Practucal: Investigation Populations

Question 1

What 2 strategies investigate non motile organisms

Answer 1

Quadrats and transects

Question 2

Explain mark capture release

Answer 2

1. Capture a sample of species and count them
2. Mark them in a harmless way eg. Dot with paint
3. Release them back into the habitat
4. Wait a week
5. Capture a second sample
6. Count how many orgs are marked

Question 3

What is the equation for population size from mark capture release

Answer 3

No in 1st sample x no in 2nd sample/ no MARKED in 2nd sample

Question 4

What are the 3 assumptions with mark capture release

Answer 4

1. The marked samples had enough time and opportunity to mix back in with the population
2. The ,raking technique didn’t affect the orgs chance of survival and the mark still has to be visible
3. There are no change in poluation sizes (birth death or migration) during the study period

Question 5

How to measure an environmental factor and species distribution in a coastal system

Answer 5

1. Place tape measure in straight line from shore to inland (transect)
2. Place à 1mx1m quadrat at 10m intervals along the transect
3. Count the number of squares containing marram grass
4. Calculate % cover
5. Measure ph at each quadrat using a ph probe

Question 6

How to measure ph w/out a ph probe

Answer 6

Sieve to remove debris 
Add barium sulfate 
Add distilled water 
Add universal indicator 
Compare to ph chart

Question 7

Why does ph decrease inland

Answer 7

Shores = lost of broken shells made of CaCO3 = alkali 
Inland = decomposing vegetation = acid