(m) possible sources of medicines

The idea

Medicines come from several sources. Many were originally discovered in plants: aspirin from willow bark, digoxin from foxgloves and quinine from cinchona. Microorganisms are a major source of antibiotics, for example penicillin from the fungus Penicillium, and bacteria such as Streptomyces yield many antibiotics. Some medicines are derived from animals, such as insulin historically from animal pancreas, and others are now made synthetically or by genetic engineering, for example human insulin produced by modified bacteria. Soil and marine organisms are being screened for new drugs. Understanding these sources helps explain why antibiotic resistance and loss of biodiversity matter. MCQ items test whether you can match a medicine or group of medicines to its correct source category, so classify each option as plant, microorganism, animal, synthetic or recombinant.

What earns the marks

• Plants are a source of medicines, for example aspirin from willow and digoxin from foxgloves.
• Microorganisms such as the fungus Penicillium and bacteria of the genus Streptomyces are sources of antibiotics.
• Some medicines have been obtained from animals, for example insulin historically extracted from animal pancreas.
• Many medicines are now produced synthetically or by genetic engineering, such as human insulin from modified bacteria.
• New medicines are sought by screening organisms from soil and marine environments.

Common mistakes and how to put them right

• Attributing penicillin to a plant.

  Put it right: Penicillin is produced by the fungus Penicillium, a microorganism.

• Assuming all medicines are synthetic.

  Put it right: Many originate from plants, microorganisms or animals, though synthetic and recombinant production is now common.

• Confusing the source organism with the disease treated.

  Put it right: Identify the organism or material that produces the medicine, not the condition it treats.

Exam tips

• Classify each option by source category — plant, microorganism, animal, synthetic or recombinant — before choosing.
• Recall named examples such as aspirin from willow and penicillin from Penicillium to test each option.
• Reject options that name a medicine but give a source organism that does not produce it.