AS Biogeochemical Cycles

Question 1

Anthropogenic

Answer 1

Adjective describing outcomes caused by human activities.

Question 2

Biogeochemical cycle

Answer 2

A series of linked processes which use and re-use elements such as carbon, nitrogen, phosphorus, iron and sulfur, as they move between biotic and abiotic reservoirs.

Question 3

Decomposers

Answer 3

Organisms that break down dead organic matter, releasing nutrients in the process. Many bacteria and fungi are decomposers. They secrete enzymes onto the dead organic matter and absorb the products of digestion.

Question 4

Detritivores

Answer 4

These are heterotrophic animals that ingest and digest dead organic matter. Examples include: earthworms, millipedes, woodlice, dung beetles and slugs. They often break up the dead organic matter into smaller pieces, providing access to decomposers.

Question 5

Dynamic equilibrium

Answer 5

A balance created by active processes whose impacts cancel each other out.

Question 6

Haber Process

Answer 6

The industrial process that combines nitrogen from air with hydrogen from natural gas to produce ammonia.

Question 7

Homeostasis

Answer 7

The maintenance of a state of equilibrium.

Question 8

How humans impact the carbon cycle

Answer 8

deforestation, afforestation, combustion of fossil fuels, ploughing soils, use of landfill sites, cattle ranching, growing rice

Question 9

How humans impact the nitrogen cycle

Answer 9

Haber process (manufacture of ammonia), use of artificial fertilisers, planting legumes, draining fields

Question 10

How humans impact the phosphorus cycle

Answer 10

Use of artificial fertiliser, mining of phosphate rocks

Question 11

Legumes

Answer 11

Plants with symbiotic nitrogen fixing bacteria in root nodules eg peas and beans.

Question 12

Sustainable management of the carbon cycle

Answer 12

conservation of carbon stores, use fossil fuel alternatives, carbon sequestration, CCS

Question 13

Sustainable management of the nitrogen cycle

Answer 13

reduction of internal combustion engine vehicles, catalytic converters, reduce run off of organic waste, decreased use of artificial fertiliser, use of organic fertiliser, increased use of legumes

Question 14

Sustainable management of the phosphorus cycle

Answer 14

Increase the use of biological and organic waste to land, leave more crop biomass in the soil

Question 15

Why is phosphorus often a limiting factor in plant growth and agriculture?

Answer 15

Phosphorus compounds have low solubility and there is no gaseous reservoir of phosphorus.

Question 16

Photosynthesis

Answer 16

a process in the carbon cycle that moves carbon as CO2 from the atmosphere into carbohydrates in eutrophic organisms

Question 17

Respiration

Answer 17

process in the carbon cycle which moves carbon in carbohydrates in living organisms into the atmosphere in the form of CO2

Question 18

Fossilisation

Answer 18

a process in the carbon cycle which transfers carbon on the remains of living organisms into carbonate rocks

Question 19

Combustion

Answer 19

a process in the carbon cycle which transfers carbon in the form of hydrocarbons in fossil fuels and biofuels into the atmosphere as CO2

Question 20

Food chain transfer

Answer 20

a process in the carbon cycle which transfers carbohydrates up trophic levels in a food chain

Question 21

Reservoirs of Carbon

Answer 21

Atmosphere (CO2, CH4), Oceans (dissolved CO2), Living things and DOM (carbohydrates), The Lithosphere (fossil fuels, carbonate rocks and fossils)

Question 22

Reservoirs of Nitrogen

Answer 22

Atmosphere (N2 and NOx), Oceans and freshwater (dissolved nitrates and ammonium ions), Living things and DOM ( Proteins, DNA), The Lithosphere (rocks and soil)

Question 23

Reservoirs of Phosphorus

Answer 23

Living things and DOM (DNA, RNA, proteins, ATP, bones), The Lithosphere (phosphate rocks), Marine sediments (from sinking DOM and weathered rocks)

Question 24

Ionisation

Answer 24

the process in the nitrogen cycle where lighting provides the energy to convert N2 to nitrates

Question 25

Nitrogen Fixation

Answer 25

the process in the nitrogen cycle where nitrogen fixing bacteria, living on the roots of legumes, convert N2 in the atmosphere into ammonia

Question 26

Nitrification

Answer 26

the process in the nitrogen cycle where nitrifying bacteria living in the soil convert ammonia into nitrites and nitrates. These bacteria are aerobic.

Question 27

Denitrification

Answer 27

the process in the nitrogen cycle where denitrifying bacteria living in the soil convert nitrates back into atmospheric nitrogen. These bacteria are anaerobic.

Question 28

Root absorption

Answer 28

a process in the both the nitrogen and phosphorus where nitrates, ammonium ions and phosphates in solution are taken up by the roots of plants

Question 29

Ammonification

Answer 29

the process in the nitrogen cycle where nitrogen compounds in living things are broken down into ammonia as they decompose

Question 30

Mountain building and weathering

Answer 30

a process in the phosphorus cycle where phosphorus can be moved from the deep ocean to exposed land and then broken down by weathering