1.
State what is meant by a gene pool.
[1 mark]
- all the alleles in a population
JD SCIENCE
Evolution, speciation and biodiversity
Indicative marking points. Award marks for equivalent scientific or mathematical wording. Do not issue this sheet with the student worksheet.
2.
State what is meant by Hardy–Weinberg.
[1 mark]
- p² + 2pq + q² = 1
3.
State what is meant by directional selection.
[1 mark]
- favours one extreme
4.
State what is meant by stabilising selection.
[1 mark]
- favours the mean
5.
State what is meant by genetic drift.
[1 mark]
- random change in allele frequency
6.
State what is meant by succession.
[1 mark]
- community change over time to a climax
7.
State what is meant by an ecosystem.
[1 mark]
- community + abiotic factors
8.
State what is meant by conservation.
[1 mark]
- maintaining biodiversity
9.
State what is meant by mark-release-recapture.
[1 mark]
- N = (n1 × n2) / n_marked in second sample
10.
State what is meant by niche.
[1 mark]
- the role of a species
11.
Devon is asked about a gene pool in a Edexcel Biology paper.
(a) [2 marks]
- allele frequency
(b) [3 marks]
- changes with selection
12.
Devon is asked about Hardy–Weinberg in a Edexcel Biology paper.
(a) [2 marks]
- assumes no selection, large population, random mating
(b) [3 marks]
- estimates carriers
13.
Devon is asked about directional selection in a Edexcel Biology paper.
(a) [2 marks]
- mean shifts
(b) [3 marks]
- e.g. antibiotic resistance
14.
Devon is asked about stabilising selection in a Edexcel Biology paper.
(a) [2 marks]
- variation falls
(b) [3 marks]
- e.g. human birth mass
15.
Devon is asked about genetic drift in a Edexcel Biology paper.
(a) [2 marks]
- stronger in small populations
(b) [3 marks]
- founder and bottleneck
16.
Devon is asked about succession in a Edexcel Biology paper.
(a) [2 marks]
- pioneer species
(b) [3 marks]
- deflected succession / plagioclimax
17.
HWE q²=0.04. q and 2pq if p=0.8
[3 marks]
- Final answer: q=0.2, 2pq=0.32
18.
Mark-release: 40 marked, 50 recaptured of which 10 marked. N
[3 marks]
- Final answer: 200
19.
A population grows from 80 to 100. Percentage increase
[3 marks]
- Final answer: 25%
20.
Simpson: two communities, higher D means
[3 marks]
- Final answer: higher diversity
21.
If p=0.9, frequency of homozygous dominant
[3 marks]
- Final answer: 0.81
22.
40 of 200 snails are striped recessive. q²
[3 marks]
- Final answer: 0.20
23.
Devon carries out a Edexcel-style required practical linked to populations, evolution and ecosystems. This is a typical Edexcel required-practical style question.
(a) [2 marks]
- Independent: the independent variable for this topic
- Dependent: the measured outcome
(b) [2 marks]
- keep all other variables constant
- so the test is fair / only one variable is changed
(c) [2 marks]
- repeat and calculate a mean / use a tighter method
24.
Devon carries out collecting valid data for populations, evolution and ecosystems. This is a typical Edexcel required-practical style question.
(a) [2 marks]
- Independent: a chosen factor
- Dependent: a quantitative measurement
(b) [2 marks]
- calibrated instrument
- so the test is fair / only one variable is changed
(c) [2 marks]
- systematic error from zero error
25.
Devon carries out drawing a graph for populations, evolution and ecosystems. This is a typical Edexcel required-practical style question.
(a) [2 marks]
- Independent: x-variable
- Dependent: y-variable
(b) [2 marks]
- same scale / same apparatus
- so the test is fair / only one variable is changed
(c) [2 marks]
- not drawing a line of best fit through the trend
26.
Devon carries out evaluating a method about populations, evolution and ecosystems. This is a typical Edexcel required-practical style question.
(a) [2 marks]
- Independent: method change
- Dependent: precision / accuracy
(b) [2 marks]
- same sample size
- so the test is fair / only one variable is changed
(c) [2 marks]
- too few repeats
27.
Compare a gene pool with Hardy–Weinberg.
[4 marks]
- all the alleles in a population
- p² + 2pq + q² = 1
- give one linked difference
28.
Compare Hardy–Weinberg with directional selection.
[4 marks]
- p² + 2pq + q² = 1
- favours one extreme
- give one linked difference
29.
Compare directional selection with stabilising selection.
[4 marks]
- favours one extreme
- favours the mean
- give one linked difference
30.
Compare stabilising selection with genetic drift.
[4 marks]
- favours the mean
- random change in allele frequency
- give one linked difference
31.
Apply your knowledge of an ecosystem to this situation: dynamic
[3 marks]
- dynamic
32.
Apply your knowledge of conservation to this situation: in situ vs ex situ
[3 marks]
- in situ vs ex situ