Tool 1: Experimental Techniques (DP IB Biology: HL): Exam Questions

35 mins9 questions
1a
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2 marks

Some students used paper chromatography to separate out the photosynthetic pigments in a leaf. The resulting chromatogram can be seen below.

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Using the measurements made by the students, calculate the Rf values for carotene and chlorophyll B and complete the table below.

Pigment

Rf value

Carotene

 

Chlorophyll B

 

1b
2 marks

Explain what the results in part (a) show about the properties of the photosynthetic pigments.

1c
3 marks

The method used to prepare the photosynthetic pigments for chromatography requires the use of propanone. As a health and safety precaution, a student using this method decided to use water instead of propanone.

State what the student’s results would have shown and explain why..

2a
6 marks

Describe how a student would prepare a microscope slide containing a sample of cells from a piece of plant tissue, and how the student would view this sample under a light microscope.

2b
2 marks

Name the two pieces of equipment, used as accessories to a standard light microscope, to measure the size of the specimen being viewed.

3a
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4 marks

A small island off the coast of Iceland formed around 200 years ago. The graph shows data collected from historical records and more recent scientific research, estimating the percentage cover of different plant species since the island was formed. 

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The island is small, with a surface area of about 100 square metres. Describe how the group of biologists could determine the present-day mean percentage cover of grass on the island.

3b
4 marks

The biologists hypothesised that the results shown in the graph in part (a) were due to succession taking place on the island.

Explain why the biologists think this. Use the graph in part (a) to support your answer.

3c
1 mark

If the biologists just wanted to study the abundance of broad-leaved trees on the island in part (a), they could have used frequency rather than percentage cover.

Suggest why this would be possible.

3d
2 marks

The biologists in part (a) are trying to decide if the grasses and broad-leaved trees that are currently present on the island represent the climax community.

State two features of a climax community.

3e
3 marks

With reference to the island ecosystem, describe what may be observed if cyclical succession were to take place.