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CAIE A-Level Biology AS 9.1 The Gas Exchange System Questions

Practise gas-exchange system questions by identifying airways and tissues, interpreting photomicrographs and linking alveolar structure to diffusion.

Syllabus
2028–2030
Course
Biology 9700
Level
AS

Exam points

  • identify trachea, bronchus, bronchiole, alveoli and blood vessels in micrographs
  • compare cartilage, smooth muscle, cilia, goblet cells and squamous epithelium by location
  • explain diffusion across alveoli using thin walls, capillaries and maintained gradients

Covered syllabus points

9.1.1—Structure of human gas exchange system9.1.2—Tissue distribution in gas exchange system9.1.3—Gas exchange image recognition9.1.4—Plan diagrams of trachea and bronchus walls9.1.5—Airway secretory and ciliated cells9.1.6—Airway and alveolar tissue functions9.1.7—Gas exchange between alveolar air and blood

Question 1

[Maximum number: 7]

The trachea of the gas exchange system branches into two airways, each of which enters a lung.

Question (a)

(a)

Name the airways that branch from the trachea to enter the lungs.

[ 1 ]

Question (b)

(b)

Fig. 1.1 is a photomicrograph of a section through part of the trachea.

Fig. 1.1

Fig. 1.1

[ 6 ]

Question (i)

(i)

In Fig. 1.1, one of the tissues in the trachea is labelled T.

Describe the structural features of tissue T visible in Fig. 1.1.

[ 3 ]

Question (ii)

(ii)

Identify structure X in Fig. 1.1 and outline the features that helped your identification. structure X=

[ 3 ]

Question 2

[Maximum number: 4]

Question (a)

(a)

Fig. 5.1 is a photomicrograph of a section through the lungs showing a bronchus and some alveoli.

Fig. 5.1

Fig. 5.1

[ 4 ]

Question (i)

(i)

State the function of tissue X labelled in Fig. 5.1.

[ 1 ]

Question (ii)

(ii)

Describe how the distribution of tissue X in the trachea differs from that shown in Fig. 5.1.

[ 1 ]

Question (iii)

(iii)

Describe how the epithelial tissue, Y, is adapted for its function.

[ 2 ]
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