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A Level Biology : Content > Topic 5A : Ecosystems & Photosynthesis > Flashcards

Topic 5A : Ecosystems & Photosynthesis Flashcards

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1
Q

ecosystem

A

all the organisms living in a particular are and all the abiotic factors

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2
Q

habitat

A

the place where an organism lives

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3
Q

population

A

all organisms of one species in a habitat

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4
Q

population size

A

the number of individuals of one species in a particular area

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5
Q

community

A

all the organisms of different species that live in the same habitat and interact with each other.

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6
Q

abiotic factors

A

non-living features of ecosystem eg temperature and water availability

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7
Q

biotic factors

A

living features of ecosystem eg the presence of predators

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8
Q

abundance

A

the number of individuals of one species in a particular area

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9
Q

distribution

A

where a species is within a particular area

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10
Q

biosphere

A

part of atmosphere and earth inhabited by living organisms

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11
Q

niche

A

role of an organism in its environment including abiotic and biotic interactions

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12
Q

anthropogenic factors

A

changes which influence the organic world and are introduced into nature by human activity

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13
Q

give an example of how an abiotic factor can affect the abundance of organisms

A

when abiotic conditions are ideal, organisms cab grow and reproduce. for example, when temperature of surroundings is ideal for metabolic reactions to take place so they don’t have to use up as much energy maintaining their body temperature so more energy can be used for growth and reproduction increasing the abundance.

when abiotic conditions aren’t ideal, organisms cant grow and reproduce as fast. for example, when temperature of surroundings is lower or higher than optimum, they have to use a lot of energy to maintain right body temperature so less energy available for growth and reproduction

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14
Q

interspecific competition

A

organisms of different species compete with each other for same resources

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15
Q

explain how interspecific competition affects an organisms growth and reproduction

A

Interspecific competition between two species can mean that the resources available to both populations are reduced.

this means both populations will be limited by a lower amount of food and they will have less energy for growth and reproduction, so the population sizes will be lower for both species.

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16
Q

intraspecific competition

A

when organisms of the same species compete with each other for the same resources.

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17
Q

carrying capacity

A

maximum stable population size of a species that an ecosystem can support

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18
Q

predation

A

when an organism (predator) kills and eats another organism (prey)

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19
Q

what is meant by population size of predators and prey being interlinked

A

as population of one changes, it causes the other population to change

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20
Q

how do niches affect the abundance and distribution of organisms in a habitat

A

no two species can occupy the same niche so interspecific competition occurs where the species that are more adapted outcompete the other species

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21
Q

primary succession

A

happens on newly formed or exposed so there is no soil or organic material to start with, its bare rock

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22
Q

secondary succession

A

happens on land thats been cleared of all plants but soul remains

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23
Q

what is the name given to species that are first to colonise an area during succession

A

pioneer

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24
Q

explain what happens during primary succession

A

abiotic conditions are hostile so only pioneer species grow because they are specially adapted to cope with harsh conditions.

pioneer species die and microorganisms decompose the dead organic material forming a basic soil and changing the abiotic conditions.

conditions are less hostile (soil can retain water) so new organisms with different adaptations can move in and grow.

these die making the soil deeper and richer in minerals so larger plants can grown and retain even more water.

some new species may change the environment so that it becomes less suitable for the previous species

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25
Q

explain what happens during secondary succession

A

at each stage, different plants and animals are better adapted for the improved conditions move in, out compete the other species and become the dominant species in the ecosystem.

as succession goes on, ecosystem becomes more complex and biodiversity increases

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26
Q

what are the pioneer species during secondary succession

A

larger plants

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27
Q

what is the final stage of succession

A

climax community

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28
Q

climax community

A

the ecosystem is supporting the largest and most complex community of plants/animals it can.

a self sustaining community with relatively constant biodiversity and species range.

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29
Q

species

A

similar organisms that can reproduce to give fertile offspring

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30
Q

climatic climax

A

climax community for a particular climate

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31
Q

plagioclimax

A

when succession is stopped artificially

human activities prevent succession stopping a climax community from developing

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32
Q

phosphorylation

A

adding phosphate to a molecule

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33
Q

photophosphorylation

A

adding phosphate to a molecule using light

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34
Q

photolysis

A

splitting of molecule using light

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35
Q

hydrolysis

A

splitting of molecule using water

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36
Q

redox reactioms

A

reactions involving oxidation and reduction

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37
Q

oxidation

A

when oxidised, electrons are lost and possible hydrogen is lost or oxygen is gained

38
Q

reduction

A

when reduced, electrons are gained and possible hydrogen is gained or oxygen is lost

39
Q

what do plants need energy for

A

protein synthesis

DNA replication

active transport

photosynthesis

cell divison

40
Q

what do animals need energy for

A

muscle contraction

maintenance of body temperature

active transport

DNA replication

cell division

protein synthesis

41
Q

photosynthesis

A

process where energy from light is used to break apart the strong bonds in water molecules

42
Q

what are the products of photosynthesis

A

glucose and oxygen (released in the atmosphere)

43
Q

how do animals obtain glucose

A

by eating plants or other animals then respira the glucose to release the energy

44
Q

name the process that is used to synthesise ATP from ADP

A

phosphorylation and it uses energy from an energy releasing reaction

45
Q

what enzyme catalyses the synthesis of ATP

A

ATP synthase

46
Q

what enzyme catalyses the hydrolysis of ATP

A

ATPase

47
Q

describe the structure of chloroplast

A

outer and inner chloroplast envelope keeping reactants close to reaction sites.

thylakoids have large surface area to allow as much light energy to be absorbed

grana (stacked up thylakoids)

lamellae (linked thylakoid membranes)

lots of ATP synthase to produce ATP during light-dependent reaction.

stroma (gel like) containing enzymes, nutrients, sugars and organic acids and oil droplets

48
Q

what photosynthetic pigments are present in chloroplast

A

chlorophyll A

chlorophyll B

carotene

49
Q

where in the chloroplast, are photosynthetic pigments found

A

thylakoid membranes - attached to proteins

50
Q

what is the function of photosynthetic pigments

A

coloured substances that absorb light energy needed for photosynthesis

51
Q

photosystem

A

when protein and pigment combine

52
Q

what are the two photosystems

A

photosystem I

photosystem II

53
Q

what wavelength works the best for photosystem I

A

700 nm

54
Q

what wavelength works the best for photosystem II

A

680 nm

55
Q

coenzyme

A

molecule that aids the function of an enzyme by transferring a chemical group from one molecule to another.

56
Q

what coenzyme is used in photosynthesis

A

NADP which transfers hydrogen from one molecule to another

57
Q

what two stages make up photosynthesis

A

light dependent reaction & light independent reaction

58
Q

what two processes occur during the light dependent reaction

A

non cyclic photophosphorylation

cyclic photophosphorylation

59
Q

during the light-dependent reaction what is light energy absorbed used for

A

make ATP from ADP and inorganic phosphate

make reduced NADP from NADP

photolysis

60
Q

does the light-dependent reaction require light energy

A

yes

61
Q

where does the light-dependent reaction occur

A

thylakoid membranes

62
Q

what are the products of non cyclic photophosphorylation

A

ATP

reduced NADP

oxygen

63
Q

explain what happens during non cyclic photophosphorylation

A

PSII absorbs light energy which excites electrons in chlorophyll causing them to move to a higher energy level as they have more energy and they move along the electron transport chain to PSI.

as they move along the electron transport chain they must be replaced so light enegy splits water into protons, electrons and oxygen

excited electrons lose energy as they move along and this energy is used to transport protons into thylakoids so it has higher concentration than stroma forming a proton gradient across membrane.

protons move down concentration gradient into stroma via ATP synthase forming ATP.

light energy absorbed by PS1 which excites electrons again to an even higher level.

electrons transferred to NADP along with protons from stroma forming reduced NADP.

64
Q

explain what happens during cyclic photophosphorylation

A

electrons are passed back to PSI via electron carriers so they are recycled and can repeatedly flow through PSI

65
Q

what is the product of cyclic photophosphorylation

A

small amounts of ATP

66
Q

where does the light-independent reaction take place

A

stroma

67
Q

does light-independent reaction require light energy

A

no but it uses ATP and reduced NADP from the light-dependent reaction

68
Q

another name for light-independent reaction

A

calvin cycle

69
Q

explain the process of calvin cycle

A

carbon dioxide enters leaf through stomata and diffuses into stroma where it combines with RuBP and RUBISCO catalyses it producing unstable 6-carbon compound which breaks down into two molecules of GP.

hydrolysis of ATP (light-dependent) provides energy to turn GP into GALP and this reaction also uses protons from reduced NADP which is recycled to NADP.

some GALP is converted into useful organic compounds and some continues in the cycle to regenerate RuBP.

two molecules of GALP make a hexose sugar but five out of six molecules are used to regenerate RuBP which uses the rest of the ATP.

70
Q

how are carbohydrates produced from GALP and GP

A

simple sugars are made of two GALP molecules together and polysaccharides are produced from joining hexose sugars together in different ways

71
Q

how are lipids produced from GALP and GP

A

made using glycerol which is synthesised from GALP and fatty acids which are synthesised from GP

72
Q

how are amino acids produced from GALP and GP

A

some amino acids are made from GP

73
Q

how are nucleic acids produced from GALP and GP

A

sugar in the RNA is made using GALP

74
Q

producers

A

production of organic molecules using sunlight energy by organisms eg plants

75
Q

how do producers store energy

A

as biomass

76
Q

primary consumers

A

organisms that eat producers

77
Q

secondary consumers

A

they eat primary consumers

78
Q

tertiary consumers

A

they eat secondary consumers

79
Q

trophic level

A

the (feeding) position a species occupies in a food chain

80
Q

what % of total available energy is lost when transferred to next trophic level

A

90

81
Q

what % of the available energy is never taken in

A

60

82
Q

biomass

A

total dry mass of tissue or mass of carbon measured over a given time in a specific area

83
Q

gross productivity

A

the rest of the available energy (40%) taken in

84
Q

respiratory loss

A

75% of gross productivity lost to environment when organisms use energy produced from respiration for movement or body heat.

85
Q

net productivity

A

the amount of energy thats available to the next trophic level

25% of gross productivity becomes biomass

86
Q

net primary productivity

A

total energy available to other trophic levels after respiratory lossess

87
Q

gross primary productivity

A

total energy in plant biomass within a given volume or area

88
Q

formula linking NPP and GPP

A

NPP = GPP - respiration

89
Q

food chain

A

simple lines of energy transfer/ a series of organisms each dependent on the next as a source of food

90
Q

food web

A

a system of interlocking and interdependent food chains

A Level Biology : Content (18 decks)

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