Biology - The carbon cycle

Question 1

As living things grow, they take in elements, including what two things?

Answer 1

Carbon and nitrogen - to use in their bodies

Question 2

What is the carbon cycle?

Answer 2

The process of carbon moving between the living and non-living world

Question 3

Carbon is present in the atmosphere as what?

Answer 3

Carbon dioxide

Question 4

Carbon dioxide is absorbed by plants and built into what?

Answer 4

Carbohydrate molecules such as sugars (happens during photosynthesis)

Question 5

The plants uses some of these sugars to make other molecules such a s what? (3 things)

Answer 5

Cellulose, fats, proteins - uses to grow

Question 6

What happens after the plant uses some of the sugars to grow?

Answer 6

Animals eat the plants and carbon compounds are passed into them and become part of their bodies

Question 7

What does respiring do?

Answer 7

Returns some carbon dioxide back to the atmosphere

Question 8

What happens when plants and animals die?

Answer 8

Soil bacteria and fungi known as decomposers digest their bodies (decay)
and carbon dioxide is released back into the atmosphere through respiration

Question 9

Not all plant and animal bodies decay. What happens to them? What does this form?

Answer 9

Some are buried under layers of silt and over millions of years begin to fossilise. This forms fossil fuels such as coal, oil and gas

Question 10

Humans extract fossil fuels and do what with them?

Answer 10

Burn them to release energy

Question 11

Burning fossil fuels releases what?

Answer 11

The carbon that was stored millions of years ago as carbon dioxide

Question 12

In a stable environment the amount of carbon dioxide released should what?

Answer 12

Approximately equal the amount absorbed

Question 13

What two main groups of microbes are involved in the decay of dead plants, animals, and animal waste?

Answer 13

Bacteria and fungi

Question 14

Decay happens more in what season?

Answer 14

Autumn

Question 15

What are the 5 right conditions microbes need to survive and respire?

Answer 15

Food, oxygen, a suitable temperature, moisture, suitable pH

Question 16

Explain the term ‘carbon sinks’

Answer 16

In oceans there are invertebrate animals with shells to protect bodies. Shells made of calcium carbonate. Animals gain carbon from digesting plants into shells. When dead, shells are difficult to decay, and sink to bottom of ocean. Fragments compressed to form rocks (limestone + chalk). Because they store carbon in this way, oceans are called carbon sinks

Question 17

How is the carbon eventually released back into the atmosphere from carbon sinks?

Answer 17

Some of the limestone rocks become exposed above the sea level. The rocks are then eroded by weathering, and the carbon is released as carbon dioxide into the air.