1.
D
[1]
2.
A
[1]
3.
(a)
sodium/Na
(b)
unclear correlation between V and T;
depends on the nature of the substrate and its concentration;
sometimes high V with low T (e.g. experiment 1 for sucrose) /
sometimes high V with high T (e.g. experiment 2 for NaCl);
2 max
higher salt/NaCl concentrations increase T and V;
increase in puddling with increase in salt/NaCl;
no clear relationship between the number of visits and the
concentration of salt/NaCl;
2 max
(c)
(d)
(e)
(f)
1
(i)
sodium/Na
1
(ii)
retention of sodium/Na from laboratory solutions and natural
puddles;
definite loss of potassium from laboratory solutions but loss/gain
uncertain from natural puddles;
slight loss of magnesium from laboratory solutions and uncertain
gain/loss from natural puddles;
calcium uncertain in both cases / variation in data for calcium;
more conclusive results in laboratory solutions / conditions
more reliable in laboratory solutions / greater variation in
natural puddles;
Accept reference to error bars/ranges in data in place of
uncertainty.
3 max
males have longer/wider digestive tracts for greater absorption of fluid;
ileum of males has greater surface area;
which allows faster/more absorption in males than in females;
2 max
puddling provides needed sodium/Na because their (larval) food does not
supply enough sodium/Na;
sodium/Na needed for neural activity;
greater flight/neural activity in males than in females;
Accept other reasonable suggestions.
1 max
[12]
4.
B
[1]
5.
A
[1]
6.
D
[1]
IB Questionbank Biology
1
7.
D
[1]
8.
C
[1]
9.
A
[1]
10.
A
[1]
11.
(a)
Fibrous protein:
keratin / elastin / fibroin / collagen / myosin / actin / other named
example;
Globular protein:
hemoglobin / myoglobin / named enzyme / named peptide hormone /
named antibody / albumin / other named example;
Example of both fibrous and globular protein needed to gain the
mark. Check any other answers for validity.
IB Questionbank Biology
1 max
2
(b)
(c)
both are polypeptides / chains of amino acids joined by peptide
bonds / have primary structure;
globular proteins have tertiary structure whereas fibrous proteins
do not (may have extended secondary structure);
globular proteins are rounded in shape while fibrous proteins
are elongated / OWTTE;
globular proteins are (generally) soluble while fibrous tend
to be insoluble;
2 max
polar amino acids are soluble/have stable interactions in water/
extracellular fluid/cytoplasm;
non-polar amino acids are soluble/have stable interactions in
the lipid bilayer;
polar amino acids strongly hydrophilic and non-polar amino
acids are repelled by water/are hydrophobic;
(help to) retain protein in position in the membrane;
polar amino acids form hydrophilic channels/protein pores
in membranes;
transmembrane proteins have polar amino acids on either
side of the membrane;
3 max
[6]
12.
C
[1]
13.
(a)
(i)
(ii)
(b)
primary structure is (number and) sequence of amino acids;
joined by peptide bonds;
secondary structure is folding pattern;
held by H-bonds;
α-helix / β-sheet;
3 max
example of fibrous (e.g. collagen/myosin/keratin) and of
globular (e.g. hemoglobin /myoglobin/catalase);
fibrous are long, narrow shape while globular are rounded;
fibrous are usually structural and globular are usually functional/
metabolic;
fibrous are insoluble in water while globular are (usually) soluble;
Award [1 max] if no example provided.
2 max
oxidation is addition of oxygen while reduction is removal;
oxidation is removal of H+, reduction is addition;
oxidation is loss of electrons, reduction is gain;
1 max
[6]
IB Questionbank Biology
3