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A Level Biology > Module 4 Section 2: Biodiversity > Flashcards

Module 4 Section 2: Biodiversity Flashcards

1
Q

What are the human population growth factors affecting biodiversity

A

Habitats loss
Over-exploitation
Urbanisation
Pollution

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2
Q

How does habitat loss affect biodiversity

A

Human develop destroys habitats which decreases habitat diversity
E.g. deforestation in the Amazon to make way for grazing and agriculture

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3
Q

How does over-exploitation affect biodiversity

A

A greater demand for resources (such as food, water and energy) means a lot of resources are being used up faster than they’re replenished
E.g. industrial fishing can deplete the populations of certain fish species and may cause extinction
This decreases genetic diversity within populations, as well decreasing species diversity

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4
Q

How does urbanisation affect biodiversity

A

Growing cities and road developments can isolate species, meaning populations are unable to interbreed and genetic diversity is decreased

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5
Q

How does pollution affect biodiversity

A

High amounts of pollutants can kill species or destroy habitats which decreases biodiversity
E.g. high levels of fertiliser flowing into a river can lead to a decrease in fish species

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6
Q

What is monoculture

A

When large areas or land are devoted to a single variety of crop
This is to feed a growing number of people
E.g. palm oil plantations

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7
Q

How does agriculture decrease biodiversity

A

Habitats are lost as land is cleared to make way for the large field, reducing habitat diversity
Local and naturally occurring plants and animals are seen as weeds and pests, and so are destroyed with pesticides, reducing species diversity
Heritage (traditional) varieties of crops are lost because they don’t make enough money and so are not planted any more, which reduces species diversity

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8
Q

What is climate change

A

The variation in Earth’s climate e.g. temperature or rainfall patterns
Occurs naturally but current climate change is caused by humans increasing emissions of greenhouse gases (CO2)

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9
Q

How does climate change affect different areas of the world

A

Some places will get warmer/ colder or wetter/ drier
All of these are likely to affect global biodiversity

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10
Q

How does climate change affect biodiversity

A

Most species need a particular climate to survive
A change in climate may mean that areas become uninhabitable
This can cause an increase or decrease in the range of some species which can change biodiversity
Some species may be forced to migrate to a more suitable area, causing a change in species distribution
Migrations usually decrease biodiversity in the areas the species migrate from, and increase biodiversity in the areas they migrate to
If there’s no suitable habitat to migrate to, the species is a plant or the change is too fast, the species become extinct
This will decrease biodiversity

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11
Q

How does deforestation reduces biodiversity

A

Reduces number of trees in an area
If only a specific type of tree is felled, species diversity is reduced
Destroys habitats and reduces number of animal species present in an area by removing food source and home
Animals are forced to migrate to other areas to ensure survival, increases biodiversity or neighbouring areas

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12
Q

Different reasons why maintaining biodiversity is important

A

Ecological reasons
Economic reasons
Aesthetic reasons

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13
Q

What is an ecosystem

A

All the biotic and abiotic components living in a particular area

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14
Q

What does an interdependent ecosystem mean

A

The organisms depend on eachother to survive
If one species is lost, it can have drastic effects on an ecosystem

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15
Q

Examples of effects of losing a component in an interdependent ecosystem

A

Disruption of food chains:
If primary consumer numbers fall then both secondary and tertiary populations can decline
Disruption of nutrient cycles:
Decomposes improve quality of soil by recycling nutrients, if numbers of decomposes decline it can reduces growth of plants and therefore food availability

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16
Q

What are keystone species

A

Species in an ecosystem which many other species depend upon
Without them the ecosystem would change drastically

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17
Q

What types species can be keystone species

A

Often predators which are needed to control prey populations
Can be modifiers which maintain the environment needed for the ecosystem
Can be hosts which are plants that provide a particular environment

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18
Q

Why do we maintain biodiversity for ecological reasons

A

To protect species
To maintain genetic resources

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19
Q

What are genetic resources

A

Refer to any material from plants, animals or microorganisms that contain genes that we find valuable

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20
Q

Examples of genetic resources

A

Can be:
Crops
Plants used for medicine
Microorganisms used in industrial processes
Animals breeds

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21
Q

Why maintain genetic resources

A

Provide us with a variety of everyday products
Allow us to adapt to changes in the environment

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22
Q

How do genetic resources provide us with a variety of everyday products

A

Food and drink
Clothing: fibres and fabrics are made from plants and animals
Drugs: from plant compounds
Fuels: organisms are used for renewable fuels (ethanol, biogas), fossil fuels are non renewable so are of economic importance
Other industrial materials: wood, paper, dyes, adhesives, oils, rubbers, pesticides are from plants and animals species

Many of these resources are important to the global economy as they can be traded at global scale

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23
Q

How do genetic resources allow us to adapt to changes in the environment

A

Climate change may result in some crops failing (possibly due to droughts)
We can use genes from a plant that’s resistant to droughts to genetically engineer a drought resistant crops (if we have such genetic resources to choose from)

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24
Q

Why should we maintain biodiversity for economic reasons

A

Soil erosion and desertification can occur due to deforestation, it can reduces a country’s ability to grow crops which can lead to economic dependence on other nations

Large scale biodiversity loss results in economically beneficial species becoming extinct before their benefits have been discovered

Monoculture can result in soil depletion (gradual reduction in nutrients from one species of plant being continuously grown) which produces weaker crops, farmers will become dependent on expensive pesticides and fertilisers to fend of insects and microorganisms to maintain productivity

Areas rich in biodiversity provide an attractive environment that people enjoy. These areas can promote tourism which can bring in income

Diverse areas have more potential for manufacturing new products in the future which can be beneficial to humans

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25
Q

Why should we maintain biodiversity for aesthetic reasons

A

Natural wonder can inspire musicians and writers which can bring pleasure for many others through books and music
Studies show that patients recover more rapidly from stress and injury which exposed to plants and a natural environment

Biodiversity areas can be relaxing and enriching

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26
Q

What is biodiversity

A

The variety of living organisms in an area

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27
Q

What is a species

A

A group of similar organisms able to reproduce to give fertile offspring

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28
Q

What is a habitat

A

The area inhabited by a species
It includes the physical factors, like the soil and temperature range, and the living (biotic) factors, like availability of food or the presence of predators

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29
Q

What does habitat diversity mean

A

The number of different habitats in an area
E.g. sand dunes, woodland, meadows

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30
Q

What does species diversity mean

A

The number of different species (species richness) and the abundance of each species (species evenness) in an area
E.g. a woodland could contain many different species of plants, insects and birds

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31
Q

What does genetic diversity mean

A

The variation of alleles within a species (or population of species
E.g. the variation of alleles within the dog species gives us different breeds

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32
Q

What is species richness

A

The number of different species in an area
Higher the number of species, greater the species richness

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33
Q

How to measure species richness

A

Take random samples of a habitat and count the number of different species

34
Q

What is species evenness

A

The measure of the relative abundance of each species in an area
The more similar the population size of each species, the greater the species evenness

35
Q

How to measure species evenness

A

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

36
Q

What is the student T test

A

Used to compare the mean values of two sets of data

t = (x̄1-x̄2) / √(σ1^2/n1) + (σ2^2/n2)

x̄1, x̄2: mean of populations 1 and 2
σ1, σ2: standard deviation of populations 1 and 2
n1,n2: total number of values in sample 1 and 2

37
Q

What is the spearman’s rank correlation coefficient calculation

A

Spearman’s rank correlation coefficient is used to consider the relationship of between two sets of data

rs = 1 - 6Σd^2 / n(n^2 - 1)

rs: correlation coefficient
d: difference in ranks
Σ: sum of number of pairs of data

38
Q

Method of spearman’s rank

A

Rank each value in the data set from smallest to largest
Repeat this for the other data set
Find the difference between the ranking of each row (can be negative)
Square these differences to get d^2
Add these up to get Σd^2
Plug into equation

39
Q

Why is having high genetic biodiversity important

A

Species that contain greater genetic biodiversity are likely to be able to adapt to changes in their environment so are less likely to become extinct
There are more likely to be some organisms within the population that carry an advantageous allele which allows them to survive in altered conditions

40
Q

What makes genetic biodiversity

A

All species share the same genes but have different alleles
Difference in alleles in species creates genetic biodiversity
Greater number of alleles the greater the genetic biodiversity

41
Q

What factors increase genetic biodiversity

A

To increase numbers of alleles:
Mutations in the DNA of an organism which create new alleles
Interbreeding between different populations, when an individual migrates from one population and breeds with a member of another population so alleles are transferred between two populations (known as gene flow)

42
Q

How genetic biodiversity can decrease

A

Number of possible alleles in a population must decrease:
Selective breeding, where only a few individuals within a population are selected for their advantageous characteristics and bred

Natural selection causes species to evolve to contain mainly the alleles which code for advantageous characteristics, slowly the alleles coding for less beneficial characteristics will be decreased

Genetic bottlenecks where a few individuals within a population survive an event or change (e.g. disease or habitat destruction), this reduces the gene pool so only the alleles of the surviving members of the population are available to be passed on to offsprings

43
Q

What is polymorphism

A

Alleles of the same gene are found at the same point (locus) on a chromosome
Polymorphism is a locus that has more than 1 allele
Genes with a single allele existing are monomorphic

44
Q

How to work out genetic biodiversity using measurements of polymorphism

A

Proportion of polymorphic gene loci = number of polymorphic gene loci / total number of loci

Can multiply by 100 to find percentage

45
Q

What is In Situ conservation

A

On site conservation
Involves protecting species in their natural habitat
Conservation ensures the survival of endangered species

46
Q

Method of In Situ conservation

A

Establishing protected areas such as national parks and wildlife reserves
Protects species and habitat by restricting urban and industrial development and farming
Can also be done with Marine Conservation Zones where human activities are controlled

Controlling the introduction of species that threaten local biodiversity

Habitat protection methods such as controlling water levels to conserve wetlands and trimming trees to conserve woodlands

Promoting particular species by protecting food sources or nesting sites

Giving legal protection to endangered species by making it illegal to kill or trade them

47
Q

Advantage and disadvantage of In Situ conservation

A

Both species and habitat are conserved
Large populations can be protected

Difficult to control factors which threaten a species

48
Q

What is Ex Situ conservation

A

Means off site conservation
Involves protecting a species by removing part of the population from a threatened environment and placing it in a new location
Often last resort

49
Q

Method 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

Making botanical gardens to grow rare plants for conservation, research, display and education

Seed banks where seeds can be frozen and stored without losing their fertility
Provides a source of seeds if natural reserves are destroyed

50
Q

Advantage and disadvantage of Ex Situ conservation

A

Animals are protected in controlled environment (predation and hunting can be managed)
Used to reintroduce species that have left an area

Difficult and expensive to create and sustain the right environment
Animals are less likely to exhibit natural behaviour and may not breed successfully

51
Q

What is the Rio Convention on Biological Diversity

A

CBD:
Aims to develop international strategies on the conservation of biodiversity and how to use animal and plant resources in a sustainable way
Convention made it part of international law that conserving biodiversity is everyone’s responsibility
Provides guidance to governments on how to conserve biodiversity

52
Q

What is the CITES agreement

A

Convention of International Trade in Endangered Species
Agreements designed to increase international cooperation in regulating trade in wild animal and plant specimens
Member countries make it illegal to kill endangered species
Helps to conserve species by limiting trade through licensing, making it illegal to trade in products made from endangered animals (ivory)
Designed to raise awareness of threats to biodiversity through education

53
Q

Example of local conservation agreements to protect special areas in the UK

A

The Countryside Stewardship Scheme (CSS)
Aims to conserve wildlife and biodiversity and improve and extend wildlife habitats by promoting management techniques to landowners
Landowners were paid to follow management techniques e.g. regenerating hedgerows and leaving grassy margins around the edges of field for flowers
Since the introduction the scheme species have begun to rebuild in numbers

54
Q

How to measure genetic diversity

A

Measuring genetic polymorphism
Investigating the proportion of heterozygotes
Proportion of gene variants

55
Q

Equation for simpson’s index

A

D = 1 - ( Σ(n/N)^2 )

n = the total number of organisms of a particular species
N = the total number of organisms of all species

56
Q

What is the null hypothesis

A

States there will be no significant difference or correlation between the variables you are measuring
Always starts with “there is no significant difference”
Data can be statistically analysed to see whether or not to reject the null hypothesis

57
Q

What may make a mean value more likely to be down to chance

A

If two means are the same for both data sets then the values that are more spread out will be more likely to be down to chance

58
Q

Formula for degrees of freedom

A

df = n1 + n2 - 2

59
Q

Why use Simpsons index of diversity

A

It takes into account species richness and species evenness

60
Q

Use Simpsons index of diversity

A
61
Q

Sampling techniques for animals overview

A

Pooter
Sweep nets
Pitfall traps
Tree beating
Kick sampling

62
Q

Sampling techniques for crawling ground insect

A

For crawling ground insects you could use a pitfall trap
This is a small pit that insects can’t get out of

Can use a pooter
A device that allows you to safely suck small insects through a tube into a jar

63
Q

Sampling techniques for small organisms living in soil or leaf litter

A

Tullgren funnel
Where a soil or leaf litter sample is put on a mesh filter at the top of a funnel and a light is shone down onto it.
Organisms move away from the heat created by the light and fall out of the funnel and into a collecting beaker.

64
Q

Sampling techniques for aquatic organisms

A

For some aquatic organisms you could use kick sampling
You gently kick the bottom of a stream then use a net to collect the organisms that have been disturbed

65
Q

Sampling techniques for organisms in long grass or vegetation
Can use a sweep net

A

Can use tree beating where a white clothe is laid below the tree or bush and the plant is shaken to make the organisms fall out

66
Q

Why use random sampling

A

This avoids bias in the sample
Such as sampling bias

67
Q

Why use non random sampling

A

When there is a lot of variety in the distribution of species in the habitat and you want to ensure all the different areas are sampled

68
Q

How to increase reliability in the sample

A

Use random sampling
Select a larger population to minimise the effects of chance

69
Q

Explain the non random sampling techniques

A

Systematic: samples taken at fixed intervals, often along the line
Opportunity: when samples are chosen by the investigator (east but biased)
Stratified: when different areas in a habitat are identified and sampled separately in proportion to their part of the habitat as a whole

70
Q

How would you use random sampling to study plant species in a field

A

Pick random sample sites by dividing the field into a grid using measuring tapes and using a random number generator to select coordinates.

71
Q

How would you use systematic sampling to count plant species in a field along a distance

A

Quadrats could be placed along a line (transect) from an area of shade in the corner to the middle of the field
A sample would be taken at specified points
Each quadrant would be a sample site

72
Q

How can a belt transect be used in systematic sampling

A

Two parallel lines are marked and samples are taken of the area between the two lines

73
Q

How would you use stratified sampling to study a field that has two different species of plants in it

A

A heathland may have patches of gorse in it
The heath and gorse areas would be sampled as separate strata and each group would have a random sample taken which is proportional to its size

74
Q

How to sample plants overview

A

Point quadrat
Frame quadrat

75
Q

What is a point quadrat

A

Bar with holes in at intervals
At set intervals a pin is pushed through the holes
Any plants that touch the pin are recorded

76
Q

What is a frame quadrat

A

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

77
Q

How must quadrats be used to get a representative sample of the population while studying the distribution of organisms

A

Quadrats should be used following a random sampling technique
To study how the presence and distribution of organisms across an area of land varies, the quadrats can be placed systematically along a line or belt transect.

78
Q

How to use frame quadrats to measure density of a population in a habitat

A

If individual large plants can be seen clearly then they can be counted in a 1mx1m quadrat
This gives the density per square meter
Is not an estimate

79
Q

How to use frame quadrats to measure frequency of a population in a habitat

A

For hard to count organisms (grass or moss)
Count number of particular species is present in the small squares of the quadrat

80
Q

How to use frame quadrats to measure percentage cover of a population in a habitat

A

Used for speed as data can be collected quickly
Used when species is abundant and difficult to count
Estimate by eye of the area in a quadrat covered by a particular species

81
Q

How to ensure reliability with a quadrat

A

Sample should be taken at a number of points
Calculate mean of individual quadrats to get an average value for a particular organism per m²
To get the total value of the population multiply the mean value per m² by the total area

82
Q

How to estimate animal population size

A

Capture-mark-release-recapture
Compare number of unmarked individuals and marked individuals in second sample
The greater number of marked individuals recaptured, the smaller the population
Must let population redistribute before recapturing

A Level Biology (27 decks)

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