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Biology Unit 4 > Nutrient Cycles > Flashcards

Nutrient Cycles Flashcards

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1
Q

What is problem with combustion in carbon cycle

A

Combustion fossil fuels unbalances cycle

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2
Q

How is deforestation problem in carbon cycle

A

It stops plants from dealing with extra co2 from combustion of fossil fuels

Less plants = less photosynthesis to remove co2 from atmosphere

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3
Q

Describe role of saprobiotic organisms in the carbon cycle

A

They secrete enzymes onto dead organisms to break molecules into smaller ones
Molecules then absorbed by diffusion
This carbon released as co2 when decomposer respires

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4
Q

What are the 2 important greenhouse gases

A

Co2 and methane

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5
Q

How do greenhouse gases lead to global warming

A

Make atmosphere thicker so heat can’t escape

Heat close to earth’s surface so earth gets hotter

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6
Q

When is methane produced

A

When micro organisms break down organic molecules

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7
Q

How does climate change lead to loss of species

A

Affects the niches available in a community

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8
Q

Explain why co2 concentration of the atmosphere is less on a summer’s day than on a winter’s day

A

Summer = more light + temperature = more photosynthesis

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9
Q

How does nitrogen in atmosphere become ammonium-containing molecules

A

Only plants called legumes

They have mutualistic bacteria which can fix nitrogen

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10
Q

How do nirate ions become ammonium-containing molecules

A

Absorbed by active transport

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11
Q

How does nitrogen in the air become ammonium ions?

A

Nitrogen is fixated by free living bacteria

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12
Q

How does ammonification occur

A

Saprobiotic feeders release ammonia which then forms ammonium ions in the soil

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13
Q

How does denitrification occur

A

Only occurs in water logged soil where there’s lack of oxygen
As there’s more anerobic bacteria which converts soil nitrates into gaseous nitrogen

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14
Q

How does nitrite (no-2) become nitrate (no-3)

A

Nitrification:

Oxidation occurs from O2 in air
Allowed to happen by free living aerobic bacteria in soil that is nitrifying bacteria

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15
Q

How does ammonium ions become nitrite (no-2)

A

Nitrification:

Oxidation occurs from O2 in air
Allowed to happen by free living aerobic bacteria in soil that is nitrifying bacteria

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16
Q

What is the first 2 stages in eutrophication

A

NO-3 is limiting factor

NO-3 is leached into water so no longer limiting factor so plants grow exponentially

17
Q

What are the eutrophication stages after NO-3 is leached into water

A

Algal bloom

Algae absorb all light so lower plants have none

Light becomes limiting factor for lower plants
So lower plants die

18
Q

What are the eutrophication stages after the lower plants die

A

Dead plants are no longer limiting factor for saprobiotic organisms which grow exponentially

Saprobiotic organismsuse O2 for respiration so less O2

O2 becomes limiting factor for aerobic organisms

19
Q

What are the eutrophication stages after O2 becomes the limiting factor for aerobic organisms

A

Lake life die so more NO-3

Less aerobic organisms so less competition for Anerobic organisms which grow exponentially

20
Q

What are the eutrophication stages after anaerobic organisms grow exponentially

A

Anaerobic organisms decompose their material so more NO-3 and toxic waste
Substance released at same time
Hydrogen sulphide produced
Water known as putrid

21
Q

Describe the carbon cycle

A 
Co2 in air
Photosynthesis by plants
Plants consumed by animals
Plants + animals respire
Plants + animals die
Micro organisms respire

Extra = combustion fossil fuels

22
Q

What is organic/natural fertiliser

A

Dead and decaying remains of plants and animals and animal waste

23
Q

What is inorganic/artificial fertiliser

A

Mined rocks and deposits then converted into different forms and blends

24
Q

What does research show about fertilisers

A

A combination or organic and inorganic fertilisers leads to the greatest long-term increase in productivity

25
Q

Why are fertilisers needed in agricultural ecosystems

A

Crops are repeatedly grown on same area of land
Minerals taken up by crops aren’t returned as crop consumed away from land
Mineral ion levels in soil reduced
This limits rate of photosynthesis
Fertilisers used to replace mineral ions

26
Q

What are the effects of nitrogen fertilisers

A

Reduces species diversity
Leeching
Eutrophication

27
Q

How does nitrogen fertiliser reduce species diversity

A

Nitrogen rich soils favour the growth of rapid growing species (eg grass) which out-compete many other species

28
Q

What is leeching

A

Pollution of watercourses

29
Q

What causes eutrophication

A

Leeching of fertiliser into watercourses

Biology Unit 4 (14 decks)

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