State four features that distinguish insects from arachnids.

Cambridge International IGCSE Biology (0610) — 1.3 Features of organisms · State · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

Insects:
1. Three pairs of jointed legs
2. Body divided into head, thorax and abdomen
3. One pair of antennae
4. Usually two pairs of wings

Arachnids:
1. Four pairs of jointed legs
2. Body divided into cephalothorax and abdomen
3. No antennae
4. No wings

Examiner tips

Use the exact wording from the mark scheme; list each feature clearly.
Separate insect and arachnid features to avoid confusion.
Keep the answer concise – no extra explanation needed.
Use bullet points or numbered list for clarity.

Common mistakes

Mixing up the number of leg pairs (e.g., saying insects have four pairs).
Forgetting that insects have a head, thorax and abdomen but not mentioning the cephalothorax of arachnids.
Including extra features not asked for, such as eyes or mouthparts.

Mark scheme (4 marks)

Insects have three pairs of jointed legs whereas arachnids have four pairs
Insects have a body divided into three parts (head, thorax and abdomen) whereas arachnids have two parts (cephalothorax and abdomen)
Insects have one pair of antennae whereas arachnids have no antennae
Insects (normally) have two pairs of wings whereas arachnids have no wings

Key terms in this question

insects · arachnids