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AQA Biology A Level > Energy Transfers and Nutrients Cycles > Flashcards

Energy Transfers and Nutrients Cycles Flashcards

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1
Q

What is an ecosystem?

A

all the organisms living in a particular area and all the non-living (abiotic) conditions

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2
Q

What is biomass?

A

the mass of living material in an organism / the chemical energy stored in the plant

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3
Q

How can biomass be measured?

A

the mass of carbon an organism contains / the dry mass of its tissue per unit area

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4
Q

Why is dry mass?

A

the mass of the organism with the water removes

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5
Q

Why is dry mass of an organism used instead of wet mass?

A

as the water content of living tissue varies

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6
Q

How is dry mass measured?

A
  1. a sample of the organism is dried (often in amnestying oven set at a low temp )
  2. it is weighed at regular intervals
  3. once the mass becomes constant you know the water has been removed
    THE MASS OF CARBON IS GERNAL TAKEN TO BE 50% OF THE DRY MASS
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7
Q

What are the units for dry mass?

A

kgm-2

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8
Q

How can you estimate the a mount of chemical energy stored in biomass?

A

by burning the biomass in a calorimeter

the amount of heat give off tells you know much energy is present in the sample

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9
Q

Describe a calorimeter

A
  1. a sample of dry biomass is burnt and the energy released is used to heat a know volume of water
  2. the change in temperature of the water is used to calculate the chemical energy of the dry biomass
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10
Q

What is gross primary production (GPP)?

A

the total amount of chemical energy converted from light energy by plants in a given area

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11
Q

What is respiratory loss (R)?

A

approximately 50% of the GPP

the amount of energy lost to the environment as heat when the plants respire

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12
Q

What is the Net primary production (NPP)?

A

the energy available to the plant for growth and reproduction (after respiratory loss has been deducted from GPP) and the energy available to the next trophic level in the food chain

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13
Q

The equation for NPP

A

NPP = GPP - R

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14
Q

What are the units for GPP?

A

kJm-2yr-1 (kilojoules per square meter per year)

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15
Q

How do consumers store their chemical energy?

A

alos in biomass

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16
Q

How do consumers get energy

A

by ingesting plant material or animals that have eaten plant material

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17
Q

Hoe much energy is lost as food is transferred to the next trophic level?

A

90%

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18
Q

How is 90% of energy lost as its transfer between trophic levels?

A
  • not all the food is eaten (plant roots, bones) so not all there energy is taken in
  • some arts are indigestible so are egested as faeces
  • some energy is also lost to the environment through respiration or exertion of urine
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19
Q

What is net production

A

the energy in consumers that is available to the next trophic level in food chain

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20
Q

What is the equation for net production (N)

A

N= I (chemical energy in ingested food) - (F (chemical energy lost in faeces and urine) + R (energy lost through respiration) )
N=I - (F+R)

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21
Q

How do you calculate % efficiency of energy transfer?

A

net production of trophic level/ net production of previous trophic level x100

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22
Q

What happens to energy transfers as you move up the food chain?

A

they usually become more efficient as plants contain more indigestible matter

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23
Q

List the levels of a food chain

A
  • producer
  • primary consumer
  • secondary consumer
  • tertiary consumer
  • decomposer
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24
Q

What is a decomposers role ?

A

to breakdown dead of undigested material allowing nutrients to be recycled

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25
Q

How can you increase NPP?

A
  • energy lost to other organisms (pests) can be reduced through simplification of food webs
  • the energy lost through the respiration of livestock can be reduced
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26
Q

How can simplifying foods webs increase efficiency?

A

pests reduce the amount of energy available for crop growth and thus NPP of crops and reducing the amount of energy available for humans
- simplifying food webs, that don’t involve humans, energy loss will be reduces and NPP will increase

27
Q

How can pests be removed?

A

Chemically and and biological methods can be used

28
Q

How can respiratory loss be reduced?

A

By controlling the conditions they live in soo more is used for growth and less is lost through respiration

  • movement increases respiration so animals are kept in pens
  • they area often indoors and keeps warm so less energy is lost via generating body heat
29
Q

How does rescuing reparatory loss increase efficiency?

A
  • more biomass is produced
  • more energy can be stored
  • increasing net production
  • and energy efficiency
30
Q

What is a natural ecosystem?

A

one that hasn’t been changed by human activity
contain nitrogen and phosphorus that are recycled though food webs
but this is often disrupted through human activity

31
Q

What is Saprobionts role?

A

Feed on remains of d dead plants, animal sand waste
-they makes them a type fo decomposer and it allows important chemical elements in the remains to be recycled
Secret enzymes and dodgers food externally them absorb the required nutrients via extracellular digestion
-during this process organic molecules are broken down into organic ions

32
Q

What are mycorrhizae

A

fungi that from symbolic relationships with the roots of plants
they are made up if thin hyphae that connect to the plant roots

33
Q

What do hyphae do?

A
  • increase the SA, increasing the absorption of ions from the soil
  • increase water uptake
34
Q

How much of the atmosphere is made up of Nitrogen?

A

78%

35
Q

what do plants and animals require ignorer to use this atmospheric nitrogen?

A

bacteria to convert it into nitrogen continuing compounds

36
Q

What is nitrogen fixation

A

-atmospheric nitrogen goes too nitrogen containing compounds

37
Q

What carry out biological nitrogen fixation

A

rhizobium (type of bacteria)

38
Q

What does rhizobium do

A

turns nitrogen to ammonia which goes to ammonium ions sued by plants

39
Q

Where are rhizobium found

A

in side root nodules of leguminous plants

40
Q

What relationship do rhizobium form witty plants§

A

mutualistic relationships they provided plants with nitrogen compound and the plant provides them with carbohydrates

41
Q

what is ammonification

A

nitrogen compounds from dead organisms or animal faces are turned into ammonia then into ammonium ions by saprobionts

42
Q

What is nitrification

A

when ammonium ions in soil turn into nitrogen compounds that can be used by plants eg nitrates

43
Q

What do nitrosomanas do

A

change ammonium ions into nitrates

44
Q

What do nitrobacter do

A

change nitrites into nitrates

45
Q

what is denitrification

A

nitrates in the soil are changed into nitrogen ass by denitrifying bacteria under aerobic conditions eg in waterlogged soils

46
Q

How else does nitrogen gas get into an ecosystem

A

lighting fixed atmospheric nitrogen into nitrogen oxide

artificial fertilisers are produced from atmospheric nitrogen via the harder process

47
Q

Why do plants require phosphorous?

A

to make biological molecules

48
Q

Where are phosphate ions found?

A

in rocks and dissolved in the ocean as PO4 3-

49
Q

How can phosphate ions dissolved in water and soil be assimilated?

A

by plants and other producers during the phosphorus cycle

50
Q

What does assimilated mean?

A

absorbed the used to make more complex molecules

51
Q

Name the seven steps of the phosphorus cycle?

A
  1. Phosphate ions in rocks are released into the soil by weathering
  2. They are teen init the plants through the roots (Mycorrhizae greatly increase the rate at which phosphorous can be assimilated)
  3. Transferred trough the food chain as animals eat the plants and in turn are eaten
  4. lost from the animals via excretion
  5. Saprobionts are involved in breaking down the dead plants and animals, releasing phosphate ions into the soil for assimilation by plants.
  6. Weathering rocks also realise phosphate ions into sea, lakes and rivers. These are taken up by producers such as algae and passed into the food chain via birds.
  7. The waste produced by sea birds (GUANO) and contains a high proportion of phosphate ions, returning a significant amount of phosphate ions to the soils acting as a natural fertiliser
52
Q

Describe two ways of nutrients loss

A

CROPS TAKE UP MINERAL IONS FROM THE SOIL TO GROW AS THEY BUILD THEIR TISSUE
- plants are harvested and removed decreasing ions as they will not decompose in the field thus aren’t returned to the soil via decomposers
ANIMALS EAT GRASS AND OTHER PLANTS TAKING UP THEIR NUTRIENTS
-when they are slaughtered of moved somewhere else they cannot return the nutrients to the soil

53
Q

What is the perps of using fertilisers?

A

they replace the lost mineral ions so more energy from the ecosystems can be used for growth increasing the efficiency of energy transfers

54
Q

What are artificial fertilisers

A

inorganic

contain pure chemicals (ammonium nitrate) as powder or pellets

55
Q

What are natural fertilisers?

A

organic matter

include manure composted vegetables crop residue and sewage sludge

56
Q

What can an increase to fertilisers applied to plants lead to?

A

fertilisers leaching into waterways

57
Q

What is leaching?

A

where water soluble compounds in the soil are washed away by rain or irrigation systems

58
Q

What can leaching lead to?

A

if washed into near by ponds and rivers it can lead to eutrophication

59
Q

What causes Eutrophication?

A

excess nutrients

60
Q

Describe Eutrophication

A
  1. Mineral ions laced from fertilised fields stimulate the rapid growth of age in ponds and rivers
  2. Large amounts of algae block light from reaching the plant below
  3. eventually the plants die because they’re unavailable to photosynthesise enough
  4. Bacteria feed on the dead plant matter. The increased numbers of bacteria reduce the oxygen concentration in the water by carrying out aerobic respiration
  5. Fish and other aquatic organism die because their isn’t enough dissolved oxygen
61
Q

How can chemical fertilisers cause environmental issues

A

inorganic ions are really soluble

so excess mineral ions are more likely to leach especially if applied just before heavy rainfall

62
Q

Why is the leaching of natural fertilisers less likely

A

as nitrogen and phosphorous are still contained in organic molecules that require to be decomposed by micro-organisms before absorption
therefore realse into soil for uptake is more controlled and leaching is less likely as phosphates are less soluabel

63
Q

Why is the leaching of phosphates less likely than nitrates?

A

as phosphates are less soluble in water

64
Q

How can fertilisers cause plants to die?

A

too much of a particular plant can cause plants to die as they change the balance of the soil

AQA Biology A Level (66 decks)

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