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Ecosystems Flashcards

1
Q

What is the definition of ecosystems?

A

consists of all the abiotic and biotic organisms that interact with one another in a defined area

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2
Q

What is meant by biotic factors?

A

interactions between LIVING organisms e.g.
- number of plants and animals

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3
Q

What is meant by abiotic factors?

A

non-living components, play a crucial role in forming an ecosystem

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4
Q

What are the five abiotic factors?

A
  1. light
  2. temperature
  3. water availability
  4. oxygen availability
  5. soil type
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5
Q

Why is light an important abiotic factor?

A

influence the growth and behaviour of photosynthetic organisms - producers

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6
Q

Why is temperature an important abiotic factor?

A

affects activity of enzymes that regulate metabolic and reproductive activities
warm conditions = plants may develop faster

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7
Q

Why is water availability an important abiotic factor?

A

critical for cellular activities, for maintaining cellular osmotic balance

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8
Q

Why is oxygen availability an important abiotic factor?

A

vital for survival of aerobic organisms as they need it to release energy

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9
Q

Why is soil type an important abiotic factor?

A

influences the soils drainage capacities and the nutrients it can offer to organisms

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10
Q

What is a trophic level?

A

stages in the food chain/web that represent the movement of biomass and energy through various organisms

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11
Q

What are the different trophic levels?

A

1.Producers = make their own food (photosynthesis)
2. Primary Consumer = herbivores
3. Secondary consumer = consumers primary e.t.c
4. Saprobionts (decomposers)

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12
Q

Why are decomposers important for the food chain?

A

decompose complex materials in dead organisms into simpler substances to obtain their food, release nutrients back into the ecosystem

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13
Q

What is the definition of biomass?

A

total mass of living material present in a certain time/ specific place

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14
Q

How is biomass measured?

A

grams m (-2) on land
g m (-3) aquatic

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15
Q

How is biomass calculated?

A

biomass present in each organism x total no. of organisms in that trophic level

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16
Q

What is meant by ecological efficiency?

A

the efficiency with which biomass or energy is transferred from one trophic level to the next

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17
Q

What is dry mass needed for?

A

for fresh material to be measured

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18
Q

How is dry mass calculated?

A
  • burn dry mass in a calorimeter
  • measure the volume + temp change of surrounding water
  • use these values to calculate an estimate for heat
  • energy released burnt from biomass
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19
Q

What is the definition of gross primary production (GPP)?

A

total volume of solar energy that plants convert into organic matter, storing chemical energy within biomass

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20
Q

What is meant by Net Primary Production (NPP)?

A

chemical energy that is available to the next trophic level after accounting for respiratory losses
energy converted into biomass

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21
Q

How is the NPP calculated?

A

NPP = GPP - R(respiration)

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22
Q

How is the ecological efficiency calculated?

A

energy/biomass available after transfer (DIVIDED BY) energy/biomass available before transfer

x 100

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23
Q

What are the factors that contribute to biomass loss at each trophic level?

A
  • not all solar energy captured by leaves/not right wavelength for photosynthesis
  • water availability
  • energy lost during photosynthesis
  • energy lost as heat during respiration
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24
Q

How does human activity affect trophic levels?

A

agriculture reduces the number of trophic levels

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25
What are detritivores?
are another class of organism involved in decomposition, increases the surface area for the decomposers to work on
26
DRAW THE NITROGEN CYCLE
CHECK ITS IN DESK
27
What is meant by nitrogen fixation (what is the chemical formula for this process)?
N2 +h2 -> NH3 - process is carried out by nitrogen fixing bacteria (Rhizobium) - contain the enzyme nitrogenase - this form of nitrogen can be absorbed by plants
28
What are the two ways nitrification can occur?
1. nitrifying bacteria (Nitrosomonas) oxidise ammonium compounds into nitrites (no2-) 2. Nitrobacter oxidise nitrites into nitrates (no3-)
29
What is the chemical symbol for ammonium?
NH3
30
What does nitrification allow plants to do? What is meant by the term?
assimilation when producers absorb useful substances and incorporate them into other compounds
31
What is the chemical formula for denitrification?
in the absence of o2 denitrifying bacteria convert nitrates in the soil back to nitrogen gas (only occurs in aerobic conditions) n03- -> n2 (atmospheric nitrogen)
32
What is ammonification?
decomposers converts nitrogen containing materials (dead organisms/waste) into ammonium compounds NH3 ->NH4+
33
DRAW THE CARBON CYCLE
CHECK NOTES FOR DIAGRAM
34
What are the 8 key processes in the carbon cycle?
1. Photosynthesis 2. consumption (along the food chain) 3. respiration 4. decomposition 5. formation of fossil fuels 6. combustion 7. weathering 8. volcanic activity
35
How is photosynthesis involved in the carbon cycle?
takes C02 out of the atmosphere
36
How is the formation of fossil fuels involved in the carbon cycle?
carbon, stored in dead organic matter, doesn't decompose due to an increase in temp and pressure
37
What causes some daily fluctuations in CO2 levels?
- respiration - photosynthesis (hours of day light)
38
What causes some of the seasonal variations in CO2 levels?
- in summer = increased photosynthesis - winter it is reduced, higher levels of CO2
39
What causes some of the annual CO2 levels to fluctuate?
- increase in greenhouse gas emissions - increased deforestation - global warming - decreased - solubility of co2 in oceans , dissolves in warmer temps
40
What is meant by succession?
process by which ecosystems change over time due to changes in the environment, causing the biodiversity in the area to change
41
What is meant by primary succession?
occurs on newly formed/exposed land e.g. bare rock, with no soil or organic material
42
What is meant by secondary succession?
occurs in areas where an existing community has been removed, leaving soil intact, but no plant or animal species
43
What is the first seral stage, what is the first community present called?
Pioneer community e.g. pioneer species = algae and lichens
44
What are some of the adaptations of the pioneer species?
- ability to produce large quantities of seeds and pores - seeds that germinate rapidly - tolerance to extreme environments
45
What is the second seral stage of successions?
intermediate community small plants and bushes as the environmental conditions continue to improve, new species move in
46
What is meant by humus?
when organisms of pioneer species die and decompose small organic products are released into soil
47
What is the final seral stage?
Climax community in a stable state and there is very little change overtime more dominant species = less biodiversity than intermediate community
48
What is a plagioclimax and how does it occur?
when succession is halted artificially by human activity - agriculture - deforestation - burning as a mean of forest clearance
49
What is meant by the distribution of organisms?
where organisms are found within an ecosystem
50
What is a line transect and how is it used?
involves laying a line of tape along the ground and taking samples at regular intervals
51
What is a belt transect and how is it used?
two parallel lines are marked, samples are taken of the area between two specified points
52
What type of sampling are belt and line transects?
systematic sampling non-random sampling
53
What are the advantages of using systematic sampling over random sampling?
+ allows scientists to see how different abiotic factors in different areas affect the distribution of species + see how plant species change as you move more in land
54
What is meant by the abundance of organisms?
refers to the number of individuals of a species present in an area at any given time
55
How does immigration and births affect the number of organisms?
increase the number
56
How does emigration and deaths influence the number of organisms?
decreases the number
57
What is the definition of population?
a group of similar organisms living in a given area at a given time
58
What is the equation to work out an estimate number of PLANTS in the population?
number of individuals in sample (DIVIDED) area of sample m2
59
What is the method to work out the estimate population size of ANIMALS?
1. capture as many individuals as possible in sample area 2. mark and tag each 3. release the marked animals back, allow them time to redistribute 4. recapture as many individuals in the same sample area 5. record the number of marked and unmarked individuals 6 use Lincolns index to estimate population size
60
How is Lincolns index used to estimate ANIMAL population size?
number of individuals in the first sample x no. in the second sample (DIVIDED) number of recaptured marked individuals
61
What is Simpson's Index of Diversity (D) used for?
biodiversity present within a habitat
62
What is the equation for Simpson's Index of Diversity (D)?
D = 1 - (sum of) (n/N)2 N = total number of organisms in the ecosystem n = number of individuals species ans 1 = infinite diversity 0 = no diversity

Biology Kireth (17 decks)

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