3.4.7 - INVESTIGATING DIVERSITY

Question 1

the genetic diversity of species is measured by comparing differences in the base sequence of DNA or differences in the base sequence of mRNA.

give two other ways in which genetic diversity between species is measured (2)

Answer 1

1. comparing measurable/observable characteristics/features
2. comparing amino acid sequences of the same protein (haemoglobin, cytochrome c)

Question 2

what is meant by genetic diversity? (1)

Answer 2

number of different alleles of the each gene

Question 3

suggest one source through which scientists obtained DNA from otters that were alive before hunting occurred (1)

Answer 3

bones/skin/preserved remains/museums

Question 4

some populations of animals that have never been hunted show very low levels of genetic diversity.

other than hunting, suggest two reasons why populations might show very low levels of genetic diversity (2)

Answer 4

1. inbreeding
2. population may have been very small - genetic bottleneck
3. population may have started with a small number of individuals - founder effect

Question 5

species richness and an index of diversity can be used to measure biodiversity within a community.

what is the difference between these two measures of biodiversity? (1)

Answer 5

species richness only measures the number of different species, it does not measure the number of individuals of a species

Question 6

ecologists investigated the size of an insect population on a small island. they used a mark-release-recapture method. to mark the insects they used a fluorescent powder. this powder glows bright red when exposed to UV light.

the ecologists captured insects from a number of sites on the island. suggest how they decided where to take their samples (2)

Answer 6

1. draw grid over map of area
2. select squares/coordinates at random

Question 7

ecologists investigated the size of an insect population on a small island. they used a mark-release-recapture method. to mark the insects they used a fluorescent powder. this powder glows bright red when exposed to UV light.

give two assumptions made when using the mark-release-recapture method (2)

Answer 7

any two:

1. no emigration/immigration
2. no losses to predation (predators)
3. marking does not not affect survival
4. birth rate and death rate are equal
5. (in this case) all insects belong to the same population

Question 8

ecologists investigated the size of an insect population on a small island. they used a mark-release-recapture method. to mark the insects they used a fluorescent powder. this powder glows bright red when exposed to UV light.

suggest the advantage of using fluorescent powder in this experiment (2)

Answer 8

any pair:

1. only grows brightly with UV, so doesn’t make insects more visible
2. so doesn’t affect/increase predation

OR

1. glows brightly with UV marking visible
2. so makes it easy to pick out labelled insects

Question 9

what two measurements are needed to calculate an index of diversity? (2)

Answer 9

1. number (population) of individuals of each species
2. total number of individuals/number of species/species richness