransmitter
b. cell-to-cell communication / cell recognition
c. channels «for passive transport» / facilitated diffusion
d. pumps / active transport
e. cell adhesion
f. «immobilized» enzymes/enzymes embedded in the membrane
g. electron transport / electron carriers
a. metabolism is all enzyme-catalyzed reactions in a cell/organism/is anabolism plus catabolism
b. anabolism is synthesis of polymers/complex/larger molecules/larger substances «from smaller molecules/monomers»
c. catabolism is breaking down «complex» molecules/substances «into simpler/smaller ones/into monomers»