22-23 Final Exam / S4 / Biology / Suggested Answer / P. 1 of 4
Queen Elizabeth School Old Students’ Association Secondary School
Final Exam 2022 – 2023
Secondary 4 Biology Suggested Answer
A
Multiple-Choice Questions (1 marks each, 36 marks total)
1 B
11 C
21 A
31 B
2 C
12 A
22 D
32 A
3 D
13 A
23 C
33 C
4 B
14 D
24 D
34 D
5 C
15 A
25 C
35 A
6 A
16 B
26 B
36 D
7 C
17 C
27 B
8 B
18 D
28 B
9 D
19 D
29 A
10 C
20 A
30 B
B
Structural Questions (84 marks total)
1.
Correct test + correct result
Food substances
(a) Glucose in an
energy drink
(b) Vitamin C in
orange juice
(c) Proteins in milk
(1)
Test
Use Clinistix paper
Positive result
The test end of Clinistix paper changes from
pink to purple
or blue.
Or: Use Benedict’s test
Or: A brick-red precipitate is
formed.
The colour of the DCPIP solution changes
from blue to colourless.
The test end of Albustix paper changes from
yellow to green.
Use DCPIP solution
Use Albustix paper
(Total: 3 marks)
2.
(a)
(b)
(c)
3.
(a)
(b)
25oC
(1)
Egg stains on clothes is a kind of protien which can be digested by protease.
(1)
Protease is protein in nature which can be denatured by higher temperature.
(1)
Boiling denature the protease present in the washing powder that make it fail to
digest the layer of gelatin.
(1)
Protease present in the washing powder remain functional in non-boiled solution
and digest the layer of gelatin.
(1)
The egg stains on clothes were digested by the protease into amino acids
(1)
Amino acids is readily soluble and be washed away by water.
(1)
(Total: 7 marks)
The salt solution has a lower water potential than that of the root cells.
Water moves out of the root cells by osmosis.
The plant cells become plasmolysed and cannot support the plant body.
active transport
diffusion
(1)
(1)
(1)
(1)
(1)
(Total: 5 marks)
22-23 Final Exam / S4 / Biology / Suggested Answer / P. 2 of 4
4.
(a)
(b)
(c)
5.
(a)
(b)
(c)
6.
(a)
(b)
(c)
(d)
it is maintained by the rigidity of the veins / vascular bundles / xylem running
through the leaves
(1)
and the turgidity of the mesophyll cells/ thin-walled cells
(1)
a large amount of water is lost from the leaves by transpiration / transpiration
rate is very high
(1)
water absorption rate cannot keep up with the rate of water loss
(1)
mesophyll cells lose water and become flaccid
(1)
thus can no longer support the leaves to maintain their upright position / so the
leaves become drooped
appearance shown in photograph X
(1)
the leaves are flat / fully extended
(1)
and thus the exposed surface can be oriented towards the light source
(1)
therefore maximizing light absorption for photosynthesis
(1)
(Total: 9 marks)
Add iodine solution to a slice of potato tuber.
(1)
If starch is present, it turns blue-black.
(1)
The bud in the tuber grows and develops a new shoot and adventitious roots
using the food reserves in the tuber.
(1)
Green leaves are formed in the new shoot. The leaves carry out photosynthesis. (1)
Some of the food made is passed down to form a new tuber.
(1)
The offspring produced by tubers are genetically identical to their parents.
(1)
If the parent genotype lacks the resistance to the diseases, the whole population
will be the same.
(1)
The process of producing offspring by seeds and fruits involves the fusion of
gametes.
(1)
This leads to genetic variation among offspring.
(1)
A strain of potatoes that are resistant to the diseases may be developed in the
population.
(1)
(Total: 10 marks)
The pollen grain landed on the stigma develops a pollen tube.
(1)
The pollen tube carries the male gametes
(1)
down the style and through the ovary.
(1)
When reaching the ovule, the pollen tube releases the male gametes into the
ovule.
(1)
X: sepals
(1)
Y: ovary wall
(1)
(i) animals
(1)
(ii) The fruit walls are fleshy
(1)
Reduces overcrowding / competition between offspring and the parent
(1)
Allow the offspring to colonise new areas
(1)
(Total: 10 marks)
22-23 Final Exam / S4 / Biology / Suggested Answer / P. 3 of 4
7.
(a)(i) in either oviduct
(1)
(ii) cover the cervix
(1)
(b)(i) Spermicide
(1)
(ii) Spermicide can kill sperm.
(1)
(c) The ovum is moved along the oviducts by the beating action of the cilia
(1)
and the muscular contractions of the oviduct wall.
(1)
(d) Both ova and sperms are haploid cells.
(1)
When a sperm and an ovum fuse together, the diploid chromosome number is
restored.
(1)
(Total: 8 marks)
8.
(a)
(b)
(c)
Male sexual characteristics are controlled by male sex hormones.
(1)
Tying and cutting structure 1 will not affect their production in the testes.
(1)
(i) The ejaculated semen is trapped inside the condom and
(1)
the sperms are prevented from entering the vagina / meeting the egg.
(1)
(ii) It can prevent the transmission of sexually-transmitted diseases.
(1)
(i) The jelly coat of the egg thickens and hardens.
(1)
(ii) It can prevent the entry of other sperms.
(1)
This can prevent the chromosome number of the zygote from getting larger
than normal / prevent the formation of abnormal embryo.
(1)
(Total: 8 marks)
9.
(a)
(b)
(c)
(d)
(2)
ciliary muscle
4th – 8th seconds
Pupils get smaller
This reduces light entering the eye/prevents photoreceptors from being damaged by
bright light
(1)
(1)
(1)
(1)
(Total: 6 marks)
10.
(a) A → B → H → G → F → E
(b)(i) B
(ii) C, G
(c) On reaching the observation deck, the air pressure on the two sides of the eardrum
became unequal.
The eardrum was pressed outwards.
Thus, it could not vibrate freely in response to sound vibrations.
(2)
(1)
(1)
(1)
(1)
(1)
(Total: 7 marks)
22-23 Final Exam / S4 / Biology / Suggested Answer / P. 4 of 4
11.
Water, warmth, oxygen are the environmental conditions for seed germination.
(0/1)
Water can activate the enzyme,
and serve as medium for chemical and enzymes reaction.
It can also soften the seed coat and,
help to transport food substances to the growing regions.
Water is also required for cell enlargement.
(1)
(1)
(1)
(1)
(1)
max 4
As for warmth, the enzymes function best within the optimum temperature range.
The maintenance of optimal enzymatic activities is very important
for growth and development as enzymes govern many cellular activities.
(1)
Oxygen can oxidise the food substance to release energy during respiration.
The energy can support the metabolic activities such as growth and cell division.
max 8
(1)
(1)
Mark award for communication:
Mark
Clarity of expression and relevance to the
question
2
 Answers are easy to understand. They are
fluent showing good command of language.
 There is no or little irrelevant material.
1.5
 Language used is understandable but there is
some inappropriate use of words.
 A little relevant material is included, but does
not mar the overall answer.
1
 Markers have to spend some time and effort
on understanding the answer(s).
 Irrelevant material obscures some minor
ideas.
0
 Language used is incomprehensible.
 Irrelevant material buries the major ideas
required by the question.
(1)
Logical and systematic presentation
 Answers are well structured showing
coherence of thought and organisation
of ideas.
 Answers are organised, but there is
some repetition of ideas.
 Answers are a bit disorganised, but
paragraphing is evident. Repetition
is noticeable.
 Ideas are not coherent and systematic.
Candidates show no attempt to
organise thoughts.
Communication skills max 3
(Total: 11 marks)
End of Paper