WAEC 2020 Biology · Question 48

Use the following Classes of Arthropoda to answer the question below I. Crustacea II. Insecta III. Arachinda…

Question

Use the following Classes of Arthropoda to answer the question below I. Crustacea II. Insecta III. Arachinda IV. Chilopoda Which of the classes is characterised by the possession of two pairs of antennae?

A.I
B.II
C.III
D.IV

Answer: A. I

Explanation written with AI and checked against the answer key

Step 1: Analyze the question You are asked which class of Arthropoda has two pairs of antennae.

Step 2: Explain the concept Arthropod classes are distinguished mainly by the number of body parts, legs, and antennae:

| Class | Examples | Antennae | Legs | |---|---|---|---| | Crustacea | Crab, prawn, crayfish, lobster | 2 pairs | 5 or more pairs | | Insecta | Grasshopper, cockroach, housefly | 1 pair | 3 pairs | | Arachnida | Spider, scorpion, tick | None | 4 pairs | | Chilopoda | Centipede | 1 pair | 1 pair per body segment |

Step 3: Solution

Insecta (II): one pair of antennae, so it is ruled out.
Arachnida (III): no antennae at all, so it is ruled out.
Chilopoda (IV): one pair of antennae, so it is ruled out.
Crustacea (I): two pairs of antennae (one long pair and one short pair), so it fits.

Step 4: Answer The class with two pairs of antennae is Crustacea (I), which is option A.

Tip: Count the antennae as 2-1-0-1. Crustacea has 2 pairs, Insecta has 1, Arachnida has 0, and Chilopoda has 1. Remember "Crabs have Complex antennae (two pairs)" to link Crustacea with the number 2.

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