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CAIE A-Level Biology A2 16.3.3 Genetic Control in Prokaryotes Questions

Explain genetic control in prokaryotes using evidence from each question and mark scheme.

Syllabus
2028–2030
Course
Biology 9700
Level
A2

Exam points

  • Explain genetic control in prokaryotes.

CAIE A-Level Biology A2 16.3.3 Genetic Control in Prokaryotes Questions question 1

[Maximum number: 7]

Gene expression in a cell is controlled. When a gene is expressed (switched on), the gene is transcribed. When a gene is not expressed (switched off), the gene is not transcribed.

Environmental changes can cause some genes to be switched on or switched off.

Question (a)

(a)

An example of control of gene expression in prokaryotes is regulation in the lac operon.

The lac operon is a length of DNA that is made up of different parts.
Fig. 3.1 shows a simple diagram representing the lacI (regulatory) gene and the lac operon.

Fig. 3.1

Fig. 3.1

[ 7 ]

Question (i)

(i)

Outline the main features of the lac operon.

[ 3 ]

Question (ii)

(ii)

Explain the role of the l a c I gene in the regulation of the lac operon.

[ 4 ]
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