ANSWER KEY UNIT TEST
1. B
2. C
3. D
4. C
5. B
6. A
7. C
8. C
9. D
10.C
11. C
12.B
13.B
14.A
15.B
16.B
17.D
18.A
19.D
20B
21. B
22. B
23. B
24. A
25.C
1a. [2 marks]
Markscheme
a. disaccharide name
eg: lactose, glucose and galactose
b. both monomers that make up mpa
eg: maltose, glucose and glucose
eg: sucrose, glucose and fructose
1b. [3 marks]
Markscheme
a. amylase breaks down/catalyzes/hydrolyses starch to maltose
b. lipase breaks down/catalyzes/hydrolyses fats to fatty acids and glycerol
c. proteases/peptidases break down/catalyze/hydrolyze proteins into smaller
polypeptides/dipeptides/amino acids
Award [2] if all three enzymes and substrates named correctly and one further mark for all three
products named
correctly.
Allow specific enzymes
1c. [2 marks]
Markscheme
a. both are unsaturated fatty acids
OR
both have two carbon atoms joined by a double bond
b. in cis-fatty acids the two H atoms are on the same side while in trans-fatty acids they are on
opposite sides
OR
cis-fatty acids are healthier than trans-fatty acids
OR
cis-fatty acids have a lower boiling/melting point than trans
OR
cis-fatty acids have a kink «in the chain» but trans do not
Accept answer in an annotated diagram
2a. [8 marks]
Markscheme
a. contraction of muscle «layers»/peristalsis helps move food
OR
circular muscle contraction prevents backward movement of food
OR
longitudinal muscle contraction moves food along gut
b. peristalsis/muscle contractions mix food with intestinal enzymes
c. enzymes digest macromolecules into monomers
Accept an example for mp c
d. pancreatic enzymes/amylase/lipase/endopeptidase «chemically» digest food in«lumen of»
small intestine
e. «pancreatic» amylase digests starch
OR
lipases digest lipids/fats/triglycerides
OR
endopeptidases/dipeptidases digest proteins/polypeptides
f. bile/bicarbonate secreted into the small intestine creates favorable pH for enzymes
OR
bile emulsifies fat
g. some final digestion into monomers is associated with epithelial cells/epithelium «of small
intestine»
h. mucosa layer/inside surface/lining of small intestine contains villi/finger-like projections
i. villi/microvilli increase surface area for better absorption
j. villi absorb products of digestion/monomers/mineral «ions»/vitamins
k. glucose/amino acids enter blood «capillaries»
OR
lipids enter lymph vessels/lacteals
l. absorption involves active transport/diffusion/facilitated diffusion
m. different nutrients are absorbed by different transport mechanisms
2c. [3 marks]
Markscheme
a. leptin suppresses/inhibits appetite
b. is secreted by adipose tissue/fat «storage» tissue
c. level is controlled by amount of adipose tissue/«ongoing» food intake
d. leptin targets cells in hypothalamus/appetite control centre in brain
e. causes hypothalamus/control centre in brain to inhibit appetite
f. if amount of adipose tissue increases, blood leptin concentration rises
3a
7a. State the name of the bacterium that can cause stomach ulcers. [1 mark]
Markscheme
Helicobacter pylori ✔
To award [1] full scientific name is required.
Examiners report
A large number stated the complete binomial name, as expected; many provided only a
partial name; a noticeable number wrote E. coli, something else irrelevant or left the box
blank.
3b
Markscheme
a. vitamin E and thioctic acid both improve healing rate «compared with nizatidine alone»
OR
all trials with antioxidant/three trials improve healing rate «compared to N alone» ✔
b. adding vitamin E increases healing rate more than adding thioctic acid
OR
adding both vitamin E and thioctic acid increases healing rate to highest level «but still less
than 100 %» ✔
Giving values alone is not enough.
4a
Markscheme
aids peristalsis / reduces risk of intestinal disorders/cancer/constipation / reduces hunger
5a
Markscheme
1.
2.
3.
4.
5.
protein/muscle lost for energy ✔
lack of blood plasma proteins ✔
leading to tissue fluid retention/edema/swollen abdomen/kwashiorkor ✔
lethargic/little interest in surroundings ✔
thin muscles/flaky appearance of skin/sparse hair with lack of pigmentation
✔
f. physical/mental development retarded ✔ g. lack of menstrual cycle ✔
5b
Markscheme
cod/fish liver oil
OR
oily fish «accept correctly named example» Check examples on the Internet if necessary.
OR
egg yolk
OR
«fortified/enriched» dairy product ✔ i.e. milk/cheese/yoghurt.
Allow any two sources for the mark. Mark only the first two.
Do not accept sunlight, as source has to be dietary, nor dietary supplements. Reject fish
alone.
5c
Both one cause from left column and one symptom from right column required for the
mark.
For the cause, do not accept risk factors, e.g. high sugar intake/obesity, lack of exercise,
genetic predisposition, etc.
Other valid symptoms could be: slow-healing sores, dizziness, tiredness, red/swollen gums,
kidney/back pain, nerve damage, erectile dysfunction.
Markscheme
Northern Territory ✔
Markscheme
less sun in winter than in summer
OR
colder in winter so cover up/indoors more
OR
skin has more exposure to sun in summer ✔ Accept other valid suggestions.
Accept vice versa.
Markscheme
a. «lack of vitamin D results in» calcium «ions» not absorbed from gut in sufficient
quantities ✔
b. calcium salts not deposited or reabsorbed
OR
affects bone mineralization ✔
c. bones become softened/weakened ✔
d. can cause rickets «in children»/osteomalacia «in adults» ✔
Markscheme
Not necessary to present answer in a table. Accept other valid similarities and/or
differences. Award marks for complete lines only.
18c. [7 marks]
Markscheme
a. sinoatrial node/SAN is a specialized group of muscle cells
OR
sinoatrial node/SAN is located in the right atrium ✔
b. acts as a pacemaker/controls the heart rate
OR
initiates/generates the heart beat/starts the cardiac cycle ✔
c. sends out electrical signal/impulses/depolarisations ✔
d. electrical signal stimulates contraction «of heart muscle» ✔
e. signal passes through walls of atria/passes to AV node ✔
f. then through walls of the ventricles ✔
g. medulla «oblongata of brain» can change/increase/decrease the rate ✔
h. through nerves/named example of nerve/autonomic/sympathetic/ parasympathetic nervous
system ✔ In mph, only accept vagus nerve for slowing heart rate and sympathetic nerve for
accelerating it.
i. one nerve increases the rate and the other decreases it ✔
j. epinephrine/adrenaline increases heart rate/force of contraction ✔
k. epinephrine/adrenaline prepares the body for vigorous activity/is part of fight or flight
response ✔
19a. [1 mark]
Markscheme
both labelled clearly as in diagram ✔
[Source: BlueRingMedia/Shutterstock]
9
Markscheme
breakdown/weakening of heart muscle
OR
electrolyte imbalance affecting the cardiac cycle
OR
low blood pressure/heart rate ✔
10
Markscheme
compare:
a. no difference in the P wave/QRS wave OR
both traces have all 4 waves/PQRST ✔
contrast:
b. delayed T wave
OR
T wave is shorter/higher in hypocalcemia ✔
Allow reference to events in the cardiac cycle for mpa or mpb Allow converse statements
for mpb.
Markscheme
a. repolarization of ventricles ✔
b. ventricles are in diastole/relaxation ✔