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Ecological techniques and statistics questions Mark Scheme



M1. (a) (i) Accurate means without error/free from mistakes when callipers
used
Reliable means that figure can be reproduced when measurement
Repeated/show little variation about true value
2




(ii) If data unreliable, there will be a wide range of values
Large standard deviation…

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(e) Unidentified bird remains small percentage of total prey/found
in few stomachs
Significant numbers of rabbits/rats eaten and these are pests
2
[15]



M2. (a) (i) Method of positioning quadrats,
E.g. Find direction and distance from specified point/find
coordinates on a grid/split area into squares

Method of generating random numbers…

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rainfall, the more daffodil flowers

Negative correlation/the higher the temperature the fewer daffodils
in flower

All statistically significant so not likely to be/not due to chance
2 max
[8]



M3. (a) (i) Will work in all weather conditions/hairs will stick to it even if
shrew/animal is wet/withstand rain
1

(ii)…

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(d) (i) One mark for a valid explanation based on individual shrews
entering more than one hair tube/many hairs from same
shrew/shrews enter without leaving hair
1

(ii) Rules out differences due to changes in population/changes
in environmental conditions

That could be produced by births/deaths/migration/specific
example of environmental conditions affects…

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(ii) There was a probability of less than 0.05/5 in a hundred/5%
In the context of less than
Accept converse: probability of more than 95%

That the difference was due to chance
Look for idea of difference (between sites)
2




(b) (i) (Would not be reliable as) number of species…

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(e) (i) The site/site U with most people/34.6 has the largest ratio/3.24
Accept: as number of people increases, ratio
increases

(Large value of ratio due to) large biomass ÷ small number/large
size ÷ small number/biomass greater than abundance
Explanation of seaweed ratio
2




(ii) 1. Fewer larger animals/more smaller animals…

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(b) (i) 1
1

(ii) (p =) 0.05/ 5%
(ignore 95%)
1

(iii) value for
2
exceeds critical value/ 125.8 > 10.8
Results unlikely to be due to chance/ have a biological cause
P < 0.1% / < 5%
2 max




(c) (i) biomass respired/ GPP ­ respiration = NPP…

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respiration / use of oxygen by cells/ diffusion/ gas exchange
to gain credit point made must concern oxygen
1




(b) (i) there is no difference between the partial pressure of oxygen
in the two groups / the partial pressure of oxygen is the same
in each group
1

(ii) results…

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(iii) woodlice eat large amount of leaves
copper stored/accumulates in body
2




(f) (i) mutation
1

(ii) (as a component of) nucleic acids / DNA / RNA / nucleotides
phospholipids
ATP/ADP
2 max

(iii) arsenictolerant plants would not be able to take up phosphates /
take up a little phosphate…

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