Biology questions, chapter 8

Nama / NameKelas / ClassTarikh / Date

Respiratory Systems in Humans and Animals

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

Section A: objective questions

16 marks

Choose the best answer for each question.

Question 1

What is the respiratory surface of an insect?

Spiracle
Tracheole
Air sac
Lamella

Show answerHide answer

Tracheoles are the fine tubes where gases are exchanged with the cells; the spiracle is only the opening.

For the teacher: Remembering, low difficulty, standard 8.1

Textbook p. 129

Question 2

What is the function of the lamellae in fish gills?

Pump water into the mouth
Support the gill filaments
Give a large surface area with many capillaries
Close the operculum

Show answerHide answer

Lamellae are thin, flat projections on the filaments, richly supplied with capillaries.

For the teacher: Remembering, low difficulty, standard 8.1

Textbook p. 129

Question 3

Why do large organisms need a special respiratory structure?

Their TSA/V is small, so diffusion alone is too slow
Their TSA/V is large
They have no cells that need oxygen
They live only in water

Show answerHide answer

Volume increases faster than surface area, so the ratio TSA/V decreases.

For the teacher: Understanding, low difficulty, standard 8.1

Textbook p. 128

Question 4

Which structure does a frog use for gaseous exchange when it is inactive?

Gills
Tracheoles
Alveoli
Skin

Show answerHide answer

An inactive frog exchanges gases through its thin, moist, permeable skin.

For the teacher: Remembering, low difficulty, standard 8.1

Textbook p. 130

Question 5

Which is NOT a characteristic of all respiratory structures?

Large total surface area to volume ratio
Thin
Surrounded by blood capillaries
Moist

Show answerHide answer

Insect tracheoles have no blood capillary network; gases go directly to the cells.

For the teacher: Understanding, low difficulty, standard 8.1

Textbook p. 131

Question 6

What happens in an insect during exhalation?

Abdominal muscles contract and pressure in the trachea rises
Abdominal muscles relax and pressure falls
The diaphragm relaxes
The operculum closes

Show answerHide answer

Contraction of abdominal muscles raises air pressure in the trachea and forces air out through the spiracles.

For the teacher: Understanding, medium difficulty, standard 8.2

Textbook p. 132

Question 7

During inhalation in a fish, the floor of the buccal cavity is lowered and the operculum opening is closed. What is the effect?

Pressure increases and water leaves
Pressure falls and water enters the mouth
Water flows out through the operculum
The gills contract

Show answerHide answer

Increased volume lowers the pressure, so water with dissolved oxygen enters the mouth.

For the teacher: Understanding, medium difficulty, standard 8.2

Textbook p. 133

Question 8

Which muscles contract during inhalation in humans?

Internal intercostal muscles and diaphragm
External intercostal muscles only
Abdominal muscles
External intercostal muscles and diaphragm

Show answerHide answer

External intercostals lift the ribcage and the diaphragm flattens.

For the teacher: Remembering, low difficulty, standard 8.2

Textbook p. 134

Question 9

Which change occurs in the thoracic cavity during exhalation?

Volume decreases, pressure increases
Volume increases, pressure decreases
Volume and pressure both increase
Volume and pressure both decrease

Show answerHide answer

The ribcage moves down and in and the diaphragm domes upward; air is pushed out.

For the teacher: Understanding, medium difficulty, standard 8.2

Textbook p. 134

Question 10

What is the partial pressure of oxygen in the atmosphere at sea level (760 mm Hg, 21% oxygen)?

21 mm Hg
760 mm Hg
160 mm Hg
0.23 mm Hg

Show answerHide answer

0.21 × 760 = 159.6, about 160 mm Hg.

For the teacher: Applying, medium difficulty, standard 8.3

Textbook p. 137

Question 11

Oxygen combines with which substance in erythrocytes?

Carbonic anhydrase
Plasma
Bicarbonate ion
Haemoglobin

Show answerHide answer

Oxygen combines with haemoglobin to form oxyhaemoglobin.

For the teacher: Understanding, low difficulty, standard 8.3

Textbook p. 136

Question 12

In which form is most carbon dioxide transported in the blood?

Oxyhaemoglobin
Bicarbonate ion
Carbaminohaemoglobin
Carbonic acid

Show answerHide answer

About 70% travels as bicarbonate ion, 23% as carbaminohaemoglobin and 7% dissolved.

For the teacher: Remembering, low difficulty, standard 8.3

Textbook p. 137

Question 13

Blood in the pulmonary artery compared with the pulmonary vein has:

Lower oxygen and higher carbon dioxide partial pressure
Higher oxygen and lower carbon dioxide partial pressure
Higher oxygen and higher carbon dioxide partial pressure
Lower oxygen and lower carbon dioxide partial pressure

Show answerHide answer

The pulmonary artery brings deoxygenated blood to the lungs.

For the teacher: Analysing, medium difficulty, standard 8.3

Textbook p. 136

Question 14

Which disease is caused by swollen, thickened bronchiole walls that narrow the air passage?

Emphysema
Chronic bronchitis
Asthma
Tuberculosis

Show answerHide answer

This describes asthma. Emphysema damages alveoli; bronchitis involves mucus and inflammation.

For the teacher: Understanding, low difficulty, standard 8.4

Textbook p. 138

Question 15

Which statement about emphysema is correct?

Bronchioles are blocked by mucus
Bronchioles narrow suddenly
The diaphragm stops working
Alveoli lose elasticity and surface area falls

Show answerHide answer

Damaged alveolus walls enlarge and lose elasticity.

For the teacher: Analysing, medium difficulty, standard 8.4

Textbook p. 138

Question 16

A person's diaphragm no longer contracts. What is the immediate effect on inhalation?

Air enters faster
Thoracic volume rises less, so less air enters
No effect, because intercostal muscles do not help
Pressure in the lungs rises

Show answerHide answer

The diaphragm helps increase thoracic volume; without it, pressure falls less and less air is drawn in.

For the teacher: Applying, medium difficulty, standard 8.2

Textbook p. 134

Section B: structured questions

26 marks

Answer all questions. Write your answers in the spaces provided.

Question 17

Answer the following about respiratory structures in different organisms.

[1 mark] (a)Name the respiratory structure of a fish.

Show answerHide answer

Gills (filament and lamella)1

Tick each point you got.

[1 mark] (b)Name the respiratory structure of an insect.

Show answerHide answer

Tracheole (tracheal system)1

Tick each point you got.

[1 mark] (c)Name the respiratory structure of a human.

Show answerHide answer

Alveolus1

Tick each point you got.

[2 marks] (d)Name two structures a frog uses for gaseous exchange.

Show answerHide answer

Skin1
Lungs1

Tick each point you got.

For the teacher: Remembering, low difficulty, standard 8.1

Textbook p. 129

Question 18

The alveolus is adapted for efficient gaseous exchange.

[3 marks] (a)State three adaptations of the alveolus.

Show answerHide answer

Any 3 points

Large number of alveoli give a large total surface area1
Wall is one cell thick1
Wall is moist so gases dissolve1
Surrounded by a network of blood capillaries (any three)1

Tick each point you got.

[1 mark] (b)Why do insects not need blood capillaries for gaseous exchange?

Show answerHide answer

Tracheoles deliver air directly to the body cells1

Tick each point you got.

For the teacher: Understanding, low difficulty, standard 8.1

Textbook p. 131

Question 19

Explain the mechanism of inhalation in humans.

[2 marks] (a)State what the intercostal muscles and the diaphragm do.

Show answerHide answer

External intercostal muscles contract, ribcage moves up and out1
Diaphragm contracts and flattens1

Tick each point you got.

[2 marks] (b)Explain how air enters the lungs.

Show answerHide answer

Volume of the thoracic cavity increases and pressure decreases1
Higher atmospheric pressure forces air into the lungs1

Tick each point you got.

[1 mark] (c)State one similarity between the breathing mechanism of humans and of fish.

Show answerHide answer

Both involve changes of volume and pressure in the respiratory cavity (muscles expand and contract the cavity)1

Tick each point you got.

For the teacher: Understanding, low difficulty, standard 8.2

Textbook p. 134

Question 20

Carbon dioxide released by body cells is carried to the lungs.

[1 mark] (a)Which enzyme in the erythrocyte catalyses the reaction between carbon dioxide and water?

Show answerHide answer

Carbonic anhydrase1

Tick each point you got.

[2 marks] (b)Name the ion in which most carbon dioxide is carried, and its percentage.

Show answerHide answer

Bicarbonate ion1
70%1

Tick each point you got.

[3 marks] (c)Explain how carbon dioxide leaves the blood in the lung capillaries.

Show answerHide answer

Bicarbonate ion diffuses back into the erythrocyte and combines with H+ to form carbonic acid1
Carbonic acid breaks down into carbon dioxide and water1
Carbon dioxide diffuses into the alveolus and is exhaled1

Tick each point you got.

For the teacher: Applying, medium difficulty, standard 8.3

Textbook p. 137

Question 21

A long-time smoker is diagnosed with chronic bronchitis and early emphysema.

[2 marks] (a)What happens to the bronchioles in chronic bronchitis?

Show answerHide answer

Inflamed, swollen and blocked1
Excess mucus; damaged cilia cannot remove it, causing coughing1

Tick each point you got.

[3 marks] (b)Explain why the smoker becomes breathless in emphysema.

Show answerHide answer

Alveolus walls are damaged and lose elasticity1
Total surface area for gaseous exchange decreases1
Less oxygen diffuses into the blood1

Tick each point you got.

[1 mark] (c)Name one other disease that is part of COPD.

Show answerHide answer

Asthma1

Tick each point you got.

For the teacher: Applying, high difficulty, standard 8.4

Textbook p. 138

Back to notes Chapter 9 questions Model papers