Organisms in the environment: Distribution of organisms

Question 1

factors affecting distribution

Answer 1

• temperature
• nutrients
• light
• water
• oxygen
• carbon dioxide

Question 2

what can be used to measure of distribution of organisms?

Answer 2

quadrat: a square frame divided into a grid

Question 3

How can we use quadrats?

Answer 3

• make a map of area to investigate
• use random number generator to find where to place quadrat
• count organisms in quadrat/ area covering quadrat

Question 4

How can we use transects?

Answer 4

• mark out a line

- collect data along line by using quadrats next to each other or at intervals

Question 5

Experiment: measuring distribution of pleurococcus

Answer 5

• select tree
• use compass to find north facing side of tree
• mark a vertical line transect on north side
• measure percentage of pleurococcus covering quadrat at intervals up the transect
• repeat for east, south and west side

Question 6

What is reliable data?

Answer 6

• repeatable

- reproducible

Question 7

What is valid data?

Answer 7

• reliable

- answer original question

Question 8

How does sample size affect results?

Answer 8

• a small sample may not be representative

- therefore larger samples produce more valid and reliable results

Question 9

How to improve validity?

Answer 9

• use random samples
• make sure samples are spread out
• ensure variables are controlled