Material cycles

The diagram shows the carbon cycle.

Complete the two labels in the diagram to identify the processes involved in the carbon cycle.

Explain the role of decomposers in the carbon cycle.

Decomposition can take place aerobically or anaerobically.

What is meant by the term anaerobically ?

Human activity has led to rising carbon dioxide levels in the atmosphere.

This contributes to global warming and reduces global biodiversity.

Describe two ways in which human activity can reduce local biodiversity.

Which row shows the correct order of some processes in the water cycle?

Bread mould is a type of fungus that decomposes plant material.

A student investigates the effect of temperature on decomposition.

• They leave slices of bread at three different temperatures.

• Each day the student records the area of each slice of bread covered by mould.

Which is a correct statement about these results?

Tick (✓) one box.

Look at the results for 20 °C.

Calculate the increase in area covered by mould between day 5 and day 10.

The diagram shows the water cycle.

Complete the diagram.

Use the words from the list.

Collection Condensation Evaporation Precipitation Respiration

Explain why transpiration is important to the plant communities in an ecosystem.

Which process in the water cycle returns water to the land from the atmosphere?

A Condensation

B Evaporation

C Precipitation

D Transpiration

The diagram shows some of the levels of organisation within the ecosystem.

Complete the diagram using words in the list.

Explain why the carbon cycle is important to plants.

Materials are cycled in the environment.

Complete these sentences about cycled materials.

Choose words from this list. You can use each word once, more than once or not at all.

decomposition condensation nutrition

photosynthesis translocation transpiration

Plants remove carbon from the atmosphere by the process of........

Plants return water to the atmosphere by the process of........

Nitrogen is returned to the soil by the process of........

Describe two ways that the water cycle is important to humans.

Abiotic and biotic factors can affect ecosystems.

Which two are biotic factors?

Tick (✓) two boxes.

The diagram shows a weather chart over 3 days.

The 24-hour rainfall for Sunday April 3 is ~1 mm.

Explain what is meant by the term ~1 mm.

Plants are an important part of ecosystems.

Which day would plants be most likely to take up water from the soil at the fastest rate?

Tick (✓) one box.

Explain your answer.

The flowchart in Fig. 12.1 shows bacteria involved in cycling nitrogen.

Identify which of the bacteria in Fig. 12.1, if present in large amounts, would make the soil poor for plant growth.

Tick (✓) one box.

Explain why large amounts of these bacteria would make the soil poor for plant growth.

Abiotic and biotic factors can affect the bacterial communities.

Which is a biotic factor?

Tick (✓) one box.

Plants are an important part of any community.

Fig. 12.2 shows the effect of abiotic factors on the rate of photosynthesis by plants.

Explain why lines X, Y and Z level out at different rates of photosynthesis.

Carbon is recycled in the ecosystem.

Which process helps reduce the level of carbon in the atmosphere?

A Photosynthesis

B Respiration

C Translocation

D Transpiration

Water is cycled in nature.

Name one abiotic factor that affects water uptake by a plant.

Look at the diagram of the carbon cycle.

Which process is shown by arrow X in the diagram above?

Tick (✓) one box.

Which process releases carbon when organisms die ?

Tick (✓) one box.

The graph shows how carbon dioxide levels in the atmosphere have changed during the last 160 000 years.

Read this statement:

Carbon dioxide levels in the atmosphere are rising out of control.

What evidence is there in the graph for and against this statement?

Look at the section of the graph for the last 20 000 years.

What conclusions can be made about the release of carbon dioxide into the atmosphere and also its removal from the atmosphere during the last 20 000 years?

Describe how human activity has contributed to the trends in the graph and suggest how this activity could affect biodiversity.

The information in the box is part of a scientific journal report.

Growing crops with shiny leaves could cause an annual global cooling of over 0.1 °C.

This is almost 20% of the total global temperature increase since the Industrial Revolution.

Most crop plants have non-shiny leaves.

A few varieties of crop plants do have shiny leaves but they do not all produce high yields.

Explain how scientists could use selective breeding to help reduce global temperatures.

Look at the diagram of part of the nitrogen cycle.

What is happening at X?

Water is cycled in nature.

Name one abiotic factor that affects water uptake by a plant.

Look at the diagram of the carbon cycle.

Which process is shown by arrow X in the diagram?

Tick (✓) one box.

Which process releases carbon when organisms die ?

Tick (✓) one box.

The graph shows how carbon dioxide levels in the atmosphere have changed during the last 160 000 years.

Read this statement:

Carbon dioxide levels in the atmosphere are rising out of control.

What evidence is there in the graph for and against this statement?

Look at the section of the graph for the last 20 000 years.

What conclusion can be made about the release of carbon dioxide into the atmosphere and also its removal from the atmosphere during the last 20 000 years?

Describe how human activity has contributed to the trends in the graph and suggest how this activity could affect biodiversity.

The information in the box is part of a scientific journal report.

Growing crops with shiny leaves could cause an annual global cooling of over 0.1 °C.

This is almost 20% of the total global temperature increase since the Industrial Revolution.

Most crop plants have non-shiny leaves.

A few varieties of crop plants do have shiny leaves but they do not all produce high yields.

Explain how scientists could use selective breeding to help reduce global temperatures.

Look at the diagram of the carbon cycle.

Which process is shown by the arrow labelled X ?

A Decomposition

B Evaporation

C Photosynthesis

D Respiration

Some countries plant new forests to help reduce their greenhouse gas emissions.

Why does planting new forests help reduce greenhouse gas emissions?

A Trees produce biomass.

B Trees take carbon dioxide from the air.

C Trees put oxygen into the air.

D Trees take water from the soil to prevent flooding.

Look at the diagram of the water cycle.

Complete these sentences about the diagram.

Choose words from the list.

combustion evaporation photosynthesis precipitation

run-off respiration transpiration

Arrows labelled A represent the process of........

Arrows labelled B represent the process of........

Arrows labelled C represent the process of........

How many predators does the shrimp have in this food web?

When plant material is decomposed by fungi, there is an increase in temperature.

Complete the sentences to explain why.

Choose words from the list.

endothermic excretion exothermic

respiration photosynthesis

During decomposition fungi release energy from the plants by the process of

........

This process releases energy as heat because the reaction is

........

Dogfish and minnows are fish that live in lakes.

Dogfish build nests to lay their eggs in. Minnows lay their eggs in the same nests as dogfish.

The dogfish protect the nest from predators.

Minnows move in and out of the nest. This helps to remove harmful bacteria and get oxygen to the eggs.

Dogfish usually eat minnows. When the dogfish have eggs they do not eat minnows.

Dogfish have two different interactions with the minnows.

Write down the names of these two types of interactions.

Describe when each interaction takes place.

One of the interactions benefits both minnows and dogfish.

Explain how.

Countries can compensate for their greenhouse gas emissions by planting new trees.

Why does planting new trees help compensate for their greenhouse gas emissions?

A Produces biomass

B Removes carbon dioxide from the air

C Releases oxygen into the air

D Water absorbed from the soil prevents flooding