Gas Exchange

Question 1

Explain one feature seen in the alveolus in the diagram which allows efficient gas exchange
(2 marks)

Answer 1

It’s wall is one cell thick.(1) This minimises the diffusion distance between the air and the blood.(1)

OR

It has a good blood supply. (1)This means it will maintain its concentration gradient.(1)

Question 2

The sequence in which air passes through them during an exhalation.
bronchus, nasal cavity, alveolus, trachea, and bronchioles

Alveolus is first.

(1 mark)

Answer 2

Alveolus –) bronchioles –) bronchus –) trachea –) nasal cavity

Question 3

Describe the actions of the intercostal muscle and diaphragm during inhalation. (2).

Answer 3

The external set of intercostal muscles contracts and pulls the ribs up and out(1) and the diaphram contracts and flattens.(1)

Question 4

Describe how the contraction of Organ 1 (diaphram) aids the inhalation process (2).

Answer 4

(Organ 1/diaphragm) flattens / moves downwards; (1)
The thorax/chest/lung volume increases; (1)

OR/AND

The pressure in the thorax/chest/lung decreases; (1)
Air moves/is drawn into the thorax/chest/lungs from high to low pressure / down a pressure gradient; (1)

Question 5

Explain why a person with lung disease is often breathless and unable to exercise. (3)

Answer 5

A person with lung disease is often breathless and unable to exercise because less air is exhaled.(1) This means that there will be less carbon dioxide removed (1)and there will be less respiration going on.(1)

Question 6

Describe the role of the diaphragm and the intercostal muscles in inhalation. (4).

Answer 6

The diaphragm contracts and flattens. (1) The external set of intercostal muscles will contract to pull the ribcage up and out(1). This will increase the volume of the chest cavity(1). It will also decrease the air pressure in the lungs(1). Air is drawn into the lungs (1)

Question 7

The horse breathes faster and deeper when running. Explain why the horse continues to breathe faster and deeper for a period of time after it has stopped running (2).

Answer 7

To allow the breakdown of the lactic acid(1) which is a product of the anaerobic respiration that occurred.(1)

To supply more oxygen(1)
To repay oxygen debt(1)

Question 8

Some people are promoting e-cigarettes as a healthier alternative to smoking normal cigarettes.

(i) Suggest why using e-cigarettes may be thought to be less harmful than smoking normal cigarettes. (4)

(ii) Suggest why many doctors are concerned about promoting the use of e-cigarettes to young people.(2)

Answer 8

Contain less tar; [1 mark]
Contain fewer carcinogens / have a lower risk of cancer; [1 mark]
There is less risk of emphysema / lung disease / damage to alveoli / chronic bronchitis / damage to cilia; [1 mark]
There is less carbon monoxide in their smoke; [1 mark]
They pose less risk of heart disease / strokes; [1 mark]
They show less risk of addiction / nicotine levels can be controlled; [1 mark]

(i) e-cigarettes may be thought to be less harmful as it contains less tar(1). It also has less of a risk of lung disease and getting chronic bronchitis(1) and there’s less carbon monoxide in the smoke.(1) This also means that theres less risk of them being addicted(1)

(ii) Many doctors are concerned about promoting the use of e-cigarettes because it might convince non-smokers to start using e-cigarettes(1) and the e-cigarettes will be addictive as they contain nicotine. (1)

OTHERS:
It may also be harmful as it has unknown risks (1)
Nicotine can increase the risk of blood clots / increase blood pressure(1)
E-cigarette use may lead to smoking(1)

Question 9

Suggest why age may affect the likelihood of dying from lung cancer. (2)

Answer 9

Older people are more likely to develop cancer (1). This is because the DNA inside cells are more likely to mutate(1)

OTHERS:
Older people may have smoked for a longer period(1)
Older people may have a weak immune system.