Nutrient Cycles (pg 213-219)

Question 1

6 steps in carbon cycle

Answer 1

1. living organism respire and produce CO2 as waste product of respiration, released into atmosphere
2. CO2 trapped plants during photosynthesis, converted into organic compounds (starch, glucose)
3. stored living organisms as organic compounds such as proteins and fats
4. animals get carbon by eating plants/other animals, decomposers obtain carbon from dead remains of other living organisms
5. carbon stored in fossil fuels (coal, oil, natural gas), fuel wood also contain carbon
6. burn fuels, carbon returned to atmosphere as carbon dioxide

Question 2

global warming

Answer 2

rise in the average temperature on Earth

Question 3

main reason increased levels of carbon in the atmosphere

Answer 3

peoples need for energy and as a result burning of fossil fuels

Question 4

4 ways humans effect carbon dioxide levels

Answer 4

-power stations burn coal for electrical energy
-burn substances (petrol) in cars/buses for transport
-factories provide work many release CO2
-people without electricity burn wood, coal, gas give them heat and light

Question 5

steps in oxygen cycle

Answer 5

1. during respiration, oxygen gas taken in living organisms and carbon dioxide given off into atmosphere
2. plants use CO2 for food making process, photosynthesis
3. plants form oxygen by-product photosynthesis. oxygen released into atmosphere, used respiration other organisms

Question 6

nitrates

Answer 6

form of nitrogen that can be used by plants to make proteins

Question 7

ammonia

Answer 7

gas containing nitrogen that is converted into nitrites and nitrates by bacteria in the nitrogen cycle

Question 8

nitrites

Answer 8

from of nitrogen that is converted into nitrates by bacteria in the nitrogen cycle

Question 9

why do organisms need nitrogen

Answer 9

build proteins in their bodies

Question 10

how is nitrogen passed through ecosystems

Answer 10

through food webs

Question 11

how to plants get nitrogen

Answer 11

soil

Question 12

3 ways nitrogen gas converted to nitrates

Answer 12

1. industrial process: expensive, artificial fertilisers made hence the expense
2. lightning: provide enough energy small amounts nitrogen become nitrates not enough all living organisms
3. fixation by legumes: most efficient way change nitrogen gas into usable form of nitrates by action of bacteria live in swellings called nodules in roots of legume plants

Question 13

8 steps nitrogen cycle

Answer 13

1. nitrogen-fixing bacteria in root nodules of legumes changes nitrogen gas into nitrates (or lightning)
2. nitrates dissolve water in soil and plants absorb nitrates through roots, plants use nitrates make proteins
3. plant proteins eaten by consumers form animal proteins
4. consumers release nitrogen from bodies in form waste products mainly urine and faeces contain high amounts of nitrogen compounds. in nature waste products returned soil
5. decomposers obtain nitrogen from bodies of decaying organisms and from breakdown of urine and faeces, process decomposition forms ammonia
6. ammonia changed nitrites by nitrite bacteria in soil
7. nitrate bacteria change nitrites into nitrates and return soil
8. nitrogen released back into atmosphere through action of bacteria called denitrifying bacteria, break down nitrates form nitrogen gases, fires also release nitrogen gas back into atmosphere

Question 14

eutrophication

Answer 14

excess algal growth owing to an abundant supply of plant nutrients which causes problems for other organisms in the system

Question 15

how does farming effect nitrogen cycle

Answer 15

crop plants absorb nitrates from soil when plants harvested nitrogen not returned soil by decomposition, little nitrogen left, farmers add artificial fertilisers soil

Question 16

how are wetlands being effected by nitrogen cycle

Answer 16

nitrates from fertilisers washed off land into rivers and dams causes algae grow fast forms layer across surface blcoking out light then eutrophication

Question 17

glaciers

Answer 17

large mass of ice never melts and moves very slowly down mountainsides

Question 18

leaching

Answer 18

movement of dissolved mineral salts

Question 19

how does global warming effect water cycle

Answer 19

evaporation and precipitation rates increased leading to floods
glacial retreat supply water to glaciers from precipitation cant keep up water loss melting

Question 20

how does deforestation effect water cycle

Answer 20

less trees release water vapour results less rain when rain occurs water run-off or leaching instead soaked up

Question 21

how does the building of dams effect water cycle

Answer 21

stops natural flow of water, flows into damn brings silt which builds up and reduces amount water dam can store leads increase evaporation
result droughts downstream leaving areas no water supply

Question 22

salination

Answer 22

build up of salts in the soil

Question 23

how does agriculture effect water cycle

Answer 23

irrigation removes water natural source causes leaching , fertilisers pollute water

Question 24

irrigation

Answer 24

artifical watering of land that does not get enough water through rainfall