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Biology Noor > 13.4 13.5 Energy Transfers and Nutrient Cycles > Flashcards

13.4 13.5 Energy Transfers and Nutrient Cycles Flashcards

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1
Q

What is biomass?

A

Total mass of carbon in a specific area at a given time.

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2
Q

How is biomass measured?

A

In terms of mass of carbon or dry mass of tissue per given area.

Chemical energy stored in dry biomass can be measured using calorimetry.

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3
Q

Food chain

A

Producer–> Primary consumer –> Secondary consumer –> Tertiary consumer

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4
Q

What can energy loss occur due to?

A

Respiration
Excretion of faeces or urine

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5
Q

Percentage efficiency equation

A

Percentage efficiency= energy after/ energy before x100

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6
Q

How to measure energy loss mostly in plants?

A

NPP= GPP - R

NPP= Net primary productivity
GPP= Gross primary production
R= Respiratory losses

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7
Q

How to measure energy loss mostly in consumers?

A

N= I - (F+R)

N= net production
I= chemical energy ingested
F= chemical energy lost in faeces and urine
R= chemical energy lost by respiration

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7
Q

Units for rate of productivity

A

kJ m-2 year-1

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8
Q

Suggest one reason for conserving woodlands.

A

Conserving habitats.
Increasing biodiversity.

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9
Q

Suggest what you should do to ensure all water is removed from a tissue / sample.

A
  • Regularly weigh and Heat (less than 100 °C)
  • Until mass is constant
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10
Q

Gross Primary Productivity

Net Primary Production

A
  • GPP= Chemical energy store in plant biomass, in a given area or volume. (Rate of photosynthesis)
  • NPP= Chemical energy store in plant biomass after respiratory losses to the environment have been taken into account.
    NPP= GPP -R
  • NPP is available for new plant growth and reproduction OR available for other trophic levels in the ecosystem, such as herbivores and saprobionts.
  • kJ ha–1 year–1 OR kJ km–2 year–1 OR kJ km–3 year–1
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11
Q

The percentage of the light energy trapped by the producers is very low. Give two reasons why.

A
  • Reflected / absorbed by water vapour;
  • Reflected from producers / wrong wavelength;
  • Transmitted / passes between chloroplasts/ between plants / too few chloroplasts;
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11
Q

The biomass of primary consumers is less than the biomass of producers. Explain why.

A
  • Loss of energy/heat / use of energy / less energy to be passed on;
  • In respiration;
  • In excreta / excretion / urine / carbon dioxide;
  • Inedible parts / indigestible parts / egesta / egestion / to decomposers;
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12
Q

Describe how and explain why the efficiency of energy transfer is different at different stages in the transfer.

A
  • Some light energy fails to strike/is reflected/not of appropriate wavelength;
  • Efficiency of photosynthesis in plants is low/approximately
  • 2% efficient;
  • Respiratory loss / excretion / faeces / not eaten;
  • Loss as heat;
  • Efficiency of transfer to consumers greater than transfer to producers/approximately 10%;
  • Efficiency lower in older animals/herbivores/ primary consumers/warm blooded animals;
  • Carnivores use more of their food than herbivores;
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13
Q

Explain how the intensive rearing of domestic livestock increases net productivity

A
  • Slaughtered when still growing/before maturity/while young so more energy transferred to biomass/tissue/production;
  • Fed on concentrate /controlled diet /controlled conditions/so higher proportion of (digested) food absorbed/lower proportion lost in faeces / valid reason for addition;
  • Movement restricted so less respiratory loss / less energy used;
  • Kept inside/heating/shelter / confined so less heat loss / no predators;
  • Genetically selected for high productivity;
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14
Q

Describe the need for plants to both photosynthesise AND respire

A
  • In the dark no ATP production in photosynthesis;
  • Some tissues unable to photosynthesise/produce ATP;
  • ATP cannot be moved from cell to cell/stored;
  • Plant uses more ATP than produced in photosynthesis;
  • ATP for active transport;
  • ATP for synthesis (of named substance);
15
Q

Define carbon sink.

A

Store of carbon
e.g peat

16
Q

What are mycorrhizae?

A
  • Fungal associations between plant roots and fungi.
  • Provide large SA for uptake of water and inorganic ions.
  • Absorbs and holds minerals and water easily.
17
Q

Outline advantages of having mycorrhizae growth near plants.

A
  • Mycorrhizae help plants to defend themselves (causing an increase in crop yield);
  • Mycorrhizae help plants to take up nitrates/phosphates (causing an increase in crop yield);
18
Q

Saprobiants

A

Organisms that digest their food externally and then absorb products.

19
Q

What is nitrogen cycle needed for?

A

To create DNA, RNA, amino acids, ATP etc.

20
Q

Stages of nitrogen cycle

A
  1. Nitrogen fixation
  2. Ammonification
  3. Nitrification
  4. Denitrification
21
Q

Nitrogen fixation

A

Nitrogen fixing bacteria convert nitrogen gas (N2) to ammonia (NH3).

22
Q

Ammonification

A

Saprobiants convert nitrogen containing compounds to ammonia.

23
Q

Nitrification

A

Nitrifying bacteria oxidises ammonia to nitrites, then nitrites to nitrates.

24
Q

Denitrification

A

Denitrifying bacteria converts nitrates to nitrogen gas.

25
Q

Describe the role of saprobionts in the nitrogen cycle.

A
  • (use enzymes to) decompose proteins / DNA / RNA / urea;
  • Producing / releasing ammonia / ammonium ions;
26
Q

Give two examples of biological molecules containing nitrogen that would be removed when a crop is harvested.

A
  1. amino acid/protein/ polypeptide/peptide;
  2. nucleic acid/nucleotide/base;
  3. DNA;
  4. RNA / pre-mRNA / mRNA / rRNA / tRNA
  5. ATP/ADP;
  6. NAD/NADP (reduced or not);
  7. Cyclic AMP/cAMP;
  8. Chlorophyll;
27
Q

Describe how the action of microorganisms in the soil produces a source of nitrates for crop plants.

A
  1. Protein/ AAs/ DNA converted into ammonia
  2. By saprobiants.
  3. Ammonia is then converted to nitrite
  4. Then nitrite to nitrate
  5. By nitrifying bacteria
  6. Nitrogen gas to ammonia
  7. By nitrogen fixing bacteria
28
Q

Plants absorb a number of other nutrients from the soil including phosphates. Describe why phosphates are needed by a growing plant.

A
  • production of phospholipids;
  • in cell membranes;
  • synthesis of ATP;
  • production of DNA;
  • production of RNA;
  • production of NADP
29
Q

Explain the phosphorus cycle.

A
  1. Phospholipids, RNA, DNA from dead organisms converted into phosphate ions
  2. Decomposed by saprobiants.
  3. Phosphate ions also found in waste and remains
  4. Phosphate ions are transported by streams and lakes
  5. Form sedimentary rock
  6. Weathering and erosion of rocks help the phosphate ions to dissolve in oceans, lakes and soils.
  7. Phosphates become available for absorption by plants to incorporate into biomass.
30
Q

Describe how a lack of phosphates in the soil surrounding a plant can affect its growth

A
  • (Required to) make ATP/glucose phosphate, so less respiration/less energy for growth;
  • (Required to) make nucleotides, so less DNA/mRNA/tRNA for cell division/production of protein (for growth);
  • (Required to) make RuBP/NADP, so less CO2 fixed/reduced into sugar;
  • (Required to) make phospholipids for membranes;
30
Q

Describe how a lack of phosphates in the soil surrounding a plant can affect its growth

A
  • (Required to) make ATP/glucose phosphate, so less respiration/less energy for growth;
  • (Required to) make nucleotides, so less DNA/mRNA/tRNA for cell division/production of protein (for growth);
  • (Required to) make RuBP/NADP, so less CO2 fixed/reduced into sugar;
  • (Required to) make phospholipids for membranes;
31
Q

Describe the process of eutrophication.

A
  • Nitrates / Phosphates / Ammonium ions flushed into waterway
  • Increased algal bloom
  • Light blocked out
  • Submerged aquatic plant unable to photosynthesise and die
  • Increase in saprobionts so increases rate of aerobic respiration
  • Saprobionts / aero.resp organismsn die as lack of oxygen (anoxic)
  • Increase in anaerobic microorganisms
  • Production of toxins
32
Q

Examples and advantages of natural fertilisers

A
  • Manure, seaweed, peat
  • Cheap
  • Free if from own livestock.
33
Q

Advantages of artificial fertilisers.

A
  • Contain exact amounts of minerals.
  • More water soluble.

Biology Noor (30 decks)

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