Distribution of Organsims

Question 1

Where an organism is found is affected by what environmental factors?

Answer 1

• Temperature
• Availability of water
• Availability of oxygen and carbon dioxide
• Availability of nutrients
• Amount of light

Question 2

What is a habitat?

Answer 2

A place where an organism lives

Question 3

What is the distribution of an organism?

Answer 3

Where an organism is found

Question 4

What are two ways of studying the distribution of an organism?

Answer 4

• Measuring how common an organism is in two sample areas, using quadrats, and compare them
• Study how the distribution changes across an area eg. by placing quadrats along a transect

Question 5

What is a quadrat?

Answer 5

a square frame enclosing a known area

Question 6

How do you compare how common an organism is in two sample areas using a quadrat? (Hint: there are 6 steps)

Answer 6

1) Place a quadrat on the ground at a random point within the first sample area
2) Count all the organisms within the quadrat
3) Repeat steps 1 and 2 as many times as you can
4) Work out the mean number of organisms per quadrat within the first sample area
5) Repeat steps 1-4 in the second sample area
6) Finally compare the two means

Question 7

How do you work out the population size of an organism in one sample area? (Hint: there are 2 steps)

Answer 7

1) work out the mean number of organisms per Metres squared

2) Then multiply the mean by the total area of the habitat

Question 8

How do you use transects to study the distribution of organisms? (Hint: There are 4 steps)

Answer 8

1) Mark out a line in the area you want to study using a tape measure
2) Then collect data along the line
3) you can do this by just counting all of the organisms you’re interested in that touch the line
4) or you could collect data using quadrats. These can be placed next to each other along the line or at intervals, for example every 2 m.

Question 9

How would you make sure your results are as reliable as possible when using transects and Quadrats?

Answer 9

• Take a large sample size. Bigger samples are more representative of the whole population
• Use random samples. If all of your samples are in one spot, and everywhere else is different, the results you get won’t be reproducible.