F2 IS QZ 08 anwers

Label Diagram (7 marks)

Label the diagram below which shows you the structure of the human breathing system: (7)

Fill in the Blanks (9 marks)

1    When we breathe in, the intercostal muscles (1) contract, leading to upwards and outwards (1) movement of the ribs. At the same time, the diaphragm (1) becomes flattened. This actions increases (1) the volume inside the chest and decreases / reduces (1) the gas pressure inside. Therefore, air flows in / moves in / is drawn into (1) the lungs.

2     In humans, gaseous exchange occurs in the air sacs (1) of the lungs. In there, oxygen enters the blood (1) from the air while carbon dioxide (1) leaves the blood to air.

Multiple Choice (5 marks)

Circle the letter of the best answer for each question.

Directions: The diagram on the next page shows a model used to demonstrate the action of the diaphragm in breathing. Refer to the diagram and answer questions 1 and 2.

1.      Which of the following shows the parts of the respiratory system that the model represents?

	Glass tube	Y-shaped tube	Bell jar	Rubber sheet
A.	Chest wall	Diaphragm	Trachea	Bronchus
B.	Diaphragm	Trachea	Bronchus	Chest wall
C.	Bronchus	Chest wall	Diaphragm	Trachea
D.	Trachea	Bronchus	Chest wall	Diaphragm

2.      What will happen when we push the rubber sheet upwards?

(I)   The balloons become larger.

(II)  The balloons become smaller.

(III)        The gas pressure inside the bell jar increases.

(IV)        The gas pressure inside the bell jar decreases.

A.   (I) and (III)             B.    (I) and (IV)             C.   (II) and (III)       D.    (II) and (IV)

Direction: The following diagram shows a model to simulate the action of the intercostal muscles during breathing. Refer to the diagram and answer questions 3 and 4.

3.      Which of the following about the structures represented by bars A and B is correct?

	Bar A	Bar B
A.	Rib	Intercostal muscle
B.	Rib	Backbone
C.	Backbone	Intercostal muscle
D.	Backbone	Rib

4.      Which of the following is simulated in position X?

	Intercostal muscles	State of breathing
A.	Contracts	Breathing out
B.	Contracts	Breathing in
C.	Relaxes	Breathing out
D.	Relaxes	Breathing in

5.      What happens to the oxygen and carbon dioxide contents in the blood after passing through the lungs?

	Oxygen	Carbon dioxide
A.	Increases	Increases
B.	Increases	Decreases
C.	Decreases	Increases
D.	Decreases	Decreases

Challenging Questions (Bonus 2 marks)

Draw a flow chart to show the sequence of air flow during breathing out.

air sac => small tubes => bronchi => trachea => Nose / mouth