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Biology paper 2 2022 AQA GCSE Separate science > ecology > Flashcards

Flashcards in ecology Deck (78)
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1
Q

what is the definition of a habitat

A

-environment in which an organism lives in

2
Q

what is the definition of community

A

a community is the population of all different species that live in the same habitat

3
Q

ecosystem defintion

A

both biotic and abiotic parts of an environment and how they interact.

4
Q

what is the definition of a population

A

total number of organisms of the same species living in the same geographical area.

5
Q

what do plants compete with each other for?

A
  • light
  • minerals
  • water
  • space
6
Q

what do animals compete with each other for?

A
  • food
  • water
  • mating partners
  • territory
7
Q

what is interdependance?

A

when all the different species of a community depend on each other.

8
Q

how do plants rely on other living organisms

A

plants rely on bees to disperse their pollen

and rely on birds to disperse seeds in their faeces.

9
Q

if a species disppears from a community, the whole community is affected. without bees what can happen to plants?

A

without bees lots of plants would be unable to reproduce as they would not get pollenated.
animals which feed on these plants, could run out of food and their populations would fall.

10
Q

in most communities, populations of different species remain constant. what is this called

A

a stable community. a stable community is one where all species and environmental factors are in balance so that population sizes remain fairly constant.

11
Q

biotic factors (living)

A

competition between species (one species outcompeting other so numbers are no longer sufficient enough to breed could lead to extinction)
availability of food
new predators arriving( prey population can fall or competition can compete with other predators)
new pathogens

12
Q

abiotic factors

A
light intensity
temperature
moisture levels
oxygen levels (for aquatic plants) 
carbon dioxide levels  ( for plants)
soil ph and mineral content
wind intensity and direction
13
Q

every food chain starts with a :

A

producer

14
Q

what do producers do

A

synthesise complex molecules

15
Q

producers source of biomass in all communities

A

glucose- biomass

16
Q

primary consumers

A

primary consumers eat producers

17
Q

secondary consumers

A

secondary consumers eat primary consumer

18
Q

food chain

A

producer- source of all biomass in a community
biomass such as glucose passes down food chain to other organisms
producers synthesise complex molecueles
primary consumers eat the producer
secondary consumers eat the primary consumer
tertiary consumer- eats secondary consumer

19
Q

what are consumers that kill and eat other animals called

A

predators

20
Q

animal that is being eaten

A

prey

21
Q

what can be represented by a food chain

A

feeding relationships within a community

22
Q

all food chains begin with a producer

A

a produce synthesisises complex moclecules. producer usually green plant or algae which make glucose by photosynthesis

23
Q

why is random sampling used

A

used to compare numbers of organisms in different areas

24
Q

using a quadrat

A

a quadrat is a wooden or plastic square
place it on the ground
count numbers of organisms inside the quadrat
can be used to sample plants or slow moving animals

25
Q

in random sampling where is quadrat placed

A

random sampling used to compare number of organisms in different areas
quadrat placed in random locations across the area. one way to do this could be to use random numbers to select different locations
count numbers of organisms in each quadrat
move quadrat to a different random location and count number of organisms over there.
do this until you have large number of random locations

26
Q

how to make results more valid

A

place the quadrat a large number of times.

27
Q

whats wrong with only placing the quadrat once

A

-might not give us a sample that represents the whole area accurately.
must place quadrat large number of times to get valid results.

28
Q

total population size

A

total population size=total area/ area sampled x number of organisms of that species counted in a sample.

29
Q

sampling along a transect line why is it used

A

used to investigate whether a number of species changes as we move across a habitat. transect- piece of rope or tape measure place the transect line so that it runs across habitat we are looking it. use a quadrat to count number of organisms at intervals on the transect.

30
Q

we use sampling along A transect, to see

A

how numbers of species have changed as we move across a habitat

31
Q

sand dune

A

species of plant we find on a sand dune change as we move inland from the sea.we can measure this using sampling along a transect.
first place a tape measure on the dune, runnning from the beach inland. now place first quadrat at start of transect and count different plants in the quadrat
move the quadrat closer in land by a set distance such as 2m count number of plants again. keep doing this as we move further inland.

32
Q

why must we carry out the transect a number of times

A

to get valid results. move tape measure along and repeat whole process we can get valid data this way on how the number of species change across the dune.

33
Q

why are all materials recycled

A

to provide building blocks for future organisms

34
Q

what is the carbon cycle

A

the carbon cycle returns carbon from organisms to the atmosphere as carbon dioxide to be used by plants in photosynthesis

35
Q

describe carbon cycle

A

carbon cycle starts with carbon dioxide in the atmosphere
the only way that carbon can enter the carbon cycle is by photosynthesis
in photosynthesis carbon is combined with water to make glucose
carbon dioxide returns back into the atmosphere by aerobic respiration

36
Q

two key processes in the carbon cycle

A

photosynthesis brings carbon into the cycle

respiration returns carbon back to the atmosphere as carbon dioxide

37
Q

explain each step of the carbon cycle

A

-plants and algae take in carbon dioxide from the atmosphere in photosynthesis.
carbon is used to make carbohydrates, proteins and fats which make up the cells of plants and algae
-the plants and algae respire, so carbon is released back into the atmosphere as carbon dioxide.
-plants and algae can be eaten by other animals
-these animals can be eaten by other animals
-at this point, the carbon that was in the plants has now become a part of the carbohydrates, fats and proteins in the cells of animals.
-the animals respire and some of the carbon is released back into the atmosphere as carbon dioxide.
-animals release waste products such as faeces.
and eventually all plants and animals die
-carbon in waste products and dead remains
-waste products and dead remains are broken down by decomposers such as bacteria and fungi.
-when these decomposers carry out respiration, the carbon in the waste and the dead remains is returned to the atmosphere as carbon dioxide.

38
Q

why are decomposers extremely important

A

because they cycle materials through an ecosystem

as well as returning carbon to the atmosphere as carbon dioxide, they also release mineral ions into the soil.

39
Q

under certain conditions sich as lack of oxygen, decomposers cannot function effectively. what happens if this happens

A

the carbon in the dead remains slowly converted to fossil fuels. over millions of years, large amount of carbon dioxide becomes trapped underground in fossil fuels. combusting fossil fuels releases huge amount of carbon dioxide back into the atmosphere.

40
Q

describe the water cycle

A
  • most water in the Earth is found in oceans. and this water is known as salt water.
  • energy from the sun causes water to evaporate from the surface of the sea
  • this water vapour travels into the air and cools down
  • as it cools down, the water vapour condenses to form clouds
  • water in the clouds falls to the ground as precipitation.
  • precipitation also includes rain, snow, hail and sleet
  • precipitation contains fresh water which does not contain any salt.
  • once water hits the ground, it simply evaporates back into the atmo as water vapour.
  • some of the water passes through rocks and forms aquifers
  • alot of the water forms streams and rivers
  • eventually, the water in the streams and rivers drains out back into the sea.
41
Q

how do living organisms play a part in the water cycle

A
  • ;living organisms such as plants take up water in the roots. the water passes through the xylem. the water passes out of the leaves through the stomata as water vapour. this is known as transpiration
  • animals take in water through food and drink. water is released in urine, faeces and when they exhale.
42
Q

what do pyramids of biomass represent

A

pyramids of biomass represent relative amount of biomass at each trophic level of a food chain

43
Q

what is a trophic level

A

the trophic level of an organism is how many steps it is away from the start of its food chain

44
Q

definition of biomass

A

biomass is amount of living or recently dead biological matter in an area. biomass is transferred from each trophic level to the level above it on the food chain.

45
Q

producers transfer how much percent of incident light energy used for photosynthesis to produce biomass

A

1 percent

46
Q

how much percentage of biomass from each trophic level is transferred to the level above it

A

10 percent

47
Q

what factors cause the loss of biomass moving up the food chain

A
  • used in life processes such as respiration
  • not all the matter is eaten or digested some is egested as waste products
  • some absorbed material is lost as waste eg water snd urea in urine
  • energy is used in movement and to keep animals warm
  • large mounts of gluocse are used in respiration
48
Q

defnitions of terms in organising an ecosystem

A

biomass- amount of living or recently dead biological matter in an area. biomass is transferred from each trophic level to the level above it in the food chain,
food chain- shows feeding relationships within a community
food webs- organisms usually have more complex feeding relationships with more than one predator or more than one food source
predator- consumer that eats and kills other animals
-prey- eaten by predators
trophic level- trophic level of an organism is the number of steps it is from the start of the food chain.

49
Q

a number of factors affect the rate of decomposition LIST And explain them:

A

temperature-chemical reactions work faster in warmer conditions. decomposition takes place faster in warmer conditions because enzymes work faster in higher temperature but temperature must not be too hot because then enzymes could denature and decomposers could die
water levels: the chemical reactions for decay require water. water also makes food easier to digest.
availability of oxygen- decomposers carry out aerobic respiration so requires good oxygen supply compost bins may have holes to allow oxygen to enter. gardeners may use forks to mix compost regularly

50
Q

when biological material decays, compost is produced

what is used by gardners for

A

its used by gardeners and farmers as a natural fertiliser
to do this- they have to provide optimum conditions for decay, if more oxygen is available, they respire aerobically producing heat. the increased temperature increases the rate of decay so the compost is made quicker.

51
Q

in the absence of oxygen, decomposers carry out anaerobic decay which produces methane’

A

the methane can be burnt as fuel- known as biogas

52
Q

what are biogas generators used to produce

A

methane- require a temperature of 30 degrees so the microorganisms keep respiring it needs to be used immediately so cannot be stored as liquid.

53
Q

what is a producer

A

green plant or algae synthesises complex molecules, and makes it own food by photosynthesis

54
Q

what is a food chain

A

represents feeding relationships within a community

55
Q

what is a consumer

A

organism that eats other organisms for food

56
Q

what is a herbivore

A

organism that only eats producers (plants or algae)

57
Q

what is a predator

A

predators are consumers that kill and eat other animals

58
Q

what is a prey organism

A

organisms that are killed and eaten by other organisms.

59
Q

what is an apex predator

A

carnivores without any predators

60
Q

what proportion of biomass is transferred from each trophic level to the one above

A

approximately 10 percent

61
Q

why is biomass lost between trophic levels (answer from spec)

A

not all matter ingested is absorbed some is egested as faeces
some absorbed material is lost as waste sich as carbon dioxide and water in respiration and water and urea in urine.
large amounts of glucose are used in respiration
energy lost due to movement

62
Q

spec points about tranfer of biomass

A

Producers are mostly plants and algae which transfer about 1% of the
incident energy from light for photosynthesis.
Only approximately 10% of the biomass from each trophic level is
transferred to the level above it.
Losses of biomass are due to:
• not all the ingested material is absorbed, some is egested as faeces
• some absorbed material is lost as waste, such as carbon dioxide and
water in respiration and water and urea in urine.

63
Q

what is the carbon cycle

A

process that retruns carbon from organisms to the atmosphere as carbon dioxide which can be used by plants

64
Q

what is the water cycle

A

process that provides fresh water for plants and animals on land before draining into seas and rivers

65
Q

what is a decomposer

A

organism that breaks down dead plant or animal matter
waste products and dead remains are broken down by decomposers.
decomposers are extremely important as they cycle materials through an ecosystem.
as well as returning carbon to the atmosphere as co2, they also release mineral ions in the soil.

66
Q

what is the role of decomposition

A

returns carbon to the atmosphere and mineral ions to the soil from dead matter.

67
Q

what factors affect rate of decay by decomposers

A

oxygen levels, moisture levels temperature and ph

68
Q

what does anaerobic decay produce

A

methane

69
Q

how can methane gas be used

A

can be burnt and used as a fuel biogas

70
Q

what do trophic levels tell us

A

organisms position on a food chain

71
Q

why is dry biomass more useful than wet biomass

A

because the moisture content of organisms canvary widely and produce inaccurate results

72
Q

only 1 percent of light energy that falls on producers is absorbed and used for

A

photosynthesis to produce biomass

73
Q

approximately 10 percent of biomass from each trophic level is transferred

A

to the level above it

74
Q

efficiency of biomass

A

gain in biomass/ total biomass intake

75
Q

what is meant by food security

A

having sufficient food to feed the population

76
Q

what factors affect food security

A

1) increasing birth rates means more food is required
2) new pests and pathogens can destroy crops
3) conflicts in countries can affect availability of food and water
4) climate change can affect food production for example no rains causing crops to fail
5) changing diets in developing countries mean food resources which are already in low amounts become even more scarce as demand for them increases.

77
Q

Biotic factors

A

biotic factors are living factors that can affect a community
availability of food-more food means organism can breed more successfully and therefore population can increase
competition- if one species is better adapted to the environment than another, then it will outcompete it until numbers of the lessdapated species are insufficcient to breed
new pathogen when a new pathogen arises, population does not have resistance so can be wiped out quickly
new predators- compete with existing predators cause prey population to fall

78
Q

abiotic factors non living factors that can affect a community

A

light intensity- light is required for photosynthesis, the rate of photsynthesis affects the rate at which the plant grows plants can be food sources or shelter for organisms
temperature- affects the rate of photosynthesis
wind intensity and direction- wind affects rate of transpiration transpiration affects the temperature of the plant and the rate of photosynthesis as it transports water and mineral ions to teh leaves
carbon dioxide levels in plants- co2 affects the rate of photosynthesis in plants and also affects the distribution of prganisms as some organisms thrive in high co2 environments
oxygen leves in aquatic animals- most fish need a high concentration of oxygen inorder to survive
oxygen levels vary in water unlike in air
moisture levels- both plants and animals need water inorder to survive
soil ph and minerals