Which of the following instruments is used to estimate the number of plants in a habitat?

1. Analyze the question You are asked which instrument is used to estimate the number of plants in a habitat. This is about ecological sampling methods.

2. Explain the concept In ecology we rarely count every organism in a habitat, so we sample. Different tools suit different organisms:

• Pooter: a small suction device for collecting tiny insects such as ants.
• Pitfall trap: a container buried in the soil to catch crawling animals such as beetles and spiders.
• Quadrat: a square frame (often 1 m × 1 m) placed on the ground to count or measure plants, or other slow-moving or stationary organisms, in a sample area.
• Sweep net: a net swept through vegetation to catch flying or perching insects.

3. Solution

• A pooter, pitfall trap and sweep net are all for collecting animals (mainly insects and other arthropods).
• Only the quadrat is used for plants. You place it at random points, count the plants inside, find the average per quadrat, then multiply by the total area of the habitat to estimate the population.

Estimated population = (average number per quadrat) × (total habitat area ÷ area of one quadrat)

4. Answer The option labelled "quadrant" is clearly a misspelling of quadrat, the correct term. So the answer is C.

5. Exam tip Remember this pairing: Quadrat = Quantity of plants. Both start with "Q". Also note that the spelling "quadrant" is a common typo in past questions. JAMB often tests the tool matched to its target organism: pooter, pitfall and sweep net are for animals, and the quadrat is for plants.