Year 8 Science · Unit 1 · Lesson 23

Matter and Energy Cycling, Carbon, Water and Nutrients

Foundation Worksheet

Name

Date

Class

Learning Goals

Use key vocabulary to describe the carbon cycle and nitrogen cycle processes.
Match cycling processes (photosynthesis, respiration, decomposition, nitrification, etc.) to their correct descriptions.
Explain the role of bacteria in the nitrogen cycle.

Warm Up

Fill the gap

Choose the correct word from the word bank to complete each sentence. Not all words will be used, two are distractors.

carbon photosynthesis respiration decomposition nitrogen nitrification phosphorus evaporation combustion

Plants remove CO₂ from the atmosphere through the process of , which converts carbon dioxide and water into glucose and oxygen. Animals release CO₂ back into the atmosphere through cellular , which converts glucose into energy. When organisms die, fungi and bacteria break down their bodies through , releasing back into the atmosphere and returning nutrients to the soil.

The element makes up 78% of the air but cannot be used directly by plants. Specialised bacteria in the soil convert it into ammonium through nitrogen fixation; other bacteria then convert ammonium into nitrates through the process of , which plants can absorb through their roots. Unlike the carbon and nitrogen cycles, the cycle has no atmospheric phase, it moves only between rock, soil, living things and water.

Your Turn

Match each term to its definition

Draw a line connecting each process on the left to its correct description on the right. Or write the matching letter next to each term.

Process	Your answer	Description
Photosynthesis		A. The breakdown of dead organic matter by bacteria and fungi, releasing nutrients and CO₂.
Respiration		B. Bacteria in soil converting atmospheric nitrogen (N₂) into ammonium that plants can use.
Decomposition		C. The burning of fossil fuels, releasing stored carbon as CO₂ into the atmosphere.
Nitrogen fixation		D. Plants using sunlight to convert CO₂ and water into glucose, removing carbon from the atmosphere.
Combustion		E. Bacteria converting ammonium into nitrates that plants absorb through their roots.
Nitrification		F. The cellular process in living things that releases energy from glucose, producing CO₂ and water as waste.

Show What You Know

1. The phosphorus cycle is described as having "no atmospheric phase." What does this mean, and how does phosphorus get from rocks into plants?

Recall 2 marks

2. A student says: "When a leaf falls off a tree and rots, the carbon in it disappears forever." Is this correct? Use what you know about the carbon cycle to explain your answer.

Recall 2 marks

Wrap Up

In one sentence, what was the main idea of this lesson?