Organisms Respond to Changes in their Internal and External Environments: Stimuli, Both Internal and External, are Detected and Lead to a Response - Survival and Response (Kineses and Taxes)

Question 1

How do organisms increase their chances of survival?

Answer 1

• By responding to changes in their environment

Question 2

Define the term stimulus

Answer 2

• Any change in the internal or external environment

- E.g change in temperature, light intensity or pressure

Question 3

Which simple responses help a mobile organism stay in a favourable environment?

Answer 3

• Taxes

- Kineses

Question 4

What is a tactic response (taxis)?

Answer 4

• Directional movement in response to a stimulus

- The direction of the stimulus affects the response

Question 5

What is a kinetic response (kinesis)?

Answer 5

• Non-directional (random) movement in response to a stimulus
• Changes the speed an organism moves at and the rate at which its direction changes
• The intensity of the stimulus affects the response