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M6 C23: ecosystems Flashcards

1
Q

what are some examples of abiotic factors?

A

temperature
light
pH
water and humidity

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2
Q

how does temperature affect ecosystems?

A

Each species has a different optimum temperature
The further away from the optimum, the fewer can survive.
Ectothermic animals can grow faster (can’t control their own temp.)

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3
Q

how does light affect ecosystems?

A

Greater light intensity = greater rate of photosynthesis, more seeds produced, higher population, more animals can be supported
some may grow bigger leaves to absorb more light or develop pigments to require less light

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4
Q

how does pH affect ecosystems?

A

can break bond in enzymes used in reactions in metabolic reactions. slow rate of reactions, organisms less likely to survive

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5
Q

how does water and humidity affect ecosystems?

A

increased humidity means less water loss due to transpiration
water is scarce only species that are adapted to dry conditions will increase/maintain their population.

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6
Q

how does oxygen availability affect ecosystems?

A

aquatic ecosystems, it is beneficial to have fast flowing, cold water as it has high concs. of oxygen. Water-logged soil = less oxygen

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7
Q

how does soil factors affect ecosystems?

A

it provides the minerals needed for growth
water (for photosynthesis)
anchorage for the roots

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8
Q

what is clay soil?

A

Few air spaces, Retains water and flood easily
Eg. clay

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9
Q

what is sand soil?

A

Lots of large air spaces
Does not retain water
Eg. Sand

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10
Q

what are some examples of adaptations of organisms to abiotic factors?

A

otters have webbed feet – can walk on land and swim in water
whales have a thick blubber – keep warm in cold seas where food is plentiful
bears hibernate in winter – increase chance of survival as they conserve energy in coldest months

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11
Q

what are some examples of biotic factors?

A

competition
food
territory
breeding partners

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12
Q

what are some examples of adaptations of organisms to biotic factors?

A

monkeys use twigs to fish for termites – another source of food
scorpions dance dance before mating – ensures that they are the same species
Some bacteria produce antibiotics – kills other species of bacteria

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13
Q

what is a ecosystem?

A

Made up of all the living organisms that interact with one another in a defined area, and also the physical factors present in that region

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14
Q

what is the biosphere?

A

global sum of all ecosystems, representing the part of the Earth where life exists.

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15
Q

what is a producer?

A

Makes its own food, usually by photosynthesis.​

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16
Q

what is a carnivore?

A

Eats only other animals.

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17
Q

what is a herbivore?

A

Eats only plants.​

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18
Q

what is a omnivore?

A

Eats both animals and plants.​

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19
Q

what is a primary consumer?

A

Eats producers. Usually a herbivore.​

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20
Q

what is a secondary producer?

A

Eats primary consumer, usually a carnivore but could also be a herbivore.​

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21
Q

what is a trophic level?

A

position or stage that an organism occupies in a food chain.

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22
Q

what is biomass?

A

mass of living material present in a particular place or in particular organisms. Energy stored within biomass can be passed along the food chain to different trophic levels.

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23
Q

how much biomass of each organism is passed onto the next trophic level?

A

Consumers at each trophic level convert at most 10% of the biomass in their food to their own organic tissue.

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24
Q

why is only 10% of biomass passed onto the next trophic level?

A

-not all parts of an animal can be digested
-Energy from cellular respiration is transferred by heating the surroundings
-used to provide energy for movement, growth, etc
-lost in urine and faeces

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25
why are fewer trophic levels more efficient?
-Energy is lost at each trophic level​ -Not all energy is passed to consumer as not all parts are digested​ -Energy is lost through respiration, excretion, heat and movement​ -The consumer loses up to 90% of the energy at each level / 10%passed on​
26
what are methods of measuring biomass?
Mass of fresh material present​- (easiest method but unreliable as mass of water varies greatly)​ Dry mass​ - (most accurate but organisms have to be killed and put in an oven at 80°C to evaporate all the water)
27
what units are used to meassure biomass?
Areas of land ​- g/m-2 (grams per square metre) ​ Areas of water -g/m-3 (grams per cubic metre)​ The energy available at each tropic level is measured in:​ KJm-2yr-1 (kilojoules per metre squared per year)​ This allows for seasonal changes in photosynthesis and feeding patterns.
28
what is ecological efficencey?
The efficiency with which biomass or energy is transferred from one trophic level to the next.
29
how is the efficiency of producers affected?
- only convert 1-3% of the sunlight into chemical energy, therefore biomass.​ -Not all solar energy available is used for photosynthesis 90% is reflected -Limiting factors of photosynthesis (water availability/ CO2)​ - Some energy lost in photosynthetic reactions
30
what happens in the nitrogen cycle?
1. Nitrogen gas is fixed into nitrate compounds by bacteria in root nodules or lightning 2. Plants take in nitrates from soil to make protein for growth 3. Nitrogen compounds (protein) passed along a food chain 4. Decomposers (soil bacteria and fungi) convert protein and urea to ammonia 5. Ammonia is converted to nitrates by nitrifying bacteria 6. Nitrates are converted to nitrogen gas by denitrifying bacteria
31
why do we need the nitrogen cycle?
nitrogen-containing compounds exist on earth in finite amounts … no external source replenishing. Must be recycled!​
32
what is decomposition?
Chemical process. Compound broken down into constituent molecules.
33
what are decomposers?
Organism that feeds on/breaks down dead matter. ​ Convert organic compounds into inorganic compounds. ​ They are saprotrophs ​ Examples: bacteria, fungi
34
what are detrivores?
Speed up decay process; feed on detritus (dead material)​ Break dead matter down into smaller pieces. Increases SA for decomposers.​ Examples: maggots, earthworms, woodlice
35
what happens in nitrogen fixation?
Nitrogen gas is converted into nitrogen containing compounds​ Azotobacter and Rhizobium bacteria contain nitrogenase enzyme to convert nitrogen and hydrogen into ammonia.
36
what do Azotobacter (Free living bacteria ) do?
produce ammonia from nitrogen gas. Make amino acids. Release them when they die.
37
what do mutalistic bacteria do?
live in root nodules in peas and beans. Obtain carbohydrates from plant and plant gets amino acids from bacteria
38
what is ammonification?
Production of ammonia from organic compounds e.g. urea, proteins, nucleic acids. ​ Saprobionts microorganisms release ammonia into the soil.
39
what happens in nitrification 1?
Nitrifying bacteria oxidise ammonium compounds. (e.g. Nitrosomonas)​ Ammonium ions are converted to nitrite ions (NO2-)​ Oxidation reaction: aerated soil required
40
what happens in nitrification 2?
Nitrite ions converted to Nitrate Ions (NO3-)​ This requires oxygen, too. Nitrobacter bacteria do this
41
when does denitrification occur?
Occurs when soils become waterlogged – short of O2
42
what happens in denitrification?
Anaerobic bacteria carry this out​ Soil nitrates converted to nitrogen in the atmosphere​ Reduced nitrogen compounds available to plants – for land to be productive it must be kept well aerated.
43
what percentage of the earths atmosphere is CO2?
0.04%
44
what processes remove CO2?
photosynthesis
45
what processes put CO2 back into the atmosphere?
combustion- burning of fossil fuels respiration decomposition of dead organisms
46
what are some fluctuations that occur in CO2 concentration?
increases during the night as photosynthesis isn't occurring, stomata are closed in winter leaves shed so photosynthesis doesn't occur, shorter day length
47
why has the levels of CO2 increased over the past few hundred years?
deforestation- less plants to get rid of CO2 by photosynthesis combustion of fossil fuels released by burning fuels
48
what does the sea do in regards to CO2 concentration?
it acts as a carbon sink as CO2 dissolves in the sea
49
how is the sea absorbing CO2 an example of positive feedback?
high temperatures means that less CO2 is dissolved. change in temp is reinforced by less CO2 dissolved
50
what is the greenhouse effect?
heat from the sun reflected from earths surface when reaches the atmosphere some rays pass through other layers are either reflected back into space or trapped in the ;layer by greenhouse gases
51
how is methane produced?
when decomposers break down dead remains of organisms. microbes in primary consumers digest food that has been eaten
52
what increases the concentrated of methane?
more cattle more decaying waste eg landfill more extraction of fossil fuels
53
what are some consequences of global warming?
changes in temperature/ precipitation failure of crops ice caps melt which increase sea levels food chains affected timing of seasons flooding extreme weather events alter niches
54
what is an ecosystem?
biological community of interacting organisms and their physical environment. It consists of the biotic components (living organisms) and the abiotic components (non-living aspects such as water, sunlight, and soil).
55
what is a community?
an intricate network of interactions among different populations coexisting in the same area
56
what is succession?
process of an ecosystem changing over time
57
what are pioneer species?
the 1st organisms that begin to colonise in a certain area
58
what are some examples of pioneer species?
marram grass algae lichin
59
what are some features of a pioneer species?
-produce large quantities of easily dispersible seeds or spores -rapid germination -ability to photosynthesise to create food -ability to fix nitrogen, soil usually has few nutrients -can withstand extreme conditions
60
what are stages in succession called?
a seral stage
61
what are the stages of primary succession?
barren landscape pioneer species intermediate species climax community
62
what happens in the first seral stage? (barren landscape)
Firstly, seeds and spores that are carried by the wind land on the exposed rock/ barren landscape and begin to grow
63
what happens in the first seral stage? (pioneer species)
These pioneer species colonise the new land (often moss and lichens) As they die and decompose, the dead organic matter (humus) forms a basic soil
64
what happens in the first seral stage? (intermediate community)
-Seeds of small plants and grasses, land on this basic soil and begin growing (adapted to survive in nutrient-poor soils) -As they die and decompose, the new soil becomes deeper and more nutrient-rich -Larger plants and small trees, that require deeper, more nutrient-rich soil, can now begin to grow as soil is deeper
65
what happens in the first seral stage? (climax community)
the soil is sufficiently deep, contains enough nutrients and can hold enough water to support the growth of large trees These final species to colonise the new land become the dominant species of the now complex ecosystem final community formed, containing all the different plant and animal species that have now colonised the new land, is known as the climax community
66
what stage of primary succession contains the most biodiversity?
the intermediate community as the climax community has low species eveness as it has a dominant species as animals live there
67
what happens during secondary succession?
a disruption to the intermediate/ climax community Happens on land that has been cleared of all plants, but where the soil remains goes back to intermediate community and over time returns to a climax community
68
what happens in animal succession?
the change of animals in a ecosystem, takes longer as they have to migrate and move to new habitat. eg from herbivores in intermediate stage to carnivores in climax
69
what is deflected succession?
when a community remains stable only because human activity prevents succession the plagioclimax that develops is one that is different to any of the natural stages of the ecosystem.
70
what is a plagioclimax?
When human activities prevent succession, stopping the normal climax community from developing, so succession is stopped artificially.
71
what is an example of a plagioclimax?
The management of a nature reserve prevents the growth of large trees. This keeps the land as heathland and is done to protect some of the small reptiles that inhabit the area.
72
what is an example of deflected successiomn?
sheep grazing on grass prevents the growth of woodland even though it could support it.

Biology (23 decks)

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