4.2 - Biodiversity

Question 1

What is biodiversity?

Answer 1

A measure of variation found in the living world.

Question 2

What is a habitat?

Answer 2

Where an organism lives.

Question 3

What is a species?

Answer 3

A group of organisms that can breed together to produce fertile offspring. They share similar physical characteristics, anatomy, biochemistry and genetics.

Question 4

What is species diversity?

Answer 4

The number of species and abundance of each species that live in a particular location.

Question 5

What is species richness?

Answer 5

The number of different species found in a habitat.

Question 6

What is species evenness?

Answer 6

The degree to which each species is represented. If each species is found in similar numbers biodiversity is even. If each species is found in differing numbers it is uneven.

Question 7

What does abundance mean?

Answer 7

The number of individuals of a species.

Question 8

What is genetic biodiversity?

Answer 8

The variation within individuals of the same species. Genetic variation accounts for the differences within species - why we don’t all look the same. Genetic variation creates breeds within species e.g. spaniels and labradors.

Question 9

Describe sampling methods and the advantages and disadvantages of each.
Note: for representative data the number of samples taken should be equivalent to 1% of the total area. E.g. 100m2 area, 1m2 quadrat = 10 samples taken.

Answer 9

Random: select habitat at random using randomly generated coordinates. Removes bias from data collected but may not be representative - rare/infrequent species may be missed, so biodiversity may be underestimated.
Non-random opportunistic: habitat chosen deliberately. Quicker - no random coordinates needed but can lead to bias, so biodiversity may be underestimated or overestimated.
Non-random stratified: habitat divided into areas and sampled separately. Sampling within areas may be random. Ensures all habitats of interest are sampled but areas of differing sizes may be under/over sampled.
Non-random systematic: samples taken at fixed intervals across habitats, sampling for change over distance, e.g. from shore to dunes. Shows change in biodiversity with change in conditions but only species along belt transect recorded.

Question 10

State the way in which plant numbers may be counted.

Answer 10

By individual numbers of each species
Percentage cover.
Abundance using the ACFOR scale - Abundant, Common, Frequent, Occasional, Rare.

Question 11

Describe the method for random sampling of a habitat.

Answer 11

Grid area and randomly select area to be sampled.
Set up grid using tape measures at right angles.
Generate random coordinates using a random number generator.
Place left hand corner of quadrat at coordinate.
Record the number of individuals of each species in the quadrat, use 50% rule.
Repeat multiple times so that 1% of area is covered.
Percentage cover can be used for frame quadrats when frequency is hard to measure.

Question 12

Describe the errors that might arise when using random sampling to estimate biodiversity.

Answer 12

Misidentification of plant species - use a key to reduce error.
50% in rule is subjective - may lead to under/over estimation.
% cover count is subjective - may lead to under/over estimation.
Can be difficult placing quadrat in rough terrain - could use point frame quadrat.
Placing of quadrat at coordinate may be inaccurate - grid area within sample area or use GPS.

Question 13

Describe the method for sampling using a belt transect.

Answer 13

Decide on area to be sampled using research/prior knowledge - this depends on factor being investigated, e.g. shade to light in a woodland.
Place tape to span area of interest.
Line transect - count plants touching tape.
Belt transect - use left hand rule to place quadrat on tape. Continuous belt transect - move quadrat along tape. Interrupted belt transect - place quadrat at determined intervals along tape e.g. every 1m.

Question 14

Describe the errors that might arise when using transects to estimate biodiversity.

Answer 14

Only plants along line counted.
May be biased.
Misidentification of plant species - use a key to reduce error.
50% in rule is subjective - may lead to under/over estimation.
% cover count is subjective - may lead to under/over estimation.
Can be difficult placing quadrat in rough terrain - could use point frame quadrat.

Question 15

Describe the methods for catching invertebrates and the advantages/disadvantages.

Answer 15

Sweep net - move net with figure of eight motion, tip net contents onto white sheet for identification. +: catch small invertebrates hidden in long plants; catch flying insects. -: disturbance causes invertebrates to fly/flee misidentification.
Pooter - place tube over invertebrate, suck through second tube, drawing invertebrate into chamber. +: individual collection of organism. -: limited to size of tube.
Tree knocking - place white sheet under tree and knock firmly, invertebrates fall onto sheet. +: can collect samples from areas that are not suitable for net. -: invertebrates by fly/jump off/hold on; care with damage to trees.
Pitfall trap - dig hole in ground and place collecting cup in hole; may contain water to prevent insects crawling out; cover to prevent flooding. +: traps can be set and left to collect data over time. -: chance if organism falls in; organisms may prey on one another; organism may drown in water.
Tullgren funnel - place soil sample in funnel, switch on lamp, invertebrates move away from heat and light and fall into collecting cup; may contain ethanol to kill samples. +: can collect difficult to find invertebbrates. -: inhumane killing samples.

Question 16

What is the mark, capture, release method?

Answer 16

A known number of individuals are captured, marked and released, C1.
Appropriate method of marking is used so that it doesn’t harm the organism.
A second random known number of individuals are captured, C2.
The number of marked individuals recaptured, C3, is recorded and then they are released.
Population size can then be calculated from this data using the formula: Total population = (C1x C2)/ C3.

Question 17

What are the conditions needed for mark-release-recapture investigations to give reliable results?

Answer 17

Marking not removed.
No immigration/emigration.
Sufficient time for marked individuals to mix with the population.
No births/deaths.
Sampling method is the same for each collection.

Question 18

How can you ensure reliable survey results?

Answer 18

Random samples – no bias involved.
Larger sample size.
Larger sample area.
Smaller quadrat when sampling plants.
Same technique in each habitat.
Random number generator generating coordinates for quadrat placement.
Control/note abiotic variables.

Question 19

What is an allele?

Answer 19

Different version of a gene.

Question 20

What does locus mean?

Answer 20

The position along a chromosome at which a gene is located.

Question 21

What is a polymorphic gene locus?

Answer 21

A locus that has more than two alleles.

Question 22

Which two factors determine biodiversity?

Answer 22

Species richness and species evenness.

Question 23

What is Simpson’s index of diversity and what does it measure?

Answer 23

D= 1 - [ ∑(n/N)2 where n = number of individuals of a species and N is the total number of the population (all the n’s added together).
The diversity of a habitat.
Takes account of species richness and evenness.
A high index value (closer to 1) is more diverse than a low index value.
The richer and more even a habitat, the more stable it is.

Question 24

Why is a rich and even habitat is more stable?

Answer 24

More habitats for organisms to live in.
More food sources.
More breeding sites.
More inter and intraspecific interactions.

Question 25

What is the importance of genetic diversity?

Answer 25

Increase in naturally occurring mutations may confer selection pressure.
Protects individuals from disease/death, e.g. Ash dieback - all trees genetically identical so no natural immunity to fungus.

Question 26

How do you calculate genetic diversity?

Answer 26

Count number of loci of interest - this is number of individuals in population x2 (because each individual has two alleles for each gene).
Count number of heterozygotes in population (heterozygotes have two different alleles at a locus and so are more genetically diverse than homozygotes who have the same allele).
Genetic diversity = Number of heterozygous loci/total number of loci in population.
The closer the value to 100%, the greater the genetic diversity.

Question 27

How do you calculate polymorphic genetic diversity?

Answer 27

Count population and multiply by number of loci of interest.
Count number of individual heterozygous for each allele.
Calculate mean of heterozygous population.
Divide by total allele population.

Question 28

What is climate change?

Answer 28

Significant and long lasting changes in weather patterns - do not refer to global warming!

Question 29

What is a monoculture?

Answer 29

A crop consisting of one strain of a species, e.g. palm oil trees.

Question 30

In which way do humans use the environment?

Answer 30

Agriculture - farming to produce more food.
Destruction and fragmentation of habitats - farming, housing, road networks, logging.
Overuse of Earth’s resources - water, minerals, fossil fuels.
Pollution.
Overpopulation.

Question 31

Describe the impact of agriculture on ecosystems.

Answer 31

Habitat destruction for farming, logging etc. Reduction in biodiversity - fewer habitats, fewer food sources, fewer inter-/intraspecies interactions.
Monocultures - large scale plating of single crop. Reduction in biodiversity. Reduction in genetic diversity, reduction in naturally occurring resistance to pests and disease, increased susceptibility to disease e.g. Ash dieback.
Selective breeding. Reduction in biodiversity. Reduction in genetic diversity, reduction in naturally occurring resistance to pests and disease. Leads to genetic erosion.

Question 32

Describe the impact of loss of genetic diversity.

Answer 32

Species are less able to adapt to changes in climate -
remember that individuals that already carry a favourable adaptation survive; it is NOT the change that causes the adaptation.
Inbreeding leads to further loss of genetic diversity.
Natural resistance to disease is lost; susceptibility to disease is increased.
Reduction in biodiversity.
Loss of different habitats.
Loss of food sources.

Question 33

Describe the impact of climate change.

Answer 33

Increase/decrease in rainfall.
Increase/decrease in temperature.
Increase in violent climatic events e.g. flooding, hurricanes.
Mobile species unable to adapt are forced to migrate away from changing ecosystems - sooner or later they will run out of space to move.

Question 34

Describe the ways in which human infrastructures impact on species migration.

Answer 34

Major human developments and infrastructures.
Agricultural land.
Large bodies of water- reservoirs, dams.

Question 35

What is a keystone species?

Answer 35

One that has a disproportionate effect upon its environment despite its abundance e.g. wolves of Yellowstone Park.

Question 36

What is soil depletion?

Answer 36

Loss of soil fertility.

Caused by removal of minerals by continuous cropping.

Question 37

Describe the interdependence of organisms.

Answer 37

Complex natural ecosystems take millions of years to evolve.
Intra species interaction occur within species e.g. blue tits compete for nesting sites in a tree.
Interspecific interaction occur between species e.g. cheetahs hunt antelopes.
If these interactions are disturbed, food webs are altered and may collapse.
Biodiversity is reduced. Habitats become unstable. Extinction occurs.

Question 38

How does the removal of a keystone species impact biodiversity?

Answer 38

Keystone species may be a predator and limit populations of prey, e.g. sea otter and anemones.
Keystone species may be a plant eg sugar maple tree has deep roots, stabilise soil and prevent soil erosion.
Loss of keystone alters habitats, allows other species to predominate, food webs altered.
Or food webs collapse and species may become extinct.

Question 39

What is genetic erosion?

Answer 39

Decline of genetic diversity.

Question 40

Describe the impact of genetic erosion.

Answer 40

Plants, fungi or animals that may hold solutions to problems are lost e.g. medicinal uses.
Species less able to withstand climate change are reduced in abundance or become extinct.
Reduction in gene pool reduces genomes available for beneficial genetic modification/cross breeding/ selective breeding.

Question 41

What are economic reasons to maintain biodiversity?

Answer 41

Contributes to many natural cycles that cannot be done by Man. Regulation of atmosphere and climate. Nutrient recycling- carbon and nitrogen cycles. Detoxification and purification of wastes - plants used to collate waste chemical spills, toxins removed when plants removed. Formation and fertilization of soils.
Crop pollination.
Crops such as timber, food and fuel.
Molecules as potential medicines.
Maintenance of landscapes and ecosystems.
Reduction in erosion, flooding etc.
And because we like it - chlorophyllia. Tourism. Recovery - mental and physical. Reduction in stress.

Question 42

What does the term endangered species mean?

Answer 42

Species are at risk of becoming extinct because their population has fallen so low that the numbers are at a critical level for continued survival.

Question 43

Suggest 2 reasons why a species may be endangered.

Answer 43

Poaching. Their habitat is being destroyed.

Question 44

What is in situ conservation?

Answer 44

Protecting species in their natural habitat.

Question 45

What are example methods of in situ conservation?

Answer 45

Establishing protected areas such as national parks & wildlife reserves.
Marine conservation zones - where fishing is controlled.
Controlling or preventing the introduction of species that threaten local biodiversity.
Legal protection to endangered species.

Question 46

What are advantages of in situ conservation?

Answer 46

Both species & habitat are conserved.
Large populations can be protected.
Less disruptive than removing organisms from their habitats.

Question 47

What are disadvantages of in situ conservation?

Answer 47

Some factors that are threatening a species may be difficult to control, such as poaching, predators, disease or climate change.

Question 48

What is ex situ conservation?

Answer 48

Protecting species by removing part of the population from a threatened habitat.

Question 49

What are example methods of ex situ conservation?

Answer 49

Relocating organisms to a safer place - free from poachers.
Breeding organisms in captivity then reintroducing them to the wild.
Botanic gardens grow a rare plants and reintroduce them into suitable habitats.
Seed banks provide a useful store of seeds if natural reserves are destroyed.

Question 50

What are advantages of ex situ conservation?

Answer 50

Can protect individual animals in a controlled environment - predation & hunting can be managed more easily.
Can be used to reintroduce species to an area.

Question 51

What are disadvantages of ex situ conservation?

Answer 51

Small numbers of individuals cared for.
Difficult & expensive to create & sustain the right environment.
Animals that are habituated to human contact may be less likely to exhibit natural behaviour & may catch a human disease.
Many species cannot breed successfully in captivity.

Question 52

What does CITES stand for?

Answer 52

Convention on International Trade in Endangered Species.

Question 53

What are the aims of CITES?

Answer 53

Regulate trade in endangered species.
Allow trade of less endangered species.
Ensure that trade does not endanger wild populations.
Prohibit trade in wild plants.
Allow trade in artificially propagated plants.

Question 54

State two ways in which the CITES agreement is helping to save endangered species, such as the black rhinoceros.

Answer 54

Permits to hunt are only issued to certain people.

Different countries cooperate to deal with poachers and illegal trade.

Question 55

What does CBD stand for?

Answer 55

(Rio) Convention on Biological Diversity.

Question 56

What are the aims of CBD?

Answer 56

Sustainable use of ecosystems.
Promote ex situ conservation methods.
Share access to scientific knowledge relating to biodiversity & share genetic resources.
Raise the profile of biodiversity to governments & encourage international cooperation.

Question 57

Give an example of a local conservation agreement used to protect special areas in the UK.

Answer 57

The Country Stewardship Scheme (CSS).

Question 58

Give an example of how the CSS works.

Answer 58

Pay landowners to use regenerate hedgerows & grow wildflowers around the edges of fields to increase species habitats and food sources.

Question 59

What are the benefits of hedgerows?

Answer 59

Reduce soil erosion.
Attract beneficial insects and reduce pests.
Increase plant diversity.
Provide habitat.

Question 60

Outline the potential benefits to agriculture of maintaining the biodiversity of wild plants.

Answer 60

Selective breeding reduces genetic diversity & results the whole crop/herd to an outbreak of disease.
A wild plant could have resistance to this disease.
If the wild plant was bred with the crop plant, some of the offspring may have the good characteristics of both plants.
These would then be selected and bred from again so that new stocks of plants can be built up.