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biology > Populations In Ecosystems > Flashcards

Populations In Ecosystems Flashcards

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1
Q

The larger the sample ………

A

The more reliable the data

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2
Q

Why should the student not stop collecting data half way up the graph

A

Because the line has not reached the plateau so all the data is not being represented

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3
Q

Why should the student stop collecting data after the line plateaus

A

Because it would not improve the outcome of the data and would be a waste of time

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4
Q

How would you decide the number of samples to take to collect representative data

A

Calculate the running mean after 10 samples and continue until it stops increasing

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5
Q

What does a point quadrat do

A

Measures the frequency of how often a species is found

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6
Q

What does a frame quadrat do

A

Measures percentage cover of a species in an area

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7
Q

3 things to consider when using quadrats

A

Size of the quadrat depending on the size of species measured and how they are distributed in an area
Number of samples being taken in the area - the more samples the more reliable
Position of each quadrat to produce unbiased results - random sampling must be used

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8
Q

Why use random sampling in a uniform area

A

Avoid bias
Representative data
Allows for the use of statistical tests

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9
Q

Random sampling method

A

Set out a grid using tape measures at right angles
Divide into coordinates
Use a random number generator to pick coordinates
Count organisms in the quadrat on each coordinate
Record data
Repeat

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10
Q

How to measure data in an irregular size area

A

Divide into spaces and number them
Use random number generator to pick space
Place quadrat
Count
Repeat

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11
Q

When to use a belt transect

A

When the area varries and the abundance/ distribution of organisms changes
Measures percentage cover

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12
Q

Method using a belt transect

A

Lay out a tape measure and place quadrat frame at right angles at regular intervals
Use a pin quadrat to count species touching the pins
Flip quadrat frame over to the other side of the transect and repeat

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13
Q

Advantages of belt transect

A

Gives more info on abundance

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14
Q

Disadvantages of belt transect

A

Takes longer than a line transect
Might damage environment from standing on it

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15
Q

Frequency of species equation

A

Number of quadrat contains species / total number of quadrats X 100

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16
Q

Method of mark release recapture

A

Capture a number of animals
Mark them
Release them and allow for reintegration
Collect second sample
Count and record
Use MRR equation to estimate population size

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17
Q

MMR equation

A

Organisms in sample 1 X organisms in sample 2 / number of marked organisms recaptured

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18
Q

MRR assumptions

A

Proportion of marked to unmarked in sample 1 and 2 is the same as the whole population
Marked sample distributed themselves evenly
Population have definite boundaries
Few births and deaths
Marking method is not toxic and more liable to predation
Mark has not rubbed off

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19
Q

What is succession

A

Change in community over time due to changes in abiotic and biotic factors

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20
Q

How does succession change over time

A

Starts with pioneer species in harsh abiotic conditions and low diversity
Biodiversity increases over time and then becomes a climax community with more stable abiotic conditions
Biodiversity is lower because more dominant species outcompete others

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21
Q

How do the first species colonise an area

A

Wind dispensable seeds to reach isolated areas
Rapid seed germination
The ability to to photosynthesis
Ability to fix nitrogen because soil has no nutrients
Tolerant to extreme conditions

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22
Q

How is soil made by pioneering species

A

Weathering of rock and decomposition of dead organisms add nutrients to the soil which means more small plants colonise like Moses and ferns and the area become hostile
Process repeats and a thicker layer of developed

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23
Q

Why do pioneer species become replaced by other species over time

A

Competition prevents pioneer species from photosynthesising or absorbing water

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24
Q

What is a climax community

A

A stable community where no further succession occurs

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25
Q

How do successional changes effect animals

A

Depending what plants are present depends what animas are present because of food source availability
Flowering plants bring pollinators

26
Q

Features of succession

A

Abiotic factors become less hostile
Greater variety of habitats and food sources
More complex food webs lead to more competition
Increase in biomass

27
Q

What is secondary succession

A

The same a primary succession accept it starts from wildfires , tsunamis, hurricanes , deforestation clearing and area of land
But it happens quicker because seeds are already in the soil and from animal poop

28
Q

How does dead organic matter change during succession

A

Increases because animals poop adding to soil and plants grow, die and decompose

29
Q

How does humidity change during succession

A

Increases because rate of transpiration locally increases and air movement decreases due to plant protection

30
Q

How does PH change during succession

A

Decreases because rain leaches basic ions from sea spray out of sandy soil and more plants die and decompose

31
Q

How does rate of evaporation change during succession

A

Decreases because humidity increases so water potential decreases

32
Q

How does sodium chloride conc change during succession

A

Rain leches basic ions out of Sand soil
Less sea spray reaches ground

33
Q

How does soil temp change during succession

A

Increases because soil composition increases in dead organic matter so drainage decreases which increases water content

34
Q

How does wind speed change during succession

A

Decreases because plants provide a wind break so air movement decreases

35
Q

How is marram grass adapted

A

Hairs , stomata and rolled leaf shape reduces conc gradient of water by diffusion
Thick waxy cuticle avoids evaporation of water

36
Q

What is ecology

A

The study of relationships between organisms and their environment

37
Q

How does competition effect a population

A

More competition means less chance of getting food so organisms die

38
Q

How does predation effect a population

A

More predation means prey population decreases

39
Q

How does disease effect a population

A

More disease causes a population decrease

40
Q

How does food availability effect a population

A

More food available means more population growth

41
Q

How does temp effect population

A

Lower temp means less vegetation growth so more animals die of starvation

42
Q

How does pH effect population

A

Incorrect pH means that vegetables can’t grow so more animals die of starvation or other food sources decrease

43
Q

How does water availability effect population

A

Less water causes dehydration for animas and plants can’t grow

44
Q

How does light effect population

A

Low light means plants can’t photosynthesis so can’t grow

45
Q

How does natural disasters effect a population

A

Kills animals prevents them from reaching food , kills the food source

46
Q

What is a micro habitat

A

A small pocket within a habitat
E.g pythons live on trees but wood lice live in the bark cracks

47
Q

What is intraspesific competition

A

Competition of individuals within the same species

48
Q

What is interspesific competition

A

Competition between individuals of different species

49
Q

Why is it difficult to obtain valid data on predator - prey relationships

A

The labs results are not accurate because the environment is limited so their are no external factors
Whilst in the wild it is impossible to count every individual

50
Q

what is carrying capasity

A

maximum population that can be supported by an environment long term

51
Q

why is their a lag time in the first phase of a population growth curve

A

because organisums are acclimatising to the environment so no reproduction

52
Q

why is their exponential growth in the second phase of a population growth curve

A

reproduction rates high - birth rates higher than death rates

53
Q

why is there fluctuation in the final phase of population growth curve

A

lots of intraspesific competition because population is over carrying capasity and then a limiting factor will bring down the population

54
Q

how will the population growth curve change for bacteria

A

it is quicker because bacteria reproduces quicker
less ossilation in stage 3
then a decline phase because food in a petri dish runs out

55
Q

how does temperature effect cold blooded organisums populations

A

if temp is lower enzymes work more slowly so metabolic rate is lower so carrying capasity is lower

if temp is higher enzymes denature reducing carrying capasity

56
Q

how does temperature effect warm blooded animal populations

A

they can maintain constant body temperatures but the further from optimum temp the more energy used to maintain temp so less available for reproduction so reduced carrying capasity

57
Q

how does light effect population size

A

more light alllows more photosynthesis so more plant growth and food availabilty carrying capasity increases

58
Q

how does pH effect population size

A

as you move away from the optimum more enzymes denature so less enzyme substrate complexes so carrying capasity decreases

59
Q

how does water and humidity effect population size

A

more water means plants can grow more because it allows for more photosynthesis so acrrying capasity increases

60
Q

what is polarding and when is it done

A

chop canopy off the tree and it will grow again
done because grazing animals are around and they would eat the sprouts if they are low enough

61
Q

what is coppicing and when is it done

A

cut the tree down really low to a stump over time the stump grows new sprouts
done because it was over dominating other plants

62
Q

why is controlled heath burning done

A

kills dominanting species
heat activated seeds germination of other species

biology (17 decks)

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