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Biology > Energy and Ecosystems > Flashcards

Energy and Ecosystems Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

define trophic level

A

stages in the food chain

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2
Q

define biomass

A

total mass of living material in a specific area at a given time

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3
Q

define food chain

A

feeding relationships

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4
Q

define food web

A

many food chains linked together

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5
Q

define saprobionts

A

decomposers that break down DOM to form simple molecules from complex ones

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6
Q

define producer

A

photosynthetic organisms which synthesise organic substances from light, H2O, CO2

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7
Q

define consumer

A

organisms that obtain energy by consuming other organisms

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8
Q

define primary consumer

A

directly eats consumers

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9
Q

define secondary and tertiary consumer

A 
sec = eat primary consumer 
tert = eat secondary consumer
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10
Q

most sugars synthesised by plants are used as…

A

respiratory substrates

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11
Q

other sugars synthesised by plants make up biological molecules which form…

A

the biomass of the plant

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12
Q

biomass can be measured in terms of mass of _____ or dry mass of _____ per given ____.

A

carbon, tissue, area

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13
Q

how can the chemical energy stores in dry biomass be estimated?

A

calorimetry

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14
Q

in any ecosystem, plants synthesise organic compounds from….

A

atmospheric or aquatic CO2

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15
Q

define the 4 steps of calorimetry

A
  1. sample dried in oven (evap H2O)
  2. sample weighed + placed in the bomb + ignited in O2 atmosphere
  3. heat from combustion transferred to H2O = thermometer increases in temp
  4. can calculate energy content
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16
Q

what is calorimetry

A

used to estimate the energy contained in a substance by measuring the heat generated during its combustion

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17
Q

what 2 things you should note about the stirrer during calorimetry

A
  1. stirrer increases accuracy = makes sure heat passes thru evenly
  2. use plastic one = so doesn’t absorb heat
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18
Q

when do you stop drying the sample?

A

until a constant mass is reached

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19
Q

what is the formula for energy content of sampler?

A

4.2 x vol of H2O x temp change / mass of sample

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20
Q

name 3 reasons why only 1-3% of Sun’s energy converted to OM

A
  1. 90% sun rays reflected by clouds or absorbed by atmo.
  2. not all wavelengths can be absorbed
  3. light not fall on chloroplast
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21
Q

name 4 reasons why energy is lost between trophic levels

A
  1. parts of organism not consumed
  2. excretory products i.e. urine
  3. can’t be digested, lost in faeces
  4. losses thru respiration
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22
Q

why is there only 4/5 trophic levels?

A

insufficient energy is available to support a large enough breeding pop.

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23
Q

define gross primary production (GPP)

A

chemical energy store in plant biomass in a given area/volume in a given time

24
Q

plants use around 20-50% of gross ______ ________ in _________ losses (R).

A

primary production, respiratory

25
Q

define net primary production (NPP)

A

chemical energy store in plant biomass after respiratory losses to the environment are taken into account

26
Q

what is the formula for NPP

A

NPP = GPP - R

27
Q

NPP is available to for what 2 things?

A

growth and reproduction

28
Q

NPP is available to other ______ levels in the ecosystem i.e. herbivores and _________

A

trophic, decomposers

29
Q

how is the net production of consumers (N) calculated?

A

N = I (F + R)

30
Q

what do these mean in the formula: I, F and R

A 
I = chemical energy store of ingested food
F = energy lost in faeces/urine 
R = energy lost in respiration
31
Q

what is the formula for calculating the % efficiency of energy transfers

A

energy available AFTER transfer / energy available BEFORE transfer x 100

32
Q

name 3 ways farming practices have been designed to increase efficiency of energy transfer

A
  1. simplifying food webs = reduces energy losses to non-human food chains
  2. restricting movement of animals i.e. in cages (less resp)
  3. environment heated (reduces heat loss)
33
Q

name the 3 main features of nutrient cycles

A
  • flow of nutrients is cyclic not linear
  • saprobiontic organisms release nutrients for reuse
  • nutrients recycled in ecosystems
34
Q

why is phosphorus important (3 reasons)

A
  • DNA/RNA phosphodiester backbone (strengthens DNA)
  • ATP 3 phosphates (stores/releases energy)
  • phospholipid bilayer (allows lipid soluble molecules thu)
35
Q

which is slower: nitrogen or phosphorus cycle and why?

A

phosphorus as main reservoir is minerals as there is no air component

36
Q

describe the phosphorus cycle in 6 steps

A
  1. phosphorus as phosphate (PO4^3-) in sedimentary rock deposits brought to surface by geological uplifting
  2. weathering/erosion = phosphates dissolve
  3. absorbed by plants
  4. absorbed by animals
  5. excess phosphate excreted + accumulates (guano)
  6. death of organisms = saprobionts release phosphorus
37
Q

name the 2 reasons why nitrogen is important

A
  • makes up amino acids/proteins

- makes up nucleic acids

38
Q

what is nitrogen fixation

A

when atmospheric nitrogen is converted into nitrogen containing compound in the soil

39
Q

name the 2 types of fixation

A
  • biological

- industrial (Haber process)

40
Q

biological fixation is catalysed by __________ and is ________

A

nitrogenase, anaerobic

41
Q

nitrogen fixating bacteria respires….

A

aerobically

42
Q

role of free living bacteria in nitrogen fixation

A
  • reduces gaseous nitrogen to ammonia

- nitrogen rich compounds released when they decay

43
Q

role of mutualistic bacteria in nitrogen fixation

A

live in root nodules of legumes (obtain carbohydrates from plant and plant acquires amino acids from them)

44
Q

what is ammonification

A

production of ammonia (NH3) from ammonium (NH4)

- saprobiontic organisms carry it out

45
Q

what is nitrification

A

ammonia oxidised into nitrite then oxidised into nitrate which plants can absorb by active transport

46
Q

what is denitrification

A
  • converts soil nitrates into gaseous nitrogen

- occurs when soil is anaerobic i.e. waterlogged

47
Q

what mycorrhizae

A

a type of fungi that has a symbiotic relationship with the plant and assists in the uptake of H2O and inorganic ions

48
Q

what is the role of hyphae on mycorrhizae?

A

increase SA for H2O = mineral uptake

49
Q

why do we use fertilisers? (2)

A
  • replace nitrates/phosphates lost by harvesting plants/ removing livestock
  • increases crop yield/productivity
50
Q

what are organic fertilisers

A
  • made up of DOM, decaying OM or organic waste
  • add OM to soil = reduce erosion + hold H2O
  • release nutrients over long period of time
51
Q

what are inorganic fertilisers

A
  • mined from rocks/deposits

- enriched in nitrogen/phosphorus/potassium

52
Q

name 2 advantages of inorganic fertilisers

A
  • guaranteed composition (determine rates of application/ effect on crop)
  • concentrated = smaller amounts applied so reduces transport costs
53
Q

name the 3 main environmental effects of nitrogen containing fertilisers

A
  • reduces biodiversity
  • leaching
  • eutrophication
54
Q

describe leaching

A

nitrates become soluble in rainwater and is carried out of soil. can lead to water pollution and eutrophication

55
Q

describe the process of eutrophication in 6 steps

A
  1. algal bloom (increase cell division) = block light
  2. photosynthetic plants die = reduce O2
  3. increase decomposition = saprobionts use O2
  4. less O2 = animals die
  5. anaerobic saprobionts decompose DOM
  6. release toxic substances = H2O putrid

Biology (25 decks)

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