A1. Survival and Response

Question 1

Any change in the internal or external environment, eg, a change in temperature, light intensity or pressure, is called a

Answer 1

stimulus

Question 2

Simple responses
Simple mobile organisms, eg, woodlice, have simple responses to keep them
in a favourable environment. Their response can either be

Answer 2

tactic or kinetic

Question 3

Tactic response (taxis)

Answer 3

• Directional movement in response to a stimulus.
• The direction of the stimulus affects the response.

Question 4

Kinetic response (kinesis)

Answer 4

• Non-directional (random) movement in response to a stimulus
• The intensity of the stimulus affects the response.

Question 5

Tip: If an organism moves towards a stimulus it’s a _________taxis, and if it moves away from a stimulus it’s a _________taxis.

Answer 5

Tip: If an organism moves towards a stimulus it’s a positive taxis, and if it moves away from a stimulus it’s a negative taxis.