Author: Philip Colls
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Biodiversity booklet revision questions                NAME:
Q1. A student investigated the distribution of plants in a heathland.
The table below shows the number of plants he found in a sample area of 1 m^2.

Species of plant

Number counted in
1 m^2

Common heather | 2
Red fescue | 14
Vetch | 2
White clover | 8
 
(a) | What is the species richness of this sample? |
(1)
(b)     Calculate the index of diversity of this sample. Show your working.
Use the following formula to calculate the index of diversity.
d = 
where N is the total number of organisms of all species
and     n is the total number of organisms of each species

 
Index of diversity = ____________________ (2)
(c)     Suggest how this student would obtain data to give a more precise value for the index of diversity of this habitat.
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_________________________________________________(2)  (Total 5 marks)
Q2. The table shows the numbers of adult butterflies in two areas of the same tropical forest. In the logged area some trees had been cut down for timber. In the virgin forest no trees had been cut down. The two areas were the same size.
 
| Logged forest | Virgin forest
Butterfly species | Number | n(n–1) | Number | n(n–1)
Eurema tiluba | 72 | 5112 | 19 | 342
Cirrochroa emalea | 43 | 1806 | 132 | 17292
Partenos sylvia | 58 | 3306 | 14 | 182
Neopithecops zalmora | 6 | 30 | 79 | 6162
Jamides para | 37 | 1332 | 38 | 1406
Total | 216 | 11586 | 282 | 25384
(a)     Describe a method for finding the number of one of the species of butterfly in the virgin forest.
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_________________________________________________________________(2)
(b)     The index of diversity of a forest can be calculated using the equation

Calculate the index of diversity for the virgin forest. Show your working.

 
Answer ____________________
(2)
(c)     What does the table show about the effects of logging on the butterfly populations?
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(2)  (Total 6 marks)
Q3. (a)     What is a species?
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(2)
(b)     Scientists investigated the diversity of plants in a small area within a forest. The table shows their results.
 
Plant species | Number of individuals
Himalayan raspberry | 20
Heartwing sorrel | 15
Shala tree | 9
Tussock grass | 10
Red cedar | 4
Asan tree | 6
Spanish needle | 8
Feverfew | 8
The index of diversity can be calculated by the formula
 
where
d = index of diversity
N = total number of organisms of all species
n = total number of organisms of each species
(i)      Use the formula to calculate the index of diversity of plants in the forest. Show your working.

Answer = ____________________
(2)
(ii)     The forest was cleared to make more land available for agriculture.
After the forest was cleared the species diversity of insects in the area decreased. Explain why.
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(Extra space) ___________________________________________________
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____________________________________________________________(3)
(Total 7 marks)
Q4.
(a)     Ecologists measured the body lengths of male and female thorny lizards living in the same habitat. The ecologists measured the body lengths to the nearest 5 mm.
The graph shows how they presented their results.
 
Give two differences in the variation in body length of male and female thorny lizards.
1. _________________________________________________________________
___________________________________________________________________
2. _________________________________________________________________
_________________________________________________________________(2)
(b)     Another group of ecologists investigated biodiversity of lizards in a woodland area. Their results are shown in the table.
 
Lizard species | Number of individuals
Dominican giant anole | 5
Hispaniolan green anole | 11
Hispaniolan stout anole | 22
Bark anole | 91
Hispaniolan grass anole | 13
Cope’s galliwasp | 5
Cochran’s least gecko | 8
Peninsula least gecko | 1
The index of diversity can be calculated using the formula
 
where
d = index of diversity
N = total number of organisms of all species
n = total number of organisms of each species
(i)      Use the formula to calculate the index of diversity of lizards in the woodland area. Show your working.

Answer = ____________________(2)
(ii)     The ecologists also determined the index of diversity of lizards in an oil palm plantation next to the woodland area. They found fewer species of plant in the oil palm plantation. Lizards feed on plants and insects.
Explain why fewer species of plant would lead to fewer species of lizard in the oil palm plantation.
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___________________________________________________ (3)(Total 7 marks)
Q5.
(a)     What two measurements are needed to calculate an index of diversity?
1. _________________________________________________________________
2. _________________________________________________________________
(2)
(b)     A herbicide is a chemical used to kill weeds. Ecologists investigated the effect of a herbicide on crop yield and the diversity of insects. They sprayed different fields with the same volume of different concentrations of the herbicide. At harvest, the ecologists determined the mean crop yield and the mean index of diversity of insects for fields that had received the same concentration of the herbicide.
The figure below shows their results.
 
Concentration of herbicide sprayed on field / mg dm^−3
(i)      Some fields acted as controls. They were sprayed with a solution that did not contain the herbicide. Explain the purpose of these control fields.
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______________________________________________________________
(1)
(ii)     Suggest an explanation for the relationship between the concentration of herbicide and the mean crop yield.
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(2)

(iii)     Explain the relationship between the concentration of herbicide and the mean index of diversity of insects.
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(Extra space) ___________________________________________________
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____________________________________________________________(3)
(Total 8 marks)
Q6. Scientists investigated the effect of different types of animal farming on the diversity and number of dung beetles. They determined the number of dung beetle species and their total number on intensive (I), rough grazing (R) and organic (O) farms.
Figure 1 and Figure 2 show some of their results.
 
Figure 1 | Figure 2
 
(a)     What is the mean species richness for dung beetles on the rough grazing farms?
___________________________________________________________________
(1)
(b)     In addition to the information provided in Figures 1 and 2, what other measurement is required to calculate an index of diversity for dung beetles?
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_________________________________________________________________(1)
(c)     Explain what the standard deviations suggest about the difference in mean total number of dung beetles between the different types of farm.
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(2)
(d)     The scientists placed traps to collect the dung beetles at sites chosen at random.
Explain the importance of the sites being chosen at random.
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(1)
(e)     On the intensive farms, the farmers had removed hedges to increase land for grazing. This resulted in a decrease in the diversity of birds on these farms.
Explain why the removal of hedges caused a decrease in the diversity of birds.
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(3)
(Total 8 marks)

Q7. 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)
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
(b)     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.
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_________________________________________________________________(1)
(c)     By how many times is the species diversity in the canopy greater than in the understorey? Show your working. Use the following formula to calculate species diversity.
d = 
where N is the total number of organisms of all species and n is the total number of organisms of each species.
 
 Answer = ____________________       (3)
(d)     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.
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 (3)
(Total 8 marks)
Q8.
The vegetation on a large heap of waste from an old mine was investigated. The table shows the results of the measurements of certain factors in 1m^2 frame quadrats placed on the south-facing slope.

Quadrat

Angle of
slope / °

Vegetation
cover / %

Moisture
content of
soil / %

pH of
soil

1
2
3
4
5
6

45
30
25
12
7
1

60
70
68
100
85
100

17.2
14.6
20.3
23.5
21.0
21.2

5.6
4.2
5.2
7.1
5.4
6.8

(a)     Which of the factors measured are abiotic?
___________________________________________________________________
(1)
(b)     Describe how the investigators could obtain the value for vegetation cover in each quadrat.
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(2)
(c)     The correlation between vegetation cover and soil moisture content was tested statistically. These two factors were found to be positively correlated, and p < 0.05. Explain what this result means.
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(2)
(d)     At first the waste heap had no plants growing on it. Some of the first plants to colonise it were small herbaceous plants. Explain one way in which colonisation by herbaceous plants could change the physical environment.
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(2)
(Total 7 marks)

Mark schemes
Q1.
(a)      4:
1
(b)     2.68(6).
If answer incorrect:
Σn(n-1) = 242 = 1 mark
N(N-1) = 650 = 1 mark
2
(c)     1.      Take more samples and find mean;
2.      Method for randomised samples described.
Allow larger area = 1 mark
2
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Q2.
(a)     suitable method of capture;
mark individuals and release;
count percentage recaptured / use Lincoln index / equation;
2 max
(b)     
(accept 3.1 / 3.122)
2
(c)     decrease in total numbers of butterflies;
(reject population)
change in proportion of species / example(s);
increase in diversity in logged forest / calculation(4.01);
2 max
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Q3.
(a)     1.      Group of similar organisms / organisms with similar features / organisms with same genes / chromosomes;
1. Accept: same number of chromosomes
1. Accept: smallest taxonomic group
1. Reject: genetically identical. Only allow 1 max if mentioned
1. Q Neutral: similar genes / chromosomes
2.      Reproduce / produce offspring;
2. Accept: breed / mate
3.      That are fertile;
3. Neutral: that are ‘viable’
‘Produce fertile offspring’ = 2 marks
2 max
(b)     (i)      Correct answer of 6.97 to 7 = 2 marks;
One mark for 6320 as numerator or 906 as denominator;
2
(ii)     1.      Decrease in variety of plants / fewer plant species;
1. Accept: reference to monoculture or description
1. Neutral: fewer plants
2.      Fewer habitats / niches;
2. Neutral: fewer homes / less shelter
3.      Decrease in variety of food / fewer food sources;
3. Neutral: less food
3. Accept: less variety of prey
3
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Q4.
(a)     1.      Females are (generally) longer / larger / bigger / up to 115(mm) / males are (generally) shorter / smaller / up to 100(mm);
Ignore: tall
Accept: females have a larger / 90 modal / peak / most common value and males have a smaller / 80 modal / peak / most common value
Accept mean length of females greater / mean length of males shorter
Reject: use of mean in relation to 80 mm or 90 mm
Reject: Most of the females are 90 mm long / most of the males are 80 mm long
2.      Females show a greater range / variation / males show a narrower range / variation.
Accept: correct use of figures from the graph: the range of males is 50 to 100 and of females is 50 to 115 / the spread is 50 for males and 65 for females
2
(b)     (i)      2.6 to 2.7 = 2 marks;
          Incorrect answer but evidence of a numerator of 24180 OR 156 × 155 or denominator of 9014 = 1 mark;
2
(ii)     (Fewer plant species) − no mark
1.      (So) few(er) habitats / niches;
Ignore habitat size
Q Neutral: fewer homes
2.      (So) lower diversity of insects / fewer insect species / fewer insect types;
Q Neutral: fewer insects
Accept less variety of insects
3.      (So) fewer food sources / less variety of food.
Q Neutral: less food
Ignore references to pesticides, farmers’ actions, competition between lizards and evolution
3
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Q5.
(a)     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
2
(b)     (i)      (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’
1
(ii)     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+)
2
(iii)    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
3
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Q6.
(a)     14;
1
(b)    Number (of individuals) in each species (of dung beetle);
Accept: population of each species.
1
(c)     1.      No overlap in standard deviations;
Accept: no overlap in error bars.
2.      (Difference in mean total) significant/is not due to chance/is real;
2
(d)     No bias;
Ignore: ‘representative sample’.
1
(e)     1.      Removes species/types of plant/insect;
Accept: decrease in plant/insect diversity.
2.      Fewer food sources;
Ignore: less food.
Accept: less variety of food.
Accept: removes a food source.
3.      Fewer habitats/niches;
Accept: loss/removal/destruction/ of a habitat.
Accept: no habitat.
Ignore: homes/shelters.
3
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Q7.
(a)     Species richness measures only number of (different) species / does not measure number of individuals.
1
(b)     Trees vary in height.
1
(c)     1.      Index for canopy is 3.73;
2.      Index for understorey is 3.30;
3.      Index in canopy is 1.13 times bigger;
If either or both indices incorrect, allow correct calculation from student’s values.
3
(d)     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%.
3
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Q8.
(a)     angle, moisture and pH
(all required)
1
(b)     system for subdividing quadrat into, e.g. many squares;
method of estimating cover in small squares, e.g. counting those where cover over 50%, or cover at points (of intersection);
(not just ‘count squares with vegetation’ unless very small)
2
(c)     increasing vegetation cover is related to increasing moisture content
(allow ‘affects‘ moisture content or vice versa, not ‘causes); 
correlation is significant / not due to chance / can reject null hypothesis
/ only 1 in 20 / 5% probability that the correlation is due to chance;
2
(d)     factor; and linked effect e.g.
wind-blown particles trapped;
accumulation of soil;
OR
accumulation of organic / dead / decomposed matter / humus;
increase in mineral ions / improved water retention / improved
soil structure;
OR
nitrogen fixation;
increased nitrate concentration / improved soil fertility;
2 max
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