B7 The Carbon Cycle (page 90)

Question 1

What happens to all the nutrients in our environment?

Answer 1

they are constently being recycled - there’s a nice balance between what goes in and what goes out again.

Question 2

How are Elements cycled back to the start of the food chain?

Answer 2

by Decay.

Question 3

Living things are made of what?

Answer 3

they are made of materials they take from the world around them.

Question 4

Plants turn elements like carbon, oxygen, hydrogen and nitrogen from the soil and the air into what?

Answer 4

into the complex compounds (carbohydrates, proteins and fats) that make up living organisms.

These get passed up the food chain.

Question 5

How are these complex compounds materials returned to the environment?

Answer 5

in waste products, or when the organisms die and decay.

Question 6

How do Materials decay?

Answer 6

they’re broken down (digested) by microorganisms.

This happens faster in warm, moist, aerobic (oxygen rich) conditions because microorganisms are more active in these conditions.

Question 7

when the materials decay, how do this help plants?

Answer 7

decay puts the stuff that plants need to grow (e.g. mineral ions) back into the soil.

Question 8

In a stable community, what happens to the materials that are taken out of the soil and used by plants etc?

Answer 8

they are balanced by those that are put back in. There’s a constant cycle happening.

Question 9

What is the constant cycling of carbon called?

Answer 9

The Carbon Cycle.

See picture of the carbon cycle on page 90.

Question 10

How is CO2 removed from the atmosphere?

Answer 10

by green plants and algae during photosynthesis.

Question 11

What is the carbon used to make?

Answer 11

glucose, which can be turned into carbohydrates, fats and progeiins that make up the bodies of the plants and algae.

Question 12

When the plants and algae respire, what happens to the carbon?

Answer 12

some carbon is returned to the atmosphere as CO2

Question 13

When the plants and algae are eaten by animals, what happens with some of the carbon?

Answer 13

some carbon becomes part of the fats and proteins in their bodies. The carbon then moves through the food chain.

Question 14

When the animals respire, what happens to some carbon?

Answer 14

some carbon is returned to the atmosphere as CO2

Question 15

When plants, algae and animals die, what happens next?

Answer 15

other animals (called detritus feeders) and microorganisms feed on their remains. When these organisms respire, CO2 is returned to the atmosphere.

Question 16

Animals also produce waste, how is this broken down?

Answer 16

it is broken down by detritus feeders and microorganisms.

Question 17

The combustion (burning) of wood and fossil fuels also releases what?

Answer 17

CO2 back into the air.

Question 18

Carbon (and energy) is constantly being cycled from where?

Answer 18

constantly being cycled from the air, through food chains (via plants, algae and animals, and detritus feeders and microorganisms) and eventually back out into the air again)

Question 19

Carbon is very important for living things why?

Answer 19

it’s the basis for all the organic molecules in our bodies.

Question 20

What causes materials to decay? (1 mark)

Answer 20

Microorganisms/detritus feeders break them down/digest them (1 mark)

Question 21

Describe how carbon is removed from the atmosphere in the carbon cycle? (1 mark)

Answer 21

By green plants and algae in photosynthesis