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A-level Biology > 7 - Genetics And Ecosytems > Flashcards

7 - Genetics And Ecosytems Flashcards

1
Q

Habitat definition

A

The place where an organism lives

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2
Q

Population definition

A

All the organisms of one species in a habitat

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3
Q

Community definition

A

Populations of different species in a habitat make up a community

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4
Q

Ecosystem definitions

A

A community, plus all the non living conditions in the area in which it lives

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5
Q

Abiotic definition

A

The non living features of the ecosystem

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6
Q

Biotic definition

A

The living features of the ecosystem

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7
Q

Niche definition

A

The role of a species within its habitat

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8
Q

Adaptations definition

A

A feature that memebrane of a species have that increases their chance of survival amd reproduction

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9
Q

The niche a species occupies within a habitat includes what 2 things

A

It’s biotic interactions
It’s abiotic interactions

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10
Q

T or f

A niche can only be occupied by one species

A

T

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11
Q

What will happen if two species try to occupy the same niche

A

They will compete until one is more successful

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12
Q

What 3 ways can adaptations be

A

Physiological
Behavioral
Anatomical

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13
Q

What is a physiological adaptation

A

Process inside their body

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14
Q

What is a Behavioral adaptation

A

The way an organism acts

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15
Q

What is an anatomical adaptation

A

Structural features of the body

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16
Q

Describe natural selection

A

Organism with better adaptations are more likely to survive, reproduce and pass on the alleles for their adaptations , so the adaptations become more common in the population

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17
Q

Every species is adapted to use an ecosystem in ….

A

It’s won unique way

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18
Q

Are organisms only adapted to abiotic conditions

A

No they also adapt to biotic conditions

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19
Q

Give an example of how otters adapt to abiotic conditions

A

They have webbed paws, so they can walk on land and swim effectively

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20
Q

Give an example of how seals adapt to abiotic conditions

A

Thick layer of blubber, keep them warm in cold seas and increase chance of survival because they can live in places where food is plentiful

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21
Q

Give an example of how hedgehogs adapt to abiotic conditions

A

Lower their rate of metabolism over winter. This increases their chance of survival as they can conserve energy during there coldest months

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22
Q

Give an example of how otters adapt to biotic conditions

A

use rocks to smash open shellfish and clams
Increase serval chances as gives them access to another source of food

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23
Q

What is a population size

A

The total number of organisms of one species in a habitat

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24
Q

What is carrying capacity

A

The maximum stable population size of a species that an ecosyetm can support

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25
Q

Does carrying capacity varie due to abiotic or biotic factors

A

Both

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26
Q

How does abiotic factors effect carrying capacity
+eg

A

When they are idea for a species ( eg, light, water , space available, tempers are, chemical composition) organisms can grow fast and reproduce successfully

Eg. When the temperature of a mammals surroundings is the urea temperature for metabolic reactions to take place, they don’t have to use as much energy maintains their body temp.mso a lot of energy can use for growth and reproducing, so population size will increase

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27
Q

What is interspecific competition
+eg

A

When organisms of differnt species compete with each other for the same resources
Eg. Red and grey squirrels compete for the same food source and habitat in the uk

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28
Q

What does interspecific competition cause

A

Competition between Two species can mean that the resources available to both populations are reduced
So both populations will be limited by a lower amounts of food, so they will have less energy for growth and reproduction, so population sizes will be lower for both species

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29
Q

What will happen if two species are competing but one is better adapted that the other to its surroundings

A

The less adapted species is likely to be out competed

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30
Q

What is intraspecific competition

A

When organisms of the same species compete with each other for the same resources

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31
Q

Explain how species population varies by intraspecific competition

A

The population of a species increases when recorded are plentiful. As th population increases theeell be more organism competing for the same amount of space and food

Eventually resources such as food and space become limiting- there isn’t enough for all the organism. The populations then begins to decline

A smaller population then means there there’s less completion for space and food, which is better for growth and reproductions - so the population. Starts to grow again

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32
Q

What is predation

A

Where an organism kills and eats other organisms

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33
Q

The population sizes of predators and prey are….

A

Interlinked

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34
Q

Explain how prey and predators populations sizes are interlinked

A

Prey pop increases, so more food for predators, so predators pop grows

As Predator pop increases more prey is eatean so prey pop falls

As prey pop falls there’s less food fro predators so they pop reduces and so on

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35
Q

How’d do other factors effect predator prey relations

A

It’s thought that the population of a species initially declines because there’s too many of them for the amount od food available. This is then accelerated by predation for the predator

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36
Q

What is succession

A

The process by which an ecosystem changes over time

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37
Q

What are the two types of succession

A

Primary
Secondary

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38
Q

When does primary succession occur

A

This happens on land that’s been newly formed or exposed
Eg. Where a volcano has erupted to form a new rock surface or where sea
Level dropped exposing new land .
No soil or organic material to start with

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39
Q

Where does secondary succession happen

A

On land that’s been cleared of all the plants but soil remains
Eg, a forest fire

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40
Q

Describe primary succession

A

1) abiotic conditions are hostile (no soil), pioneer species grow
2) pioneer species change the abiotic conditions - they die and miccrogansums decompose the dead organic materal ( humus). Forms soil
3) makes conditions less hostile eg. Soil holds water. New organisms move in and outcompete and become the dominant species
4) some new species may chmage the environment so that it becomes less suitable for the previous species
5) ecosystem becomes more complex , biodiversity increases
6) reaches a climax community,

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41
Q

What is a climax community

A

The ecosystem is supported the largest and most complex communities of plants and animals. It’s stable

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42
Q

What does which species that make up the climax communities depend on

A

What the climate is like in an ecosystem

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43
Q

The climate community for a particular climate is called…

A

Climatic climax

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44
Q

Give an example of a climatic climate

A

Polar climate - there’s not much avalaible water , temps are low and there are massive changes between the seasons . Larger trees won’t ever be able to grow in these conditions, so the climatic climax contains only herbs and shrubs but it’s still the climax community

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45
Q

When succession is stopped artificially , what is the climax community called

A

Plagioclimax

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46
Q

Give an example of human activity’s preventing succession

A

Regularly mown grassy fields worn develeop shrubs and trees even if climate do the ecosystem could support the, the growing points of the plants are cut of by the lawnmower so larger plants can’t establish themselves

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47
Q

What is conservation

A

The protection and managements of ecosystems

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48
Q

What does conservation sometimes involve (in terms of succession)

A

Preventing succession in order to preserve an ecosystem in its current stage of succession.
Eg. Moorland in Scotland that provide habitats for many spaces of plants and animals. If moorland left to natural processes suchcceion would lead to the climax community of spruce forest. So loss of moorland habitat and could leave to the loss of some plants and anaimks that currently live there

49
Q

What are another 2 wats to manage succession to conserve the Moreland ecosystem

A

1)animals are allowed to graze on the land, this is similar to mowing - animals eat growing points of the shrubs and trees, which stops them establishing themselves

2) mamaned fires are lit. After fires secondary succession will occur on the moorland- the species that grow back first are the species that are being conserved. Larger species will take longer to grow back and will be removed again the next time the moor is burnt

50
Q

What is conservation

A

The protection and management of species and habitats in a sustaible way

51
Q

What does sustaible mean

A

Enough resources are taken to meet needs of people today , without reducing the ability of people in the future to meet their own needs

52
Q

Give 4 examples of conservation techniques

A

1) plants can be conserved using seed banks, if a plant become extinct in the wild, the stored seeds can be used to grow new plants
2) finishing quotas are limits to amounts of certain fish species that fisherman are allowed to catch, they help conserve fish species by rescuing the numbers that are cuaght and killed
3) protected areas such as national parks and nature reserves protect habitats, restricts urban development, industrial development and farming
4) endangered species can be bred in captivity to increase numbers then returned to the wild

53
Q

Page 178- evaluating conservation

A
54
Q

How should you sample an area

A

Samples should be random to avoid bias
(Eg, grid and random number generator)
Repeat to reduce Likleyhood that your results are down to chance

55
Q

How can the number of individuals of a whole area by estimated from a sample

A

Take a mean of the data in each sample and multiply to account for the size of the whole area

56
Q

What is a non motile organism and how are they investigated

A

Ones that don’t move
Use quadrants and transects (these can also be used on slow moving organisms)

57
Q

What is species frequency when using a quadrat

A

The number of individuals of each species

58
Q

Apart form species frequency what else can a quadrat be used to measure

A

Percentage cover

59
Q

What is a transect used for

A

To help find out how plants are distributed across an area

60
Q

What is a belt transect

A

Quadrants are placed next to each other along the transect to work out species frequency and percentage cover along the transect
To cover a larger distance, quadrats can be placed at intervals along the line

61
Q

What is it called when a belt transect us used but the quadrats are placed at intervals along the line

A

Interrupted belt transect

62
Q

What is used to measure the abundance of more motile species

A

Mark release recapture

63
Q

How to carry out mark-release-recapture

A

1) capture a sample of species using an appropriate technique, count the,
2) mark them in a harmless way eg. Paint
3) release them, back to the habitat
4) wait a week them take a second sample form the same population
5) count how many of the second Sample are marked, then use the equation to estimate total population size

64
Q

What is the equation to estimate total population size during mark release recapture

A

total pop size = number caught in first sample. X number caught in 2nd sample
——————————————————————————————-
Number marked in the second sample

65
Q

What assumptions are you making during mark release recapture

A

1) the marked sample has had enough time and opportunity to mix back in with the population
2) the marking hasn’t effected the individuals chances of survival, and the marking itself is still visible
3) there are no changes in population size due to birth death and migration during the period of study

66
Q

How could you investigate the effect of an environmental factor on the distribution of species

(Eg, soil og on marram grass)

A

1) take measure as a transect for, shore to inland
2) 1m2 quadrats divided into 100 squares
3) place quadrat next to tape measure (ensure u place the quadrat the same way relative to the tape measure each time )
4) count the squares containing marram grass and record results as percentage cover
5) at each sample point measure ph
6) repeate every 10 m along transect

67
Q

How do you measure ph of soil

A

Digital PH probe
Or
Take a sample and use a sieve to remove debris- test tube, add barium sulfate, distilled water ph indicator shake and leave to settle
Check colour against a ph chart

68
Q

Why does PH decreases as you move inland on the beach

A

Near shore lots of shell fragments which are made of calcium carbonate ,( alkaline), and Inland rotting vegetation adds organic matter wich is more acidic

69
Q

What could you do to mitigate risks of fieldwork at the beach

A

Read tide times
Suitable clothing and footwear
Wash hands

70
Q

What are some ethical issues surrounding fieldwork

A

All fieldwork affects the environment where it’s carried out
Eg . Lots of people walking over grass
Plan to have the smallest impact (eg, restrict where they walk)

71
Q

What is the null hypothesis

A

No significant differnce

72
Q

What is the alternative hypothesis

A

There is significant differnce
(Any diff is not due to chance)

73
Q

How do you work out the degrees of freedom

A

Number of catagories - 1

74
Q

What is the chi squared test

A

A statistical test that’s used to see if the results of an experiment support a theory

75
Q

What is the theory that is used to predict a result in the chi squared test

A

The expected result

76
Q

The experiment is carried out and the actual result is recorded, what is this in the chi squared test

A

Observed result

77
Q

What does the chi squared test do

A

Compare observed and expected results
The outcome either supports or rejects the null hypothesis

78
Q

You can never prove that a null hypothesis is true, but what can you do

A

Reject or accept null hypothesis

79
Q

What is the critical value

A

The value of chi squared that corresponds to a 0.05 level of probability that the differnce between the observed and expected value is due to chance

80
Q

What does the chi squared test do

A

Finds out if there is a significant differnce between the observed and expected results

81
Q

If your chi squared results are larger than or equal to the critical value then….

A

There is a significant differnce between observed and expected results
Null hypothesis is rejected

82
Q

What are the 3 types of sampling

A

Quadrat
Transect
Mark release recapture

83
Q

Quadrats and transects are used for ….

A

Non mobile organisms

84
Q

What is a quadrats used

A

Estimate population numbers in an area
You can extrapolate the data for the whole habitat
You can record number of individuals or % cover

85
Q

T or f
Quadrat use random sampling

A

T

86
Q

What is a transect used for

A

Shows distribution along an environment gradient

87
Q

What type of sampling is a transect

A

Systematic

88
Q

What are the 2 types of transects.

A

Belt transect ( places a quadrat )
Point transect (records what’s on the line)

89
Q

How are mobile organisms investigated

A

Mark release recapture

90
Q

How to carry out mark release recapture with pitfall traps

A

animals are captured, eg using pitfall traps
they are counted and marked in a harmless, inconspicuous way and then released
traps are used again a few days later to recapture a sample of animals
the numbers of marked and unmarked animals caught in the traps are recorded

91
Q

What are the conditions for using students t tests

A

The data must be continuous and normally distributed
The variance of the populations should be equal
The samples must be independent of each other

92
Q

What is variation

A

The difference that exist between individuals

93
Q

Variation within a species means ……

A

Individuals in a population can show a wide range of different phenotypes

94
Q

What causes genetic variation within species

A

Although they have the same genes they have different alleals

95
Q

What is the main source of genetic variation

A

Mutations

96
Q

How is genetic variation introducers ( 4 )

A

Mutations
Crossing over
Independent segregation of chromosomes
Random fertilisation of gametes in sexual reproduction

97
Q

Variation within a species can also be caused by differences in the …..

A

Environment

98
Q

Most variation within a species is caused by combination of genetic and environmental factors, but which results in evolution

A

Genetic variation

99
Q

What is evolution

A

The frequency of an allele in a population changes over time

100
Q

Why do individuals of the same species vary

A

Different alleals

101
Q

what is natural selection

A

Individuals vary, some are better adapted to the selection pressures than others
Thus means there are different levels of survival and reproductive sucesss in a population
Individuals with a phenotype that increases their chance of survival are more likeY to survive , reproduce and pass on their genes
So a greater proportion of the nect generation inherit the beneficial alleles
So frequency of the beneficial alleles in the gene pool increases from generation to generation

102
Q

What are the three types of natural selection

A

Satbalising
Directional
Disruptive

103
Q

What is stabilising selection

A

Where individuals with alleles for characteristics towards the middle of the range are more likely to survive and reproduce,

104
Q

When does stabilising selection occur

A

it occurs when the environment isn’t changing and it reduces the range of possible phenotypes

105
Q

What is directional selection

A

Where individuals with alleles for a single extreme phenotype are more likely to survive and reproduce. This could be in response to an environmental change

106
Q

What is disruptive selection

A

Where individuals the alleles for extreme phenotype at either end of the range are more likely yo survive and reproduce.

107
Q

When does disruptive selection occur

A

When the environment favours more than one phenotype

108
Q

What is speciation

A

The development of new species from existing species

109
Q

When does speciation occur

A

When populations of th same species become reproductively isolated - changes in allele frequency causes changes in phenotype, which mean they can no longer interbreed to produce fertile offspring

110
Q

How could species become reproductively isolated

A

Physical barrier such as a flood or an earth quack divides a species causesimg some individuals to be separated from the main population
This is known as geographical isolation

Or

Without physical separation + known as sympatric speciation

111
Q

What does geographical isolation lead to

A

Allopathic speciation

112
Q

What does allopathic speciation require

A

Geographical isolation

113
Q

Describe allopattric speciation

A

1) populations that are geographically separated will experience slightly different conditions
2) so populations experience different selection pressures and so different changed in allele frequencies
3) different alleles will be more advantageous in diff populations, allele frequencies also chmage as mutations occur independently in each pop ,genetic drift may also affect the allele frequencies in one or both populations
4) ch ages in allele frequencies will lead to differences accumulating in the gene pools of the separated population causing chmages in phenotype frequencies
5j eventually they won’t be able to breed with each other to produce fertile offspring - they will be reproducatubly isolated - two grouped become separated species

114
Q

Describe sympatric speciation

A

Random mutation could occur within a population, preventing memebres of that populations breeding with other members of the species

115
Q

Reproductive isolation occurs becuase changing in alleles and phenotypes in some individuals prevent that from breeding successfully
What does theses chmages inculde

A

Seasonal - individuals form the same population develope different flowering or mating seasons or become sexually active at differnt times of the year
Mechanical - changing in genitalia prevent successful mailing
Behavioral - a group of individuals develop courtship rituals that arnt attractive to the main population

116
Q

What is genetic drift

A

Type of evolution
When chance, rather than environmental factors, dictate which individuals survive , breed and pass on their alleles

Ex.
Individuals within a population show variation in their genotypes, by chance the allele for one genome is passed on to the offspring more oftern than others, so number of individuals with that allele increases, changes in Alelelfrequency in two isolation populations could lead to reproductive isolation and speciation

117
Q

T or f
Natural selection and genetic drift work alongside each other

A

T

118
Q

Evolution by genetic drift usually had a greater effect in ………
Why

A

Smaller populations
Where chance has a greater influence. In larger population any chance variations in allele frequency tend to even out across the whole population

119
Q

What causes ghe diversity of earth

A

Speciation and evolutions chmages
Started with one population, population was divided and new populations evolved into sperate species, new species divide again

A-level Biology (8 decks)

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