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CAIE A-Level Biology A2 14.2.3 Guard Cells Questions

Explain guard cells and their role in stomatal control using evidence from each question and mark scheme.

Syllabus
2028–2030
Course
Biology 9700
Level
A2

Exam points

  • Explain guard cells and their role in stomatal control.

CAIE A-Level Biology A2 14.2.3 Guard Cells Questions question 1

[Maximum number: 4]

Fig. 4.1 shows a diagram of a stoma, its guard cells and adjacent epidermal cells.

Fig. 4.1

Fig. 4.1

Question (a)

(a)

Guard cells have chloroplasts while epidermal cells do not have chloroplasts.

State one other difference, visible in Fig. 4.1, between guard cells and epidermal cells.

[ 1 ]

Question (b)

(b)

During stomatal closure:

[ 3 ]

Question (i)

(i)

identify the ion that diffuses from the guard cells to epidermal cells

[ 1 ]

Question (ii)

(ii)

compare the relative water potential of the guard cells with that of epidermal cells

[ 1 ]

Question (iii)

(iii)

describe the change in volume of the guard cells.

[ 1 ]
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