Nutrient Cycles (Cambridge O Level Biology)

Fig. 1 represents the carbon cycle.

Fig. 1

Use Fig. 1 to answer the following questions.

Name the process labelled U.

[1]

Name a group of organisms that are responsible for the process labelled W.

[1]

 List two letters that identify respiration.

[2]

 State which letter identifies photosynthesis.

Suggest reasons why the mean percentage of carbon dioxide in the atmosphere has increased during the last 100 years.

The functioning of ecosystems relies on the cycling of nutrients.

Fig. 1 shows part of the nitrogen cycle.

Fig. 1

State the name of process A in Fig. 1 and give the type of organism that converts ammonium ions to nitrate ions.

[2]

Describe how the nitrate ions used in process C enter the roots of plants.

[3]

State the name of the structure in plant cells where process D occurs.

[1]

State the process that occurs at B.

[1]

Fig. 1 shows a pyramid of biomass and part of the carbon cycle.

Fig. 1

[1]

[1]

Some fungi and bacteria are decomposers

Define the term decomposer.

[1]

[1]

Describe how human activities are affecting the carbon cycle.

Fig. 1 shows part of the carbon cycle.

Fig. 1

Identify the processes shown by arrows A, B and C on Fig. 1.

Choose words from the list.

(i)

On Fig. 1 draw one arrow to represent photosynthesis.

Label this arrow with a letter D.

[1]

On Fig. 1 draw one arrow to represent respiration.

Label this arrow with a letter E.

The functioning of ecosystems relies on the cycling of nutrients.

Fig. 1 shows part of the nitrogen cycle.

Fig. 1

State the name of process A in Fig. 1 and give the type of organism that converts ammonium ions to nitrate ions.

Describe how nitrate ions enter the roots of plants shown by arrow C on Fig. 1.

State the process that occurs at B.

Suggest why it is important that molecules that contain nitrogen are added to the soil.