Carbon cycle

Question 1

Purpose of the carbon cycle?

Answer 1

Show how carbon moves from the atmosphere, through various animals and plants, then back into the atmosphere again.

Question 2

The 6 processes in the carbon cycle

Answer 2

1. Photosynthesis
2. Respiration
3. Feeding
4. Decomposition
5. Combustion
6. Fossilisation

Question 3

Explain the process of photosynthesis

Answer 3

• Captures energy from the sun
• Removes carbon dioxide from the atmosphere
• Incorporates CO2 into plant material in the form of glucose

Question 4

What is glucose converted into

Answer 4

Glucose is converted into complex organic molecules such as:

• Carbohydrates
• Fats
• Proteins

Question 5

Describe how does carbon circulate in through the food chain

Answer 5

• The carbon containing molecules are passed to consumers who feed on the plants
• This is done through food chains/ food webs
• It circulates the carbon to all living organisms

Question 6

Describe the process of respiration in plants

Answer 6

• Glucose is broken down
• Energy released is used to form ATP ( molecule for storing and transferring energy in cells)
• The ATP is used to carry out diff. activities by the organism within the cell
• Thus, CO2 gas is the waste product and is given off into the atmosphere

Question 7

What is the result of respiration?

Answer 7

The complex organic molecules containing carbon are broken down into small CO2 molecules, which is released into the atmosphere.

Question 8

Simplified definition of decomposition

Answer 8

When organisms die, they begin to break down and decompose

Question 9

Who carries out decomposition and give examples?

Answer 9

Microorganisms:

• Bacteria
• Fungi

Question 10

Describe the process of decomposition

Answer 10

• The microorganisms break down the large complex biological molecules
• It then release smaller molecules into the surroundings
• Some molecules are used by the microorganisms as nutrients that are broken down during respiration

Question 11

What is the result of decomposition

Answer 11

Carbon from the complex molecules that contain carbon would be released as CO2 back into the atmosphere

Question 12

Equation for decomposition

Answer 12

A –> B + C + D […]

Question 13

What is combustion?

Answer 13

When wood, fossil fuels such as coal/ oil and natural gas are burned

Question 14

How are fossil fuels formed

Answer 14

• Formed from the remains of living organisms from millions of years ago
• Carbon in fossil fuels have been locked away, deep underground and was unavailable for release into the atmosphere.

Question 15

Describe the process of combustion

Answer 15

• Ppl burn fossil fuels [coal/ oil in power plants, motorised vehicles such as cars/ planes/ trucks] or burn rubbish in incinerators
• Most of the carbon quickly enters the atmosphere as CO2 gas

Question 16

The simplified definition of feeding

Answer 16

Moves carbon in the form of biological molecules along the food chain

Question 17

Describe the process of fossilisation

Answer 17

• If condition are not favourable for the process of decomposition, dead organisms decay slowly/ not at all
• These organisms build up and, if compressed over millions of years, can form fossil fuels (coal, oil, natural gas)

Question 18

Explain how a carbon atom in fossil fuel can end up in the cell of a plant.

Answer 18

a. Carbon in fossil fuel released as CO2 through combustion
b. When plant PHS, absorb the carbon
c. CO2 converted into glucose