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Biology questions, chapter 11
Nama / NameKelas / ClassTarikh / Date

Immunity in Humans

45 marks. Use Practice to check each answer as you go, or Exam to answer everything against the clock first.

Section A: objective questions

12 marks
Choose the best answer for each question.
1

Question 1

What is an antigen?
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B
Antigens are foreign particles that enter the body and stimulate the immune response. Antibodies are the proteins made against them.
For the teacher: Remembering, low difficulty, standard 11.1.1
Textbook p. 200
2

Question 2

Which of the following is part of the first line of defence?
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C
Hydrochloric acid destroys bacteria in food and drink (first line, chemical). Fever and phagocytosis are the second line; memory cells are the third.
For the teacher: Remembering, low difficulty, standard 11.1.2
Textbook p. 201
3

Question 3

Lysozyme is found in tears, saliva and nasal mucus. What is its function?
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A
Lysozyme is an antimicrobial enzyme that breaks down the cell wall of some bacteria.
For the teacher: Understanding, low difficulty, standard 11.1.2
Textbook p. 201
4

Question 4

A cut on the skin becomes red, swollen and painful. Which chemical released by the damaged tissue causes the blood capillaries to widen?
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B
Histamine widens the capillaries and makes them more permeable so phagocytes can reach the infected area (inflammation).
For the teacher: Understanding, low difficulty, standard 11.1.2
Textbook p. 203
5

Question 5

Which cells carry out phagocytosis?
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C
Neutrophils and monocytes are phagocytes, a type of leucocyte.
For the teacher: Remembering, low difficulty, standard 11.1.2
Textbook p. 202
6

Question 6

In phagocytosis, which structure combines with the phagosome to release lysozyme onto the bacterium?
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D
The phagosome combines with a lysosome, which secretes lysozyme into it and destroys the bacterium.
For the teacher: Understanding, low difficulty, standard 11.1.2
Textbook p. 202
7

Question 7

Antibodies clump bacteria together so that phagocytes can trap them easily. What is this action called?
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C
Agglutination = clumping of pathogens. Precipitation involves dissolved antigens; neutralisation involves toxins; lysis breaks the bacterium down.
For the teacher: Understanding, low difficulty, standard 11.2.1
Textbook p. 204
8

Question 8

Bacteria produce a toxin that harms body cells. Which action of antibodies makes the toxin harmless?
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D
Antibodies bind with the toxin and neutralise it.
For the teacher: Understanding, low difficulty, standard 11.2.1
Textbook p. 204
9

Question 9

Which situation is an example of natural passive immunity?
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D
The baby receives the mother's antibodies in colostrum, so it is natural and passive. The other options are natural active, artificial active and artificial passive.
For the teacher: Applying, medium difficulty, standard 11.3.1
Textbook p. 207
10

Question 10

A hiker is bitten by a poisonous snake. What should the doctor give?
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A
Antiserum contains ready-made antibodies and gives immediate protection. A vaccine is too slow because the body needs time to make its own antibodies.
For the teacher: Applying, medium difficulty, standard 11.3.1
Textbook p. 207
11

Question 11

Which statement correctly compares artificial active immunity with artificial passive immunity?
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C
In active immunity the lymphocytes make antibodies (and memory cells), so it lasts long. Passive immunity uses antibodies from outside and is temporary.
For the teacher: Analysing, high difficulty, standard 11.3.2
Textbook p. 208
12

Question 12

Which cells does HIV attack and destroy?
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A
HIV spreads in and destroys lymphocytes, so the immune system is progressively weakened.
For the teacher: Remembering, low difficulty, standard 11.4.1
Textbook p. 209

Section B: structured questions

33 marks
Answer all questions. Write your answers in the spaces provided.
13

Question 13

Diagram 1 shows the first line of defence of the body.
Diagram of the first line of defence: lysozyme in tears, mucous membrane, blood clotting, hydrochloric acid and skin
Diagram 1
[1 mark] (a)What is the function of hydrochloric acid in the stomach?
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Tick each point you got.
[2 marks] (b)How does the mucous membrane of the respiratory tract protect the body?
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[1 mark] (c)State one way in which blood clotting protects the body.
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For the teacher: Remembering, low difficulty, standard 11.1.2
Textbook p. 201
14

Question 14

State the correct order of the stages of phagocytosis by writing the letters P to S.
LetterStage
PThe phagosome combines with a lysosome
QThe phagocyte extends a pseudopodium towards the bacterium
RThe bacterium is ingested and forms a phagosome
SLysozyme destroys the bacterium
[2 marks] (a)Order of the stages (first to last)
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[1 mark] (b)Name the process in which phagocytes trap and digest pathogens.
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[2 marks] (c)Phagocytosis belongs to which line of defence? Is this line specific?
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For the teacher: Understanding, low difficulty, standard 11.1.2
Textbook p. 202
15

Question 15

Choose the action of antibodies described in each statement.
[1 mark] (a)Antibodies bind to toxins produced by bacteria.
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Neutralisation
[1 mark] (b)Antibodies react with dissolved antigens to form an insoluble complex.
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Precipitation
[1 mark] (c)Antibodies mark the antigens so that phagocytes recognise them.
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Opsonisation
[1 mark] (d)Antibodies cause the bacterium to break down.
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Lysis
For the teacher: Understanding, low difficulty, standard 11.2.1
Textbook p. 204
16

Question 16

Diagram 2 shows the antibody level in the blood of individual X after two injections. Diagram 3 shows individual Y after two injections of a different substance. The dashed line is the level of immunity.
Two graphs of antibody level against time in months. Individual X: level 20 after the first injection, then 60 after the second at month 4. Individual Y: level 55 at once, below the level of immunity by month 3, 56 again after the second injection at month 4
Diagram 2 (left): individual X. Diagram 3 (right): individual Y
[2 marks] (a)What substance was injected into X? Give a reason.
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[1 mark] (b)What substance was injected into Y?
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[2 marks] (c)State the antibody level of X after the first injection and explain why a second injection is needed.
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[2 marks] (d)State two differences in the immunity gained by X and Y.
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For the teacher: Analysing, medium difficulty, standard 11.3.2
Textbook p. 208
17

Question 17

State the type of immunity acquired in each situation.
[1 mark] (a)A boy is infected with chickenpox and recovers.
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[1 mark] (b)A foetus receives antibodies from its mother through the placenta.
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[1 mark] (c)A student is given the BCG injection.
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For the teacher: Applying, low difficulty, standard 11.3.1
Textbook p. 206
18

Question 18

A man was infected with HIV 9 years ago and now suffers from chronic diarrhoea and fungal infections.
[1 mark] (a)What does AIDS stand for?
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[2 marks] (b)Explain why the man is easily infected by other diseases.
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[2 marks] (c)State two ways HIV can be transmitted.
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Any 2 points
Tick each point you got.
For the teacher: Understanding, medium difficulty, standard 11.4.1
Textbook p. 209
19

Question 19

Aziman stepped on a rusty nail during a mountain climbing trip, and he had never been vaccinated against tetanus.
[1 mark] (a)Which injection should the doctor give?
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[2 marks] (b)Explain your answer.
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[2 marks] (c)Why is it still important for children to complete the vaccination schedule?
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For the teacher: Evaluating, high difficulty, standard 11.3.1
Textbook p. 207