Distribution of Organisms

Question 1

What is a habitat?

Answer 1

HABITAT is where an organism lives

Question 2

What is meant by the DISTRIBUTION of an organism?

Answer 2

DITRIBUTION is where an organism is found

Question 3

What 5 environmental factors influence where an organism lives?

Answer 3

1. Temperature
2. Water - availability
3. Oxygen or Carbon dioxide - availablity
4. Nutrients - availability
5. Light - amount

Question 4

What two ways can you measure the distribution of an organism?

Answer 4

1. Get two sample areas and compare the amount of organism (use of a QUADRAT)
2. Study how the distribution changes accross an area (by placing QUADRATS along a transect)

Question 5

What is a quadrant?

Answer 5

Square frame enclosing a know area.

Question 6

How do you use a quadrat?

Answer 6

1. Place a quadrat on the ground at a random point within fiorst sample area.
2. Count all organisms within the quadrat
3. Repeat steps 1 and 2 as many times as you can.
4. Work out mean and mode number of organisms per quadrat within first sample area
5. Repeat steps 1-4 above for second sample area and compare

Question 7

How doe you work out population size using a quadrat?

Answer 7

1. Work out mean number of organisms per m2 (assuming your quadrat is 1 metre by 1 metre)
2. Then multiply the mean by the TOTAL AREA 9in m2) of the habitat
3. Example - if the open field is 800 m2 and there are 22 metres per quadrat then the size of the daisy population in field is 22x 800 = 17,600 daisies

Question 8

What is a transect?

Answer 8

This is like two pegs in the ground which are connected by a straight line of string

Question 9

How does a transect assist us with finding out about the distribution of an organism?

Answer 9

1. Mark out a line in an area (such as a field) that you want to study.
2. Collect data along the line (ie just count all the organisms that you are researching which touch the line)
3. Or you can use a quadrat to collect data by placing them next to the line or ar intervals

Question 10

When collecting environmental data what two things do you need to think about?

Answer 10

Reliability and Validity

Question 11

When collecting environmental data how can you make your results more reliabile?

Answer 11

When using quadrats and transects the more times you repeat it (ie the larger number of samples) the larger your sample size.

The bigger the sample the more representative of the whole population.

Question 12

When collecting environmental data how can you make your results more valid?

Answer 12

1. To be more valid you must ensure the results are reliable.
2. You must control all variables
3. Toy must usually determine a difference in distribution between two sample areas is down to one environmental factor
4. You must control all other variables to ensure any change is down to the factor you are investigating
5. If you don’t control other variables then any coorelation may be unreliable as it could be caused by a factor other than the factor you are investigating
6. You could also improve validity by using random samples as opposed to focusing on one small area.