4 CELLS, HUMAN

REPRODUCTION AND
HEREDITY
 4 Cells, Human Reproduction
and Heredity
S ECTIONAL E XERCISE
4.1 Cells efer to Textbook
p.3–21
4.1

A. True or false (6 marks)

Sectional Exercise

Write ‘T’ for a true statement and ‘F’ for a false statement.

1. All living things are made up of more than one cell. F

2. Amoeba is an example of unicellular organisms. T

3. A plant cell has a nucleus but an animal cell does not. F

4. Light microscopes are commonly used in the school laboratory. T

5. A longer objective has a higher magnification. T

6. There are 23 pairs of chromosomes in a human body cell. T

B. Multiple-choice (9 marks)
Choose the correct answer for each question.

1. Which of the following structures can only be found in plant cells but not in animal cells?
(1) Cell wall
(2) Cytoplasm
(3) Chloroplast
A. (1) and (2) only B. (1) and (3) only
C. (2) and (3) only D. (1), (2) and (3) B

2. The photomicrograph shows some cells. Which of the following

is the function of structure X of the cells?
A. To support and give shape to the cell
X
B. To carry out photosynthesis
C. To control cell activities
D. To carry out chemical reactions A

2
 Cells, Human Reproduction and Heredity 4

Directions: Questions 3 and 4 refer to the following eyepieces and objectives for a light
microscope.

Eyepieces 5X, 10X, 15X

Objectives 4X, 10X, 40X, 100X

3. Which of the following combinations shows the lowest and highest magnifications of the
microscope? 4.1
Lowest magnification Highest magnification
A. 50X 20X

Sectional Exercise
B. 50X 1500X
C. 20X 600X
D. 20X 1500X D

4. Which of the following combinations allows the observation of the largest number of cells in
a specimen?
Eyepiece Objective
A. 5X 4X
B. 5X 100X
C. 10X 4X
D. 15X 40X A

5. The picture on the right is observed under a microscope. Which of the

following is the image observed?

A. B.

C. D.

3
 4 Cells, Human Reproduction and Heredity

6. To prepare a slide of ox eye cells, we add methylene blue solution to the cells to
A. avoid the formation of air bubbles on the slide.
B. stain the cells for easier observation.
C. kill the microorganisms on the cells.
D. preserve the colours of the structures. B

7. Which of the following statements about the nucleus is correct?

A. It carries genetic materials DNA.
4.1
B. It is at the centre of all cells.
C. It contains structures which produce food.
Sectional Exercise

D. It controls the movement of substances into and out of the cell. A

8. The structures shown in the photomicrograph below are

A. plant cells.
B. animal cells.
C. chromosomes.
D. DNA. C

9. A girl was born with chromosomal disorders. Which of the following can be the full set of
chromosomes in her body cell?
(1)  (2)  (3)

1 2 3 4 5 1 2 3 4 5 1 2 3 4 5

6 7 8 9 10 11 12 6 7 8 9 10 11 12 6 7 8 9 10 11 12

13 14 15 16 17 18 13 14 15 16 17 18 13 14 15 16 17 18

19 20 21 22 XX 19 20 21 22 XY 19 20 21 22 X

A. (1) only B. (2) only

C. (1) and (3) only D. (2) and (3) only C

• In (1), there is an extra chromosome 21. This is known as Down syndrome.

• In (3), an X chromosome is missing. This is known as Turner syndrome (特納氏綜合症).
It is a chromosomal disorder in females.

4
 Cells, Human Reproduction and Heredity 4

C. Questions (32 marks)

1. Make a biological drawing to show the structures of any two cells in the photomicrograph
below. Label the drawing with the words given. (7 marks)

cell membrane cell wall cytoplasm nucleus

cell wall
4.1
cytoplasm

nucleus

Sectional Exercise
Correct drawing (1m) cell
Correct labellings (4m) membrane
Use smooth and clear
solid lines (1m)
Draw in pencil (1m)

2. The following diagram shows an animal cell undergoing an important process.

S
R

P Q

(a) Name the process. (1 mark)

Cell division (1m)

(b) Describe what is happening during period X. (2 marks)

The nucleus and the cytoplasm (1m) divide into two. (1m)

(c) Describe what is happening during period Y. (2 marks)

The daughter cells absorb nutrients (1m) and grow bigger. (1m)

(d) At which stage (P, Q, R or S) does the cell make a copy of the genetic materials?
(1 mark)
P (1m)

5
 4 Cells, Human Reproduction and Heredity

3. The photo below shows a light microscope.

(i) eyepiece (1m)

(ii) objective (1m)

coarse adjustment
(iii) clip (1m) (vii) knob (1m)
4.1
fine adjustment
(viii) knob (1m)
Sectional Exercise

(iv) stage (1m) (ix) arm (1m)

(v) diaphragm (1m)

(x) base (1m)

(vi) mirror (1m)

(a) Label parts (i) to (x) of the microscope. (10 marks)

(b) Match the parts of the microscope with their descriptions by writing the corresponding
letters a, b, etc. in the blanks below. The first one has been done for you as an
example. (9 marks)

Part of the microscope Description

(i) (a) Used for making large adjustments in focusing

(ii) (b) The lens nearest to the object
(iii) (c) The part we use to carry the microscope
(iv) (d) The place where the object is held for viewing
(v) (e) The lens closest to our eyes
(vi) (f) Adjusts the amount of light entering the microscope
(vii) (g) The bottom stand of the microscope
(viii) (h) Used for making small adjustments in focusing
(ix) (i) Reflects light onto the object
(x) (j) Holds the object on the stage

(i) e (ii) b (iii) j (iv) d (v) f

(vi) i (vii) a (viii) h (ix) c (x) g

Each answer (1m)

Total Score :   / 47

6
 Cells, Human Reproduction and Heredity 4

4.2 How are cells organized in living things? efer to Textbook

p.22–28

A. True or false (5 marks)

Write ‘T’ for a true statement and ‘F’ for a false statement.

1. Different types of cells have different sizes, shapes and functions. T

2. Nerve cells are short so they can carry messages faster. F

E 3. Some organs group together to form a tissue. F 4.2

E 4. Different systems work together to support our lives and keep us healthy. T

Sectional Exercise
E 5. The leaf is one of the organs of plants. T

B. Multiple-choice (3 marks)
Choose the correct answer for each question.

1. Cell X is found in plants. It is likely

A. a root hair cell. cell X

B. a transporting cell.
C. a leaf cell.
D. a fat cell. A

E 2. Which of the following correctly arranges the levels of organization?

A. cell, organ, tissue, system
B. cell, tissue, organ, system
C. tissue, system, organ, cell
D. tissue, system, cell, organ B

E 3. Each small circle in the following diagrams represents a cell. Which of the diagrams best
represents a system?
A. B. C. D.

7
 4 Cells, Human Reproduction and Heredity

C. Questions (7 marks)
E 1. Bioprinting is a new technology that can be used to ‘print’ living tissues.
EM
ST

bio-ink

4.2
bio-paper
Sectional Exercise

(i) Bio-ink is added to a (ii) Additional layers are (iii)Bio-ink fuses together (iv)A living tissue is
layer of bio-paper. printed, one layer on and the bio-paper is printed.
top of another. dissolved.

(a) In bioprinting, bio-ink is used. What does the bio-ink contain? (1 mark)
Living cells (1m)

(b) Printing an organ is more difficult than printing a tissue. Why? (3 marks)
A tissue is made up of (i) the same type (1m) (the same type/different
types) of cell while an organ is made up of (ii) different types (1m) (the same
type/different types) of tissues. Therefore, it is more (iii) complicated and difficult to print
an organ than a tissue (1m) .

(c) Patients with severe skin damage (e.g. having burns) need to replace the damaged skin
with new skin. In the future, doctors can print the new skin with the bio-ink made from
the patient’s own skin cells. The flow chart below shows the key steps in obtaining
enough skin cells for making the bio-ink. Fill in the blanks. (3 marks)

1 Obtain the 2 Allow them to 3 Add chemicals to

patient’s grow and make the cells
stem cells (1m) . divide (1m) differentiate (1m)

into more cells. into skin cells.

Total Score :   / 15

bioprinting 生物打印技術
8
 Cells, Human Reproduction and Heredity 4

4.3 Human reproduction efer to Textbook

p.29–47

A. True or false (8 marks)

Write ‘T’ for a true statement and ‘F’ for a false statement.

1. Human reproduction involves the fusion of male and female sex cells. T

2. An ovum carries an X chromosome and a Y chromosome. F

3. An ovum can move by itself to meet a sperm. F 4.3

4. Implantation usually takes place in the ovary. F

Sectional Exercise
5. Exchange of materials between the mother and the foetus takes place at the
umbilical cord. F
placenta
6. During birth, the head of the baby usually comes out of the mother’s vagina first. T

7. During menstruation, some blood will pass out through the vagina. T

8. Wearing loose clothing during sleep can reduce the chance of wet dreams. T

B. Multiple-choice (10 marks)

Choose the correct answer for each question.

1. The diagram below shows a human sperm.

Which of the following is the function of structure Y?

A. It stores food.
B. It produces a fluid.
C. It enables the sperm to swim.
D. It carries genetic materials. C

2. Which of the following cells contain the largest number of chromosomes?

(1) Sperm
(2) Zygote
(3) White blood cell
A. (1) and (2) only
B. (1) and (3) only
C. (2) and (3) only
D. (1), (2) and (3) C

9
 4 Cells, Human Reproduction and Heredity

3. Which parts of the male and female reproductive systems produce sex hormones?
Male reproductive system Female reproductive system
A. Testis Ovary
B. Testis Vagina
C. Penis Uterus
D. Sex gland Ovary A

4. Every body cell of Alice carries 46 chromosomes. Alice has a son, who was born normal.
4.3
How many chromosomes are there in each body cell of Alice’s son?
A. 12
Sectional Exercise

B. 23
C. 46
D. 92 C

Directions: Questions 5 and 6 refer to the figure below, which shows the important processes in
human reproduction.

P Q R

5. Where do process P and process R take place?

Process P Process R
A. Uterus Ovary
B. Uterus Vagina
C. Oviduct Vagina
D. Oviduct Uterus D

6. How long does it take from process P to the birth of the baby?
A. About 9 weeks
B. About 38 weeks
C. About 6 months
D. About 12 months B

10
 Cells, Human Reproduction and Heredity 4

7. Fertilization is
A. the formation of sperms and ova.
B. the fusion of a sperm and an ovum.
C. the cell division of sperms and ova.
D. the formation of an embryo. B

8. Through which of the following structures can the foetus get nutrients and oxygen from the
mother’s body?
4.3

Sectional Exercise
A

C
B

9. Which of the following statements about puberty is INCORRECT?

A. Every boy has wet dreams at puberty.
B. In general, girls usually enter puberty earlier than boys.
C. Larynx becomes larger in males at puberty.
D. Secondary sexual characteristics appear at puberty because of the increased levels of
sex hormones in our bodies. A

10. Which of the following statements about menstruation is INCORRECT?

A. The start of menstruation in females is a sign showing that their bodies have reached
sexual maturity.
B. After menstruation, the uterine lining will thicken again to prepare for the implantation
of the embryo.
C. Menstruation must last for five days for all females.
D. The length of a menstrual cycle is not the same for all females. C

11
 4 Cells, Human Reproduction and Heredity

C. Questions (26 marks)

1. Label the parts of the male and female reproductive systems below. Also, fill in the blanks to
state the functions of them. The first one has been done for you as an example. (15 marks)

Male reproductive system (d) sperm duct (1m)

(a) urethra

Carries semen and transports sperms

4.3 (i) urine out of the
body
(e) sex glands (1m)
Sectional Exercise

(b) penis (1m) produce a fluid which

contains (iii) nutrients (1m)
ejects (ii) semen (1m) to
for sperms
the female reproductive
system during sexual
intercourse
(f) testis (1m)

where (iv) sperms (1m)

(c) scrotum (1m) and sex hormones are
produced
a bag of skin which holds
the testes

Female reproductive system

(g) oviduct (1m)

carries the ovum to the

(v) uterus (1m)

(h) uterus (1m)

(i) ovary (1m)

where a foetus grows and where (vi) ova (1m) are

develops before its birth produced

(j) vagina (1m)

receives the (vii) penis (1m)

during sexual intercourse
baby passes through here
at birth

12
 Cells, Human Reproduction and Heredity 4

2. Complete the table below which summarizes the number of chromosomes in human body
cells and sex cells. (6 marks)
Male Female
Sex cell
Body cell Sex cell (sperm) Body cell
(ovum)
No. of chromosomes 46 (a) 23 (1m) (b) 46 (1m) 23
No. of autosomes (c) 44 (1m) 22 44 (d) 22 (1m)
4.3
Sex chromosomes (e) XY (1m) half in number: X (f) XX (1m) X
half in number: Y

Sectional Exercise
3. The diagrams below show a 28-day menstrual cycle and the changes in the thickness of the
uterine lining.

P Q
28 1
27 2
26 3
25 4
period I
24 5
Q
period IV
23 6
P (1m)
22 period II 7

21 R (1m) 8
R S
20 9
period III
19 S (1m) 10
18 11
17 12
16 13
15 14

(a) How does the thickness of the uterine lining change during the menstrual cycle? Put the
letters P, Q, etc. in the boxes to show your answers. The first one has been done for you
as an example. (3 marks)

(b) What is the name of the process that takes place during period I? (1 mark)
Menstruation (1m)

(c) During which period is ovulation most likely to occur? (1 mark)

Period III (1m)

Total Score :   / 44

13
 4 Cells, Human Reproduction and Heredity

4.4 Being parents efer to Textbook

p.47–52

A. True or false (5 marks)

Write ‘T’ for a true statement and ‘F’ for a false statement.

1. A woman does not have menstruation when she is pregnant. T

2. Pregnant women should not do exercise. F

4.4 3. Parents only have the responsibility to provide daily necessities for their children. F

4. The length of pregnancy usually increases with the size of the mammal. T
Sectional Exercise

E 5. Using condoms in sexual intercourse can help prevent the transmission of AIDS. T

E B. Fill in the blanks (5 marks)

1. A woman can take birth control pills to prevent the release of ova from the
ovaries.

2. The rhythm method is the most unreliable method among all birth control
methods.

3. A (a) condom or (b) diaphragm acts as a barrier to prevent sperms

from reaching the ovum.

4. Sexually transmitted diseases are infectious diseases that can be passed from one
person to another through sexual contact.

E C. Matching (4 marks)

Match the birth control methods with their working principles by writing i, ii, etc. in the blanks
below.

Birth control method Working principle

(a) Condom (i) Tie and cut the oviducts or sperm ducts
(b) Rhythm method (ii) Act as a barrier to prevent sperms from reaching the ovum
(c) Sterilization (iii) Stop ovulation by using sex hormones
(d) Birth control pills (iv) A natural method without using birth control devices

(a) ii (1m)   (b) iv (1m)   (c) i (1m)   (d) iii (1m)

Total Score :   / 14

14
 Cells, Human Reproduction and Heredity 4

4.5 Heredity and variation efer to Textbook

p.53–69

A. True or false (10 marks)

Write ‘T’ for a true statement and ‘F’ for a false statement.
1. The zygote formed after fertilization receives half of its genetic information from the
father and half from the mother. T

2. In a ‘genetic traits tree’, a square is commonly used to represent a male. T 4.5

3. Blood group is an example of continuous variation. F
4. A bar chart can be used to present the data of discontinuous variation.

Sectional Exercise
T

5. Some variations cannot be changed by the environment. T

(Normally, only one sperm
6. Twins are formed by two sperms fusing with the same ovum. can enter an ovum.) F

7. Identical twins have the same IQ. (IQ is a continuous variation. It is determined F
by both heredity and environment.)
E 8. There are four different kinds of bases on the DNA strands. T

E 9. If 20% of the bases on DNA is A, 20% of the bases is T. T

E 10. Every three bases on DNA encode one ‘message’. T

B. Multiple-choice (8 marks)
Choose the correct answer for each question.

1. Which of the following cells determine(s) the traits we inherit from our parents?
(1) The sperm from the father
(2) The ovum from the mother
(3) The brain cells from both parents
A. (1) only
B. (3) only
C. (1) and (2) only
D. (2) and (3) only C

2. Which of the following variations in humans show(s) a continuous range of differences?

(1) Height
(2) Ear lobe
(3) Foot length
A. (1) only
B. (2) only
C. (1) and (3) only
D. (2) and (3) only C

15
 4 Cells, Human Reproduction and Heredity

3. The graph below shows the distribution of the body mass of a group of students.

Distribution of the body mass of a group of students

4.5 6
Number of
students
Sectional Exercise

0
44.5 47.5 50.5 53.5 56.5 59.5

Body mass (kg)

According to the graph, what conclusion can be drawn?

A. Students who have a body mass of 44.5–47.5 kg are abnormal.
B. The largest number of students among the group have a body mass of 50.5–53.5 kg.
C. Variation in the body mass of humans is clear-cut.
D. The body masses of students are related to their diets. B

4. Which of the following can be the causes of variations?

(1) Differences in genetic materials
(2) Cell division
(3) Diet
A. (1) and (2) only
B. (1) and (3) only
C. (2) and (3) only
D. (1), (2) and (3) B

5. Which of the following information can be used to prove whether two persons are identical
twins or not?
A. Their genetic materials
B. Their sex
C. Their blood groups
D. Their eye colours A

16
 Cells, Human Reproduction and Heredity 4

6. Which of the following statements about identical twins is INCORRECT?

A. They are of the same sex.
B. Their genetic materials are the same.
C. They result from a single zygote.
D. Their body masses are the same. D

E 7. Which of the following statements about DNA is INCORRECT?

A. The structure of DNA was discovered several hundred years ago. 4.5
B. DNA consists of two strands of bases.
C. Base C on one strand always pairs with base G on the other.

Sectional Exercise
D. DNA is found inside the nucleus of a cell. A

E 8. The sequence of bases on a DNA strand is ATGTTCCATGCG. Which of the following shows
the correct sequence of bases on the complementary strand?
A. CGAABCTGCTAT
B. CGAGGTTGCTAT
C. TACAAGGTACGC
D. TACAAGGTABAG C

C. Fill in the blanks (10 marks)

1. The features each generation inherits from their parents are called (a) traits ,
which are determined by the (b) DNA in the nucleus of cells.

2. The differences in features among individuals of a species are called (a) variations ,
which are determined by (b) heredity and the (c) environment .

3. We can draw a (a) histogram to present the data of continuous variation. On

the other hand, we can draw a (b) bar chart to present the data of
discontinuous variation.

E 4. The two strands of DNA are twisted around one another that makes DNA a
(a) double helix . There are (b) four kinds of bases on the
strands and the sequence of the bases encodes instructions for cells to make
(c) proteins which have various functions in the body.

17
 4 Cells, Human Reproduction and Heredity

D. Questions (27 marks)

1. Study the ‘genetic traits tree’ below which shows whether different members in a family can
roll their tongues or not.

I
1 2
Key:
4.5
black = tongue roller
II white = non-tongue roller
Sectional Exercise

3 4 5

(a) How many daughters does this family have? (1 mark)

Two (1m)

(b) State the individuals who cannot roll their tongues in this family. (1 mark)
2, 4 (1m)

(c) (i) Which parent (father or mother) is the tongue roller in this family? (1 mark)

Father (1m)

(ii) Does the next generation inherit the trait of tongue rolling ability? If yes, state the
individual(s). (2 marks)

Yes, (1m) individuals 3 and 5 can roll their tongues. (1m)

(d) Can the eldest child in this family roll the tongue? (1 mark)
Yes (1m)

2. A group of students use a mobile phone app to measure their resting heart rate. The following
table shows the results.

Resting heart rate

56–60 61–65 66–70 71–75 76–80 81–85 86–90 91–95
(beats per minute)
Number of students 3 7 12 9 5 2 1 1

18
 Cells, Human Reproduction and Heredity 4

(a) Based on the data, explain whether heart rate is a continuous or discontinuous
variation. (2 marks)
Continuous variation, (1m) because it shows a continuous range of differences. (1m)

(b) Draw a histogram to present the data. (5 marks)

Distribution of resting heart rate of a group of students

4.5

12

Sectional Exercise
10

Number 8
of
students 6

2 Correct title (1m)

Correct x-axis (1m)
Correct y-axis (1m)
55.5 60.5 65.5 70.5 75.5 80.5 85.5 90.5 95.5 Correct drawing of bars (2m)
Resting heart rate (beats per minute)

E 3. The photo on the right shows a model in science. It is used to show the
structure of a material found in our body cells.

(a) Write the full name of this material. (1 mark) X

Deoxyribonucleic acid (1m)

(b) In which part of a cell is this material found? (1 mark)

Inside the nucleus of a cell (1m)

(c) This material is packed in some thread-like structures. Name these thread-like
structures. (1 mark)
Chromosomes (1m)

(d) What does X represent in this model? (1 mark)

Bases (1m)

(e) This material is often described as ‘book of life’. Write ONE of its importance. (1 mark)
It controls all the activities within our cells. (1m) / It determines the traits we inherit from our

parents. (1m) (Or any other reasonable answers)

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 4 Cells, Human Reproduction and Heredity

4. The table below shows the information of a pair of twins.

Louis Ray
4.5
big nose, small eyes, small mouth, big nose, big eyes, big mouth,
Appearance
without ear lobes with ear lobes
Sectional Exercise

Height 175 cm 180 cm

Body mass 67 kg 70 kg

Colour of skin yellow skin yellow skin, but darker than Louis

(a) Are Louis and Ray identical twins or non-identical twins? (1 mark)
Non-identical twins (1m)

(b) Briefly explain your answer in (a). (3 marks)

Louis and Ray do not (i) look like each other (1m) . Louis has
(ii) small eyes, small mouth and does not have ear lobes (1m)

while Ray has (iii) big eyes, big mouth and ear lobes (1m) .

(c) Complete the paragraph below to describe how the type of twin in (a) is formed.
(5 marks)
This type of twin results from (i) two different (1m) zygotes. Each zygote
develops into a baby. The babies have (ii) different (1m) genetic materials, so
they may be of (iii) the same (1m) or (iv) different (1m) sex. They
may also look (v) different from (1m) each other.

Total Score :   / 55

20
 Cells, Human Reproduction and Heredity 4

I NTEGRATED E XERCISE
A. True or false (8 marks)
Write ‘T’ for a true statement and ‘F’ for a false statement.

1. All plant cells contain chloroplasts. (Only the cells in green parts have chloroplasts, F
4.1 for example, leaves.)
2. A light microscope usually has a higher magnification than an electron microscope. F
4.1
3. When making biological drawings, we should use a pencil to draw. T U4
4.3
4. An ovum carries 23 chromosomes. T
4.3

Integrated Exercise
5. The zygote formed from fertilization carries two sets of chromosomes. T
4.3
6. Ovulation is a secondary sexual characteristic of females. F
4.5
7. Most of the genetic materials of a boy come from his father. F
4.5
8. Non-identical twins result from two different zygotes. T
4.5

B. Multiple-choice (11 marks)

Choose the correct answer for each question.

1. Which of the following structures contain(s) DNA?

4.1

Q
S

T
R

A. T only B. Q and T only

C. P, Q and R only D. Q, S and T only A

2. In the preparation of a microscope slide, the specimen should be as thin as possible so that
4.1
A. light can pass through the specimen up into the objective.
B. the cover slip can lie flat on the slide.
C. it is easier to focus onto the specimen.
D. it does not carry germs. A

21
 4 Cells, Human Reproduction and Heredity

3. Which of the following cells have the chromosomes shown in the photomicrograph?
4.1

U4
Integrated Exercise

A. A male body cell

B. A female body cell
C. A male sex cell
D. A female sex cell B

4. How many times does a zygote divide to form a 16-cell embryo?

4.1

zygote 16-cell embryo

A. 2 times
B. 3 times
C. 4 times
D. 5 times C

5. The cells shown on the right are long and have many
4.2
branches. Which of the following is most likely the function
of these cells?
A. To support the body
B. To cover the surface of the body
C. To store fats in the body
D. To carry messages throughout the body D

22
 Cells, Human Reproduction and Heredity 4

E 6. Organ X belongs to the

4.2

A. circulatory system.
B. digestive system. U4
C. reproductive system.
D. breathing system. B

Integrated Exercise
7. The strawberries we buy in the market are selectively grown
4.3
for bigger size and sweeter taste. These strawberries have
8N chromosomes in their cells while wild strawberries only
have 2N.
If regular strawberries have 56 chromosomes in each of
their cells, a cell of wild strawberries has
A. 7 chromosomes.
B. 14 chromosomes.
C. 28 chromosomes.
D. 56 chromosomes. B

8. Which of the following is NOT exchanged between the bloods of a foetus and its mother at
4.3
the placenta?
A. Red blood cells
B. Oxygen
C. Carbon dioxide
D. Nutrients A

9. Some stages of the birth of a baby are listed below.

4.3
(1) The baby is pushed out.
(2) The muscle of the uterus contracts strongly.
(3) The placenta is expelled.
(4) The amnion breaks.
Which of the following is the correct order of these stages?
A. (4)(2)(3)(1)
B. (2)(4)(1)(3)
C. (4)(2)(1)(3)
D. (2)(4)(3)(1) B

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 4 Cells, Human Reproduction and Heredity

Directions: Questions 10 and 11 refer to the graph below which shows how the thickness of the
uterine lining of a woman changes during a menstrual cycle.

Thickness of
the uterine
lining ovulation

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1 7 14 21 28 35

Day of the cycle

Integrated Exercise

10. During which period does the woman have menstruation?

4.3
A. Day 1–5
B. Day 10–15
C. Day 15–20
D. Day 20–25 A

11. The length of the menstrual cycle of the woman is

4.3
A. 15 days.
B. 20 days.
C. 25 days.
D. 28 days. D

C. Questions (31 marks)

1. Fill in the blanks to complete the steps in using a microscope listed below. Then, arrange the
4.1
steps in the correct order. (6 marks)

(a) Place the slide on the stage (0.5m) and hold it in place using the clips.

(b) Place the microscope on a bench and near a light (0.5m) source.

(c) Turn the coarse adjustment knob in the opposite direction until you see a clear image.

(d) Turn the fine adjustment knob (0.5m) to obtain the sharpest image.

(e) Turn the coarse adjustment knob (0.5m) until the objective is just above the slide.

(f) Use a low-power eyepiece and a low-power (i) objective (0.5m) for observation.
Adjust the (ii) mirror (0.5m) to obtain the most suitable brightness.

Correct order: b  f  a  e  c  d (3m)

24
 Cells, Human Reproduction and Heredity 4

2. The photomicrographs below are the images of some cells observed under a microscope.
4.1

Cell Y

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Image I Image II

Integrated Exercise
(a) Which image has a higher magnification? (1 mark)
Image II (1m)

(b) (i) If Image II is obtained using an eyepiece of 15X and an objective of 20X, what is
the magnification of the image? (2 marks)
15 × 20 (1m) = 300X (1m)

(ii) Measure and calculate the actual length of cell Y. Show your calculations clearly.
(2 marks)
3 cm
(1m) = 0.01 cm (1m)
300

3. The photo below shows a human foetus in the uterus.

4.3
(ii) umbilical cord (1m)

(i) amnion (1m)

(iii) placenta (1m)

(a) Label the structures in the photo. (3 marks)

(b) A student wonders how the foetus ‘eats food’ and ‘goes to the toilet’ inside its mother’s
body. Briefly explain to her. (3 marks)

The foetus develops in the uterus of its mother.

Through the (i) placenta (1m) , it
How does the foetus
gets (ii) nutrients and oxygen (1m)
eat food and go to
the toilet?
from its mother's blood and gets rid of
(iii) carbon dioxide and other wastes. (1m)

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 4 Cells, Human Reproduction and Heredity

4. The diagram below shows a test for determining the sex of the foetus. In the test, the watery
4.3
liquid surrounding the foetus is collected using a syringe. The watery liquid contains some
foetal cells that can then be examined under the microscope.

ultrasound watery liquid

transducer
U4
Integrated Exercise

foetus

(a) What is the function of the watery liquid? (1 mark)

It acts as a cushion to protect the foetus against shock. (1m)

(b) (i) To determine the sex of the foetus, doctors will look for some thread-like
structures in the foetal cells under a microscope. What are these structures?
(1 mark)

Chromosomes (1m)

(ii) How can the doctors determine the sex of the foetus by examining these
structures? (3 marks)

They will examine the (i) sex chromosomes (1m) . If they are (ii) XX (1m) ,
the foetus is a female. If they are (ii) XY (1m) , the foetus is a male.

foetal 胎兒的
26 ultrasound transducer 超聲波掃描探頭
 Cells, Human Reproduction and Heredity 4

E 5. Kate uses a paper to construct a DNA model as shown.

4.5

U4

Integrated Exercise
(a) State TWO features of DNA shown by the paper model. (2 marks)
Double helix (1m)

Complementary base pairing (1m)

(b) The photo on the right shows a DNA model that is much
more similar to real DNA. Compare this model with the
paper model. State TWO differences between them.
(2 marks)
In this model, the strands and the bases are made up of smaller

units. (1m) There are spaces between the base pairs. (1m)

(Or any other reasonable answers)

(c) Briefly explain the role of DNA in heredity. (5 marks)

DNA encodes ‘messages’. These ‘messages’ depend on (i) the sequence of bases (1m)

on DNA. These ‘messages’ are actually instructions for the cells

to make different types of (ii) proteins (1m) in the body, which have
various functions, such as used as structural materials of body tissues, or used as
enzymes and (iii) hormones (1m) that regulate cell activities. By controlling
(iv) the types of proteins made, (1m) DNA can determine our traits (1m) .

Total Score :   / 50

27
 4 Cells, Human Reproduction and Heredity

S PELLING C ORNER
Look at each group of figures below. Use one key term in science to describe the figures. The
letters forming the missing part of the key term can be found on the right.
1.
R C T
E R O I
U4
P U D O
N
Spelling Corner

Key term: R E P R O D U C T I O N

2.
O
M R
C O E
S
H M
O

Key term: C H R O M O S O M E

3.
A
N
R O G

Key term: O R G A N

4. C O C
M S
I O
R E
P

Key term: M I C R O S C O P E

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