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Answers to Workbook Workbook 1B  Unit 4 (Sample)

Unit 4Cells, human reproduction and heredity

Section Exercise
4.1A Basic units of living things
4.1B Observing cells using microscopes

Level 1
I Fill in the blanks (p. 1) (1 m each)
1 light microscope
2 cytoplasm; nucleus
3 cell wall
4 chloroplasts

II True or false questions (p. 1) (1 m each)

1 T
2 F
3 T
4 F
5 T
6 F

III Labelling (p. 2) (1 m each)

a eyepiece
b coarse adjustment knob
c fine adjustment knob
d objective
e diaphragm
f mirror

IV Matching (p. 2) (1 m each)

A v B vi C ii D i E iv F iii

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Answers to Workbook Workbook 1B  Unit 4 (Sample)

Level 2
I Multiple-choice questions (p. 3) (1 m each)
1 C
2 C
3 D
4 C
5 B
6 B

II Questions (p. 4)
1 a i Unicellular. (1 m)
ii It is made up of only one cell. (1 m)
b Human (or other reasonable answers) (1 m)

2 a Plant cells. (1 m)
b The cells have cell walls. (1 m)
The cells have chloroplasts. (1 m)
c
Structure Function
Cell membrane (1 m)/ It controls the movement of substances into and
out of the cell. (1 m)/
Cytoplasm (1 m)/ It is the place where many chemical reactions
take place. (1 m)/
Nucleus (1 m) It contains DNA, which controls the activities of
the cell. (1 m)
(Any two)

d Eyepiece: 10X (1 m) Objective: 40X (1 m)

e [✓] Lower magnification (1 m)

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Answers to Workbook Workbook 1B  Unit 4 (Sample)

Skill practice (p. 6)

Section Exercise
4.1C DNA in the nucleus
4.1D Cells can divide, grow and differentiate
4.1E Levels of organization of living things

Level 1
I Fill in the blanks (p. 7) (1 m each)
1 DNA
2 46
3 cell division

II True or false questions (p. 7) (1 m each)

1 T
2 F
3 T
4 F

III Matching (p. 7) (1 m each)

A iii B ii C i

Level 2
I Multiple-choice questions (p. 8) (1 m each)
1 B
2 B
3 D
4 C

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Answers to Workbook Workbook 1B  Unit 4 (Sample)

II Questions (p. 9)
1 a Female. (1 m)
She has two X chromosomes. (1 m)
b 46 (1 m)
23 (1 m)
2 a ii ➝ iv ➝ i ➝ iii (3 m)
b Yes, (1 m)
because all DNA in the nucleus makes a copy of itself before cell division
begins, so every new cell has the same copy of DNA. (1 m)

Section Exercise
4.2A Human sex cells
4.2B Human reproductive systems
4.2C Sexual maturity

Level 1
I Fill in the blanks (p. 10) (1 m each)
1 sperms; ova
2 tail
3 one set
4 nocturnal emissions; menstrual cycle

II True or false questions (p. 10) (1 m each)

1 F
2 T
3 T
4 T
5 T
6 F

III Labelling and matching (p. 11) (1 m each)

Part Name
A oviduct
B ovary
C uterus
D vagina
E sperm duct

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Answers to Workbook Workbook 1B  Unit 4 (Sample)

F sex glands
G testis
H scrotum
I urethra
J penis

A vii B vi C vii D ix E iii

F iv G i H ii I v J x

Level 2
I Multiple-choice questions (p. 12) (1 m each)
1 B
2 C
3 A
4 A

II Questions (p. 13)

1 a A is ball-shaped (1 m)
while B looks like a tadpole. (1 m)
b A cannot move by itself (1 m)
while B can swim by beating its tail. (1 m)
c The numbers of chromosomes in A and B are half of that in body cells. (1 m)
2 a W (1 m)
b breaks down (1 m)
blood (1 m)
vagina (1 m)

Section Exercise
4.2D Birth of a new life
4.2E Becoming parents
4.2F Family planning and birth control

Level 1
I Fill in the blanks (p. 14) (1 m each)
1 zygote; fertilization
2 foetus
3 Parenting

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Answers to Workbook Workbook 1B  Unit 4 (Sample)

4 Contraceptive pills

II True or false questions (p. 14) (1 m each)

1 F
2 F
3 F
4 T
5 T
6 T
7 F

Level 2
I Multiple-choice questions (p. 15) (1 m each)
1 B
2 D
3 D
4 D

II Question (p. 16)

a A: placenta (1 m)
B: umbilical cord (1 m)
C: uterus (1 m)
D: amniotic fluid (1 m)
b D (1 m)
c nutrients (1 m); oxygen (1 m); Wastes (1 m)
d It is pushed out of the mother’s body. (1 m)

Section Exercise
4.3A Heredity

Level 1
I Fill in the blanks (p. 17) (1 m each)
1 heredity
2 double helix
3 C; A; base pairing

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Answers to Workbook Workbook 1B  Unit 4 (Sample)

II True or false questions (p. 17) (1 m each)

1 F
2 T
3 T
4 F

Level 2
I Multiple-choice questions (p. 18) (1 m each)
1 D

II Question (p. 18)

a
(2 m)

b base sequences (1 m); proteins (1 m)

Section Exercise
4.3B Variations
4.3C Identical and non-identical twins

Level 1
I Fill in the blanks (p. 19) (1 m each)
1 variations
2 discontinuous
3 continuous
4 environment

II True or false questions (p. 17) (1 m each)

1 F

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Answers to Workbook Workbook 1B  Unit 4 (Sample)

2 F
3 T
4 T
5 F
6 F

Level 2
I Multiple-choice questions (p. 20) (1 m each)
1 A

II Question (p. 20)

a [✓] Peter and Paul (1 m)
b Look of earlobes (1 m)

Skill practice (p. 21)

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Answers to Workbook Workbook 1B  Unit 4 (Sample)

Skill practice (p. 22)

a

b i 16 cm (1 m)
ii 13 cm (1 m)

Unit Exercise
I True or false questions (p. 23) (1 m each)
1 F
2 T
3 F
4 F
5 T
6 F
7 F
8 T
9 F
10 F

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Answers to Workbook Workbook 1B  Unit 4 (Sample)

II Multiple-choice questions (p. 23) (1 m each)

1 A
2 D
3 A
4 C
5 C
6 A
7 B
8 A
9 C
10 A

III Questions (p. 26)

1 a The cell wall was not shown. (1)/
The title is missing. (1)/
Lines are not smooth. (1)/
Labelling lines cross each other. (1)/
The nucleus should not be shaded. (1)
(Any three) (3 m)
b

2 a i For making large adjustments in focusing. (1 m)

ii For making small adjustments in focusing. (1 m)
b Magnification of Part B = 600/15 (1) = 40X (1 m)
c i ➝ iv ➝ ii ➝ iii (2 m)
d To the left. (1 m)

3 a An ovum released from Mrs Lam’s ovary (1) fuses with one of Mr Lam’s
sperms (1) to form a zygote (1).
It divides repeatedly to form an embryo, which attaches to the thickened
uterine lining (1). (4 m)

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Answers to Workbook Workbook 1B  Unit 4 (Sample)

b Absence of menstruation / Nausea / Frequent urination / Constipation /

Feeling tired easily. (1 m)
c ii ➝ v ➝ iii ➝ i ➝ iv (3 m)
d A girl. (1 m)

4 a i chromosome (1 m)
ii double helix (1 m)
iii bases (1 m)
iv A , T , C and G (2 m)
b X: C (1 m)
Y: T (1 m)
Z: G (1 m)
c Since the code formed by the sequence of bases is now changed, (1 m)
the cell may not be able to produce the normal kind of protein. (1 m)

5 a i 4 (1 m)
ii 28 (1 m)
b 14 December. (1 m)
c i Rhythm method (1 m)
ii The day when Mandy releases an ovum may not be regular. (1 m)
iii Female sterilization. (1 m)

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