1.
B
[1]
2.
C
[1]
3.
D
[1]
4.
B
[1]
5.
B
[1]
6.
C
[1]
7.
(a)
(b)
Award [1] for each structure clearly drawn and correctly labelled.
Z lines;
actin filaments;
myosin filaments with heads;
light bands and dark bands;
3 max
Ca2+ ions released when a nerve impulse arrives at the muscle;
Ca2+ ions are released from the sarcoplasmic reticulum;
binding sites for myosin heads are exposed;
this allows cross-bridges between myosin and actin to form;
2 max
[5]
8.
(a)
(i)
(ii)
biceps and triceps correctly labelled;
(biceps = muscle on right, triceps = muscle on left)
Both needed for mark.
1
(cartilage is hard but flexible) able to absorb mechanical shocks /
allows bones to pivot or move smoothly
1
IB Questionbank Biology
1
(b)
ATP binds to myosin heads;
ATP binding causes cross bridges to break/heads detach from binding
site;
ATP broken down/hydrolysed to ADP + Pi, causing myosin heads to
change angle/become “cocked”;
myosin heads attach to binding sites on actin filament further along
sarcomere;
ADP + Pi released and myosin heads push actin filament along/power
stroke occurs;
Allow ONE mark if there is a general understanding of the role of ATP
in the sliding of filaments but without specific details.
3 max
[5]
9.
(a)
(b)
I.
II.
III.
thick filament / myosin;
Z line;
A/dark band;
vital capacity may increase slightly/appears to be unaffected by training;
Do not award the mark for increase that is unqualified.
3
1
[4]
10.
(a)
(b)
moderate-intensity exercise stimulates development (in size) of slow muscle
fibres whilst high-intensity exercise stimulates development (in size) of fast
muscle fibres;
both decrease heart rate at rest;
2
benefits:
more red blood cells after transfusion so more transport of oxygen
by hemoglobin;
enhances endurance; OWTTE
risks:
foreign blood could cause rejection / own blood banks to avoid rejection/
disease transmission;
excess of red blood cells causes clots;
bigger volume of blood increases blood pressure;
unethical/unfair advantage to athlete results in banning/disqualification;
To award [4 max] at least one risk and one benefit must be addressed.
4 max
[6]
11.
(a)
I.
II.
Z line;
actin (filaments);
IB Questionbank Biology
2
2
(b)
(i)
(ii)
slow muscle fibre (tonic)
fast muscle fibre (twitch)
contract slowly
contract rapidly;
resist fatigue
fatigue easily;
high myoglobin
low myoglobin;
aerobic metabolism
anaerobic metabolism;
very good blood supply
moderate blood supply;
high stamina
low stamina;
more mitrochondria
less mitrochondria;
Award [1] per correct row.
2 max
warm up involves gentle exercise before exercise;
warm muscles/joints are less likely to be strained/more supple;
increases blood flow/oxygen to muscles;
but there is limited scientific proof;
some people do not suffer ill effects from not warming up;
3 max
[7]
12.
(a)
(b)
Award [1] for each structure clearly drawn and correctly labelled.
light and dark bands;
Z line;
(thin) actin filaments shown with no gap between these and Z line;
(thick) myosin filaments shown with heads;
3 max
binds oxygen when level is high;
releases oxygen when level is low;
acts as an oxygen store;
allows muscles to continue with aerobic respiration for longer;
2 max
[5]
13.
(a)
Award [1] for each structure clearly drawn and correctly labelled.
Sarcomere — clearly indicated between Z lines;
Z lines;
actin filaments attached to Z line;
myosin filaments with heads;
(two) light bands;
dark band;
IB Questionbank Biology
4 max
3
(b)
(c)
calcium ions are released from the sarcoplasmic reticulum;
they expose the myosin binding sites (on actin) / cause movement of
blocking molecules/troponin;
cross-bridges form between actin and myosin molecules;
ATP provides energy;
for actin filaments to slide over the myosin filaments / for myosin to
push actin;
ATP provides energy to release myosin from binding site;
action can be repeated further along the molecule;
5 max
the resting potential of cell is negative inside compared with outside;
stimulation causes depolarization/reversal of charge on each side;
due to Na+ channels opening / Na+ flowing into the cell;
which causes an action potential;
K+ channels open / K+ flows out of the cell;
sodium potassium pump restores resting potential;
transmitted between neurons across a synapse;
neurotransmitter released into synaptic cleft;
diffuse across cleft to postsynaptic membrane;
where they bind to receptors;
influx of Na+ into cell;
which may initiate action potential;
9 max
(Plus up to [2] for quality)
[20]
14.
(a)
(b)
(c)
positive/direct correlation / as mitochondrial concentration increases so
does HAD activity
1
fur seal has greater mitochondrial concentration / vice versa;
fur seal has greater HAD activity / vice versa;
lowest value of HAD for fur seal equal to/slightly above highest sea lion
value/ no overlap of data points;
2 max
swimming muscle has a greater mitochondrial concentration than
non-swimming muscle;
the range in HAD activity is similar in both / non-swimming has slightly
larger range;
mitochondrial concentration overlaps in the middle range of values / low
mitochondrial concentration only in non-swimming muscle / highest
mitochondrial concentration only in swimming muscle;
2
IB Questionbank Biology
4
(d)
more mitochondria means more aerobic respiration;
more mitochondria in swimming muscles;
products of fatty acid oxidation could be used in respiration
(so hypothesis could be supported);
increase in HAD activity would mean an increase in fatty acid
oxidation;
little/no increase in HAD activity in swimming muscles (so
hypothesis not supported);
during diving low oxygen/hypoxic conditions so high HAD activity/
mitochondrial concentration allows aerobic metabolism to continue;
3 max
[8]
IB Questionbank Biology
5