Cycles within Ecosystems Practice Questions

Decomposers break down the dead plant material in the compost heap.

Which substance is released into the soil when decomposers break down dead plant material?

Put a cross ( ☒ ) in the box next to your answer.

☐ A nitrogen gas

☐ B mineral ions

☐ C glucose

☐ D oxygen

Explain why materials such as mineral ions must be recycled in an ecosystem.

Name the process by which water vapour is lost from the leaves of a plant.

Describe how water from the sea becomes rain that falls on the land.

Name the processes labelled A, B, C and D in Figure 1.

A ............................................

B ............................................

C ............................................

D ............................................

In autumn, dead leaves fall onto the woodland floor.

Explain how decomposers return carbon dioxide from these dead leaves to the atmosphere.

Calculate the net mass of carbon added to the atmosphere each year.

.............................................. gigatonnes

Large areas of forest are being cut down each year.

Explain how an increase in the area of forest cut down would affect the net mass of carbon added to the atmosphere each year.

Describe how distillation produces potable water from seawater.

Give one reason why desalination is not used in all areas that are short of water.

A sealed glass bottle contains soil, small green plants and a few woodlice. The bottle has not been opened for ten years. The plants and woodlice are still alive.

Explain how carbon is recycled inside the sealed bottle.

Carbon is found in the atmosphere, in the oceans, in rocks and in living organisms.

Explain how carbon is cycled between these abiotic and biotic components of the Earth.

Use the correct scientific terms in your answer.

Calculate the percentage increase in the nitrate concentration of the soil between the end of year 2 and the end of year 3.

.............................................. %

Explain the changes in the nitrate concentration of the soil shown in Figure 4.