4.7- INVESTIGATING DIVERSITY

Question 1

What is species richness?

Answer 1

No of diff species

Question 2

Suggest how this student would obtain data to give a more precise value for the
index of diversity of this habitat. (2)

Answer 2

1. Take more samples and find mean;
2. Method for randomised samples described.
   Allow larger area = 1 mark

Question 3

Species richness and an index of diversity can be used to measure biodiversity within a
community.
(a) What is the difference between these two measures of biodiversity? (1)

Answer 3

Species richness measures only number of (different) species / does not measure
number of individuals.

Question 4

Scientists investigated the biodiversity of butterflies in a rainforest. Their
investigation lasted several months.
The scientists set one canopy trap and one understorey trap at five sites.
• The canopy traps were set among the leaves of the trees 16–27 m above
ground level.
• The understorey traps were set under trees at 1.0–1.5 m above ground level.
The scientists recorded the number of each species of butterfly caught in the traps.
The table below summarises their results.

Species of butterfly Mean number of butterflies P value
In canopy In understorey
Prepona laertes 15 0 < 0.001
Archaeoprepona
demophon 14 37 < 0.001
Zaretis itys 25 11 > 0.05
Memphis arachne 89 23 < 0.001
Memphis offa 21 3 < 0.001
Memphis xenocles 32 8 < 0.001
The traps in the canopy were set at 16–27 m above ground level. Suggest why
there was such great variation in the height of the traps. (1)

Answer 4

Tree heights vary

Question 5

The scientists carried out a statistical test to see if the difference in the distribution
of each species between the canopy and understorey was due to chance. The P
values obtained are shown in the table.
Explain what the results of these statistical tests show.

Answer 5

1. For Zaretis itys, difference in distribution is probably due to chance /
   probability of being due to chance is more than 5%;
2. For all species other than Zaretis itys, difference in distribution is (highly)
   unlikely to be due to chance;
3. Because P < 0.001 which is highly significant / is much lower than 5%.

Question 6

king phillip came over for good soup

Answer 6

mneumonic

Question 7

In this investigation, what is meant by genetic diversity? (1)

Answer 7

Number of different alleles of each gene.
Accept number of different base sequences (found) in each
gene

Question 8

A group of scientists investigated genetic diversity in different species of bird. For
each species, the scientists:
• collected feathers from a large number of birds
• extracted DNA from cells attached to each feather
• analysed the samples of DNA to find genetic diversity.

The scientists concluded that the bluethroat showed greater genetic diversity than
the willow flycatcher. Explain why they reached this conclusion. Use calculations to
support your answer.(2)

WF= 708 genes exmained and 197 with genetic div

BlueThrot= 232 genes with 81 showing genetic div

Answer 8

1. Has greater proportion of genes / percentage of genes showing
   diversity;
2. Percentage is 35% compared with 28% / proportion is 0.35 compared
   with 0.28.

Question 9

.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 ultraviolet (UV) light.
(a) The ecologists captured insects from a number of sites on the island. Suggest how
they decided where to take their sample

(b) Give two assumptions made when using the mark-release-recapture method.

c- Suggest the advantage of using the fluorescent powder in this experiment.

Answer 9

1. Draw grid over (map of) area;
2. Select squares / coordinates at random.

b- 1. No emigration / immigration;

2. No losses to predation;
3. Marking does not affect survival;
4. Birth rate and death rate equal;
5. (In this case) all belong to one population.

c- 1. Only glows 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 10

Q5.(a) What two measurements are needed to calculate an index of diversity (2)

Answer 10

1. Number of (individuals of) each species;
   Accept: ‘population’ for ‘number’
2. Total number of individuals / number of species;
   Accept: ‘species richness’
   MP2 allows for other types of diversity index

Question 11

Some fields acted as controls. They were sprayed with a solution that did not
contain the herbicide. Explain the purpose of these control fields. (1)

Answer 11

(Shows) results are due to the herbicide / are not due to another factor /
(to) compare the effect of using and not using the herbicide / shows the
effect of adding the herbicide;
Neutral: allows a comparison
Neutral: ensures results are due to the independent variable
Reject: ‘insecticide’
Accept: ‘pesticide’

Question 12

Suggest an explanation for the relationship between the concentration of
herbicide and the mean crop yield. (2)

Answer 12

1. (More) weeds killed so more crops / plants survive / higher yield /
   less competition;

2. High concentrations (of herbicide) harm / damage / kill / are toxic to
crops / plants;
Accept: ‘pesticide’
Neutral: ‘insecticide’
Accept: use of figures (eg 400+)

Question 13

Explain the relationship between the concentration of herbicide and the mean
index of diversity of insects (3)

Answer 13

1. Reduced plant diversity / fewer plant species / fewer varieties of
plant;
Accept: ‘weed’ for ‘plant’
Neutral: fewer plants
Accept: only one crop species remains
2. Fewer habitats / niches;
Q Neutral: fewer homes / shelters
3. Fewer food sources / varieties of food;
Neutral: less food

Question 14

6.During the light-independent reaction of photosynthesis, carbon dioxide is converted into
organic substances. Describe how. (6)

Answer 14

1.Carbon dioxide combines with ribulose bisphosphate / RuBP;
2. Produces two glycerate (3-)phosphate / GP;
Accept: any answer which indicates that 2 x as much GP
produced from one RuBP.
3. GP reduced to triose phosphate / TP;
Must have idea of reduction. This may be conveyed by
stating m.p. 4.
4. Using reduced NADP;
Reject: Any reference to reduced NAD for m.p.4 but allow
reference to reduction for m.p. 3.
5. Using energy from ATP;
Must be in context of GP to TP.
6. Triose phosphate converted to glucose / hexose / RuBP / ribulose
bisphosphate / named organic substance;