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Y13 Biology > Topic 5 B: Energy Transfer and Nutrient Cycle > Flashcards

Topic 5 B: Energy Transfer and Nutrient Cycle Flashcards

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1
Q

Population definition?

A

All the organisms of one species living in a habitat.

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2
Q

Ecosystem definition?

A

Includes all the organisms living in a particular area.

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3
Q

Energy conversion within photosynthesis?

A

Light to chemical.

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4
Q

What are the biological molecules that energy is transferred to?

A

A - amino acids
C - cellulose
O - oils and fats (form of storage)
R - respiration
N - nitrates
S - starch (form of storage)

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5
Q

Biomass definition?

A

The mass of living material, it can also be thought of as the chemical energy stored within a plant.

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6
Q

What is a producer?

A
  • start of food chain
  • e.g., grass, plants, algae
  • undergo photosynthesis to produce own food (glucose)
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7
Q

Characteristic of primary consumer?

A
  • herbivore or omnivore
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8
Q

Characteristic of rest of consumers?

A
  • carnivores or omnivores
  • final consumer is also known as apex predator (top of food chain)
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9
Q

What are decomposers?

A
  • group of organisms that break down the complex materials in dead organisms into simple ones.
  • usually fungi and bacteria
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10
Q

What is biomass measured in the terms of?

A
  • in terms of the mass of carbon that an organism contains
  • using dry mass (water removed)
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11
Q

Equipment in inexpensive calorimetry?

A
  1. thermometer
  2. water - known volume
  3. tripod
  4. crucible - heat proof container
  5. lid - decreases amount of heat loss
  6. draught excluder - decreases amount of heat lost
  7. copper container - transfers heat from burning sample to water
  8. burning dried plant sample
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12
Q

Inexpensive calorimetry process?

A
  1. weigh crucible without sample first, and then with the sample
  2. set oven to low temperature to prevent sample from burning as could lose biomass
  3. remove and weigh the crucible at regular intervals during the drying process. Once the mass stops decreasing, the sample is fully dehydrated (all water lost)
  4. calculate mass = final mass - original mass of crucible without sample
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13
Q

How is the bomb calorimeter method different to the inexpensive calorimetry method?

A
  • electricity used in bomb calorimeter method
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14
Q

What are the limitations of inexpensive calorimetry?

A
  1. it can take a long time to fully dehydrate plant sample (burning at low temp)
  2. precise equipment is needed which may be unavailable (e.g., digital thermometer)
  3. accurate results wont be produced with a simple calorimeter (heat energy is lost)
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15
Q

What happens to most of the suns energy?

A
  • not converted into organic matter by photosynthesis
    1. 90% reflected back into space
    2. not all wavelengths of light are absorbed
    3. light may not fall onto chlorophyll molecule
    4. limiting factors may play a role e.g., low co2 levels
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16
Q

Gross Primary Production (GPP)?

A

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

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17
Q

GPP equation?

A

Gross primary production - respiratory losses = net primary production

(GPP - R = NPP)

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18
Q

Gross Primary Productivity?

A

Rate at which plants are able to store chemical energy via photosynthesis.

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19
Q

Net Primary Production?

A

Amount of energy available or left in the plants biomass after respiratory losses.
(most of the energy goes to higher trophic levels)

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20
Q

Net Productivity?

A

Rate of net primary production.

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21
Q

Why isn’t all chemical energy transferred through trophic levels?

A
  1. some of the organism isnt consumed e.g., bones and roots
  2. some parts are indigestible as lost in faeces
  3. energy lost through heat from respiration and urine
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22
Q

Net production equation?

A

Net prod = ingested food - (energy lost in faeces/urine + energy lost in respiration)

N = I - ( F + R )

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23
Q

Primary production?

A

The storing of chemical energy in the biomass of primary producers.
(- energy passed onto consumers = secondary production.)

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24
Q

Percentage efficiency equation?

A

percentage efficiency = energy available after transfer / energy available before transfer x100

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25
Q

How to increase efficiency? (food webs)

A
  1. simplifying food webs (reduces energy loss and increases NPP)
    - farmers use chemical pesticides (insecticides and herbicides)
    - farmers use biological agents (parasites, pathogenic bacteria, and viruses)
26
Q

How to increase efficiency? (reducing respiratory losses)

A
  1. reducing respiratory losses
    - control living conditions of livestock
    - so more energy is used for growth and less through respiration
    - more biomass produced so more chemical energy stored
    - increases net prod. and efficiency of energy transfer
27
Q

Method of controlling living conditions?

A
  • movement increases rate of respiration so animals are kept in pens
  • movement is restricted
  • often indoors and kept warm so less energy wasted by generating body heat
28
Q

Benefits and limitations of keeping animals in pens?

A

Benefit - more food produced in shorter space of time, often at lower cost.
Limitation - ethical issues as living conditions could distress animal.

29
Q

Overall role of microorganisms?

A

Feed on the remains of dead producers and consumers - and their waste.

30
Q

What are saprobionts?

A

True decomposers that secrete enzymes onto their food, which then digests the material externally (extracellular digestion)

31
Q

Saprobiotic nutrition?

A

Obtaining nutrients via extracellular digestion.

32
Q

Are all nutrients absorbed?

A

No, some absorbed into soil or taken into atmosphere.

33
Q

What are symbiotic relationships?

A

Fungi form these relationships with the roots of plants, also known as mycorrhizae, meaning a mutually beneficial relationship.

34
Q

How do symbiotic relationships work?

A
  1. fungi have thin, long filaments - hyphae
  2. this increases the surface area of the plant roots - more water and mineral ions can be absorbed
  3. in return, fungi receives organic compounds from the plant
35
Q

Significance and role of nitrogen cycle?

A
  • plants and animals require nitrogen to produce proteins, ATP, and nucleic acids (DNA & RNA)
  • bacteria is needed to convert nitrogen gas into nitrogen-containing compounds
36
Q

The nitrogen cycle stages?

A
  1. nitrogen fixation
  2. ammonification
  3. nitrification
  4. denitrification
37
Q

Nitrogen fixation process?

A
  1. nitrogen from atmosphere is converted into nitrogen-containing compounds, carried out by specific nitrogen-fixing bacteria.
    -bacteria and plant have symbiotic relationship
    - this bacteria is found inside root nodules of leguminous plants (e.g., peas, beans and clover)
    - however, not all plants are leguminous, if this is the case, bacteria found in soil
38
Q

Ammonification process?

A
  1. nitrogen compounds from waste products (e.g., urine and faeces) and dead organisms are converted into ammonia by saprobionts.
39
Q

Nitrification process?

A
  1. ammonium ions in the soil are converted by nitrifying bacteria into nitrogen compounds that can be used by the plant, known as nitrates.
  2. intially, nitrifying bacteria converts ammonium ions into nitrites, then a different bacteria converts nitrites into nitrates.
40
Q

Denitrification process?

A
  1. nitrates dissolved in soil are actively transported into the plant, they are then assimilated into the cell and used to make amino acids and ATP.
  2. denitrifying bacteria use nitrates in soil during respiration, this process produces nitrogen gas which returns to atmosphere.
    (this process occurs in anaerobic conditions where there is no oxygen e.g., waterlogged soil)
41
Q

Exam Question: Describe how the action of microorganisms in the soil produces a source of nitrates for crop plants (5)

A
  1. Protein / Amino Acids / Ammonia
  2. by saprobionts
  3. ammonia into nitrate
  4. nitrite into nitrate
  5. by nitrifying bacteria
  6. nitrogen to ammonia
  7. by nitrogen-fixing bacteria
42
Q

Saprobionts funtions recap?

A
  • decompose waste and dead matter via extracellular digestion, making inorganic ions available to other organisms
  • carry out ammonification
43
Q

Nitrogen-fixing bacteria function recap?

A
  • convert atmospheric nitrogen gas into nitrogen-containing compounds (e.g., ammonia)
44
Q

Nitrifying bacteria function recap?

A
  • convert ammonium ions in soil into nitrogen compounds that can be used by plants, known as nitrates
  • some convert ammonium ions into nitrites, different ones convert nitrites into nitrates
45
Q

Denitrifying bacteria function recap?

A
  • use nitrates during respiration, releasing nitrogen gas in the process
46
Q

Mycorrhizal fungi function recap?

A
  • increases surface area of root systems, helping plants to absorb water and scarce mineral ions from soil
47
Q

Why is phosphorus cycle important?

A

Plants and animals need phosphorus to make biological molecules - DNA, phospholipids, and ATP.

48
Q

Phosphorus cycle process?

A
  1. phosphate ions in rocks are released into soil by weathering
  2. phosphate ions taken into plants through roots
  3. phosphate ions transferred through food chain during feeding
  4. P ions are lost from animals via waste
  5. when animals and plants die, saprobionts break down organic compounds, releasing phosphate ions into soil for assimilation by plants. Also release P ions by faceces and urine
    (weathering of rocks also release P ions into seas which is taken up by aquatic producers e.g. algae, and passed along food chain to birds. the waste product of sea birds is ‘guano’ and contains large proportions of phosphate ions.
49
Q

Exam Question: An increase in nitrate concentration in the water entering the lake could effect algae and fish in the lake. Explain how

A
  • increase in algae concentration, blocking light
  • increased amount of decomposers breaking down dead plant material
  • decomposers use oxygen in respiration causing fish to die
50
Q

Overall function of fertilisers?

A

Replace nitrates and phosphates ions that are lost in soil.

51
Q

Characteristics of agricultural ecosystems?

A
  • crops and livestock are removed, rather than being allowed to die and decay
  • interrupts nutrients cycles as mineral ions in biomass are not returned to soil by decomposers.
  • therefore, nutrient conc in soil decreases, decreasing crop yield or milk/meat yield, reducing productivity
52
Q

What are natural fertilisers?

A

Dead and decomposed remains of organisms and their waste products e.g., manure and composted vegetables.

53
Q

Advantages and Disadvantages of natural fertilisers?

A

adv - improves soil structure which increases its water holding abilities
adv - cheaper and free if you own farm animals
disadv - no control over exact proportions of the nutrients
disadv - released over time so arent concentrated

54
Q

What are artificial fertilisers?

A

Inorganic matter containing pure chemical compounds of ammonium nitrate as powders and pellets.

55
Q

Advantages and Disadvantages of artificial fertilisers?

A

adv - more soluble in water
adv - nutrients are concentrated so smaller amounts needed which lowers transport costs
disadv - high solubility means larger quantities are washed away with rain

56
Q

Exam Question: applying very high concentrations of fertiliser to the soil can reduce plant growth. Use your knowledge of water potential to explain why. (2)

A

Decreases water potential in the soil which decreases rate of osmosis of water into the plant down water potential gradient.

57
Q

Environmental effects of fertilisers?

A
  • leaching = when water soluble compounds in the soil are washed away e.g., rain or irrigation
  • soluble nitrate and phosphate ions are found in excess in fertiliser and not taken up by plant.
  • sometimes too much fertilisers is applied
58
Q

Leaching and natural fertilisers?

A
  • less likely to occur as their release into the soil is more controlled
  • leaching of phosphate is less likely than nitrates as they are less soluble in water
59
Q

What is eutrophication?

A

When mineral ions from excess fertiliser leach from farmland into waterways, they cause rapid growth of algae at surface of water (algal bloom)

60
Q

Leaching process and outcome?

A
  1. excessive nutrients from fertilisers run off from the land into water
  2. aquatic plants flourish and grow rapidly
  3. algae also show rapid growth - algal bloom
  4. algal bloom prevents sunlight from reaching aquatic plants, water oxygen levels fall. Also more decay of aquatic life.
  5. decomposition (by saprobionts) increases, aerobic respiration of decomposers reduces dissolved oxygen further.
  6. death of organisms requiring dissolved oxygen in water
61
Q

Exam Question: Nitrate from fertiliser applied to crops may enter ponds and lakes, explain how nitrate may cause the death of fish in fresh water. (5)

A

1 - growth of algae / surface plants / algal bloom blocks light
2 - reduced / no photosynthesis so plants die
3 - saprobionts
4 - aerobically respire
5 - less oxygen for fish to respire, aerobic organisms die

Y13 Biology (11 decks)

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