Which of the following is a waste product of an insect?

Analyze the question: The question asks which substance is a waste product (excretory product) of an insect.

Explain the concept: Insects excrete nitrogenous waste mainly as uric acid. Uric acid is not very toxic and needs very little water to remove, so it is excreted as a semi-solid paste or crystals. This helps insects conserve water, which is important for small land animals that lose water quickly. Insects use Malpighian tubules for excretion. These tubules pick up waste from the haemolymph (insect blood) and empty it into the gut. The waste then leaves the body with the faeces through the anus.

Go through the options:

• A. Alkaloids: These are plant products, such as quinine and nicotine. Insects do not make them as waste.
• B. Uric acid: This is the main nitrogenous waste of insects. ✔
• C. Sweat: Sweat is produced by sweat glands in mammals. Insects have no sweat glands.
• D. Mucilage: This is a sticky substance made by plants. It has nothing to do with insect excretion.

Answer: The correct option is B. Uric acid.

Tip: Remember the pairing "Insects, birds and reptiles → uric acid." All of these are animals that save water. Also link Malpighian tubules with insects. Questions in JAMB, WASSCE and NECO often ask about this link. By contrast, mammals excrete urea through the kidneys, and sweat is a mammalian feature.