BiodiversityAQA A-Level Biology: Topic test

20 questions, 54 marks

AQA A-Level Biology

Biodiversity topic test

Total 54 marks

Name

Class

Date

1
A student surveyed a rocky shore pool and counted the individuals of each species: 9 limpets, 5 mussels, 3 dog whelks and 2 sea anemones.
(a)
What is the species richness of the pool?
[1 mark]
A4
B19
C3.4
D9
(b)
Which statement about the index of diversity is correct?
[1 mark]
AIt is the number of species in a community
BIt takes account of the number of species and the number of individuals in each species
CIt can only be calculated for a single species
DIt measures the genetic differences within one species
(c)
Calculate the index of diversity (d) for the pool. Use the formula $d = \dfrac{N(N-1)}{\sum n(n-1)}$ . Give your answer to two significant figures.
[2 marks]
Total for question 1: 4 marks
2
A farmer drained a wet meadow and sowed the whole field with a single variety of wheat each year. The farmer sprays the crop with herbicide to kill weeds and with pesticide to kill insects.
(a)
Which technique directly reduces plant species diversity on the farm?
[1 mark]
ARotating crops between fields
BAllowing a pasture to flower before it is cut
CSpraying herbicide to kill weeds among the crop
DPlanting a hedge around the field
(b)
Which change would help to balance conservation with farming?
[1 mark]
ADraining all of the remaining wet areas
BGrowing a single crop variety on all of the land
CRemoving all uncultivated land
DRotating crops and using biological control in place of some pesticide
(c)
Explain how the farmer's techniques reduce the biodiversity of the farm.
[2 marks]
Total for question 2: 4 marks
3
A student compared the shell length of a snail species on two rocky shores. At each shore she measured 40 snails. The mean shell length at shore A was 18.4 mm with a standard deviation of 1.1 mm, and at shore B it was 19.0 mm with a standard deviation of 3.2 mm.
(a)
Describe how the student could have obtained a random sample of snails at each shore, and explain why a random sample is needed.
[3 marks]
(b)
Interpret the means and standard deviations. State what they show about the variation in shell length and whether they show that the two populations differ.
[4 marks]
Total for question 3: 7 marks
4
A farm and a nature reserve were surveyed for butterflies, using the same number of random sampling points in each. In the reserve the numbers of the six species found were 20, 18, 15, 12, 10 and 5, and the index of diversity was 5.6. In the neighbouring farm field, the three species found had 70, 6 and 4 individuals.
(a)
Calculate the index of diversity for the farm field, and explain what the difference between the two values shows about the farm field and how its farming techniques could have caused it.
[6 marks]
(b)
Suggest two changes the farmer could make to increase biodiversity, and explain why a balance between conservation and farming is needed.
[6 marks]
Total for question 4: 12 marks
5
Researchers investigated genetic diversity in a population of wild cats by comparing the DNA base sequence of one gene in 40 individuals. In 36 cats the sequence was the same, and in 4 cats it differed from the others by a single base.
(a)
What does the presence of two different sequences show?
[1 mark]
ATwo species of cat are present
BThe cats are all genetically identical
CThe gene has two alleles in the population, so there is genetic diversity at this gene
DThe gene has stopped coding for a protein
(b)
How has gene technology changed the way genetic diversity is investigated?
[1 mark]
AOnly mRNA can now be compared
BDirect comparison of DNA base sequences has replaced inference from measurable or observable characteristics
CAmino acid sequences can no longer be used
DGenetic diversity can now only be investigated between species
(c)
Suggest why comparing DNA base sequences is a more reliable way of investigating genetic diversity than comparing observable characteristics.
[2 marks]
Total for question 5: 4 marks
6
Two sand dunes were surveyed with the same sampling effort. Dune 1 has five species, and one of them makes up 90% of all the individuals. Dune 2 also has five species, and each has about the same number of individuals.
(a)
Which statement is correct?
[1 mark]
ABoth dunes have the same species richness, but dune 2 has the higher index of diversity
BBoth dunes have the same species richness, but dune 1 has the higher index of diversity
CDune 1 has the higher species richness and the higher index of diversity
DBoth dunes have the same index of diversity
(b)
In the formula for the index of diversity, what does N represent?
[1 mark]
AThe number of species
BThe number of individuals of one species
CThe number of habitats sampled
DThe total number of organisms of all species
(c)
Explain why dune 1 has a lower index of diversity than dune 2 even though the species richness is the same.
[2 marks]
Total for question 6: 4 marks
7
Short sections of the coding strand of one gene were sequenced in three species. Species A: ATG CCT AAG CTT ACG GAT. Species B: ATG CCC AAG CTT ACG GAT. Species C: ATG CCT AAA CTT TCG GAT. CCT and CCC both code for proline, AAG and AAA both code for lysine, ACG codes for threonine and TCG codes for serine.
(a)
State the number of base differences between each pair of species, and suggest which two species are the most closely related.
[3 marks]
(b)
Compare the amino acid sequences coded for by the three sections, and explain why the base sequences show more differences between the species than the amino acid sequences do.
[4 marks]
Total for question 7: 7 marks
8
A conservation team compared a woodland reserve, isolated by farmland, with a large continuous forest. They sequenced one gene in 30 squirrels from each place. There were five different base sequences in the forest squirrels but only two in the reserve squirrels. The mean body mass of the reserve squirrels was 295 g with a standard deviation of 14 g, and of the forest squirrels was 310 g with a standard deviation of 31 g. A survey of mammals in the reserve found four species with 12, 8, 5 and 5 individuals, and the index of diversity for the forest was 7.1.
(a)
Compare the genetic diversity of the two squirrel populations using all of the data on squirrels, and suggest how farming could have caused the difference.
[6 marks]
(b)
Calculate the index of diversity for the mammals in the reserve, and compare it with the forest value. Suggest one change that could help to link conservation with farming here, and justify it.
[6 marks]
Total for question 8: 12 marks

End of questions

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).