Mock Exam IB DP Biology SL Paper 1 Set 9

Question

Changes in heart rate occur during and after a period of exercise.


Which structure sends messages to the sinoatrial node of the heart to cause changes in
heart rate?
A. Adipose tissue
B. Medulla of the brain
C. Pineal gland
D. Thyroid gland

Answer/Explanation

 

Question

The light micrograph shows two blood vessels, an artery and a vein, in transverse section.

What explains the different shapes of these blood vessels?
A. Arteries do not have valves.
B. Muscle cells are found only in the walls of veins.
C. Arteries have a larger lumen-to-wall thickness ratio.
D. There are fewer elastic fibres in the walls of veins.

Answer/Explanation

 

Question

Pressure changes inside the thorax cause the movement of air in and out of the lung alveoli
during ventilation. Alveolar pressure correlates to thoracic pressure. The diagram shows pressure
changes in lung alveoli during ventilation in relation to normal atmospheric pressure. What causes
forced movement of air out of the lungs at T?

Answer/Explanation

 

Question

Which structures are part of the walls of both capillaries and veins?
I. Cells
II. Pores
III. Elastic fibres
A. I only
B. I and II
C. I and III
D. I, II and III

Answer/Explanation

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