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CAIE IGCSE Biology 15.1 Drugs Questions

Practise drug and antibiotic questions by defining drugs, choosing bacterial treatment contexts and interpreting resistance data or culture plates.

Syllabus
2026–2028
Course
Biology 0610

Exam points

  • define a drug as a substance taken into the body that modifies or affects chemical reactions, distinguishing it from hormones, enzymes and antibodies
  • select antibiotics for named bacterial infections and explain how bacterial targets such as cell-wall formation are inhibited
  • explain why antibiotics treat bacterial rather than viral infections by identifying bacterial targets absent from viruses
  • identify antibiotic resistance from bacterial survival, reduced treatment effectiveness and persistent or spreading infection
  • interpret a small or absent clear zone around an antibiotic disc as evidence that bacteria continue growing
  • explain how essential antibiotic use, completing courses and limiting routine livestock treatment reduce selection and spread of resistant bacteria such as MRSA

Covered syllabus points

15.1.1—Drug as any substance taken into15.1.2—Use of antibiotics for the treatment15.1.3—Some bacteria are resistant15.1.4—Antibiotics kill bacteria but do not15.1.5—Using antibiotics only when essential

Question 1

[Maximum number: 2]

Heroin is a drug that acts on the nervous system.

Define the term drug.

Question 2

[Maximum number: 1]

Fig. 4.1 is a diagram of the human female reproductive system.

Fig. 4.1

Fig. 4.1

Chlamydia is caused by a bacterium.

Suggest a treatment for chlamydia.

Question 3

[Maximum number: 1]

Why is an MRSA infection difficult to treat?

A

MRSA is a bacterium.

B

MRSA is a virus.

C

MRSA is resistant to some antibiotics.

D

MRSA is resistant to some antibodies.

Question 4

[Maximum number: 2]

Penicillin is an antibiotic produced by the fungus Penicillium chrysogenum.

Fig. 5.1 shows the process used to produce penicillin.

Fig. 5.1 shows the process used to produce penicillin.

Explain why antibiotics, such as penicillin, affect bacteria but not viruses.

Question 5

[Maximum number: 1]

A scientist tested the resistance of one strain of bacteria to different antibiotics.

The scientist tested solutions of five different antibiotics, A to E.

She soaked a paper disc in each antibiotic solution.
The paper discs with antibiotics were placed in a Petri dish containing bacteria on agar jelly.
Fig. 4.2 is a diagram of the appearance of the Petri dish after 48 hours. The shaded areas show where bacteria grew. The clear areas show where bacteria did not grow.

Fig. 4.2

Fig. 4.2

Describe how to minimise the risk of antibiotic B developing the same results as antibiotic A.

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