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Topic 5) Energy Transfers In & Between Organisms > 5.3 - Energy & Ecosystems, 5.4 - Nutrient Cycles > Flashcards

5.3 - Energy & Ecosystems, 5.4 - Nutrient Cycles Flashcards

1
Q

What is a plants biomass?

A

The chemical energy stored in a plant
Measured in terms of the mass of carbon that an organism contains or the dry mass of its tissue per unit area per unit time

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2
Q

What do we use to measure biomass?

A

Calorimetry

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3
Q

How do we use a calorimeter in order to measure biomass?

A

A sample of biomass is burnt & the energy released is used to heat a known volume of water.
The change in temperature of the water is used to calculate the chemical energy of the dry biomass.

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4
Q

Apart from using a calorimeter, explain another method of measuring biomass?

A

Sample of organism is dried in an oven.
The sample is weighed at regular intervals.
Once the mass becomes constant, you know that all the water has been removed.
Typical units may be kg m^-2

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5
Q

What is gross primary production?

A

Total amount of chemical energy converted from light energy by plants, in a given area & time.

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6
Q

What is **respiratory loss*?

A

Amount of the gross primary production that is lost to the environment when plants respire. Approximately 50%.

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7
Q

What is net primary production?

A

Remaining chemical energy from gross primary production after *respiratory loss**es.

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8
Q

What formula links gross primary production, net primary production & respiratory loss?

A

NPP = GPP - R

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9
Q

What does GPP stand for?

A

Gross primary production

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10
Q

What does R stand for?

A

Respiratory loss

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11
Q

What does NPP stand for?

A

Net primary production

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12
Q

What is the energy from NPP used for?

A

It’s available to plant for growth & reproduction, and is stored in the plant’s biomass. It’s also the energy available to organisms at the next trophic level.

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13
Q

Why does not all energy from an ingested organism transfer to the consumer?

A

Not all the organism can be eaten (e.g. bones, roots)
Some parts cannot be digested therefor are excreted in faeces, energy is lost to environment.
Some energy is lost to environment through respiration & urine excretion.

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14
Q

Approximately how much energy from an organism is transferred to consumer?

A

10%

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15
Q

What is a consumer’s net production?

A

Energy that’s gained from eating an organism, after loosing some through excretion & respiration.

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16
Q

What does N stand for?

A

Net production

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17
Q

What does I stand for?

A

Chemical energy in ingested food.

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18
Q

What does F stand for?

A

Chemical energy lost in faeces & urine.

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19
Q

What equation is used to calculate the net production of consumers?

A

N = I - ( F + R )

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20
Q

What equation is used to calculate efficiency of energy transfer?

A

Net production of trophic level / net production of previous trophic level,
X 100

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21
Q

As you move up the food chain, energy transfer becomes…

A

More efficient

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22
Q

Why does energy transfer become more efficient as you move up the food chain?

A

As plants contain more indigestible matter than animals.

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23
Q

What is a trophic level?

A

A stage in the food chain

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24
Q

What do decomposers do?

A

Break down dead or undigested material, allowing nutrients to be recycled.

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25
Q

In order to increase efficiency, the farmer needs to increase…

A

Net primary production of crops
Net production of livestock

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26
Q

Outline 2 ways of increasing efficiency.

A
  • reducing energy lost to other organisms (e.g. pests)
  • reduce energy lost through respiration of livestock
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27
Q

Why does simplifying food webs increase efficiency?

A

As pests reduce the amount of energy available for crop growth, less energy is available to humans eating the crop.
By getting rid of food chains that don’t involve humans, NPP of the crop will increase.

28
Q

How can a farmer simplify a food chain?

A

By getting rid of pests, by using pesticides.

29
Q

What is used to kill insects?

A

Insecticides

30
Q

What is used to kill weeds?

A

Herbicides

31
Q

How does killing weeds help to simplify the food chain?

A

Killing weed removes direct competition with the crop for for energy from the Sun. Also further reduces insect numbers, as could alter their preferred habitat or food source.

32
Q

What biological agents can be used to lower pest numbers?

A

Parasites - lay egg on pest insect, killing them or reducing their ability to function
Pathogenic bacteria & viruses - kill pest

33
Q

Why does reducing respiratory loss increase efficiency?

A

More of the livestocks energy is used for growth & reproduction

34
Q

How can farmers reduce respiratory loss of livestock?

A

Keeping them in pens where movement is restricted - movement increases rate of respiration.
Keeping pens warm - less energy is wasted by generating body heat.

35
Q

What are saprobionts?

A

Microorganisms that…
-are a type of decomposer: feed on remains of dead plants & animals (and on their waste products), breaking them down, allowing important chemical elements in the remains to be recycled.
-perform extracellular digestion: secrete enzymes & digest their food externally, then absorb the nutrients they need. During, organic molecules are broken down into inorganic ions.

36
Q

What is saprobiotic nutrition?

A

Obtaining nutrients from dead organic matter & animal waste using extracellular digestion.

37
Q

What are mycorrhizae?

A

Symbiotic relationships that fungi form with plant roots.

38
Q

What are hyphae?

A

Long, thin strands that make up fungi, which connect to the plant’s root.

39
Q

What is the function of the hyphae?

A

They increase the surface area of the plant’s root system, helping the plant to absorb ions from the soil that are usually scarce.
Also increase uptake of water by the plant.

40
Q

What do the fungi gain from their mutualistic relationship with plant roots?

A

Organic compounds, such as glucose, from the plant.

41
Q

Why do plants & animals need nitrogen?

A

To make proteins, nucleic acid - DNA & RNA

42
Q

What 4 processes, that involve bacteria make up the nitrogen cycle?

A

Nitrogen fixation
Ammonification
Nitrification
Denitrification

43
Q

Explain nitrogen fixation.

A

Nitrogen gas in the atmosphere is turned into nitrogen-containing compounds.
Carried out by bacteria.
Turns nitrogen into ammonia.
Which goes on to from ammonium ions, in solution that can be used by plants.
Bacteria are found inside root nodules on leguminous plant roots.
From a mutualistic relationship with plant: they provide plant w/nitrogen compounds, plant provides them w/carbohydrates.
Some bacteria also found in soil.

44
Q

Explain ammonification.

A

Nitrogen compounds from dead organisms & animal waste are turned into ammonia by saprobionts,
Which then go on to from ammonium ions.

45
Q

Explain nitrification.

A

Ammonium ions in soil are changed into nitrogen compounds,
That can then by used by plants (as nitrates).
Nitrifying bacteria change ammonium ions into nitrites.
Other nitrifying bacteria then change nitrites into nitrates.

46
Q

Explain denitrification.

A

Nitrates in soil are converted into nitrogen gas by denitrifying bacteria,
By using nitrates in soil to carry out respiration & produce nitrogen gas.
Happens under anaerobic conditions.

47
Q

Apart from the nitrogen cycle, list 2 other ways nitrogen gets into an ecosystem.

A

Lightning
Artificial fertilizers

48
Q

Why do plants and animals need phosphorus?

A

To make biological molecules such as phospholipids
DNA, RNA, ATP

49
Q

Where is phosphorus found?

A

In rocks
Dissolved in water
- phosphate ions dissolved in water in soil can be assimilated by plants & other producers

50
Q

What is meant by assimilated?

A

Absorbed & then used to make more complex molecules

51
Q

What is the first stage of the phosphorus cycle?

A

Phosphate ions in rocks are released into the soil by weathering

52
Q

What is the second stage of the phosphorus cycle?

A

Phosphate ions are taken into plants through roots. Mycorrhizae greatly increase rate that phosphorus can be assimilated.

53
Q

What is the third stage of the phosphorus cycle?

A

Phosphate ions are transferred through the food chain as plants are eaten by animals which are eaten by others etc

54
Q

What is the fourth stage of the phosphorus cycle?

A

Phosphate ions are lost from animals in waste products.

55
Q

Whats the fifth stage of the phosphorus cycle?

A

Plants & animals excrete urine & faeces, and die,
Saprobionts break down organic compounds, releasing phosphate ions into soil
For assimilation by plants

56
Q

What is the sixth stage of the phosphorus cycle?

A

Weathering of rocks also releases phosphate ions into seas, lakes & rivers
Absorbed by aquatic producers (e.g. algae)
Passed along food chain, to birds

57
Q

What is the seventh stage of the phosphorus cycle?

A

Waste produced by sea birds is known as guano
Guano contains a high proportion of phosphate ions
Returns to soil

58
Q

What is guano?

A

Waste excreted by sea birds, containing lots of phosphate ions, often used as a natural fertiliser.

59
Q

Why is it natural to find a lack of nutrients in farms?

A

After crops use up all nutrients, they are harvested.
Therefore, don’t naturally decompose, so dont return nutrients & ions to soil.
Animals also take up nutrients when they eat plants/grass
When they are taken to a different field/slaughter house, they don’t give back nutrients through waste or decomposition.

60
Q

Are artificial fertilisers organic or inorganic?

A

Inorganic
They contain pure chemicals as powders or pellets

61
Q

Are natural fertilisers organic or inorganic?

A

Organic
They include manure, composted vegetables, crop residues, sewage sludge.

62
Q

What is leaching?

A

When water-soluble compounds in the soil are washed away (e.g. by rain).
Often washed into nearby ponds & rivers

63
Q

Why might fertilisers cause environmental issues?

A

When too much is used, fertilisers may leach into waterways.

64
Q

When/why is leaching more likely to occur?

A

When artificial chemical fertilisers are used, as they are relatively soluble.
Also when heavy rainfall occurs

65
Q

Why is leaching less likely to occur with the use of natural fertilisers than artificial?

A

Contains nitrogen & phosphorus in organic molecules, that still need to be decomposed by microorganisms before they can be absorbed by plants.
So their release into the soil is slower & more controlled

66
Q

The leaching of phosphates is … likely than the leaching of nitrates?

A

Less
Phosphates are less water-soluble

67
Q

What is eutrophication?

A

1) Mineral ions leached from fertilised fields stimulate the rapid growth of algae in ponds & rivers.
2) Large amounts of algae block light from reaching plants below.
3) Eventually, plants below die because they are unable to photosynthesise enough.
4) Bacteria feed on dead plant matter
5) This increases number of bacteria, reducing the oxygen concentration in water (respiration)
6) Fish & aquatic organisms die, due to lack of dissolved oxygen

Topic 5) Energy Transfers In & Between Organisms (3 decks)

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