Survival and response

Question 1

Why is it important that organisms respond to stimuli?

Answer 1

To increase their chances of survival

Question 2

What are two simple responses that can maintain a motile organism in a favourable environment?

Answer 2

taxis and kinesis

Question 3

What is a tactic response (taxis)?

Answer 3

Directional movement in response to a stimulus

Question 4

What is the difference between a positive and negative taxis?

Answer 4

Positive is movement towards the stimulus.
Negative is movement away from the stimulus.

Question 5

What is a kinetic response (kinesis)?

Answer 5

Non-directional movement in response to a stimulus

Question 6

Describe what happens during a kinetic response.

Answer 6

• In favourable conditions organisms move slower and change direction less (make tighter turns). This allows them to remain in favourable conditions for longer.
• The more unfavourable the stimulus, the faster it moves and the more it changes direction (bigger turns). This reduces the time spent in unfavourable conditions.

Question 7

What is a stimulus?

Answer 7

A change in the internal or external environment

Question 8

When do you use a Chi2 test?

Answer 8

When testing for the significance of differences in observed and expected categoric data

Question 9

When completing a Chi2 test, what would P<0.05 mean?

Answer 9

That there is a less than 0.05 probability that the difference between the observed and expected is due to chance

Question 10

When conducting investigations using organisms, what do you need to consider?

Answer 10

Ethical implications, where the organisms are from, returning them to their environment. Ensuring they are not harmed

Question 11

Why are organisms left in a new environment for a set period of time before recording movements?

Answer 11

Give them time to acclimatise to the environment so you can see the effect of the environment. So behaviour is typical, and not affected by handling.