1.
D
[1]
2.
B
[1]
3.
C
[1]
4.
B
[1]
5.
A
[1]
6.
A
[1]
7.
C
[1]
8.
C
[1]
9.
A
[1]
IB Questionbank Biology
1
10.
(a)
Award marks for any of the following clearly drawn and correctly labelled.
cristae;
inner membrane;
outer membrane;
intermembrane space;
matrix;
ribosomes;
DNA;
4 max
(b)
cristae provide surface area for oxidative phosphorylation;
inner membrane contains electron transport chains/ATP synthase (which
carry out oxidative phosphorylation);
outer membrane separates the mitochondrion from the rest of the cell;
mitrochondrial DNA/ribosomes make (mitochondrial) proteins;
small volume intermembrane space allows for higher concentration
of protons;
matrix has enzymes for the Krebs cycle;
3 max
[7]
11.
pyruvate (from glycolysis) enters a mitochondrion;
enzymes in the matrix remove one carbon dioxide and hydrogen from
the pyruvate;
hydrogen is accepted by NAD/forms NADH;
removal of hydrogen is oxidation;
removal of carbon dioxide is decarboxylation;
the whole process/link reaction is oxidative decarboxylation;
the product is an acetyl group which reacts with CoA/coenzyme A;
acetyl CoA enters Krebs cycle;
Accept any of the above points in the form of a clearly drawn and
correctly labelled diagram.
4 max
[4]
12.
(a)
Award [1] for each structure clearly drawn and correctly labelled.
Whole cells not necessary.
(plasma) membrane—single line surrounding cytoplasm;
nucleus — with a double membrane and pore(s) shown;
mitochondria(ion) — with a double membrane, the inner one folded
into internal projections, shown no larger than half the nucleus;
rough endoplasmic reticulum—multi-folded membrane with dots/
small circles on surface;
Golgi apparatus—shown as a series of enclosed sacs with evidence
of vesicle formation;
ribosomes — dots/small circles in cytoplasm/ribosomes on rER;
lysosome;
Award [0] if plant cell is drawn. Award [2 max] if any plant cell
structure (e.g. cell wall) is present.
IB Questionbank Biology
4 max
2
(b)
prokaryotic
eukaryotic
naked DNA
protein associated with DNA;
DNA in cytoplasm / nucleoid /
no nucleus
DNA in nucleus / nucleus present;
circular DNA
linear chromosomes/DNA molecules;
no mitochondria
mitochondria;
70S ribosomes present
80S ribosomes present;
no membrane bound organelles
internal membranes form organelles;
pili present
pili absent;
plasmids (sometimes) present
plasmids absent;
cell wall present
cell wall only present in plants/fungi;
Do not accept cell wall sometimes present.
flagella solid
flagella flexible/membrane-bound;
6 max
(c)
DNA replication is semi-conservative / each strand of DNA
acts as template;
(DNA) helicase separates two strands/forms a replication fork;
new strand built / nucleotides added in a 5´ to 3´ direction;
(deoxy)nucleoside triphosphates hydrolysed to provide energy for
nucleotide formation/base pairing;
on one strand DNA polymerase III builds continuous strand;
on other strand short chains of DNA/Okazaki fragments are formed;
each short chain starts with RNA primer;
added by RNA primase;
then remainder of chain of DNA built by DNA polymerase III;
DNA polymerase I removes RNA primer and replaces it by DNA;
DNA ligase joins DNA fragments together forming complete strand;
replication only occurs at a single replication fork;
Award credit for any of the above points clearly drawn and accurately
labelled.
8 max
(Plus up to [2] for quality)
[20]
13.
(a)
Award [1] for each of the following clearly drawn and labelled correctly.
a double layer of lipid / phospholipid molecules — with hydrophilic heads and
hydrophobic tails;
an integral protein —passing completely through the lipid bilayer;
a peripheral protein — shown on the surface and not penetrating the lipid bilayer;
an integral protein with a pore passing through its entire length / a glycoprotein
with the carbohydrate components shown / cholesterol as component in bilayer; 4
IB Questionbank Biology
3
(b)
chlorophyll is composed of a number of pigments;
absorb different colours of light;
mainly red and blue absorbed;
green light reflected;
temperature increases rate;
up to a point where enzymes denature;
light intensity increases rate;
up to a point where maximum absorbance can occur;
carbon dioxide increases rate;
up to a point where fixation is at a maximum;
(c)
6 max
Krebs cycle:[3 max]
in matrix of mitochondrion;
decarboxylation;
oxidation / removal of hydrogen by NAD and FAD;
substrate level phosphorylation;
Electron transport chain:[5 max]
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;
8 max
(Plus up to [2] for quality)
[20]
IB Questionbank Biology
4