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biology > unit 3 > Flashcards

unit 3 Flashcards

1
Q

what is an ecosystem

A

consists of all the organisms (the community) living in a particular habitat and the non-living components with which they interact

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2
Q

what is a species

A

group of organisms which can interbreed to produce fertile offspring

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3
Q

what is a population?

A

number of organisms within a particular species

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4
Q

what is biodiversity

A

variety of life within an ecosystem

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5
Q

what is a community?

A

all the organisms that live within a habitat or ecosystem

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6
Q

what is a habitat

A

the place where an organism lives

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7
Q

what is a food chain

A

a series of organisms which can depend on each other for food (energy)

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8
Q

what’s a herbivore?

A

an animal which consumes only plants to gain energy

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9
Q

what’s a omnivore?

A

an animal that consumes both plants and animals to gain energy

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10
Q

what’s a carnivore

A

an animal that consumes other animals to gain energy

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11
Q

producer:

A

any green plant that makes its own food via photosynthesis

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12
Q

consumer:

A

an animal that consumes plants or other animals for energy

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13
Q

prey:

A

animals who are hunted by predators

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14
Q

predator:

A

hunts prey to gain energy

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15
Q

food web:

A

a diagram which shows the interconnection of food chains and the feeding relationship in an ecosystem

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16
Q

niche:

A

role an organism plays within its community

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17
Q

interspecific competition:

A

individuals of different species competing for one or a few resources they require

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18
Q

intraspecific competition:

A

individuals of the same species and is for all resources required

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19
Q

biotic:

A

living factor which affects biodiversity
eg competition, predation, grazing, disease

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20
Q

abiotic:

A

non-living factor which affects biodiversity
eg temperature, pH, soil moisture, light intensity

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21
Q

quadrats:

A

used to estimate the number of plants or slow moving animals of a particular type in an area

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22
Q

errors of quadrats and how to minimise

A

not enough placed - place more

some plants may be partially in or out - decide how ur going to sample

biased - throw randomly

23
Q

pitfall traps:

A

use to sample invertebrates which live on the ground

24
Q

errors of pitfall traps and how to minimise

A

not enough to represent ecosystem - place more traps

some animals eaten by predators - check regularly

water filling in trap - drainage holes

25
Q

indicator species:

A

species that by their presence or absence indicate environmental quality/levels of pollution

26
Q

how is energy lost in a food chain

A
  • heat
  • undigested materials
  • movement
27
Q

pyramid of energy

A

shows the energy available at each link in food chain

28
Q

pyramid of numbers

A

diagram that shows the total number of organisms at each link in food chain

29
Q

photosynthesis:

A

reaction that converts light energy into chemical energy. during photosynthesis light energy along with carbon dioxide and water are used to produce sugar and oxygen

30
Q

word equation:

A

light energy
CO2 + H2O —————-> sugar + O2

31
Q

light reactions:

A

light energy from the sun is trapped by a green pigment called chlorophyll in the chloroplast. the light energy is converted into chemical energy which generates ATP. water is split into hydrogen and oxygen during the light reactions. the hydrogen is used in the second stage and the oxygen diffuses from the cell

32
Q

carbon fixation:

A

CF uses hydrogen and ATP from the 1st stage to convert carbon dioxide form the air into sugar. this stage is catalysed by enzymes : affected by temp

33
Q

fates:

A
  • sugar converts into starch (storage)
  • sugar converts into cellulose ( structural)
  • sugar is available for respiration (glucose)
34
Q

limiting factors of photosynthesis

A
  • temp
  • light intensity
  • carbon dioxide concentration
35
Q

fertiliser:

A

added to soil to increase nitrate content of soil to increase crop yield

36
Q

what is GM crops

A

involves inserting DNA into the genome of an organism to give it new or different characteristics
helps to maintain crop yield

37
Q

bioaccumulation:

A

the build up of toxic substances in living organisms

38
Q

pesticide:

A

substance used to kill insects which destroy the crop

39
Q

biological control:

A

controlling pest numbers by introducing a natural predator

40
Q

mutation:

A

random change to genetic material, they can be neutral, advantageous or disadvantageous to survive
- mutations are spontaneous and are the only source of new alleles

41
Q

mutagenic agent:

A

environmental factors which increase the rate of mutation eg extreme temp, radiation and chemicals

42
Q

adaptation:

A

inherited characteristic that makes an animal/plant well suited to its environment

43
Q

variation within a population makes it possible for…

A

… a population to evolve over time in response to changing environmental conditions

44
Q

selection pressures of natural selection:

A

food
predation
climate
disease

45
Q

natural selection:

A
  1. species produce more offspring than the environment can sustain
  2. when there are selection pressures, the best adapted individuals survive to reproduce, passing on the favourable alleles that confer the selective advantage
  3. these alleles increase in frequency within the population
  4. this can result in a population becoming better adapted to its ecological niche
46
Q

speciation (simple definition)

A

formation of a new species

47
Q

isolation barriers:

A
  • geographical barriers = physically separating groups within a population eg rivers or mountains
  • behavioural barriers = separating populations because of behaviour of individuals eg females selecting for a different male characteristic during mating season
  • ecological barriers = separating populations due local differences in the environment eg pH or salinity
48
Q

stages of speciation:

A
  1. isolation by barrier - speciation occurs after part of a population becomes isolated by an isolation barrier (ecological, behavioural or geographical)
  2. different mutations occur randomly in the each sub population causing new variation
  3. natural selection selects for different mutations in each group, due to different selection pressures
  4. each sub-population evolves until they become so genetically different that they are 2 different species (they can’t interbreed and produce fertile offspring)
49
Q

why can’t photosynthesis occur at very high temps?

A

because enzyme activity is lower

50
Q

what are nitrates?

A

they are the type of chemical found in fertilisers that plants use to make amino acids

51
Q

speciation (simple steps)

A
  1. isolation barriers
  2. mutations in each sub-population
  3. natural selection
  4. evolve into different species
52
Q

why does natural selection ensure the most favourable alleles are passed on?

A

because the species with the favourable alleles survive as they are more adapted

53
Q

products of light reactions:

A

hydrogen and oxygen

biology (2 decks)

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