Bio B4-B6 > B4.1 - Ecosystems > Flashcards

B4.1 - Ecosystems Flashcards

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1
Q

What do arrows on a food chain show?

A
  • the transfer of biomass

- transfer of energy

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2
Q

what is the difference between a food chain and a food web?

A

a food chain is a small section of the whole food web

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3
Q

what do food chains show?

A

the feeding relationship in an ecosystem

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4
Q

what are producers?

A

organisms that make their own food through photosynthesis

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5
Q

what are primary consumers?

A

animals that eat plants or algae (herbivores)

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6
Q

what are secondary consumers?

A

carnivores that eat herbivores

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7
Q

what is a tertiary consumer?

A

a carnivore that eats other carnivores

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8
Q

what are apex predators?

A

carnivores that have no other predators

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9
Q

what are decomposers

A

organisms that get energy from feeding on dead materials

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10
Q

what are consumers?

A

organisms that cannot make their own food and so have to eat other organisms

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11
Q

what are trophic levels?

A

each step in the food chain (where they feed)

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12
Q

what is a community?

A

organisms living within an ecosystem

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13
Q

define population

A

the total number of organisms of each species

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14
Q

what happens when an organism grows?

A

increases its biomass

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15
Q

state the factors affecting ecosystems and give a brief description

A
  • biotic (living - beech trees, squirrels, hedgehogs)

- abiotic (nonliving - amount of rainfall, temperature of ecosystem)

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16
Q

what biotic factors affect communities? - 4

A
  • food availability
  • breeding partners
  • COMPETITION
  • new pathogens
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17
Q

how does light intensity affect communities?

A
  • greater light available = greater plant success

- plants adapt for maximum absorption (larger leaves in low light)

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18
Q

how does temperature affect communities?

A
  • affects enzymes controlling metabolic reactions

- plants develop faster

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19
Q

what type of animals are affected by their external environments?

A

ectotherms (lizards)

rely on the sun to warm up

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20
Q

how does low moisture level affect plants?

A
  • causes plants to wilt (low turgor pressure)
  • water needed to keep cells turgid
  • affects photosynthesis
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21
Q

what does the pH of soil affect?

A
  • biological activity in soil

- availability of certain minerals

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22
Q

what kind of plants grow better in acidic soils?

A

ferns

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23
Q

what do plants need to survive? (5)

A
  • light
  • water
  • carbon dioxide
  • minerals
  • space
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24
Q

what do animals need to survive?

A
  • food
  • water
  • breeding partner
  • space (territory)
  • shelter
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25
define population
the number of organisms of each species living in an area
26
what is interdependence within a community?
how different organisms depend on each other
27
what are ecological relationships?
interactions between organisms
28
what are the three main types of ecological relationships
- predation - mutualism - parasitism
29
what is predation the relationship of?
- relationship between predator and prey - size of predator population directly affects prey population - cyclic relationship
30
what is mutualistic relationship?
- both organisms benefit
31
give an example of a mutualistic relationship
bees taking pollen from plants | bees can make honey, plants become fertilised
32
what is a parasitism relationship?
one organism gains (parasite), other suffers (host)
33
give an example of a parasitism relationship
tapeworms in a human’s digestive system
34
what is commensalism?
one organism benefits from, but the other one is unaffected
35
what is an example of a commensalistic relationship?
tree frogs use plants as protection
36
what is a biotic factor?
a factor relating to animals (ie. competition of mating)
37
what is an abiotic factor?
a factor which is not living? (ie. rainfall)
38
why do food chains not exceed 4/5 tertiary levels?
not enough energy can be transferred to sustain life processes) - because of 10% rule
39
what does a pyramid of numbers show?
- the population at each trophic level (how many there are)
40
what do pyramid of numbers not take into account?
the size of the organism present
41
how do scientists calculate biomass?
- get dead organism - dry the organism in a kiln (evaporate water mass) - then measure it CALLED DRY MASS
42
how do scientists calculate the total biomass at each trophic level?
measure average mass of each organism and multiply by the number of organisms present
43
state three reasons biomass is lost between trophic levels
- not all organism is eaten (animal bones/ plant roots) - biomass is used during respiration - some parts of organism cannot be digested (hair/teeth) - egestion - released as waste products (excretion/ urine)
44
what is the nutrient cycle?
the process in which materials are passed between biotic and abiotic components of an ecosystem
45
what is carbon used to make?
GLUCOSE which makes... - carbohydrates - fat - dna - proteins
46
in what form can organisms use nitrogen?
when part of a compound (like a nitrate)
47
why do organisms use nitrogen?
- DNA | - proteins
48
Apart from providing water to organisms, describe another benefit of then water cycle
transports nutrients (helps replenish nutrients in different habitats)
49
how is carbon removed from the atmosphere?
- photosynthesis | - when animals eat plants
50
how is carbon released back into the atmosphere? - 3
- respiration - decomposition - burning fossil fuels
51
how does the level of atmospheric carbon vary throughout 24 hours?
- decreases during daytime (photosynthesis) | - increases during nighttime (no photosynthesis, but respiration continues)
52
what are decomposers?
microorganisms which break down or decay dead organic matter at a microscopic level
53
how do decomposers help the nutrient cycle?
release nutrients (can be recycled)
54
what are detritivores?
small animals which shred organic material to small pieces (create larger surface area for decomposers) An organism that eats DOM and digests internally for nutrients
55
how do decomposers release nutrients?
- bacteria and fungi release enzymes - break down substances in the organic materials - absorb soluble nutrients + use them for growth + energy store - some others released into soil // many bacteria/fungi eaten by other organisms, resulting in the nutrients being passed on
56
how do temperatures affect rate of decomposition?
- too high = enzymes used by microorganisms denature (they die) - too low = rate of enzyme controlled reactions too slow
57
how does lack of water in environments affect rate of decomposition?
- not enough water = reactions slow down/stop
58
how does lack of oxygen affect decomposition?
decreases, oxygen needed for microorganism to respire (so cannot survive)
59
what is the equation to calculate the rate of decay of material?
rate of decay (g/day) = change in mass (g) / time (day)
60
give 3 examples of detritivores
- earthworm - woodlouse - maggot
61
what 3 factors affect rate of decomposition?
water level, temperature, oxygen level
62
Describe how water is cycled through an ecosystem.
Water evaporates from rivers and lakes and from transpiration Water condenses as clouds Water is returned through precipitation
63
Describe how carbon is cycled through an ecosystem.
Carbon dioxide is fixed through photosynthesis Respiration releases carbon dioxide Decomposition releases carbon dioxide Combustion releases carbon dioxide
64
Describe how nitrogen is cycled through an ecosystem.
Nitrogen is fixed by lightning and nitrogen-fixing bacteria. Denitrifying bacteria release nitrogen into the air from nitrates in the soil. Denitrifying bacteria covert nitrates in soil into nitrites and nitrites to ammonia. Nitrifying bacteria convert ammonia in soil into nitrates. Nitrates in soil taken up by plants and combined with carbohydrates to make plant proteins. Plant proteins either eaten by other animals to form animal protien or die and decompose to release ammonia into soil. Animals excrete ammonia and die and decompose to release ammonia into soil.
65
How is fungal infections in plant spread
- spread by wind - spores - enters leaves through the stomata
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