4.3 The Carbon Cycle

Question 1

What do autotrophs do?

Answer 1

Convert carbon dioxide into carbohydrates and other carbon compounds.

Question 2

How is carbon present in aquatic ecosystems

Answer 2

dissolved carbon dioxide and hydrogen carbonate ions.

Question 3

Where does CO2 enter a leaf?

Answer 3

Stomatal Pores

Question 4

What is Carbon Dioxide a waste product of?

Answer 4

Cell respiration

Question 5

outline the habitat of methanogens

Answer 5

anaerobic environments like swamps or marshes. in the digestive tracts of cattle

Question 6

Name the processes that release carbon into the air

Answer 6

respiration, and combustion

Question 7

in what form is carbon released in respiration and combustion

Answer 7

Carbon dioxide (Co2)

Question 8

name four geological resovoirs (sinks), that can act as a source of carbon

Answer 8

atmosphere, coal, oil, limestone, natural gas

Question 9

what would be the effect on carbon cycling if there were no decomposers present in an ecosystem?

Answer 9

Carbon would eventually be locked up in the remains of dead organisms. Dead matter would not rot. Possible gradual loss of CO2 from the atmosphere

Question 10

describe the biological origin of coal

Answer 10

plant material trapped under sediment in swampy conditions millions of years ago

Question 11

describe the biological origin of oil

Answer 11

marine plankton rapidly buried in sediment mya.

Question 12

describe the biological origin of limestone

Answer 12

shells of molluscs and other marine organisms with skeletons of calcium carbonate (CACO2) compressed on seabed

Question 13

explain the role of a dung beetle in the carbon cycle

Answer 13

Bury cow manure and the larvae feed on it. burying the dung makes it available to decomposers as food. Therefore it re-enters the trophic system

Question 14

explain the role of termites in the carbon cycle

Answer 14

they digest the cellulose in plant material, breaking it down and freeing up the carbon so it can be returned to the usable carbon pool

Question 15

explain the role of fungi in the carbon cycle

Answer 15

breaks down dead material utilizing it as food and converting it into the fungal body. this makes it available to re-enter the food chain

Question 16

how do you think fire might contribute to nutrient cycling

Answer 16

fire causes the release of nutrients from the ash of the burnt material. the nutrients released are available for renewed plant growth and the regeneration and reproduction of many fire adapted species

Question 17

what is the effect of human activity on the amount of carbon stored in sinks?

Answer 17

humans deplete fossil fuel reserves through mining

Question 18

what is a sink?

Answer 18

something that absorbs more carbon from the atmosphere than it releases e.g. plants, the ocean, and soil