Exam style question on C1
Exam style question on C1
Community structure is the distribution of organisms within an ecosystem.
Answer the question on a piece of paper, then check your answer against the model answer.
Explain the importance of the following factors in determining community structure.



Keystone species. (2 marks)
Limiting factor. (2 marks)
Competitive exclusion. (2 marks)
Examiner hint: Examples are useful to help with your explanation.
Click the + icon to see a model answer.
Exam style question on C2
Exam style question on C2
Gersmehl diagrams are representations of ecosystems.
Answer the question on a piece of paper, then check your answer against the model answer
below.
Examiner hint - in a structured answer, use brief sentences.
The diagram below represents a Gersmehl diagram of a temperate forest ecosystem.
1. Explain what is shown in a Gersmehl diagram. (2 marks
2.Complete the table below to indicate what is represented by each arrow. (2 marks)
Arrow number
Represents
Uptake by plants
Tissue death
Decomposition of litter
Weathering input
Leaching
Rainfall gain
Loss in runoff water
3. Predict how the diagram would be different if a desert ecosystem was depicted. (2
marks)
Exam style question on C3
Exam style question on C3
Biological control has benefits but also has associated risks.
Answer the question on a piece of paper, then check your answer against the model answer
below.
Examiner hint – the 6-mark question in the Option paper requires detail. Examples are very
useful in your response.
Discuss the benefits and drawbacks of the use of alien species in biological control. (6
marks)
Exam style question on C4
Exam style question on C4
There are many methods of conservation of individual species and of ecosystems.
Answer the question on a piece of paper, then check your answer against the model answer
below.
Examiner hint – the 6-mark question in the Option paper requires detail, examples are important
in your response.
Discuss the conservation of species and communities. (6 marks)
Exam style question on C5
Exam style question on C5
Evaluating population graphs is an important aspect of this topic
Answer the question on a piece of paper, then check your answer against the model answer
below.
Examiner hint – use the information provided in your response
10 pairs of Ring necked parakeets, (Psittacula kremeri), native to South America, were
accidentally released into mainland Greece in 1980 and have become an invasive nonnative species. Their diet consists of fruit, nuts, seeds and berries.
The graph shows estimated population size of the parakeets from 1980 to 1998 in a
northern suburbs of Athens.
Explain the population growth phases shown on the graph as 1, 2 and 3. (6 marks)
Examiner hint: Use correct terminology.
Exam style question on C6
Exam style question on C6
C6
Nitrogen, in the form of nitrate ions, is a major soil nutrient for plants. It is combined with
carbohydrate from photosynthesis to form amino acids. Bacteria have a role in increasing nitrate
availability in soil but they can also reduce it.
Answer the question on a piece of paper, then check your answer against the model answer below.
Discuss how bacteria can affect the availability of soil nitrate for use by plants. (6 marks)
Examiner hint: The question concerns the nitrogen cycle but needs to be confined to the role of
bacteria and soil nitrate availabilty.