The movement response of a cockroach away from a light source can be described as

Analyze the question The question asks for the correct term for a cockroach moving away from light. Two things matter: whether the response is a taxis or a tropism, and whether it is positive or negative.

Explain the concepts

• Taxis is the movement of a whole organism, or a motile cell, in response to a directional stimulus. Examples are a cockroach running or a woodlouse moving.
• Tropism is a growth response, usually in plants, where a part such as a shoot or root bends towards or away from a stimulus.
• Positive means movement towards the stimulus.
• Negative means movement away from the stimulus.
• Phototaxis is a taxis in response to light.

Step-by-step solution

1. A cockroach is an animal that moves its whole body from place to place. This is a taxis, not a tropism. That eliminates C and D, because tropisms are growth responses.
2. The cockroach moves away from the light. That makes the response negative.
3. The response is to light, so it is phototaxis.
4. Combining these gives negative phototaxis, which the question writes as "negative phototaxism" (option B).

Cockroaches are nocturnal and prefer dark, hidden places. This is why they scurry away when you switch on a light in the kitchen at night.

Answer: B. Negative phototaxism

Exam tip: Remember "Taxis = Travel, Tropism = Tree-growth." If the organism moves its whole body, use taxis. If a plant part grows or bends, use tropism. Then decide positive (towards) or negative (away).