B11 - Biodiversity

Question 1

What is biodiversity?

Answer 1

• the variety of living organisms living in an area
• includes plants, animals, fungi and other living things

Question 2

What are the different levels of biodiversity?

Answer 2

• habitat
• species
• genetic

Question 3

What is habitat biodiversity?

Answer 3

• the no. of different habitats within an area
• each habitat can support a no. of different species
  
  • UK = larger no. of habitat types
  • Antarctica = very low habitat biodiversity

Question 4

What is species biodiversity?

Answer 4

• species richness = no. of different species living in an area
• species evenness = a comparison of the numbers of individuals of species living in a community
  
  • having the same no. of species does not mean that they have the same species biodiversity
  • if the majority of the population is one type of species, the region has a low species biodiversity

Question 5

What is genetic biodiversity?

Answer 5

• the variety of genes that make up a species
• different versions of genes (alleles) lead to genetic biodiversity
  
  • this can lead to different characteristics being exhibited
  • greater genetic biodiversity allows for better adaptation to a changing environment (more resistant to disease)

Question 6

What is sampling?

Answer 6

• taking measurements of a limited no. of individual organisms present in a particular area
• can be used to estimate the no. of organism in an area
• abundance = no. of species present in an area
  
  • it can also be used to measure a particular characteristic (calculate average)

Question 7

What is random sampling?

Answer 7

• selecting individuals by chance
• no involvement in deciding which organisms to investigate
  
  • make a grid in grass with two tape measures (right angles)
  • random numbers to determine x and y coordinate
  • take sample at each coordinate

Question 8

What is non-random sampling?

Answer 8

• sample is not chosen at random
  
  • opportunistic sampling = uses organisms that are conveniently available (not very representative of the population)
  • stratified = populations divided into sub groups based on particular characteristic, random sample (proportional) is then taken from each
  • systematic = carried out using belt/line transect
  • line = marking line along ground between two poles
  • belt = parallel lines are marked (sample taken from both sides)

Question 9

What affects reliability of sampling?

Answer 9

• sampling bias:
  
  • selection process may be biased
  • e.g. you may choose to sample an area with more flowers
  • random sampling can reduce this
• chance:
  
  • organisms selected may not be representative of the whole population
  • chance cannot be completely removed but its effect can be minimised by using a larger sample

Question 10

How are animals sampled?

Answer 10

• as soon as the organisms have been counted and measured, they must be released back into the environment they were collected
• pooter:
  
  • catches small insects by sucking on mouthpiece
  • filter prevents them entering the mouth
• pitfall traps:
  
  • catches small, crawling invertebrates
  • hole is dug into ground and insects fall in
  • roof-structure prevents build up of water
  • traps are left overnight (nocturnal species are also captured)
• tree beating:
  
  • samples invertebrates living in a tree/bush
  • large white cloth stretched out to catch the organisms
• kick sampling:
  
  • studies organisms living in a river
  • river bank/bed is kicked and this disturbs the substrate
  • net is held downstream to catch the organisms

Question 11

How are plants sampled?

Answer 11

• usually sampled using a quadrat
• can also be used to sample slow moving animals
• point quadrat:
  
  • frame with a horizontal bar
  • at set intervals, there are long pins that can be pushed through to reach the ground
  • each plant touching it is recorded
• frame quadrat:
  
  • square frame divided into equal sections
  • type and no. of species is recorded
  • a random sampling technique should be used
  • to study how the presence/distribution of organisms vary, the quadrants can be placed systematically along a line/belt transect

Question 12

How to measure species richness?

Answer 12

• combination of techniques should be used
• list all species identified
• total no. of species can be calculated
  
  • to accurately identify them, identification keys are used
  • they classify organisms based on identifiable characteristics

Question 13

How to measure species evenness?

Answer 13

• list all organisms found
• calculate the no. of organisms within each species
• e.g. 50 organisms = 20 woodlice, 15 spiders, 15 centipedes (evenly distributed)

Question 14

How are frame quadrats used?

Answer 14

• density:
  
  • if large individual plants are clearly seen, count them in 1m by 1m quadrat and this gives the dentistry per square metre (absolute measure)
• frequency:
  
  • used where individual members of a species are hard to count
  • smaller grids are used to count no. of species within a quadrat
  • if a species is present in 65 out of 100 squares, its frequency is 65%
• percentage cover:
  
  • used for speed to collect data quickly
  • useful if species is abundant/difficult to count
  • it is an estimate by eye of the area

Question 15

How is animal population estimated?

Answer 15

• capture-mark-release-recapture is often used to estimate a population size
  
  • capture as many individuals of a species as possible
  • they are then marked and released
  • time is allowed for them to redistribute themselves before another sample is collected
  • they then compare the no. of marked/unmarked individuals compared to the first sample
• the greater the no. of marked individuals, the smaller the population
• species evenness is then calculated by comparing the total no. of each organism present
  
  • populations of plants/animals that are similar in size/density represent an even community
  • it can also be represented as a ratio between the no. of each organism present

Question 16

How are abiotic factors measured?

Answer 16

• e.g. light intensity and water availability
• measured at each sampling point
  
  • wind speed = anemometer
  • light intensity = light meter
  • relative humidity = humidity sensor
  • pH = pH probe
  • temperature - temp. probe
  • O2 content in water = dissolved O2 probe
• the advantages include:
  
  • rapid changes detected
  • human error is reduced
  • high degree of precision
  • data can be stored/tracked on a computer

Question 17

How is biodiversity calculated?

Answer 17

• diversity of organisms present in an area is proportional to the stability of the ecosystem
• species richness = no. of species present
• species evenness = the distribution of the no. of individuals within each species
  
  • Simpson’s Index of Diversity (D) is used as it takes into account both richness and evenness
  • D = 1 - (sum of) (n/N)^2
  • N = total no. of organisms of all species
  • n = total no. of organisms of a particular species
• ** a quadrat is often used to estimate the population of plant species in an area **
• ** always results in a value between 0 and 1 **
  
  • 0 = no diversity
  • 1 = infinite diversity

Question 18

Why is genetic biodiversity important?

Answer 18

• maintaining this is essential to the survival of a species
• those in a captive breeding programme have a reduced genetic biodiversity
  
  • differences in alleles between individuals of the same species creates genetic biodiversity (more alleles = more genetically biodiverse)
  • those with a greater genetic biodiversity are more likely to adapt to the changes (enables them to live in those conditions)
  • this is because they have the advantageous allele that will them be passed on to their offspring

Question 19

What factors affect genetic biodiversity?

Answer 19

• increase no. of alleles:
  
  • mutations in the DNA
  • interbreeding between different populations (e.g. when an individual migrates from one population to another and alleles are transferred- gene flow)
• decrease genetic biodiversity:
  
  • selective breeding = only a few individuals are selected for their advantageous characteristics and bred
  • captive breeding programmes = a small no. of captive individuals are available for breeding
  • rare breeds = no. of individuals with the less popular characteristics fall and the remaining population’s g.b.will be low (can cause problems when trying to restore numbers yet maintain heir characteristics)
  • artificial cloning = asexual reproduction
  • natural selection = species will evolve to contain advantageous traits and over time the less advantageous characteristics will fall
  • genetic bottlenecks = few individuals within a population survive an event/change (reduces gene pool), only the alleles of the surging population will be passed onto the offspring
  • founder effect = small no. of individuals create a new colony (geographically isolated), small gene pool
  • genetic drift = frequency of occurrence of an allele will vary, existence of a particular allele can disappear from a population altogether

Question 20

How is genetic biodiversity measured?

Answer 20

• measure polymorphism (genes with more than one allele)
• e.g. different alleles exist for immunoglobulin gene
  
  • prop. of polymorphic gene loci = no. of polymorphic gene loci / total no. of loci

Question 21

What is human influence on biodiversity?

Answer 21

• species are interconnected within an ecosystem, so the removal of one species can have a large effect on others
  
  • deforestation = permanent removal of large areas of forest to provide wood for building/fuel
  • agriculture = increasing amount of land has to be farmed in order to feed the growing population (monoculture has also occurred)
  • climate change = release of CO2 and other pollutants is increasing global temperatures
• other forms of pollution result from industry/agriculture (e.g. chemical pollution of waterways)
• improper disposal of waste/packaging is also a type of environmental pollution

Question 22

How does deforestation affect biodiversity?

Answer 22

• can occur naturally (wild fires), but most of them happen deliberately
• directly reduces the no. of trees present in an area
• specific type of tree felled:
  
  • species diversity is reduced
• reduces no. of animal species present in an area (destroys habitat, food, home)
• animals are forced to migrate to other areas

Question 23

How does agriculture affect biodiversity?

Answer 23

• farmers only grow a few different species of crop plants (based on characteristics)
  
  • this greatly reduces the biodiversity of the area
  • to be economically viable and no. of techniques are used to produce as many of the desired species
• deforestation:
  
  • increases area of land for growing crops/rearing animals
• removal of hedgerows:
  
  • enables them to use large machinery (plant, fertilise, harvest)
  • reduces no. of plant species present and destroys habitat of animals such as black birds, hedgehogs and invertebrates
• use of chemicals such as pesticides, herbicides:
  
  • pesticides = kills pests that eat crops or live in animals
  • reduces pest species (indirectly by destroying food source of other organisms)
• herbicides:
  
  • weeds are destroyed as they compete with cultivated plants for light, minerals and water
  • plant diversity is reduced directly (animal diversity also reduced as they lose their food source)
• monoculture:
  
  • production of only one crop will lower biodiversity as only one species is present
  • relatively few animal species are supported by only one plant species
  • growth or vast plant oil plantations is one of the leading causes of rainforest deforestation

Question 24

How does climate change affect biodiversity?

Answer 24

• increase in warming trend over the last 50 years
• increase in water vapour
• average sea level is rising
• melting of ice caps/glaciers
• decisions made will have consequences (e.g. reduces public transport)
• need to produce reliable data for issues this scale is paramount
• melting of polar ice caps:
  
  • extinction of few plant and animal species
• rising sea levels/thermal expansion:
  
  • could flood low lying land (reduces available terrestrial habitats
• higher temps./less rainfall:
  
  • drought-resistant species will become more dominant (xerophytes)
  • loss of non drought resistant species would less to a loss of some animal species that feed on them
  • those species will then be replaced by other species that feed on xerophytes
• insect life cycles/populations will change:
  
  • they are key pollinators and their extinction will affect the lives of the plants that they leave behind
  • as climate change increases, tropical insects may become more dominant and they would carry their diseases to the poles
• if climate change is low, species may have time to adapt/migrate to new areas
• this will cause a loss of native species and other ones may move into the area (species mix will change)

Question 25

Why is it important to maintain biodiversity?

Answer 25

• aesthetic:
  
  • presence of diff. plants and animals enriches our lives
  • natural world provides inspiration
  • patients recover more rapidly from stress and injury with the help of nature
• economic:
  
  • soil erosion and desertification may occur due to deforestation (reduces country’s ability to grow crops and feed its people)
  • important to conserve organisms used to make things (non-sustainable removal of materials will cause a collapse in the industry)
  • large-scale habitat and biodiversity loss will mean that important species/organisms will be lost before they are even discovered (may be medically/chemically useful)
  • continuous monoculture will result in soil depletion (no nutrients are left to be recycled, so crops that it can support will be weaker which increases their vulnerability)
  • high biodiversity provides protection (low biodiversity means that a change in condition/disease will destroy entire crops, e.g. Irish potato famine)
  • areas rich in b.d. will provide a pleasing and attractive environment (can promote tourism)
  • greater the diversity, greater the potential for manufacture of different products (food production, cures/treatment)
  • plant varieties are needed for cross breeding which leads to better characteristics such as disease resistance/increased yield (g.e. can also help to make crop plants/animals more efficient which reduces the land required to feed more people)
• ecological:
  
  • all organisms are interdependent on others for their survival (removal of one species may have a big impact on others, loss of food source or place to live)
  • keystone species are important for maintaining the structure of an ecological community, they affect many other organisms in an ecosystem (help to determine species richness and evenness)

Question 26

How is biodiversity maintained?

Answer 26

• conservation = the preservation and careful management of the environment/natural resources
  
  • species and genetic diversity can be safeguarded
  • in situ = within natural habitat
  • ex situ = out of natural habitat
• extinct = no organisms of species exist anywhere in the world
• extinct in the wild = organisms of the species only exist in captivity
• endangered = species in danger of extinction (conservation is prioritised)
• vulnerable = species that is considered likely to become endangered in the near future
• sustainable development = economic development that meets the needs of people today (does not limit ability of future generations to meet their needs)

Question 27

What is in situ conservation?

Answer 27

• maintains the genetic biodiversity and their evolutionary adaptations
• by allowing endangered species to interact with other species, it preserves the interdependent relationships
  
  • interlinked species can also be preserved
  • cheaper than ex situ

examples:
- marine (saltwater)
- aquatic (freshwater)
- terrestrial (land)

Question 28

What are wildlife reserves?

Answer 28

• controlled grazing
  
  • grazing a particular area of land will allow species time to recover
• restricting human access
  
  • providing paths to prevent plants being trampled
• controlling poaching
  
  • creating defences to prevent access, issuing fines, removal of rhino horns
• feeding animals
  
  • ensures more organisms survive to reproductive age
• reintroduction of species
  
  • adding species to areas that have become locally extinct
• culling/removal of invasive species
  
  • these species compete with native species for resources
• halting succession:
  
  • succession = natural process in which early colonising species are replaced over time
  • this is an important role played by humans in maintaining habitats for future generations

Question 29

What are marine conservation zones?

Answer 29

• vital in preserving species-rich areas such as coral reefs
• used to create areas of refuge within which populations can build up and repopulate adjacent areas
• large areas of sea are required for marine reserves as target species often move large distances

Question 30

What is ex situ conservation?

Answer 30

• removal of organisms from their natural habitat

Question 31

What are botanic gardens?

Answer 31

• here, species are actively managed to provide them with the nest resources to grow (soil nutrients, sufficient watering, removal/prevention of pests
• 35000 plant species are conserved in botanic gardens
  
  • but majority are still not conserved
  • many wild relatives of selectively bred crop species are under represented
  • wild species are a potential source of genes (resistance to pests)

Question 32

What are seed banks?

Answer 32

• example for gene bank where genetic material of plants are stored
• dried and stored at low temps (slow down rate of germination)
• many tropical seeds can be stored this way
• seed banks do not work for tropical rainforests

Question 33

What are captive breeding programmes?

Answer 33

• produce offspring of species in a human-controlled environment
• run and managed by zoos/aquatic centres
• scientists aim to create a healthy, stable population of species and reintroduce them back into its natural habitat
  
  • provide shelter, food, absence of predators and veterinary care
  • suitable breeding partners can be imported from other zoos
• maintaining genetic biodiversity can be difficult as very few breeding partners are available
  
  • mating can be arranged to ensure maximum genetic diversity
  • artificial insemination and embryo transfer allow for new genetic lines to be introduced

Question 34

What are the conservation agreements?

Answer 34

• local and international cooperation is required for the preservation of habitats and species
• IUCN (International Union for the Conservation of Nature)
  
  • assist in securing agreements between nations
  • publish red list that details the current conservation status of threatened animals
  • countries work together to conserve these species
• CITES (Convention on International Trade in Endangered Species):
  
  • regulates international trade of wild plant and animal specimens
  • as trade crosses borders, the effort to regulate it requires internal cooperation
• Rio Convention:
  
  • CBD requires countries to develop national strategies for sustainable development
  • UNFCCC is an agreement where nations help to stabilise greenhouse gas conc. within the atmosphere
  • UNCCD prevents the transformation of fertile land into desert (reduces the effect of drought)
• Countryside Stewardship Scheme:
  
  • offered payments to farmers to enhance the English landscape
  • sustaining beauty and diversity of the landscape
  • improving, extending and creating wildlife habitats
  • restoring neglected land and conserving archaeological and historic features
  • improving opportunities for countryside enjoyment
  • (replaced by Environmental Stewardship Scheme)

Question 35

How do humans affect biodiversity?

Answer 35

• negative impact = monoculture, deforestation
• positive impact = human intervention, management of land
  
  • sheep grazing (enables rare species to survive)
  • caterpillars feed on the low grass and this maintains their biodiversity

Question 36

Why may captive breeding not be suitable?

Answer 36

-diseases
- loss of resistance to local diseases (or a new disease may develop in the wild)

• behaviour
  
  • some behaviour is innate but much is learnt through copying/experience
  • e.g. learning to find food themselves
• genetic races
  
  • genetic make-up of captive animals can become so different from the original pop. that they cannot interbreed
• habitat
  
  • natural habitat must be restored to allow for captive populations to be reintroduced
  • introduction of new individuals can cause stress and tension due to competition