Old exam question OCR

from the old papers, questions i cant do

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  • Created by: sophie
  • Created on: 04-05-12 16:27

Explain how inorganic fertilizers and herbicides r


  • Run-off from fields
  • causes algal blooms
  • Decreased levels of photosynthesis 
  • Increased decomposition
  • Oxygen levels reduced by aerobic bacteria
  • organisms die due to lack of oxygen for respiration
  • Increased growth of some plant species
  • elimination of other species


  • Blows off fields
  • Kill non-target species 
  • Can blow into hedgerows
  • Ashed into water
  • Effects food chains
1 of 6

Describe a typical predator-prey relationship

Prey populatin increases when theres fer imiting factors

Provides food for predator

Predator pop increases after a time lag

Prey eaten by predator

Both decline

Cycle repeated

Prey pop is at greater levels(http://www.tiem.utk.edu/~gross/bioed/bealsmodules/pred-prey.gph1.gif)

2 of 6

How could you carry out a sand dune line transect?

Put line from shore to dune slack

Use suitable sized quadrat eg 25cm^2

At specific intervals

Use key to identify species

Record organism abundance

Record bare ground

3 of 6

Explain why many regard using predatory mites as b


harmful to other organisms

Disrupts food chains


Damages top carnivores

Pests can build up resistance

Residues can be in food

Run off causes pollution

4 of 6

Describe the major problems of enabling large-scal

Difficult maintaining temp

Difficult maintaining pH


Blocking of inlet/outlet tubes

Difficulties mixing


Conditions need to be constantly monitored

Nutrient requirement may change

5 of 6

State improvements made to crops by genetic engine

Higher yield

Disease resistant

Flood resistant

Drought resistant

Improved shelf-life of product

Improved nutrient value eg goldenrice

Herbicide resistance

6 of 6


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