Diversity

Question 1

Explain why it is more useful to calculate an index of diversity than to record species richness

Answer 1

• index of diversity measures number of each species
• so nah be many of some species/ few of others

Question 2

A scientist investigated the effect sewage entering a river
had on the distribution of organisms living in the river. Where sewage entered the river,
he found a high density of organisms but a low index of diversity.
Suggest how sewage entering the river could explain the scientist’s findings.

Answer 2

1. Described effect of sewage (eg oxygen depletion/is toxic/kills);
   Accept: increase in BOD
   Accept: eutrophication/description of eutrophication
2. Prevents some/many species colonising/ reproducing/remaining;
   Accept: only a few species survive
3. Sewage is food source for (individuals of) some/a few/species;
4. (So) increase only in their numbers

Question 3

Use your knowledge of natural selection to explain why resistance to malaria P. Vivax is so common in Africa

Answer 3

1. Mutation produced allele
2. Those with allele do not get malaria
3. So more likely to reproduce and pass on the allele
4. Over generations, allele frequency increases

Question 4

Describe how organisms are grouped in a phylogenetic classification system

Answer 4

• hierarchy of groups with no overlaps
• according to evolutionary origins/ relationships

Question 5

Haemoglobins are chemically similar molecules found in many different species.

Differences in the primary structure of haemoglobin molecules can provide evidence of phylogenetic relationships between species.

Explain how.

Answer 5

1. Mutations change base / nucleotide (sequence);
2. (Causing) change in amino acid sequence;
3. Mutations build up over time;
4. More mutations / more differences (in amino acid
   / base / nucleotide sequence / primary structure)
   between distantly related species;
   OR
   Few(er) mutations / differences (in amino acid /
   base / nucleotide sequence / primary structure)
   in closely related species;
5. Distantly related species have earlier common
   ancestor;
   OR
   Closely related species have recent common
   ancestor;