topic 7 ms answers

Question 1

In fruit flies, the genes for body colour and wing length are linked. Explain what this
means.

Answer 1

gene or loci are on the same chromosome

Question 2

GgNn crossed with ggnn
Use your knowledge of gene linkage to explain these results.

Answer 2

GN and gn are linked
GgNn individual produces mainly GN and gn gametes;
Crossing over produces some Gn and gN gametes;
So fewer Ggnn and ggNn individuals.

Question 3

Which statistical test could the scientist use to determine whether his observed
results were significantly different from the expected results?

Answer 3

chi squared
categorical data

Question 4

Explain what is meant by codominant alleles.

Answer 4

Both alleles are expressed / shown (in the phenotype).

Question 5

Explain the advantage of presenting the results as a ratio.

Answer 5

allows comparison
sample size may vary

Question 6

Explain how the Caribbean species could have evolved. from two species

Answer 6

geographical isolation
Separate gene pools
reproductive isolation
Different selection pressures
Different reproductive success
Leads to change / increase in allele frequency.

Question 7

Describe how you could use the mark-release-recapture method to estimate
the number of Anolis sagrei

Answer 7

1. Capture collect sample, mark and release;
2. Method of marking does not harm lizard / make it more visible to predators;
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 8

succession

Answer 8

colonisation by pioneer species;
Pioneers change the environment
less hostile for other/new species
increase in diversity/biodiversity;
to climax community

Question 9

Describe how you could estimate the size of a population of sundews in a
small marsh.

Answer 9

divide area to squares
random no generator
count frequency in quadrat
large sample calc mean
plants per quadrat times no of quadrats

Question 10

Suggest and explain how digesting insects helps the sundew to grow in soil
with very low concentrations of some nutrients.

Answer 10

digestion of proteins provides amino acids

Question 11

features of climax community

Answer 11

population stable
Abiotic factors constant
same species present