Carbon cycle

Describe what would happen to the carbon dioxide level in the atmosphere if there was an area of deforestation. Explain why would this effect occur?

• Carbon dioxide level will increase as there are less trees and plants removing carbon dioxide from the atmosphere via photosynthesis
• Carbon dioxide level will decrease as there are more trees and plants removing carbon dioxide from the atmosphere via photosynthesis

Describe the role the sea has in the carbon cycle?

• The sea acts as a carbon sink, absorbing carbon dioxide from the atmosphere lowering the concentration.
• The sea has no role in the carbon cycle.
• The sea acts as a carbon sink, absorbing carbon dioxide from the atmosphere increasing the concentration.

Name the processes that release carbon dioxide.

• Combustion, respiration and decomposition
• Combustion, respiration and photosynthesis
• Respiration, fossilisation and combustion

Name two places (or processes) that remove carbon dioxide from the atmosphere.

• Photosynthesis

• Dissolution into the sea

• Combustion

• Respiration

Food for decomposers is dead plant and animals. Name an organism that is a decomposer

• Maggots
• Birds
• Foxes

Decomposers cause dead plants and animals to decay and release trapped carbon into the soil. This is then free to be taken up by plants.

• true
• false

Combustion of fossil fuels releases carbon dioxide into the atmosphere. Complete the equation:

Hydrocarbon + Oxygen -->

• carbon dioxide + water

• carbon dioxide + hydrogen

• water + calcium carbonate

Name two methods of testing for the presence of carbon dioxide and explain what would be seen if carbon dioxide is present.

• Limewater – turns cloudy

• Bicarbonate indicator – yellow if above, orange if equal, and purple if below atmospheric carbon dioxide level

• Starch - turns blue/black

• Benedict's reagent - turns red if lots present, orange if medium present, turns green if a little present and stays blue if none is present

Sulphur dioxide is another waste gas produced during combustion.

• true
• false

Describe the effect that sulphur dioxide gas has on the environment.

• Acid rain

• No effect

• Global warming