CAIE A-Level Biology AS 1.2 Cells As Basic Units of Living Organisms Topic Practice

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Question 1

[Maximum number: 1]

Prostaglandins are small lipids produced in many tissues of the body. One role of prostaglandins is to cause inflammation at the site of an injury or infection. Inflammation is the normal first response of the immune system to injury or infection.

Cyclooxygenase (COX) is an enzyme that catalyses one of the steps in the reaction pathway for the formation of prostaglandins from phospholipids. The reaction pathway occurs in the smooth endoplasmic reticulum (SER) of cells. Part of the reaction pathway is shown in Fig. 1.3.

Fig. 1.3

Fig. 1.3

Suggest an advantage for this reaction pathway occurring in the smooth endoplasmic reticulum of a cell rather than in the cytoplasm.

Question 2

[Maximum number: 1]

Some students were asked to look at the photomicrograph of a cross-section of unfamiliar material and describe what they could see.

Figure for Question 2 — CAIE A-Level Biology AS

The students described the cross-section of F as:
1 circular
2 a hollow tube
3 spherical.
Which descriptions of the cross-section of F correctly state what the students could actually see?

A

1, 2 and 3

B

1 and 2 only

C

1 only

D

3 only

Question 3

[Maximum number: 1]

Fig. 3.1 is a transmission electron micrograph showing two adjacent cells in a leaf.

Fig. 3.1

Fig. 3.1

State one feature visible in Fig. 3.1, other than the cell wall, that identifies the cells as plant cells.

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