This document contains information about cell division through mitosis: 1. It describes the 5 stages of mitosis - prophase, metaphase, anaphase, telophase, and interphase. Key events at each stage like chromosome condensation, alignment at the equator, separation of chromatids, and cytokinesis are mentioned. 2. Diagrams (Figures a-e) show cell characteristics at different mitosis stages like chromosome structure, spindle fiber formation, and separation of daughter nuclei. 3. Asexual reproduction through mitosis is summarized - it allows unicellular organisms and cells in multicellular organisms to reproduce without fertilization, maintaining chromosome number. Mitosis has agricultural uses like cloning

1. D
BA
D
D
1C
2B
3D
4D
5C
6B
Answers
Objective Questions
7
8
9
10
ll
Structured Question
(a) (i) Nucleus
(ir) DNA consists of 2 polynucleotide chains that
(b) (i) Nucleotide
(ii) Tvpe of nitrogenous base
(iii)
are coiled together
,F
(c) Gene
(d) (i) Reproductive cell
(ii) Chemical substance such as the mustard gas
Essay Question (a) o Enz--vmes accelerate biochemical reactions but are not
the experiment. As such, enzymes are required only in
changed at the end of
small quantities in the
body. o The action of the enzymes is specific. that
reaction that involves certain substrates.
ts each enz_yme onlS'catalyses the
c Enzymes exhibit protein characteristics such as being sensitive towards
changes in temperature. Enzymes are destroyed at a temperature of 60"c and
the enzymatic action is stopped. At a low temperature of 10.c, the enzymatic
action is slorv. Enry-mes react at the rnaximum level at the opiirrlo-temperature.
o The erzymatic action is influenced by the medium pH. Each enzvme reacts at
the maximum level at its optimum pH. r The same enzyme catalyses the reverse reaction.
Exampie: Starch + water amylase t maitose
amr-lase Maltose ' > starch*water

2. (b) Purpose: To siudy the effect of temperature on the enz),rne activity
Apparatus/Material: -
Procedure.
I 5 rnl of saliva is collected and diluted by adding 5 ml of distilled water into
a small beaLer. 2 Test tubes labelled P, Q, R, S and T are prepared.
is poured into each test tube.
5 nrl ofstalch suspension
3 Each test tube is placed in the water bath at temperatures of 5oc, 2g"c,
37'C,45oC and 60"C. 4 After that. I ml of saliva solution is added into each test tube and the
stopwatch is started immediately. The content of each tube is stirred and a
drop of the contents is removed at I minute interr,'als to be tested with iodine
solution. This step is repeated until the iodine solution does not change
colour.
Result:
Test
tube
---- --- Time
{minute)
Temperature---r.-
(oC)
1 2 3 4 5 6 7 8 o 10
P t
o 28
R 37
e 45
T 60
Conclusion:
The action of the enzyme is influenced bv temperature. Enzymatic action is
llo-tl ut low temperatures, and increases u'ith the increase in temperature until 37"c. The enzymatic action is at ihe maximum at 37"c. Aft-er 37.c. the
enzyrnatic action decreases and stops at 60"C.

3. Objective Questions 1D
2B
3C
4B
5A
6B
7C
8B
Structured Question (a) X: spindle fibre
Y: chromosome
Z: centromere
Answers
9
tn tl,
11
12
13
t4
15
C
A
B
B
B
A
B
(b)
(c)
4
At the anaphase stage. the centromere divided and the chromatid separates, and the
chromosome is pulled by the spindle fibre at the centromere.
Essay Question
(a) 1 Mitotic cell division process
2 Before mitosis begins, the cell is in the interphase stage/state of rest. The acii1.e cell nucleus/chromosome experiences replication/doubling of DNA/nucleus
membrane is seen clearl,v/chromosome is like a granule/chromatin/long and fine
coil/there is an increase rn ihe number of mitochondriaichloroplast/organille
3 FIGURE (a)
AFcellwall
ltlt =t'4-% lllf nuctear membrane nucleus
Shows the following cell characteristics: clear nucleus membrane, chromosome
looks like a granule/chromatir,.,tong and fine coil/chiomatin netrvork. has
nucleus
At the prophase siage, the chromosorne thickens/shortens anrl looks like two
identical coils/alike/sister chromatids/alike/double helix joined at the centromere
The nucieus membrane slowly disappears/spindie fibre is formed al the end of the
prophase

4. 6 FIGURE (b) (early/end prophase)
l0
nuclear membrane
break down
centromeie
chromosome
r Shows the following cell characteristics: chromosome thickens and shortens-chromatid
ioins at the centromere, no nucleus
At the metaphase stage, the chromosomes/chromatids are arranged at the
equatorial plane and is held by the spindle fibre at the centromere
FIGURE (c)
r Shows the follou'ing cell characteristics: the chromosomes/chromatids are
arranged at the centre/fibre equatorial plane, fibres are formed
At the anaphase, each chromatid pair starts to separate at the centromere and is
pulled tou'ards opposing cell poles as a result of the contraction of the spindle fibre
FIGURE (d)
o Shows the following cell characteristics: the chromatid pair separates at the
centromere, the chromatid is pulled towards the opposing poles, the centromere
is orientated towards the pole
The spindle starts to disappear and the nucleus membrane is reformed/trvo
daughter cell nuclei are formed
At the telophase, c1'toplasm division/cl.tokinesis produces two diploid daughter
cells/that has the same number of chromosomes as the parent cell
FIGURE (e)
I Shows the following cell characteristics: cell plate is formed at the middle,
nucleus membrane exists, chromosome lengthens/coils/form coils
ll
I2
13

5. (b) (i) The process of producing a new individual from a parent without involving
fertilisation between gametes.
(iD . Cell division through mitosis on the multi-cell organism can increase the
number of cell for grou,ttr, and to replace damaged or dead cells. o unicellular organisms (Amoeba sp. and pqramecium sp.), reproduces by
splitting into two through mitosis. e Division through mitosis maintains the number of diploid chromosomes in the
daughter cell, and as such, the new organism that is formed will have the same
characteristics as the parent. . Mitosis is used in agriculture to produce flowering plants arrd fruit plants in a
larger quantity and at a higher qualiqv.