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Science questions, chapter 2
Nama / NameKelas / ClassTarikh / Date

Respiration

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

Which structure closes the trachea when food is swallowed?
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A
The epiglottis is a flap that drops down and closes the trachea when a bolus is swallowed, and moves up to open the trachea for breathing.
For the teacher: Remembering, low difficulty, standard 2.1.1
Textbook p. 48
2

Question 2

Which row describes what happens in the body when a person inhales?
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B
On inhalation the intercostal muscles contract (rib cage up and out) and the diaphragm contracts and moves down. The thoracic cavity becomes bigger, so the pressure inside falls and air is forced in.
For the teacher: Understanding, low difficulty, standard 2.1.1
Textbook p. 48
3

Question 3

Diagram 1 shows the human respiratory system. Oxygen diffuses into the blood in which labelled part?
Human respiratory system with the trachea (P), bronchus (Q), alveolus (R) and diaphragm (S) labelled
Diagram 1
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C
R points to the alveolus, the tiny air sac where oxygen diffuses into the blood capillaries. P is the trachea, Q a bronchus and S the diaphragm.
For the teacher: Remembering, low difficulty, standard 2.1.1
Textbook p. 46
4

Question 4

A student breathes out through limewater and the limewater turns cloudy. What does this show?
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D
Limewater turns cloudy when carbon dioxide is passed through it. The test shows that exhaled air has a higher concentration of carbon dioxide.
For the teacher: Understanding, low difficulty, standard 2.1.2
Textbook p. 52
5

Question 5

Oxyhaemoglobin releases oxygen when the blood reaches the body cells. Why does this happen?
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A
Oxyhaemoglobin is an unstable compound. Where the oxygen concentration is low, as around body cells, it decomposes to release oxygen and changes back to haemoglobin.
For the teacher: Applying, low difficulty, standard 2.2.1
Textbook p. 55
6

Question 6

Which adaptation of the lungs provides a large surface area for gaseous exchange?
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B
Millions of alveoli give a very large surface area. Thin walls shorten the diffusion distance, moisture lets gases dissolve and capillaries carry the gases away.
For the teacher: Understanding, low difficulty, standard 2.2.2
Textbook p. 56
7

Question 7

Why is carbon monoxide in the air dangerous to the human body?
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C
Carbon monoxide combines with haemoglobin to form stable carboxyhaemoglobin. There is less oxyhaemoglobin, so the body cells cannot get enough oxygen to release energy.
For the teacher: Analysing, medium difficulty, standard 2.3.1
Textbook p. 58
8

Question 8

Which gas is colourless with a pungent smell and is released when coal is burned in power stations?
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D
Sulphur dioxide is a colourless, pungent gas from burning coal. Nitrogen dioxide is brown and comes from vehicle fuels; carbon monoxide is odourless.
For the teacher: Remembering, low difficulty, standard 2.3.1
Textbook p. 58
9

Question 9

Which respiratory disease is caused by damage to the alveoli and cannot be cured?
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A
Emphysema is the condition of damaged alveoli caused by harmful substances such as irritants in cigarette smoke. It cannot be cured, only controlled.
For the teacher: Understanding, low difficulty, standard 2.3.1
Textbook p. 60
10

Question 10

Which feature of the gills of a fish gives a large surface area for gaseous exchange?
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B
The many filaments and the thin, flat lamellae on them give a large surface area. Being surrounded by water keeps the gills moist.
For the teacher: Understanding, low difficulty, standard 2.4.1
Textbook p. 65
11

Question 11

Why does the blood of a grasshopper not need to carry oxygen to its cells?
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C
Air enters through spiracles into the trachea, which divides into fine tracheoles. Oxygen diffuses directly into the cells, so the circulatory system is not involved.
For the teacher: Understanding, medium difficulty, standard 2.4.1
Textbook p. 65
12

Question 12

What happens to the guard cells of a leaf at night?
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D
With no light, guard cells do not photosynthesise. Water diffuses out by osmosis, so they become flaccid and straight and the stoma closes.
For the teacher: Analysing, medium difficulty, standard 2.5.1
Textbook p. 69

Section B: structured questions

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

Question 13

The flow chart shows the path of air that is breathed out from the lungs: alveolus → (a) → (b) → trachea → (c) → pharynx → nasal cavity → nostrils. Choose the correct part for each letter.
[1 mark] (a)Which part is (a) in the flow chart?
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Bronchiole
From the alveolus, air passes into the bronchiole, then the bronchus.
[1 mark] (b)Which part is (b) in the flow chart?
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Bronchus
The bronchus joins the bronchioles to the trachea.
[1 mark] (c)Which part is (c) in the flow chart?
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Larynx
Air leaves the trachea through the larynx and then passes into the pharynx.
For the teacher: Remembering, low difficulty, standard 2.1.1
Textbook p. 47
14

Question 14

Diagram 2 shows a simple model used to show the breathing mechanism.
Glass jar P with a Y-shaped tube Q, balloons R and a thin rubber sheet S across the bottom
Diagram 2
[2 marks] (a)Name the parts of the human respiratory system that are represented by R and S.
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[1 mark] (b)Which action on S represents inhalation?
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Pulling S downwards
The diaphragm moves downwards when you inhale.
[2 marks] (c)Explain why the balloons inflate when S is pulled downwards.
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For the teacher: Understanding, low difficulty, standard 2.1.1
Textbook p. 53
15

Question 15

In Experiment 2.1, a candle was lit and a gas jar divided into five equal parts was inverted over it in a basin of water, once with air and once with exhaled air. The candle went out. Table 1 shows how far the water rose in the jar.
Table 1
Type of air in gas jarFinal water level (number of parts out of 5)
Air1.0
Exhaled air0.8
[2 marks] (a)Calculate the percentage of oxygen in the air and in the exhaled air. (Each part = 20%.)
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[1 mark] (b)What conclusion can be made from this experiment?
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For the teacher: Applying, low difficulty, standard 2.1.2
Textbook p. 50
16

Question 16

Table 2 describes three harmful gases P, Q and R in the air.
Table 2
GasColour and smellOther information
PBrown, pungent smellProduced by burning petrol and diesel in motor vehicles
QColourless, no smellFound in cigarette smoke and vehicle exhaust; combines with haemoglobin
RColourless, pungent smellProduced by burning coal in power stations
[1 mark] (a)Name gas P.
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[1 mark] (b)Name gas Q.
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[2 marks] (c)A man stays in a stationary car with the windows closed and the engine running. Explain why this is dangerous.
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For the teacher: Applying, low difficulty, standard 2.3.1
Textbook p. 58
17

Question 17

Diagram 3 shows the apparatus used in Experiment 2.2. A lighted cigarette (not shown) was fixed to the open end of the rubber tube and the smoke was drawn through the cotton wool and the litmus solution by a filter pump for 10 minutes. The cotton wool turned from white to brown and the litmus solution turned from purple to red.
Cotton wool in a U-tube connected to a conical flask of litmus solution and a filter pump
Diagram 3
[1 mark] (a)Name the substance that is deposited on the cotton wool.
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[1 mark] (b)What does the colour change of the litmus solution show?
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[2 marks] (c)Amir says, "Smoking only harms the smoker." Do you agree? Justify your answer.
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For the teacher: Evaluating, medium difficulty, standard 2.3.2
Textbook p. 62
18

Question 18

You want to show that the air a person breathes out after running contains more carbon dioxide than the air breathed out when resting, using limewater.
[2 marks] (a)State the manipulated variable and the responding variable.
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[2 marks] (b)State one variable that must be kept constant and the result you expect.
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For the teacher: Creating, medium difficulty, standard 2.1.2
Textbook p. 51
19

Question 19

Photosynthesis is taking place in a leaf in bright sunlight. The stomata are open.
[1 mark] (a)Name the gas that diffuses into the leaf through the stomata.
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[2 marks] (b)Explain why this gas diffuses into the leaf and not out of it.
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[2 marks] (c)In the afternoon on a very hot day the stomata close. Explain how the guard cells close the stomata and why this helps the plant.
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For the teacher: Analysing, medium difficulty, standard 2.5.1
Textbook p. 68
20

Question 20

Diagram 4 shows the maximum volume of air in the lungs of two runners, X and Y, before, during and after a run. One of the runners is a smoker.
Line graph: runner X is 3.0 dm³ walking and 4.5 dm³ running; runner Y is 2.0 dm³ walking and 3.0 dm³ running
Diagram 4
[1 mark] (a)State the maximum volume of air in the lungs of runner X and of runner Y while running.
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[1 mark] (b)State the relationship between the type of activity and the maximum volume of air in the lungs.
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[1 mark] (c)Which runner is the smoker?
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Runner Y
Runner Y has the smaller maximum volume in both activities.
[2 marks] (d)Explain your answer in (c).
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For the teacher: Evaluating, high difficulty, standard 2.3.2
Textbook p. 77