4c cycles within ecosystems

Question 1

what are some elements that animals need to survive? what do they get to everything in the ecosystem?

Answer 1

carbon and nitrogen
they are recycled through the biotic and abiotic components of an ecosystem.

Question 2

what is carbon important to organisms?

Answer 2

it is a major component of all biological molecules. e.g., carbs, lipids, protein, DNA, and vitamins all contain carbon

Question 3

name the processes that are important in cycling carbon through ecosystems

Answer 3

• photosynthesis ‘fixes’ carbon atoms from CO2 into organic compounds
• feeding and assimilation pass carbon atoms already in organic compounds along food chains
• respiration produces inorganic CO2 from organic compounds (mainly carbs) as they are broken down to release energy
• fossilisation - sometimes living things don’t decay fully when they die due to soil conditions (decay is prevented if it is too acidic) and fossil fuels (coal, oil, natural gases, peat) are formed
• combustion releases co2 into the atmosphere when fossil fuels are burned

Question 4

how does photosynthesis relate to the carbon cycle

Answer 4

-photosynthesis ‘fixes’ carbon atoms from CO2 into organic compounds

Question 5

how does feeding relate to the carbon cycle

Answer 5

feeding and assimilation pass carbon atoms already in organic compounds along food chains

Question 6

how does respiration relate to the carbon cycle

Answer 6

respiration produces inorganic CO2 from organic compounds (mainly carbs) as they are broken down to release energy

Question 7

how does fossilisation relate to the carbon cycle

Answer 7

fossilisation - sometimes living things don’t decay fully when they die due to soil conditions (decay is prevented if it is too acidic) and fossil fuels (coal, oil, natural gases, peat) are formed

Question 8

how does combustion relate to the carbon cycle

Answer 8

combustion releases co2 into the atmosphere when fossil fuels are burned

Question 9

why is carbon recycled constantly? CC

Answer 9

because there is only a fixed amount of carbon in the world

Question 10

what happens when fossil fuels (decayed plant and fecal matter) are burned? CC

Answer 10

co2 released into air

Question 11

what happens when products are made from products from plants and animals? how are they made? what happens to them afterwards? CC

Answer 11

they are made from animals and animals which contain carbon compounds.
they are then burned and so CO2 is released into the atmosphere

Question 12

how do we get carbon compounds in plants? what happens to them afterward? CC

Answer 12

the carbon compounds in plants come from photosynthesis (from the air (CO2)) and it is then eaten by animals (so they now have carbon compounds), plant respiration (releasing CO2 back into the air), and making products like clothes

Question 13

what happens when plants die? CC

Answer 13

they decay and CO2 is released. this is because decomposers, e.g., bacteria and fungi, break down the microorganism. These decomposers release enzymes, which catalyses the breakdown of dead material into smaller molecules. Decomposers release CO2 back into the air by respiration as they break down the material

Question 14

what does respiration do? CC

Answer 14

release CO2 back into the atmosphere (plants and animals)

Question 15

draw out the carbon cycle

Answer 15

compare with p.75 in cgp or pg. 198 in textbook

Question 16

where is nitrogen used?

Answer 16

in many biological compounds e.g., proteins, amino acids, most vitamins, DNA, and ATP.

Question 17

which processes are involved in the nitrogen cycle?

Answer 17

• feeding and assimilation pass nitrogen atoms already in organic compounds along food chains
• decomposition by fungi and bacteria produces ammonia from the nitrogen in compounds like proteins, DNA, and vitamins
• the ammonia is oxidised first to nitrite and then to nitrate by nitrifying bacteria. This overall process is called nitrification.
• plant roots can also absorb nitrates. they are combined with carbs to form amino acids and then proteins, as well as other nitrogen-containing compounds

Question 18

what does denitrifying bacteria use nitrates for?

Answer 18

they use it as an energy source to convert the nitrates into nitrogen gas

Question 19

what does denitrification do?

Answer 19

reduce the amount of nitrate in the soil

Question 20

what do free living nitrogen-fixing bacteria in soil do?

Answer 20

the convert nitrogen gas into ammonia. this is then used by bacteria to make amino acids and proteins.

Question 21

what happens when bacteria die? what do they do?

Answer 21

they use ammonia, made by free-living nitrogen-fixing bacteria, to make amino acids and proteins.
when they die, their proteins decompose, releasing ammonia back into the soil

Question 22

what does nitrogen fixing bacteria in root nodules do?

Answer 22

make ammonia but this is converted by the plant into amino acids and other organic nitrogen compounds. Deat and decomposition of the plant returns the nitrogen to the soil as ammonia

Question 23

what is the symbol for a nitrate?

Answer 23

NO3-

Question 24

what is the symbol for nitrogen?

Answer 24

N2

Question 25

what is the symbol for a nitrite?

Answer 25

NO2-

Question 26

what is the symbol for ammonia?

Answer 26

NH3

Question 27

what is detritus?

Answer 27

dead matter

Question 28

is nitrogen reactive?

Answer 28

no it is very unreactive

Question 29

what is nitrogen fixation?

Answer 29

the process of turning N2 from the air into nitrogen compounds in the soil which plants can use

Question 30

what are the 2 main ways in which nitrogen-fixing takes place?

Answer 30

• lightning - there is so much energy in one bolt of lightening that it is enough to make nitrogen react with oxygen in the air to give nitrates
• nitrogen-fixing bacteria in soil and the roots of some plants

Question 31

what are the four main types of bacteria involved in the nitrogen cycle? what do each do?

Answer 31

decomposers - break down proteins (in rotting plants and animals) and urea (in animal waster) and turn them into ammonia (a nitrogen compound). this forms ammonium ions in the soil
nitrifying bacteria - turn ammonium ions in decaying matter into nitrates (nitrification)
nitrogen-fixing bacteria - turn atmospheric N2 into nitrogen compounds that plants can use
denitrifying bacteria - turn nitrates back into N2 gas. there is no benefit to living organisms

Question 32

what are the four main types of bacteria involved in the nitrogen cycle?

Answer 32

decomposers
nitrifying bacteria
nitrogen-fixing bacteria
denitrifying bacteria

Question 33

what is ammonia

Answer 33

a nitrogen compound

Question 34

how does lighting help with the nitrogen cycle?

Answer 34

it converts nitrogen gas in the air into oxides of oxygen. these dissolve in rainwater, enter the soil, and are converted into nitrates by nitrifying bacteria.

Question 35

how can humans make nitrates? what are they used for?

Answer 35

using nitrogen gas. these nitrates are usually used as fertilisers because they increase the rate of growth of crops

Question 36

what does urea decompose into?

Answer 36

ammonia

Question 37

what do plants decompose into?

Answer 37

ammonia

Question 38

what do animals decompose into?

Answer 38

ammonis

Question 39

what is the carbon cycle?

Answer 39

The way in which carbon cycles in an ecosystem.

Question 40

what does denitrifying bacteria do?

Answer 40

Convert nitrate into nitrogen gas.

Question 41

what does nitrifying bacteria do

Answer 41

Convert ammonium compounds into nitrite and nitrite into nitrate.

Question 42

what is the nitrogen cycle?

Answer 42

The way in which nitrogen cycles in an ecosystem.

Question 43

what does nitrogen fixing bacteria do?

Answer 43

Convert nitrogen gas into ammonium compounds.

Question 44

what is the difference between between normal and free-living nitrogen fixing bacteria?

Answer 44

The main difference between free-living nitrogen-fixing bacteria and symbiotic nitrogen-fixing bacteria is that free-living bacteria live independently, while symbiotic bacteria live in a close relationship with plants e.g., they form associations with the roots of legumes.
in normal nitrogen fixing bacteria, instead of entering the soil, the ammonia that the bacteria make by fixing nitrogen is passed to the plant which use it to make amino acids. in return, the plant provides the bacteria with organic nutrients (mutualism)