Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

THEOS ENVIRO > TOPIC 7 BIOGEOCHEMICAL CYCLES > Flashcards

TOPIC 7 BIOGEOCHEMICAL CYCLES Flashcards

(79 cards)

Start Studying
1
Q

What is a biogeochemical cycle?

A

biological and physical processes that move elements that are important to living organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Photosynthesis word equation?

A

carbon dioxide + water → glucose + oxygen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does respiration do?

A

puts CO2 into atmosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is respiration?

A

the conversion of organic matter into carbon dioxide and water in all living organisms, releasing energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What actually is fossilisation?

A

Incomplete decomposition of DOM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is combustion?

A

burning of organic material releases carbon dioxide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What happens as we increase marine pollution of toxic chemicals?

A

Less absorption of dissolved CO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is in the mineral nutrient cycle

A

soil
biomass
litter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Why is fossilisation included within the carbon cycle?

A

incomplete decomposition of DOM can produce long-term carbon stores

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Some organisms such as molluscs produce exoskeletons that include calcium carbonate.
What sort of rocks can this produce?

A

-this may produce rocks such as
limestone
-which now contain most of the carbon in the lithosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

List a few things that increase the rate of transfer within the carbon cycle?

A

afforestation
combustion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

List a few things that decrease the rate of transfer within the carbon cycle?

A

deforestation
pollutants in the sea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why does aerobic decomposition take place rapidly after ploughing?

A

increases the oxygen supply to decomposers living in the soil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is carbon in DOM eventually released as ?

A

CO2.
By aerobic respiration of soil organisms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Due to the absence of oxygen, respiration by anaerobic soil organisms releases ….?

A

Methane gas which is gradually oxidised to CO2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

List a few anaerobic environments produced by human activities?

A

rice padi fields

landfill sites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why does increasing carbon dioxide lead to a increase of acidity in the sea?

A

as carbon dioxide is in equilibrium with
carbonic acid and hydrogen ion/
hydrogen carbonate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What does the concentration of hydrogen ions affect in the sea?

A

ph - more hydrogen the more acidic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Example of a few biomass movements?

A

addition of compost to improve soil fertility DOM

Removing crops and livestock to eat stops DOM reaching the soil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

List a few ways to sustainably manage the carbon cycle?

A
  • use alternatives to fossil fuels
  • carbon sequestration
  • conservation of peat bogs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

78% of air is nitrogen. Why cant organisms use nitrogen in this form?

A

Nitrogen is inert

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does inert mean?

A

chemically inactive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What must plants do to nitrogen?

A

secure nitrogen in a fixed form in compounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

List two examples of nitrogen compounds?

A

nitrate ions NO3
ammonia/ammonium NH3/NH4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
How do animals secure their nitrogen compounds from?
plants or animals that have fed on plants
26
What are the 4 biological processes that contribute to the cycling of nitrogen through the biosphere?
nitrogen fixation decomposition nitrification denitrification
27
Explain the process nitrogen fixation is in the nitrogen cycle?
N2 in the air fixation by lightening fixation by bacteria in root nodules of leguminous plants then ammonia and nitrates in soil
28
What does nitrogen fixation achieve?
nitrogen gas (N₂) is converted into usable nitrogen compounds, such as ammonia (NH₃), that plants and other organisms can absorb and use for growth.
29
Explain the process of decomposition in the nitrogen cycle?
excretion, urine, breathing, sweating by animal animal waste decay by bacteria on waste absorption by plant roots then ammonia and nitrates in soil
30
What is nitrification?
nitrifying bacteria convert ammonium into nitrates
31
Why do some plants prefer nitrate?
nitrates move through soil easier too much ammonium can be toxic
32
Why do plants convert ammonium into nitrates during nitrification?
Nitrifying bacteria convert ammonium to nitrates to get energy, not to help plants — but plants benefit anyway because nitrate is a major nitrogen source they can absorb.
33
What is denitrification in relation to the nitrogen cycle?
conversion of nitrates to nitrogen by denitrifying bacteria
34
Why is denitrification important?
closes the nitrogen cycle loop - returns nitrogen to atmosphere prevents excess nitrate in soil
35
Legumes have N-fixing bacteria in their root called nodules. What do they do?
Convert nitrogen gas into nitrates that plants use to make proteins This process requires oxygen
36
Where can the N-fixing bacteria be found and what can they be?
Found in soils and be free living
37
Rhizobium is a symbiotic bacteria in root nodules of legumes. What is the enzyme called that it contains and what can it do?
nitrogenase converts nitrogen and hydrogen to ammonia
38
After ammonia is created by the rhizobium enzyme nitrogenase, what is the ammonia used for?
to make amino acids which the legumes can use to make proteins in return for supplying the bacteria with carbohydrates
39
Explain how ammonium is released into the soil during decomposition? ( THE FIRST STEP OF DECOMPOSITION )
Free-living bacteria and fungi break down animal and plant proteins the nitrogenous waste releases into the soil as a form of ammonium
40
What do the proteins made by plants do during decomposition?
enter (animals bodies) and pass through food chain
41
At each trophic level, animals metabolisms produce organic nitrogen compounds. What is the main way this is returned intro the environment?
Excretions
42
What do micro-organisms break down during the final stage of decomposition?
Molecules from excretion and dead organisms into ammonia (form of ammonium)
43
What can be directly be taken up through plant roots during nitrification?
ammonia NH3
44
Apart from being taken up by roots. What happens to most ammonia produced by decay?
converted into nitrates
45
When decay is converted into nitrates. This is accomplished in two steps. What are they called?
Bacteria of the genus Nitrosomonas oxidise (NH4) to nitrites (NO2-)
46
What do bacteria of the genus Nitrobacter oxidise the nitrites to?
Nitrates NO3
47
What is this process? when bacteria in the soil convert the nitrate back into nitrogen gas which then gets released back into the atmosphere. The process does not require oxygen.
Denitrification
48
What is one bacteria responsible for denitrification?
Pseudomonas
49
Where does pseudomonas (bacteria) live which is responsible for denitrification?
They live deep in soil and in aquatic sediments where conditions are anaerobic
50
Why do pseudomonas use nitrates as an alternative for oxygen?
for the final electron acceptor in their respiration
51
Which of these bacterial species is responsible for nitrification?
Nitrosomonas
52
What is the Haber Process and how does it affect the nitrogen cycle?
The Haber Process fixes nitrogen from the air into ammonia using high pressure, temperature, and an iron catalyst. It increases reactive nitrogen in ecosystems, mainly for fertiliser production
53
How does fertiliser use affect the nitrogen cycle?
It adds excess nitrates to soil, which can leach into water bodies, causing eutrophication.
54
What is eutrophication?
Nutrient pollution causes algal blooms, blocking light, reducing oxygen, and killing aquatic life.
55
How does soil drainage affect the nitrogen cycle?
It increases oxygen in the soil, promoting nitrification and reducing denitrification, which lowers nitrogen return to the atmosphere.
56
How does ploughing (soil disturbance) impact nitrogen levels?
It increases decomposition of organic matter, releasing more ammonium (NH₄⁺) into the soil.
57
How do legumes help sustain the nitrogen cycle?
They have nitrogen-fixing bacteria in their root nodules, which increase nitrogen levels in the soil naturally.
58
How does combustion of fossil fuels affect the nitrogen cycle?
It releases nitrogen oxides (NOx) into the atmosphere, contributing to smog, acid rain, and climate change.
59
Name one method to reduce nitrate leaching into water.
Apply fertilisers in dry weather, use low-solubility fertilisers (e.g. urea), or plant buffer strips near waterways.
60
Why do all organisms need Phosphorus?
to make DNA or RNA, cell membranes, some proteins and bones
61
How is phosphorus different from other biogeochemical cycles?
Phosphorus cycles between rocks, animals, plants and water. It has no gaseous phase because it has low solubility
62
Is the atmosphere involved within the Phosphorus cycle?
No, no gaseous phase
63
If there is no gaseous phase within the Phosphorus cycle, how do crops get there phosphorus?
From the soil
64
What fungi do plants have a symbiotic relationship with, which allows them to absorb phosphorus?
Mycorrhizal fungi
65
Explain the Phosphorus cycle?
plants are eaten by animals when plants/animals die, decomposers return phosphorus to soil this creates more soluble phosphorus compounds that are easier for plants to absorb
66
Explain the short phosphorus process within the ocean.
dead plant and animal matter can accumulate, eventually forming sedimentary rock
67
How are the nitrogen cycle and eutrophication connected?
Excess nitrogen (especially nitrates from fertilisers) can leach into rivers and lakes, disrupting the nitrogen cycle. This causes eutrophication — algae grow rapidly, block light, reduce oxygen, and kill aquatic life.
68
Where is phosphorus mainly stored?
within earths crust and deep sea sediments
69
How are phosphate ions in rocks released?
chemical weathering
70
How is most phosphorus transported?
rivers
71
When consumers eat plants and animals rich in phosphate they are digested and absorbed in the small intestine as what.....
nucleotides and phosphate ions
72
What takes up phosphate in oceans?
algae which is then eaten
73
What takes up phosphates on land?
bacteria
74
Why is it good that phosphorus if very efficiently recycled?
because the amount released by rocks is a very small fraction of the amount stored in biomass
75
What human activity has increased phosphorus dramatically?
fetilisers
76
What was, at one time a major source of agricultural phosphorus?
Guano - bird shit
77
How does mining affect the phosphorus cycle?
Mining phosphate rock for fertilisers and detergents removes phosphorus from geological stores, disrupting the natural, slow-moving cycle.
78
What is a sustainable way to manage phosphorus use?
Recycling organic waste (e.g. compost, manure) Reducing fertiliser overuse Capturing phosphorus from sewage for reuse (phosphorus recovery)
79
How does phosphorus contribute to eutrophication?
Excess phosphorus from fertilisers or sewage enters lakes and rivers, leading to algal blooms, blocked sunlight, and oxygen depletion, which harms aquatic life — a process called eutrophication.

THEOS ENVIRO (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions