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OCR A level Biology HJ > Biodiversity > Flashcards

Biodiversity Flashcards

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1
Q

what is biodiversity?

A

-the variety of living organisms in an area

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2
Q

what are the 3 different levels of diversity?

A
  • habitat diversity
  • species diversity
  • genetic diversity
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3
Q

what are some physical and biotic factors in a habitat?

A

physical factors:

  • the soil
  • temp range

Biotic factors:

  • availability of food
  • presence of predators
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4
Q

what is habitat diversity?

A

habitat diversity is the number of different habitats in an area

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5
Q

what are some examples of habitat diversity in a costal area?

A
  • beaches
  • sand dunes
  • mudflats
  • salt marshes
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6
Q

what are some examples of habitat diversity in a river valley?

A
  • meadows
  • agricultural fields
  • streams
  • woodland
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7
Q

what is a species?

A

a species is a group of similar organisms able to reproduce to give fertile offspring

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8
Q

what is species diversity?

A

species diversity is the number of different species (species richness) and the abundance of different species (species evenness) in an area

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9
Q

what are some examples of species diversity in a woodland?

A
  • plants
  • insects
  • birds
  • mammals
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10
Q

what is genetic diversity?

A

genetic diversity is the variation of alleles(versions of a gene) within a species or a population of a species

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11
Q

what are some examples of genetic diversity?

A
  • human blood type is determined by a gene with 3 different alleles
  • the variation in alleles within the dog species gives rise to different breeds, such as a Labrador or poodle
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12
Q

how is random sampling carried out?

A
  • if you were looking at plant species in a field o could pick random sample sites by dividing the field into a grid using measuring tapes
  • use a random number generator to select coordinates (to make sure that each sample site has the same probability of being chosen
  • to ensure any variation isn’t due to chance, it’s important to analyse the results statistically (this allows you to be more confident that the results are true and therefore will reflect whats going on in the whole population)
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13
Q

why would you carry out non random sampling?

A

when there’s a lot of variety in the distribution of species in the habitat and you want to make sure that all the different areas are sampled or that all the different species are sampled

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14
Q

what are the 3 types of random sampling?

A
  • systematic sampling
  • opportunistic sampling
  • stratified sampling
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15
Q

what is systematic sampling + give an example?

A

-this is when samples are taken at fixed intervals, often along a line

e.g.- if you were looking at plant species in a field, quadrats (square frames that you place on the ground) could be placed along a line (called a transect) form an area of shade in the corner to the middle of the field
each quadrat would be a sample sie

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16
Q

what is opportunistic sampling?

A

this is when samples are chosen by the investigator. it’s used because it’s simple o carry out but the data will be biased

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17
Q

whats stratified sampling?

A

-this is when different areas in a habitat are identified and sampled separately in proportion to their part of the habitat as a whole.

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18
Q

what methods can you use to catch crawling ground insects?

A
  • pitfall trap(a small pit that insects can’t get out of_

- a pooter ( a device that allows you to safely suck small insects through a tube into a jar

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19
Q

what method can you use to trap small organisms that live in soil or leaf litter?

A
  • tullgrens funnel- a sample of soil or leaf litter is put on a mesh filer at the top of a funnel and a light shone down on it
  • the light acts as a heat source and dries out the soil/ leaf litter, so organisms move away from it and fall into the beaker.
  • the mesh holds the soil/leaf litter in place but lets the small organisms pass through
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20
Q

what method can you use to trap aquatic organsisms?

A

-kick sampling- you gently kick the sediment at the bottom of a stream for a set amount of time, then hold a net downstream of where you’ve kicked and collect the organisms that have been distributed

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21
Q

what method can you use to trap organisms living in long grass?

A

sweep net- you stand still and sweep the net once from left to right through the grass, then quickly sweep the net up and turn the contents of the met into a collecting tray

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22
Q

what is the method used to estimate biodiversity of samples?

A

1- choose a site to sample (randomly or non-randomly)
2-record the number of different species or count the number of individuals of each species
3-repeat the process-take as may samples as possible (this gives a better indication of the whole habitat) + all samples should be chosen in the sample way (either all randomly or all non- randomly)
4-number of individuals for the whole habitat can be estimated by calculating the mean for the data collected in each sample and multiplying it by the size of the whole habitat
5-when sampling different habitats and comparing them, always use the same sampling technique

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23
Q

how could you investigate the impact of mowing on the biodiversity of your school playing field?

A

1- by sampling a mowed and un-owed field

2-calculate the biodiversity for each field using Simpson’s Index

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24
Q

what’s species richness?

A
  • the number of different species in an area.

- the higher the number of species, the greater the species richness

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25
Q

how is species richness measured?

A

by taking random samples of a habitat and counting the number of different species

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26
Q

what’s species eveness?

A

it’s a measure of the relative abundance of each specie in an area.
-the more similar the population size of each species, the greater the species evenness

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27
Q

how is species evenness measured?

A

by taking random samples of a habitat and counting the number of individuals of each different species

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28
Q

what’s the correlation between biodiversity, species richness and evenness?

A

the greater the species richness + species evenness, the greater the biodiversity >vice versa

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29
Q

why is simpson’s index used to calculate biodiversity instead of species richness and evenness?

A

because species that are present in a habitat in a very small numbers shouldn’t be treated the same way as those with a bigger population

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30
Q

what’s the formula for simpson’s index and what does everything represent?

A 
𝐷 = 1 -( Ʃ (n/N)2)
where...
n= total number of organisms in 1 species
N= total number of all organisms
Ʃ = 'sum of'
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31
Q

what does the value of the simpsons index tell us?

A
  • it’s always between 0 and 1
  • the closer the index to 1, the more diverse the habitat and the greater its ability to cope with change (predator)
  • low index values suggest the habitat is more easily damaged by change, making it less stable
  • the greater the species richness and evenness, the higher the value of simpson’s index
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32
Q

what’s the importance of genetic diversity?

A

if a pop has a low genetic diversity, they might not be able to adapt to changes in the environment and the whole pop could be wiped out by a single event (disease)

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33
Q

how might a population have low genetic diversity?

A

-isolated pops (those bred in captivity, zoos)

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34
Q

give an example of something that reduces genetic diversity

A

inbreeding (breeding between closely related individuals)

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35
Q

what’s polymorphism?

A
  • alleles are different versions of a gene
  • alleles of the same gene are always found at the same point (locus) on a chromosome
  • polymorphism describes a locus that has 2 or more alleles
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36
Q

whats the equation for proportion of polymorphic gene loci + what does this equation tell us?

A

proportion of polymorphic gene loci = (number of polymorphic gene loci / total number of loci)

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37
Q

what are some ways that the growth in the human pop is decreasing biodiversity?

A

1- habitat loss
2- over-exploitation
3- urbanisation
4- pollution

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38
Q

how does habitat loss decrease biodiversity?

A
  • as the human pop grows, we need to develop more land for housing and to produce food. this development is destroying habitats
  • there’s deforestation in the amazon to make way for grazing and agriculture–> this decreases habitat biodiversity–> with fewer habitats for organisms to live in, species diversity also decreases
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39
Q

how does over-exploitation decrease biodiversity?

A
  • a greater demand for resources(food, water, energy) means a lot of resources are being used up faster than they can be replenished. This can destroy habitats or it can affect species directly.
  • Industrial fishing can lead to extinction of certain species= decrease in genetic diversity= decrease in species diversity
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40
Q

how does urbanisation decrease biodiversity?

A

-sprawling cities and major road developments can isolate species, meaning populations are unable to interbreed and genetic diversity is decreased.

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41
Q

how does pollution decrease biodiversity?

A

-as the human population grows, we’re producing more waste and more pollution. High levels of pollutants can kill species or destroy habitats.

e. g.
- high levels of fertiliser flowing into a river from nearby fields can lead to a decrease in fish species in that river. This decreases biodiversity.
- some of the gases that are released from factories and cars cause acid rain, which can lower the pH of rivers, lakes and soil. many organisms can’t survive below a certain pH

42
Q

how does monoculture decrease bodiversity?

A

monoculture is the growing of a single variety of a single crop
1- habitat loss
2- loss of local plants and animals-destroyed with pesticides and herbicides, reducing species diversity
3- loss of heritage varieties- heritage (traditional) varieties of crops are lost because they don’t make enough money and so are not planted anymore, which reduces species diversity

43
Q

how is current climate change caused by humans?

A
  • increasing emission of greenhouse gases (CO2)
  • greenhouse gases cause global warming (increasing global average temp) which causes other types of climate change such as changing rainfall patterns
44
Q

how can climate change affect biodiversity?

A

changing environmental conditions:

  • some places get warmer, some colder, some wetter and other drier= global biodiversity
  • most species need a particular climate to survive so change in climate = previously inhabitable becomes uninhabitable (vice versa)

-causes an increase or decrease in the range of some species = increase or decrease biodiversity

45
Q

how does a change in environmental conditions cause a species disruption?

A

changing environmental conditions may force some species to migrate to a more suitable area, causing a change in species disruption

46
Q

how does migration affect biodiversity?

A
  • migrations usually decrease biodiversity in the areas the species migrate from, and increase biodiversity in the areas they migrate to.
  • If there isn’t a suitable habitat to migrate to, the species is a plant and can’t migrate, or if the change is too fast, the species may become extinct. This will decrease biodiversity
47
Q

whats an ecosystem?

A

an ecosystem is all the organisms living in an area and all the non- living conditions, e.g. temp

48
Q

what does it mean for organisms to be interdependent?

A

they depend on each other to survive. This means that the loss of just 1 species can have pretty drastic effects on an ecosystem such as:

  • disruption of food chains
  • disruption of nutrient cycles
49
Q

what are keystone species?

A

species that many other species in an ecosystem depend on and without which the ecosystem would change drastically

50
Q

what do keystone species do?

A
  • keystone species can be modifiers- maintaining the environment needed for the ecosystem (e.g. beaver building dams), or hosts- plants that provide a particular environment, such as palm trees
  • they tend to have a relatively low pop size but a huge effect on the environment - keystone species are often predators, keeping the population of prey in check
51
Q

what are genetic resources?

A
  • refer to any material from plants, animals or microorganisms, containing genes that we find valuable
  • genetic resources could be crops, plants used for medicines, microorganisms used in industrial processes, or animal breed
52
Q

why are genetic resources improtant?

A

they provide us with:

  • food and drink
  • clothing
  • drugs
  • fuels
  • genetic resources also allow u to adapt to changes in the environment
53
Q

what are some economic reasons for maintaining biodiversity?

A
  • many of the genetic resources are important to the global economy
  • reducing soil depletion because continuous monoculture doesn’t give enough time for the nutrient and organic material to be replaced
  • tourism
54
Q

what are some aesthetic reasons fro maintaining biodiversity?

A
  • areas rich in biodiversity provide pleasant, attractive landscapes that people can enjoy
  • by maintaining biodiversity we protect these beautiful landscapes
  • the more biodiversity in an area, the more visitors the area is likely to attract-this has some economic advantages
55
Q

why is conservation important?

A
  • biodiversity can be maintained through conservation- the protection and management of species and habitats
  • conservation is important to ensure the survival of endangered species- species which are at risk of extinction because of a low population, or a threatened habitat
  • a species that is critically endangered is likely to become extinct because its population size is too small
56
Q

what are the 2 main types of conservation?

A
  • in situ conservation

- ex situ conservation

57
Q

what is in-situ conservation?

A

in situ conservation means conservation on site- it involves protecting species in their natural habitat

58
Q

what are some methods of in-situ conservation?

A

1 -establishing protected areas such as national parks ad wildlife reserves (nature reserves)- habitats and species are protected in these areas by restricting urban development, industrial development and farming. Controlling human activity.

2 -controlling or preventing the introduction of species that threaten biodiversity.

3 -protecting habitats-e.g. controlling water levels to conserve wetlands and coppicing (trimming trees) to conserve woodlands. This allows organisms to continue living in their natural habitat.

4 -restoring damaged areas- such as a coastline polluted by an oil spill.

5- promoting particular species- this could be by protecting food sources or nesting sites

6- giving legal protection to endangered species, e.g. by making it illegal to kill them

59
Q

what are some advantages of in-situ conservation?

A
  • often both he species and their habitat are conserved—> this means that larger populations can be protected
  • its less disruptive than removing organisms from their habitats
  • the chances of the population recovering are also greater than with ex-situ methods
60
Q

what is a disadvantage of in-situ conservation?

A

-it can be difficult to control some factors that are threatening a species (such as poaching, predators, disease or climate change

61
Q

what is ex-situ conservation?

A

-ex-situ conservation means conservation off site- it involves protecting a species by removing part of the population from a threatened habitat and placing it in a new location. Ex-situ conservation is often a last resort.

62
Q

what are some methods of ex-situ conservation?

A
  • relocating an organism to a safer area
  • breeding organisms in captivity then reintroducing them to the wild when they are strong enough. Breeding is carried out in animal sanctuaries and zoos
  • botanic gardens are controlled environments used to grow a variety of rare plants for the purposes of conservation, research, display and education. Endangered plant species as well as species that are extinct in the wild can be grown and reintroduced into suitable habitats.
  • seed banks- seeds can be frozen and stored in seed banks for over a century without using fertility. Seed banks provide a useful source of seeds if natural reserves are destroyed,e.g. by disease or other natural disasters
63
Q

what are some advantages of ex-situ conservation?

A
  • it can be used to protect individual animals in a controlled environment- things like predation and hunting can be managed more easily
  • competition for resources can be reduced, and its possible to check on the health of individuals and treat them for diseases
  • breeding can be manipulated, e.g. through the use f reproductive hormones and IVF
  • it can be used to reintroduce species that have left an area
64
Q

what are some disadvantages of ex-situ conservation?

A
  • usually only a small number of individuals can be care for
  • can be difficult and expensive to create an sustain the right environment
  • animals that are habituated (used to) human contact may be less likely to exhibit natural behaviour and be more likely to catch a disease from humans
  • usually less successful than in-situ methods- many species can’t breed successfully in captivity. or don’t adapt to their environment when moved to a new location
65
Q

what are some examples of some successful international cooperation and what do they each do?

A

-Rio convention on biological diversity (CBD):
~aims to develop international strategies on the conservation of biodiversity + how to use animal and plant resources in a sustainable way
~the convention made it part of international law that conserving biodiversity is everyone’s responsibility
~it also provides guidance to governments on how to conserve biodiversity

-CITES agreement:
~designed to increase international cooperation in regulating trade in wild animal and plant species
~the member countries all agreed to all make it illegal to kill endangered species
~the agreement helps to conserve species by limiting trade through licensing, and making it illegal to trade in products made from endangered animals
~its also designed to raise awareness of threats to biodiversity through education

66
Q

what is an example of a local conservation agreements?

A
  • aims to conserve wildlife and biodiversity
  • improve and extend wildlife habitats by promoting specific management techniques to landowners
  • government s payed landowners who followed the techniques they were suggesting
67
Q

state a method for taking a random sample at a grass verge ?

A

1- mark out a grid on the grass using 2 tape measures laid at right angles.

2-use random numbers to determine the x coordinate and the y coordinate on your grid.

3-take a sample at each of the coordinate pairs generates.

68
Q

what are the 3 types of non- random sampling?

A
  • opportunistic
  • stratified
  • systematic
69
Q

describe opportunistic samplong?

A

opportunistic- this is the weakest form of sampling as it may not be representative of the population. Opportunistic sampling uses organisms that are conveniently available.

70
Q

describe stratified sampling

A

some populations can be divided into a number of strata (sub-groups) based on a particular characteristic. For instance, the population might be separated into males and females. A random sample is then taken from each of these strata proportional to its size

71
Q

describe systematic sampling

A
  • in systematic sampling different areas within an overall habitat are identified, which are then sampled separately.
  • e.g., systematic sampling may be used to study how plant species change as you move inland from the sea.
  • systematic sampling is often carried out using a line or a belt transect.
  • a line transect involves marking a line along the ground between 2 poles and taking samples at specified pints, this can include describing all f the organisms which touch the line or distances of samples from the line.
  • a belt transfer provides more info; 2 parallel lines are marked, an samples are taken of the area between he 2 lines
72
Q

what are the 2 reasons why a sample is never entirely representative of the organisms present in a habitat?

A

sampling bias and chance

  • sampling bias- the selection process may be biased. This may be by accident, or may occur deliberately. For example, you may choose to sample a particular area that has more flowers because it looks interesting. The effects of sampling bias can be reduced using random sampling, where human involvement in choosing the sample is removed.
  • chance- the organisms selected may, by chance, not be representative of the whole population. For example, a sample o f5 worms collected in a trap may be the 5 longest n the habitat. Chance can never be completely removed from the process, but its effect can be minimised by using a large sample size. The greater the number of individuals studied, the number studied, the lower the probability that chance will influence the result. Therefore the larger the sample size, the more reliable the result.
73
Q

how and what are pooters used for?

A

a pooter is used to catch small insects. By sucking on a mouthpiece, insects are drawn into the holding chamber via the inlet tube. A filter before the mouthpiece prevents them from being sucked into the mouth.

74
Q

how and what are sweep nets used for?

A

sweep nets are used to catch insects in areas of long grass.

75
Q

how and what are pitfall traps used for?

A

pitfall traps are used to catch small, crawling invertebrates such as beetles, spiders and slugs. A hole is dug in the ground, which insects fall into. It must be deep enough that they cannot crawl out and covered with a roof- structure propped above so that the trap doesn’t fill with rainwater. The traps are normally left overnight, so the nocturnal species are also tempted.

76
Q

how and what is tree beating be used for?

A

tree beating is used to take samples of the invertebrates living in a tree or bush. A large white cloth is stretched out under the tree. the tree is shaken or beaten to dislodge the invertebrates. The animals will fall onto the sheet where they can be collected and studied.

77
Q

how and what are kick sampling used for?

A

kick sampling is used to study the organisms living in a river. The river bank and bed is ‘kicked’ for a period of time to disturb the substrate. A net is held just downstream for a set period of time in order to capture any organisms released into the flowing water.

78
Q

what are the 2 main types of quadrat?

A
  • point quadrate- this consists of a frame containing a horizontal bar. At set intervals along the bar, long pins can be pushed though the bar to reach the ground. each species of plant the pin touches is recorded.
  • frame quadrat- this consists of a square frame divided into a grid of equal sections. the type and number of species within each section of the quadrat is recorded.
79
Q

what is a frame quadrat used for?

A

a frame quadrat is used to sample the population of plants living in a habitat.

80
Q

what are the 3 main ways of using a frame quadrat?

A
  • DENSITY= if individuals large plants can be seen clearly, count the number of them in a 1m by 1m square quadrat. This will give you the density per square metre. This is an absolute measure, not an estimate as the following 2 methods
  • FREQUENCY= this is used where individual members of a species are hard to count, like grass or moss. Using the small grids within a quadrat, count the number of squares a particular species is present in.
  • PERCENTAGE COVER= this is used for speed as lots of data can be collected quickly. It is useful when a particular species is abundant or difficult plant species cover.
81
Q

what do you need to do after using frame quadrats?

A
  • for each approach (density, frequency and percentage cover), samples should be taken at a number of different points.
  • the larger the number of samples taken, the more reliable your results.
  • you should then calculate the mean of the individual quadrat results to get an average value for a particular organism per m^2 (to calculate the mean value, sum the individual quadrat results, then divide by the number of samples taken).
  • To work out the total population of an organism in an area that has been samples, multiply the mean value per m^2 by the total area.
82
Q

what is meant by the capture-mark-release technique and what is it used for?

A
  • as animals are constantly moving through a habitat and others may be hidden, it can be difficult to accurately determine their population size.
  • This technique is often used to estimate a population size.
  • this involves capturing as many individuals of a species in an area as possible.
  • the organisms are marked and then released back into the community.
  • time is allowed for the organisms to redistribute themselves throughout the habitat before another sample of animals is collected.
  • by comparing the number of marked individuals with the number of unmarked individuals in the 2nd sample, scientists can estimate population size.
  • the greater the number of marked individuals recaptured, the smaller the population.
  • then calculate species evenness by comparing the total number if each organism present.
  • populations of plants or animals that are similar in size or density represent an even community and hence a high species evenness.
  • species evenness can also be expressed as a ratio between the numbers of each organism present.
83
Q

what are 6 abiotic factors and the sensor used to measured them?

A 
wind speed- anemometer
light intensity- light meter
relative humidity- humidity sensor
pH- pH probe
temperature- temperature probe
oxygen content in water- dissolved oxygen probe
84
Q

why is the fact that many abiotic factors being able to measure quickly and accurately using a range of sensors an advantage?

A
  • rapid changes can be detected
  • human error in taking a reading is reduced
  • a high degree of precision can often be achieved
  • data can be stored and tracked on a computer
85
Q

what is the number of successful species in an environment with low biodiversity?

A

relatively low

86
Q

what is the number of successful species in an environment with high biodiversity?

A

a large number

87
Q

what is the nature of the environment in an environment with low biodiversity?

A

stressful and/ or extreme with relatively few ecological niches

88
Q

what is the nature of the environment in an environment with high biodiversity?

A

relatively benign/ not stressful, with more ecological niches

89
Q

what are the type of food webs in an environment with low biodiversity?

A

relatively simple

90
Q

what are the type of food webs in an environment with low biodiversity?

A

complex

91
Q

what is the effect of a change to the environment on ecosystem as a whole in an environment with low biodiversity?

A

major effects on the ecosystem

92
Q

what is the effect of a change to the environment on ecosystem as a whole in an environment with high biodiversity?

A

often relatively small effect

93
Q

what are some factors that increase genetic biodiversity?

A
  • mutations

- interbreeding (gene flow)

94
Q

what are some factors that decrease genetic biodiversity?

A
  • selective breeding (artificial selection)
  • captive breeding
  • artificial breeding
  • natural selection
  • genetic bottlenecks
  • the founder effect
  • genetic drift
95
Q

what is meant by natural selection?

A

as a result, species will evolve to contain primarily the alleles which code for advantageous characteristics. Over time, alleles coding for less advantageous characteristics will be lost from a population, or only remain in a few individuals.

96
Q

what is meant by genetic bottleneck?

A

where few individuals within a population survive an event or change (e.g. disease, environmental change or habitat destruction), thus reducing the ‘gene pool’. Only the alleles of the surviving members of the population are available to be passed on to offspring.

97
Q

what is meant by the founder effect?

A

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

98
Q

what is meant by genetic drift?

A

due to the random nature of alleles being passed on form parents to their offspring, the frequency of occurrence of an allele will vary. In some cases, the existence of a particular allele can disappear from a population altogether. Genetic drift is more pronounced in populations with a low genetic biodiversity.

99
Q

what are the main problems with human influence on biodiversity?

A
  • DEFORESTATION- the permanent removal of large areas of forest to provide wood for building and fuel (known as logging), and to create space fro roads, buildings and agriculture
  • AGRICULTURE- an increasing amount of land ha to be farmed in order to feed the growing population. this has resulted in large amounts of land being cleared and in many cases planted with a single crop (monoculture).
  • CLIMATE CHANGE- there is much evidence that the release of CO2 and other pollutants into the atmosphere from the burning of fossil fuels is increasing global temperature.
100
Q

what are some ways that deforestation affects biodiversity?

A
  • it directly reduces the number of trees present in an area
  • if only a specific type of tree is felled, the species diversity is reduced.
  • it reduces the number of animal species present in an area as it destroys their habitat, including their food source and home. This in turn reduces the number of other animal species that are present, by reducing or removing their food source
  • animals are forced to migrate to other areas to ensure their survival. This may result in the biodiversity of neighbouring areas increasing.
101
Q

what are some way that agriculture leads to a reduction in biodiversity?

A
  • DEFORESTATION- to increase the area of land available for growing crops or rearing animals.
  • REMOVAL OF HEDGEROWS- as a result of mechanisation, farmers remove hedgerows to enable them t use large machinery to help them plant, fertilise, and harvest crops. It also frees up extra land for crop growing. This reduces the number of plant species present in an area and destroys the habitat of animals such as blackbirds, hedgehogs, mice and many invertebrates.
  • USE OF CHEMICALS SUCH AS PESTICIDES AND HERBICIDES- pesticides are used to kill pests that would eat the crops or live i the animals. This reduces species diversity directly as it destroys the pest species (normally insects), and indirectly by destroying the food source of other organisms.
  • HERBICIDES ARE USED TO KILL WEEDS- a weed is any plant growing in an areas where it is not wanted. weeds are destroyed as they compete with the cultivated plants for light, minerals and water. by destroying weeds, plant diversity is reduced directly, and animal diversity may also be reduced by the removal of an important food source.
  • MONOCULTURE- many farms specialise in he production of only 1 crop, with many acres of land being used for the growth of one species. This has an enormous local effect in lowering biodiversity as only 1 species will be supported by only 1 type of plant, this results in low overall biodiversity levels.

OCR A level Biology HJ (23 decks)

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