8.1 Cell respiration – summary of mark schemes
8.1.3
Draw and label a diagram showing the structure of a mitochondrion as seen in electron micrographs.
Mark Scheme
A.
B.
C.
D.
E.
F.
G.
H.
8.1.4
outer membrane;
inner membrane – folded into thin cristae;
cristae – shown as thin;
matrix;
intermembrane space – shown as thin;
(70S) ribosomes;
ATP synthase – shown on the inner membrane surface;
(naked) loop of DNA;
Explain aerobic respiration, including the link reaction, the Krebs cycle, the role of NADH + H+, the electron transport chain and
the role of oxygen.
Mark Scheme
A.
B.
C.
D.
E.
F.
glucose is broken down to pyruvate in the cytoplasm;
with a small yield of ATP / net yield of 2 ATP;
and NADH + H+ / NADH;
aerobic respiration in the presence of oxygen;
pyruvate converted to acetyl CoA;
acetyl CoA enters Krebs cycle;
Krebs cycle
G.
H.
I.
J.
K.
L.
M.
Krebs cycle yields a small amount of ATP / one ATP per cycle;
in matrix of mitochondrion
decarboxylation;
oxidation / removal of hydrogen by NAD and FAD;
substrate level phosphorylation;
and FADH2 / FADH + H+ / NADH / NADH + H+ /reduced compounds / electron collecting molecules;
these molecules pass electrons to electron transport chain;
Electron transport chain:
N.
O.
P.
Q.
R.
S.
T.
U.
V.
8.1.5
Explain oxidative phosphorylation in terms of chemiosmosis.
Mark Scheme
A.
B.
C.
D.
E.
F.
G.
8.1.6
electron transport chain linked to creation of an electrochemical gradient;
transfer of hydrogen to inner membrane carriers;
hydrogen ion pumped across inner membrane;
creates a concentration gradient;
electron transferred between carriers;
chemiosmosis;
hydrogen ion passes down concentration gradient;
through ATPase complex;
oxygen is final acceptor forming water;
electrons release energy as they pass along the chain;
oxygen final electron acceptor;
production of water;
builds up proton gradient / protons pumped across inner membrane;
protons flow into matrix of mitochondria through ATPase;
ATP produced;
produces 36 / 38 ATP (per glucose);
Explain the relationship between the structure of the mitochondrion and its function.
Mark Scheme
A.
B.
C.
D.
E.
mitochondria: for ATP production / aerobic respiration;
double / inner membranes of mitochondria: chemiosmosis / oxidative phosphorylation;
intermembrane space: build-up H+ concentration gradient;
inner membrane of mitochondria: electron transfer;
inner membrane: ATP synthesis;