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Biology > 19. Organisms And Their Environment > Flashcards

19. Organisms And Their Environment Flashcards

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1
Q

what is the main source of energy in biological systems

A

the sun

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2
Q

describe the flow of energy in biological systems

A
  • light energy from the sun is trapped by photosynthetic organisms
  • energy is stored as chemical energy in organisms
  • energy is eventually lost to the environment
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3
Q

what is a food chain

A

a way of showing the flow of energy between organisms starting with a producer

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4
Q

how is energy transferred between organisms in a food chain

A

by ingestion

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5
Q

what is a trophic level

A

the position that an organism holds in a food chain, food web, pyramid of numbers or pyramid of biomass

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6
Q

why are biomass transfers not 100% efficient

A

egestion
excretion
respiration
the production of inedible bones and shells

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7
Q

why do food chains usually have fewer than 5 trophic levels

A

biomass transfers are not 100% efficient and so there is often not enough energy to support 5 trophic levels

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8
Q

why is it most efficient to supply plants as food for humans

A

using the plants as food for livestock wastes energy as the biomass transfers are not 100% efficient

eating plant transfers can maximize the amount of energy gained as there is only on transfer

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9
Q

what is a food web

A

multiple interconnected food chains

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10
Q

what is a producer

A

an organism that makes its own food

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11
Q

what is a consumer

A

an organism that gets its energy by eating other organisms

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12
Q

what is a primary consumer

A

an organism that feeds on producers

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13
Q

what is a secondary consumer

A

an organism that feeds on primary consumers

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14
Q

what is a tertiary consumer

A

an organism that feeds on secondary consumers

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15
Q

what are herbivores

A

herbivores are animals that only eat plants

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16
Q

what are carnivores

A

organisms that mainly eat animals

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17
Q

what are decomposers

A

organisms that break down dead matter

18
Q

explain the impact humans have on food chains and webs by over harvesting certain species

A

many organisms rely on other organisms for food, over harvesting can reduce the amount of food available for other animals

19
Q

explain the impact humans have on food chains and webs by introducing other species into a habitat

A

introducing new organisms increases competition and can interfere with the food chain, causing organisms who cannot compete to die

20
Q

what is a pyramid of numbers

A

a pyramid of numbers shows the number of organisms at each trophic level

21
Q

what is a biomass pyramid

A

a pyramid that shows the total dry mass of organisms at each trophic level

22
Q

why is a pyramid of biomass a better way of representing a food chain than a pyramid of numbers

A

pyramids of biomass take into account the size of the organisms and are less easily misinterpreted

23
Q

describe the carbon cycle

A
  • plants fix carbon dioxide into organic molecules during photosynthesis
  • the organic carbon containing molecules are passed onto organisms that eat the plants
  • carbon dioxide is released back into the atmosphere by respiration from animals and plants
  • burning fossil fuels also releases carbon dioxide into the atmosphere
24
Q

state the effect of burning fossil fuels on carbon dioxide concentration in the environment

A

burning fossil fuels releases more carbon dioxide into the atmosphere increasing the concentration of CO2

25
Q

state the effect f deforestation on carbon dioxide concentration in the environemnet

A
  • trees take in carbon dioxide during photosynthesis
  • cutting down trees prevents this and so the atmospheric carbon dioxide concentration does not decrease
26
Q

describe the water cycle

A
  • water from lakes and oceans evaporate
  • the evaporated water condense into clouds and returns to each as percipitation
  • the water from precipitation is useful for life on land
  • the water then returns to rivers and oceans through surface runoff
27
Q

why is the water cycle imporatnt

A

living organisms require water
the water cycle provides organisms on land with a continuous supply of water

28
Q

describe how nitrogen is cycled through an ecosystem

A
  • nitrogen is fixed by lightning and bacteria
  • decomposers break dead matter down into ammonium ions
  • nitrifying bacteria convert ammonia into nitrates and nitrites
  • denitrifying bacteria release nitrogen back to the atmosphere
29
Q

what is deaminiation

A

the removal of the amine group in an amino acid

30
Q

state 4 roles of bacteria in the nitrogen cycle

A

decomposition
nitrification
denitrification
nitrogen fixation

31
Q

define population

A

a species that occupy the same habitat at the same time

32
Q

define community

A

all the different populations in an ecosystem

33
Q

define ecosystem

A

both the community and their physical environment

34
Q

state 3 factors that affect population growth rates

A

disease
predation
availability of food

35
Q

name the sections of this chart showing growth in an environment with limited resources

A
36
Q

describe the ag phase in population growth

A

the organisms are adjusting to their environment

37
Q

describe the log phase in population growth

A

the growth of the population is increasing at a fast rate

38
Q

describe the stationary phase in population growth

A

the amount of births and deaths are equal

39
Q

describe the death phase in population growth in an environment with limited resources

A

once the resources begin to be used up, organisms begin to compete for resources and organisms will die as resources become scarce

40
Q

state 4 implications of a rapidly increasing population size

A
  • more land needed for living
  • greater demands on healthcare
  • greater demands on education
  • more resources needed which puts pressure on the environment

Biology (9 decks)

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