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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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Ratio of dry biomass of animals to dry biomass of seaweeds 0.15 0.06 0.03

Ratio of dry biomass of animals to abundance of animals 0.20 0.10 0.09

Ratio of dry biomass of seaweeds to abundance of seaweeds 0.79 1.57 3.24



(d) (i) Conservation officers were working on the beaches used…

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