2.8 Photosynthesis

State why the majority of plants look green to human eyes.

[1 mark]

The effect of different colours of light on the growth of Arabidopsis thaliana (thale cress) seedlings was studied. Three different colours of light were tested and measurements of seedling height, shoot length, and biomass were taken. The results of the study are shown in the table below.

State what can be concluded about the effect of different colours of light on the growth of Arabidopsis thaliana from the data shown.

[2 marks]

Oxygen can be thought of as a waste product of photosynthesis.

Identify the process by which this oxygen is produced.

[1 mark]

The process in part c) releases oxygen into the atmosphere, increasing atmospheric oxygen concentration.

State two other impacts that photosynthesis would have had on the atmosphere of prehistoric earth.

[2 marks]

State what is meant by the term photosynthesis.

[2 marks]

The graph below shows the relationship between carbon dioxide concentration and the rate of photosynthesis.

Describe the relationship between carbon dioxide concentration and the rate of photosynthesis shown in the graph.

[2 marks]

Identify a possible limiting factor at the point labelled X in the graph in part b).

[1 mark]

[3 marks]

A student makes the following statement:

"Visible light has wavelengths between 200 and 900 µm. Red is the shortest wavelength and violet is the longest."

Identify the errors in this statement.

[3 marks]

A plant is grown in increasing concentrations of carbon dioxide whilst other factors are kept constant.

Describe what will happen to the rate of photosynthesis as carbon dioxide concentration increases.

[2 marks]

The plant in part b) is an aquatic plant. Before starting the experiment the student conducting the study boiled and then cooled the water that the plant would be placed in.

Explain why the student did this.

[1 mark]

Describe how the student could have measured the rate of photosynthesis in the study described in parts b) and c).

[2 marks]

One mark is available for clarity of communication throughout this question.

Outline how photosynthesis in early life forms caused changes to early Earth.

[5 marks]

Describe the process of photosynthesis.

[6 marks]