3.21 Carbon and Water Cycles

Question 1

What is the whole carbon cycle powered by?

Answer 1

Photosynthesis

Question 2

What do green plants use the carbon from carbon dioxide to make?

Answer 2

Carbohydrates, lipids and proteins.

Question 3

What does eating do to the carbon cycle?

Answer 3

Eating passes the carbon compounds in plants along to animals in a food chain or web

Question 4

What process do plants and animals do that releases carbon dioxide back into the atmosphere?

Answer 4

Respiration

Question 5

What happens once plants and animals die in the carbon cycle?

Answer 5

They decompose and turn into useful products. When plants and animals decompose they’re broken down by microorganisms, such as bacteria and fungi. These microorganisms are known as decomposers and they release enzymes, which catalyse the breakdown of dead materials into smaller molecules. Decomposers release carbon dioxide back into the air by respiration as they break down the material.

Question 6

How is carbon dioxide released back into the air? (3)

Answer 6

• Both plant and animal respiration while organisms are alive releases carbon dioxide back into the air.
• When plants and animals decompose they’re broken down by microorganisms, such as bacteria and fungi. These decomposers release carbon dioxide back into the air by respiration as they break down the material.
• Some useful plant and animal products, e.g. wood and fossil fuels, are burned (combustion). This also releases carbon dioxide.

Question 7

What is the first point of the water cycle?

Answer 7

Energy from the Sun makes water evaporate from the land and sea, turning it into water vapour. Water also evaporates from plants (transpiration).

Question 8

What happens after evaporation?

Answer 8

The warm water vapour is carried upwards (as warm air rises). When it gets higher up it cools and condenses to form clouds.

Question 9

What happens after condensation?

Answer 9

Water falls from the clouds as precipitation (usually rain, but sometimes snow or hail) onto land.

Question 10

What happens after precipitation? (2)

Answer 10

• Some of this water is absorbed by the soil and is taken up by plant roots. This provides plants with fresh water for things like photosynthesis. Some of the water taken up by plants becomes part of the plant’s tissues and’’ is passed along to animals in food chains.
• Water that doesn’t get absorbed by the soil will runoff into streams and rivers.

Question 11

What happens after the water is passed along to animals in food chains?

Answer 11

Like plants, animals need water for the chemical reactions that happen in their bodies. Animals return water to the soil and atmosphere through excretion (processes that get rid of the waste products of chemical reactions, e.g. sweating, urinating, breathing out).

Question 12

What happens after there is water runoff in the water cycle?

Answer 12

The water drains back into the sea, before it evaporates all over again.

Question 13

What 5 stores is carbon split between?

Answer 13

• The atmosphere
• Plants, where its locked up in biological molecules
• In the soil, which contains lots of bacteria
• In fossil fuels, which are underground
• In animals, where its locked up in biological molecules

Question 14

What happens to water during condensation?

Answer 14

Water vapour turns into liquid water

Question 15

Which three processes in the carbon cycle releases carbon dioxide into the atmosphere?

Answer 15

• Decomposition
• Combustion
• Respiration

Question 16

Which carbon-containing compound do plants produce during photosynthesis?

Answer 16

Glucose

Question 17

Which organisms decompose dead organic matter?

Answer 17

Bacteria and Fungi