populations and speciation 7.3 and 7.4

Question 1

literally the answer for any 5 marker on speciation

Answer 1

1. Geographical isolation/ allopatric speciation
2. Reproductive isolation/ no gene flow
3. Different selection pressures
4. Variation due to mutation
5. selected organisms with advantageous allele more likely to survive and reproduce/ different reproductive success
6. increases allele frequency
7. Different species cannot interbreed to produce fertile offspring

Question 2

Describe how you could use the mark-release-recapture method to estimate the number of Anolis sagrei on one of these islands (4)

Answer 2

1. Capture / collect sample, mark and release;

2.      Method of marking does not harm lizard 

3.      Leave sufficient time for lizards to (randomly) distribute (on island) before collecting a second sample;
   
4.      (Population =) number in first sample × number in second sample divided by number of marked lizards in second sample / number recaptured.

Question 3

Succession occurs in natural ecosystems. Describe and explain how succession occurs (5)

Answer 3

1. (Colonisation by) pioneer (species);

2.      Change in environment / example of change caused by organisms present;
 
3.      Enables other species to colonise / survive;
   
4.      Change in diversity / biodiversity;

5.     less hostile environment;

6.      Climax community;

Question 4

describe how you could estimate the number of plants in a field (5)

Answer 4

1. Use a grid
2. Random generator to give coordinates
3. Place quadrant at coordinate and count number of plant
4. large sample size and calculate mean
5. Mean number of plants per m2 x area of field