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OCR AS/A Level Biology Context > module 4.2.1 > Flashcards

module 4.2.1 Flashcards

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1
Q

what are the 3 levels that biodiversity is assessed by

A

the number and range of different ecosystems and habitats
the number of species and their relative abundance
the genetic variation within each species

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2
Q

what is ecosystem or habitat diversity

A

the range of different ecosystems or habitats within a particular area or region

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3
Q

what does it mean to have a high biodiversity

A

if there is a large number of different habitats within an area

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4
Q

what is an example of high biodiversity

A

coral reef
- they are very complex with lots of microhabitats and niches to be exploited

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5
Q

what happens when there is low biodiversity

A

if there are only one or two different habitats within an area

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6
Q

what is an example of low biodiversity

A

large sandy deserts typically have very low biodiversity as the conditions are basically the same throughout the whole area

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7
Q

what is species richness

A

the number of species within an ecosystem

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8
Q

what is species evenness/ diversity

A

the number of different species in an ecosystem

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9
Q

what does ecosystems with high species diversity mean

A

more stable than those with lower species diversity as they are more resilient to environmental changes

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10
Q

what is the meaning the genetic diversity within a species

A

the diversity of alleles and genes in the genome of species

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11
Q

how is genetic diversity measured

A

by working out the proportion of genes that have more than one form (allele) and how many possible alleles each gene has

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12
Q

why might genetic differences between populations occur

A

because the two populations occupy slightly different ranges in their habitat and so are subject to slightly different selection pressures that affect the allele frequencies in their populations

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13
Q

why is genetic diversity in a species important

A

it can help the population adapt to, and survive, changes in the environment
- the changes could be in biotic factors such as new predators, pathogens and competition with other species
- or the changes could be through abiotic factors like temperature, humidity and rainfall

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14
Q

what is genetic diversity limited

A

very small or isolated

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15
Q

what does inbreeding in small, isolated populations lead to

A

leads to a high proportion of individuals being homozygous (e.g. AA to aa) for many genes, resulting in lower genetic diversity
This can mean that genetic diseases caused by recessive alleles can become more common in these populations

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16
Q

why is it impossible to measure biodiversity in larger and complex ecosystems

A

simply impossible to find, identify and count every organism that exists there
- when this is the case, different samples of the area can be taken and used to make an estimate for the total species numbers in the area

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17
Q

what does finding out which species live in an ecosystem and the size of the populations require

A

the identification and cataloguing of all organisms present to build a species list
- possible for areas that are very small or where the species are very large like trees

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18
Q

what is sampling

A

a method of investigating the abundance and distribution of species and populations

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19
Q

what are the 2 types of sampling

A

random
non random

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20
Q

what is random sampling

A

the positions of the sampling points are completely random or due to chance

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21
Q

what is an advantage of random sampling

A

no bias by the person that is carrying out the sampling that may affect the results

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22
Q

what is non random sampling

A

the positions of the sampling points are chosen by the person carrying out the sampling

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23
Q

what is an advantage of non random sampling

A

individuals may deliberately place the quadrats in areas with the least species as these will be easier and quicker to count

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24
Q

what are disadvantages of non random sampling

A

there is a possibility that the person choosing could show bias towards or against certain areas
unrepresentative of the whole area

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25
Q

what is random sampling used to estimate

A

the distribution and abundance of species

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26
Q

what is the distribution of a species

A

describes how it is spread throughout the ecosystem

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27
Q

what is the abundance of a species

A

the number of individuals of that species

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28
Q

describe quadrats

A

square frames called quadrats can be used to mark off the area being sampled
quadrats are square frames made of wood or wire
they can be a variety of sizes eg. 0.25m2 or 1m2
they are placed on the ground and the organisms within them are recorded

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29
Q

describe the practical of using a quadrat

A

quadrats of different sizes can be used depending on what is being measured and what is most suitable in the space the samples are being made in

quadrats must be laid randomly in the area to avoid sampling bias
- this random sampling can be done by converting the sampling area into a grid format and labelling each square on the grid with a number
- then a random number generator is used to pick the sample points

once the quadrat has been laid on the chosen sample point the abundance or percentage cover of all the different species present can be recorded

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30
Q

what are the other techniques involving other items of equipment to measure their distribution and abundance

A

sweeping nets
pitfall traps
pooters
tullgren funnel
kick sampling

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31
Q

describe the process of sweeping nets

A

these are large, strong nets with a fine material (very small holes) that are used to catch flying insects and insects that live in long grass by sweeping the net back and forth through the grass

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32
Q

describe the process of pitfall traps

A

these are cans or jars that are buried in the ground that are used to catch ground-dwelling (often nocturnal) insects and other invertebrates as they fall into the trap

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33
Q

describe the process of pooters

A

these are small plastic or glass containers with two tubes sticking out that are used to suck up small insects and other small invertebrates
- the first tube is placed over the insect and the second tube is used by the scientist to create suction

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34
Q

describe the process of tullgren funnel

A

these are funnels with a light bulb above and a container below that are used to collect invertebrates that live in leaf litter or soil
- the leaf litter or soil is placed in the funnel and the light and heat forces the invertebrates to move down until they drop into the container

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35
Q

describe the process of kick sampling

A

this technique is used to catch freshwater invertebrates living in streams or rivers
- net in placed on the stream-bed so that the water is flowing into it and the stream-bed just above the net is churned up by the scientist (using their foot) for a set period of time. the invertebrates are carried by the stream into the net

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36
Q

what are the 3 main types of non random sampling

A

opportunistic sampling
stratified sampling
systematic sampling

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37
Q

describe opportunity sampling and example

A

involves picking and choosing sampling locations based on various non-random factors
- eg. students on a field trip may be told they can only collect samples from locations that are nearby, easy to reach, and safe

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38
Q

describe stratified sampling and example

A

involves matching the number of sampling locations in a particular habitat with the relative proportion of area that habitat covers in the whole area being studied
- eg. if 10% of a dense woodland being sampled is actually made up of grassy clearings, then 90% of the sample locations should be in the woodland habitat and 10% in the grass habitat

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39
Q

describe systematic sampling and example

A

when there is a clear change in the physical conditions across the area being studied
- eg. there may be changes in altitude, soil pH or light intensity

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40
Q

what does methods using transects help show

A

how species distribution changes with the different physical conditions in the area

41
Q

what is a transect

A

a line represented by a measuring tape, along which sample are taken

42
Q

describe the use of line transect

A

lay out a measuring tape in a straight line across the sample area
at equal distances along the tape, record the identity of the organisms that touch the line
- eg. every 2m
produces qualitative data

43
Q

describe the use of belt transect

A

place quadrats at regular intervals along the tape and record the abundance or percentage cover of each species within each quadrat
produces quantitative data

44
Q

what are the 3 main techniques used in non-random sampling

A

opportunistic
stratified
systematic

45
Q

what are examples of abiotic factors

A

rainfall
pH
temp
humidity
level of pollution

46
Q

what are components of areas with high biodiversity

A
  • large number of successful species
    • relatively benign climate with more ecological niches
    • presence of many species
    • few specific adaptations to environment
    • complex food web
    • change in enviroment has a relatively small effect on the ecosystem as a whole
    • high biodiversity index (above 0.5)
47
Q

describe components of areas with low biodiversity

A
  • Few successful number of species
  • Stressful/extreme enviroment with few ecological niches
  • Relatively few species live in the habitat
  • Very specific adaptations to the enviroment
  • Simple food webs
  • Enviromental change has a major effect on the ecosystem as a whole
  • Low biodiversity index (below 0.5)
48
Q

methods of sampling animals

A
  • Pooter
  • Sweep net
  • Pitfall traps
  • Tree beating
  • Kick Sampling
  • Quadrats (for slow moving animals)
49
Q

methods of sampling plants

A
  • Frame quadrat
  • Point quadrat
50
Q

pooter

A
  • Used to catch small insects
  • Insects drawn into the holding chamber via the inlet tube
    -Filter before the mouthpiece prevents them being sucked in by the mouth
51
Q

point quadrat

A
  • Consists of a frame containing a horizontal bar
  • At set intervals long pins are pushed through the ground along the bar
  • Each species of plant the pin touches is recorded
52
Q

frame quadrat

A
  • Square frame divided into equal grids
  • Type and number of species within each grid is recorded
53
Q

how do you collect the most valid and representative sample of an area with a quadrat

A
  • Quadrats should be used following arandom sampling technique
  • To study how the presence and distribution of organisms across some land varies, quadrats can be placed systematically along belt/ine transect
54
Q

main ways of using frame quadrats

A

DENSITY - If individual large plants can be seen clearly, count the number of them in a 1m by 1m square quadrat. (density per metre). Gives ABSOLUTE measure.

FREQUENCY - used to study biodiversity in grassland. If each gird represents 1% and there is 1 buttercup in 65/100 grids then the frequency of occurence of buttercups would be 65%

55
Q

how to get an average value of a particular organism per metre squared

A

calculate mean of individual quadrat results

56
Q

How to work out total population of an organism in an area that has been sampled

A

multiply mean value per metre squared by the total area.

57
Q

sampling

A

Can be used to estimate the number of organisms in an area without counting them all.

Number of individuals of a species present in an area = ABUNDANCE

Can be used to measure a characteristic of an organism

58
Q

results of the sample can be used to make

A

Generalisations/estimates about the …number… of organisms

Generalisations/estimates about the …distribution… of organisms

Measured …characteristics… of an organism. E.g. Sample of 200 wheat plants found the average height to be 50cm.

59
Q

Sampling is necessary because we can’t usually gather data from the entire population due to…..

A

Large/inaccessible population (it’s impossible in most cases to study the actual entire population)

Lack of resources

Sampling is the only method available when data gathering process damage the item from which we require data.

60
Q

advantage of stratified sampling

A

Minimises sample selection bias.

Ensures certain population segments are not over/under represented.

61
Q

disadvantage of stratified sampling

A

Unusable when you can’t classify every member of the population into a sub group

62
Q

line transect

A

Simply a straight line marked across a habitat.

Species that touch the line at regular intervals are identified and recorded.

Results are converted into a drawing that shows the distribution of organisms.

Used to show how communities change along a gradient.

Good way to show the changes qualitatively.

63
Q

belt transect

A

Quantitative

Similar to the line transect but gives information on abundance as well as presence/absence of species.

Involves placing quadrats along a line taken through an ecosystem

Short distance - quadrats placed continuously - continuous belt transect

Long distance - quadrats placed at intervals - interrupted belt transect

64
Q

advantage of systematic sampling

A

More straightforward than random sampling as you don’t have to measure the coordinates for each sample.

65
Q

disadvantage of systematic sampling

A

Method is biased as area you choose to put down in the transect may not be representative of the whole habitat.

66
Q

sample selection bias

A

May occur accidentally or deliberately.

E.g. You may choose a particular area to sample because it has more flowers in it or it look interesting.

Sampling bias can be reduced/eliminated by random sampling where there is no human involvement.

67
Q

chance

A

Organisms selected may not be representative of the whole population.

E.g five worms picked at random in a sample may be the longest worms in the populations so the average height taken from this sample would be unreliable.

Chance can never be completely removed from the sample but it can be minimised by using larger samples.

Greater number of individuals studied=lower the probability that chance will affect the result. Bigger sample=more reliable sample.

68
Q

factors that increase genetic biodiversity

A
  • Mutations in the DNA of the organism, creatign a new allele
  • Interbreeding between different populations .This causes alleles to be transferred between the two different populations - GENE FLOW.
69
Q

factors that decrease genetic biodiversity

A

Selective breeding (only a few members of a species are selectively bred for their desired characteristics)

Captive breeding programmes

Artificial cloning (e.g. cutting from plant)

Natural selection - alelles coding for less advantageous characterstics decline drastically from a population or are lost altogether.

Genetic bottlenecks

Founder effect

Genetic drift

70
Q

genetic bottleneck

A

few individuals of a population survive disease/environmental change/habitat destruction. Only their allelles are passed on to the successive generation, reducing the gene pool

71
Q

founder effect

A

Small number of individuals create a new colony, geographically isolated from the original. the gene pool for this new population is small.

72
Q

genetic drift

A

The process of change in the genetic composition of a population due to chance or random events rather than by natural selection, resulting in changes in allele frequencies over time

73
Q

polymorphic gene

A

a gene with more than one allele

74
Q

monomorphic gene

A

a gene with only one allele

75
Q

locus (pl. loci)

A

position of a gene on a chromosome

76
Q

high proportion of polymorphic gene loci

A

= high genetic diversity

77
Q

why is it advantageous for a species to have high genetic biodiversity

A

likely to have some individuals in the population that carries an advantageous allele which enables them to survive a change of conditions. Without these individuals the species will be extinct

78
Q

factors affect biodiversity

A

deforestation
Agriculture
Disease
Climate change

79
Q

how does deforestation affect biodiversity

A
  • Directly reduces number of trees present in an area.
  • If only a specific type of tree is felled then species diversity is reduced.
  • Reduces number of animal species in the area (destroys their habitat and source of food)
  • Animals may migrate to other areas as a result. this reduces biodiversity of other areas.
80
Q

how does removing hedgerows affect biodiversity

A

-Reduces number of plant species in the area
- Destroys habitat of blackbirds, mice, hedgehogs and many inverterbrates

81
Q

how do pesticides and herbicides affect biodiversity

A
  • reduces animal species by killing pest species. By doing this they also kill food sources of other organisms.
  • Herbicides reduce plant diversity by destroying weeds. Also kills food sources for other animals.
82
Q

how does monoculture affect biodiversity

A
  • Lowers plant diversity as only one species of plant is present.
  • Relatively few animals will be supported by one type of plant, so overall biodiversity decreases.
  • Monoculture interferes with nitrogen cycle so contributes to soil depletion.
    -Soil depletion produces weaker crops which are more vulnerable to predators, competitiors and disease.
    -Farmer will become more dependent on pesticides, herbicides and fertilisers
83
Q

how do melting of polar ice caps and rising sea levels affect biodiversity

A
  • Poles of the earth already have low biodiversity. Could lead to exticntion of the few species living there.
  • Species will migrate towards more favourable conditions.
  • Rising sea levels reduce habitat diversity be flooding low lying land.
    -Saltwater flows further up rivers, reducing habitats of freshwater plants and animals.
84
Q

how do high temp and less rainfall affect biodiversity

A

Non drought resistant species of plants will die out. animals that feed on them will die too.

drought resistant plants (xerophytes) will become more dominant.
animals that used to feed on hydrohphytes will be replaced by animals who feed on xerophytes.

85
Q

how will the change in insect life cycles and populations affect biodiversity

A

Insects adapt to climate change. They act as pollinators. If their lifecycles change, it could affect the lives of many plant species, leading to extinction

86
Q

how does disease affect biodiversity

A

-Will lower biodiversity initially through bottleneck effect.
- Eventually genetic drift will cause biodiversity to increase. Different genetic populations will occur as a long term result of disease.

Monocultured populations of crops are extremely vulnerable to disease.

87
Q

economic reasons to maintain biodiversity

A

Deforestation causes soil erosion and desertification. This reduces a country’s ability to grow crops and feed its people - May lead to economic dependence on other countries.

Important to conserve raw materials for industry. Non sustainable sourcing of raw materials will make it economically inviable to continue certain industries.

Large scale habitat and biodiversity losses will mean species with economical importance may become extinct before they are even discovered.

Undiscovered species may be economically or medically useful.

High biodiverse areas promotes tourism.

Crop yield can be increased by higher plant diversity. Genetically engineered crops may need genes from wild varieties of plants, therefore biodiversity needs to be maintained.

88
Q

scientific reasons to maintain biodiversity

A

The natural environment provides an outdoor laboratory for developing a better understanding of the natural world.

Such research has often yielded results of direct benefit to humans. (medicines etc)

89
Q

moral/ ethical argument

A

All species have the right to exist but may lack the ability to survive in the light of human kind’s modifications of the environment.

Humankind has the moral responsibility, as the dominant terrestrial organism, for the care and survival of other species.

90
Q

ecological arguments to maintain biodiversity

A

All organisms are independent on others for their survival. Removal of one species may have a significant effect on others. E.g. a food source or habitat may be lost.

Keystone species - A species which are essential to maintain biodiversity. They have a disproportionately large effect on their environment relative to their abundance.

91
Q

advantages of in situ conservation

A

Maintains genetic diversity of species

Maintains evolutionary adaptations that enable a species to adapt continually to changing environmental conditions.

Preserves interdependent relationships present in a habitat. Interlinked species may be also be preserved.

Cheaper than ex situ conservation.

Less disruptive than removing organisms from their habitats.

Facilitates scientific research of the site.

92
Q

disadvantages of in situ biodiversity

A

Endangered species may be fragmented so the area may not be large enough to ensure the survival of these species.

Genetic diversity may have already been dramatically increased.

Conditions that threatened the organisms in the area may still be present. E.g disease or interspecies competition.

Poachers and ecotourists may see the thriving area as an opportunity and may cause damage.

Cannot always provide medical response to animals.

93
Q

nature reserves (in situ)

A

Controlled Grazing - Only allows livestock to graze a particular area of land for a certain period of time to allow species to recover.

Restricts human access (paths to allow plants not to be trampled)

Controlling poaching - (fines, defences to prevent access)

Feeding animals to ensure more survive until reproductive age

Reintroducing species to areas where they are locally extinct or in decline

Halting succession so that heath-, moor- or downland doesn’t all grow into woodland so future generations can enjoy them. This often achieved through controlling grazing

94
Q

advantages of ex situ conservation

A

Organisms are completely protected from predation and poaching

Health of individuals can be monitored and medical assistance can be given as required.

Population can be more effectively managed and divided if disaster strikes

Genetic diversity of the population can be measured

Selective breeding programmes can be put into place

Modern reproductive technology can increase the chance of reproductive success

Research into reproductive physiology, lifestyle can be carried out easier of animals are in captivity.

Conservation sites can be used as attractions to raise funds for further conservation efforts.

Conservation sites can be used for education.

95
Q

disadvantages of ex situ

A

Captive populations have limited genetic diversity - more susceptible to rapid species decline/extinction with the onset of disease.

Organisms are living outside their natural habitat, which could affect their health.

Correct survival environmental conditions may be difficult to achieve.

Captivity is expensive to maintain.

Animals may not survive reintroduction into the wild.

Animals may not be accepted into wild species once reintroduced

96
Q

advantages of seed banks

A
  • Lasts longer than plants
  • allows researchers and conservation biologists to evaluate them for properties such as new sources of medicines, nutrition, and genes.
  • facilitates scientific study that could provide helpful information for conserving the remaining natural populations of the species.
  • Can control when to plant seed.
  • Immune to habitat destruction, diseases and predators.
  • can be used to reintroduce into habitats where they were once present.

-Can be used to augment new habitats with low biodiversity.

97
Q

rio convention

A

Countries involved agree to commit to conservation and sustainable use of biodiversity.

Every country has to take ownership to protecting its biodiversity.

Species can be exploited SUSTAINABLY.

Countries choose their own methods for protecting their biodiversity.

98
Q

CITES

A

Ensures that species trade of flora and fauna arent exploited unsustainably.

Appendix 1
-Endangered species/species affected by trade are protected.

Appendix 2
- Species not necessarily threatened with extinction but for which trade must be controlled to avoid them being endangered.

Appendix 3
-Species for which a country is conserving for it’s own reasons are protected.

99
Q

countryside stewardship scheme

A

Provides financial incentives for local farmers to protect their enviroment such as:

  • Conserving and restoring wildife habitats
  • Flood risk management
  • Reducing widespread water pollution from agriculture.
  • Keeping the character of the coutnryside.
  • Preserving features important to history of landscape.
    -Encourages educational access.
    -Competitive scheme - scored agaisnt local priority targets to maximise enviromental benefits

OCR AS/A Level Biology Context (24 decks)

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