Mod 4 Chap 11: Biodiversity

Question 1

Describe how biodiversity can be studied / measured at different levels.

Answer 1

• closer a region is to equator = more biodiversity
• biodiversity plays important role in conservation, informs scientists of species present
• this provides baseline for level of biodiversity in an area
• so, effect of any changes to environment can be measured from this info (e.g. effect of human activity, disease, climate change etc)
• Biodiversity can be studied at diff levels, of:
  Habitat biodiversity, Species biodiversity, and Genetic biodiversity

Question 2

Describe the study of habitat biodiversity, and give examples of habitats.

Answer 2

• reefers to no. of diff habitats found in an area
• each habitat can support a no. of diff species, so, greater the habitat biodiversity = greater the species biodiversity in that area

Examples: meadow, woodland, streams, wild grassland

Question 3

Describe the study of species biodiversity, and define species.

Answer 3

Species: a group of similar organisms able to reproduce to give fertile offspring.
Two components of species biodiversity:
- species richness: no. of diff species living in a particular area
- species evenness: a comparison of no.’s of individuals of each species living in a community

Question 4

Describe the study of genetic biodiversity.

Answer 4

• refers to variety of genes that make up a species
• many of genes making up organisms are same for all individuals in a species, but, for many genes, diff versions (alleles) exist
• this then leads to genetic biodiversity in a species which can mean quite diff characteristics are exhibited
• greater genetic biodiversity in a species = better adaption to changing environment, + is more likely to result in disease-resistant individuals
• when population of an organism has a large ‘gene pool’, it has greater chance of surviving than a pop w/ limited genetic variability
• so genetic biodiversity = important

Question 5

Define biodiversity, community and gene pool.

Answer 5

Biodiversity: The variety of living organisms present in an area

Community: All the populations of living organisms in a particular habitat

Gene pool: The variety of genetics of the individuals in a population (so large gene pool = significantly varying genetics in individuals of a pop)

Question 6

Describe how genetic biodiversity can be assessed.

Answer 6

• measuring polymorphism
• polymorphic genes have more than one allele
• but most genes are monomorphic (only have a single allele that exists for them)
• this ensures basic structure of individuals in a species remains consistent
• proportion of polymorphic genes can be measured w/ formula:

Proportion of polymorphic gene loci = no. of polymorphic gene loci / total no. of loci

(Where locus of a gene refers to position of a gene on a chromosome)
- greater proportion of polymorphic gene loci = greater genetic biodiversity in a population

Question 7

Describe the importance of sampling, and define sampling.

Answer 7

Sampling: taking measurements of a limited no. of individual organisms present in a particular area.

• can be used to estimate no. of organisms in an area, without counting them all. (No. of individuals of a species present in an area = abundance of the organism)
• can also be used to measure a particular characteristic of an organism
• after measuring sample, can use results to make generalisations / estimates about no. of organisms, distribution of species, or measured characteristic throughout entire habitat
• sampling can be done in two ways: random + non random

Question 8

Describe random sampling.

Answer 8

• means selecting individuals by chance
• each individual in pop has equal likelihood of selection
• random number tables / computers can be used to decide, you have no involvement in the choice of what is studied

Question 9

Describe a practical investigation into collecting a random sample in the field.

Answer 9

E.g. Taking a random sample at a grass verge:

• mark a grid on grass w/ two tape measures at right angles
• use random numbers to determine x and y coordinates on grid
• take sample at each of coordinate pairs generated

Question 10

Describe non random sampling.

Answer 10

• alternative method where samples is not chosen at random
• divided into three main Non Random sampling techniques:
  Opportunistic, Stratified, Systematic

Question 11

Describe Opportunistic Non Random Sampling.

Answer 11

• weakest form of sampling as may not be representative of population
• uses organisms that are conveniently available at the time

Question 12

Describe Stratified Non Random Sampling.

Answer 12

• Some populations can be divided into a no. of strata (subgroups) based on a particular characteristic
• random sample then taken from each strata proportional to its size

Question 13

Describe Systematic Non Random Sampling, and how it is carried out.

Answer 13

• when diff areas in an overall habitat are identified + then sampled separately
• often carried out using a line / belt transect

Line transect: marking a line between 2 placed poles (one at one end of chosen site + one at other), then taking samples at specified points between two points, e.g. all organisms that touch the line

Belt transect: provides more information. Two parallel lines are marked in ground, + samples are taken of area between two lines (e.g. by placing quadrants)

Question 14

Describe a practical investigation into collecting a non random sample in the field.

Answer 14

E.g. With stratified, on a heathland

• heathland may have patches of gorse on it
• so Heath + gorse areas would be sampled separately according to how much of each there was in the habitat

Question 15

Describe the issues with the reliability of sampling.

Answer 15

• a sample = never entirely representative of organisms present in a habitat
• this may be due to:
  Sampling Bias
  Chance

Question 16

Describe Sampling Bias as an issue with the reliability of sampling.

Answer 16

• selection process may be biased, may be by accident / on deliberate
• effects of sampling bias can be reduced using random sampling (as human involvement in choosing sample is removed)

Question 17

Describe Chance as an issue with the reliability of sampling.

Answer 17

• organisms selected may, by chance, not be representative of whole pop
• chance can never be completely removed from process, but it’s effect can be minimised w/ a large sample size
• as, greater no. of individuals studied = lower probability that chance will influence result
• so, larger sample size = more reliable result

Question 18

Describe some methods used to collect living animals to sample.

Answer 18

• Pooter: catches small insects, person sucks on mouthpiece + insect drawn into holding chamber via inlet tube, filter before mouthpiece stops insect being sucked into person’s mouth
• Sweep Nets: catch insects in areas of long grass
• Pitfall Traps: catch small crawling invertebrates, a deep hole in ground covered w/ roof structure to prevent filling w/ rain water, left overnight to collect nocturnal species too
• Tullgren Funnel: device to cope t small animals from sample of soil / leaf litter, sample placed on sieve fixed across wide end of funnel, light bulb above funnel to dry + warm sample, so animals move down through sieve into funnel + collecting dish, (which may contain water / alcohol to prevent escape)
• White Sheets: placed on ground below bushes branches, bush shaken so invertebrates fall onto white sheet, can then remove from sheet w/ pooter
• Light Traps: collects insects by confusing them + intercepting chosen flight path, most commonly effective for night-flying insects

Question 19

Describe some other methods used to sample plants.

Answer 19

Quadrats, two main types:

• Point quadrat: frame w/ a horizontal bar, long pins pushes through bar at set intervals to reach ground, each species of plant pin touches is recorded
• Frame quadrat: square frame divided into a grid of equal sections. Type + no. of species in each section of quadrat is recorded

Question 20

Describe how quadrats can be used to collect the most valid representative sample of an area.

Answer 20

• sample = most valid + representative when quadrats used following a random sampling technique
• but, can be placed systematically to study how presence + distribution of organisms across an area of land varies

Question 21

Describe how to measure species richness.

Answer 21

• identification keys used to accurately identify all species present in a habitat (I.e. images to identify them / questions to classify them into particular species, based on identifiable characteristics they have)
• a list should be complied of each species identified
• total no. of species can then be calculated

Question 22

Describe how to measure species evenness.

Answer 22

• take random samples of a habitat

- count no. of individuals of each diff species

Question 23

Describe the overall general method to estimate biodiversity using samples.

Answer 23

• choose a site to sample (via random / non random)
• record no. of diff species / count no. of individuals of each species
• repeat process; take as many samples as possible to give better indication of whole habitat
• estimate no. of individuals for whole habitat by calculating mean for data collected in each sample + multiplying it by size of whole habitat

Question 24

Describe how to calculate the biodiversity of a habitat using Simpsons index of diversity (D).

Answer 24

• Simpsons index if diversity (D) = better measure of biodiversity than simple way of just species richness, as takes into account both species richness + evenness

Formula:

D = 1 - ☪ (n / N)^2

Where
☪ (see notes for actual symbol) = sum of (total)
N = total no. of organisms of all species
n = total no. of organisms of a particular species

Simpsons index always results in values between 0 and 1. Higher the value = more diverse the habitat.
Practice questions.

Question 25

Describe the factors affecting genetic biodiversity, that cause it to increase.

Answer 25

To increase genetic biodiversity, no. of possible alleles in a pop must also increase, can happen through:

• mutations in DNA
• interbreeding between diff pops, alleles are then transferred between two pops, knows as ‘gene flow’

Question 26

Describe the factors affecting genetic biodiversity, that cause it to decrease.

Answer 26

To decrease genetic biodiversity, no. of possible alleles in a pop must also decrease, can happen through:

• selective breeding / artificial selection
• captive breeding programmes in zoos + conservation centres
• rare breeds (where selective breeding has been used to produce a breed of domestic animal / plant w/ characteristics that have become less popular, so numbers of this breed fall
• artificial cloning / asexual reproduction
• natural selection - only fittest / best adapted survive
• genetic bottlenecks - where few individuals in a pop survive an event / change, reducing gene pool
• the founder effect - a small no. of individuals create a new colony

Question 27

Describe how the grand scale factor of human population growth affects biodiversity in general.

Answer 27

• linked to medical improvements, hygiene, housing + infrastructure so people live longer too
• severely disrupting ecology of areas for space for building + farming to support increasing pop, decreasing biodiversity. Doing this by:
  
  • deforestation
  • agriculture: more + more land farmed to feed growing pop, so
    = masses of land cleared + monoculture (planting a
    single crop.
  • climate change: release of CO2 + pollutants into atmosphere from
    burning fossil fuels = increasing global temp,
    decreasing biodiversity by killing some organisms

Question 28

Describe how the factor of agriculture affects biodiversity in general.

Answer 28

Affects biodiversity by:

• deforestation: increases land for growing crops / rearing animals, so can increase biodiversity, but decreasing biodiversity of trees + plants at same time
• removal of hedgerows: to use large machinery for harvesting crops, reducing no. of plant species + habitats + so biodiversity in an area
• chemicals: e.g. Pesticides, kills pests that would eat crops, reducing species diversity directly, + also indirectly by destroying a food source for other organisms
• chemicals: e.g. herbicides, kill weeds as they compete w/ cultivated plants for light / minerals / water, = reduces plant diversity directly, + also maybe animal diversity indirectly by removal of a food source
• monoculture: lowers biodiversity as only one species of plant present, + lowers animals diversity too as only few species will be supported by one plant type

Question 29

Describe how the factor of deforestation affects biodiversity in general.

Answer 29

• can occur naturally, but most is deliberate result of human action
• some forest areas indirectly destroy by humans through acid rain (result of pollutants in atmosphere)
• directly reduces no. of trees in an area
• species diversity = reduced if only a specific tree type is felled
• destroy habitats on animal species, reducing no. of animal species present in an area, so this starts a chain of events killing other species reliant on that’s species for food if they are killed
• forces animals to migrate to other areas for survival, may increase biodiversity if neighbouring areas

Question 30

Describe how the factor of climate change affects biodiversity in general.

Answer 30

Global warming = rise in earth’s mean surface temp, affect biodiversity by:

• melting of polar ice caps: could extinct few plant + animal species in these regions, also causes them to migrate further + further north, both lowing biodiversity here
• rising sea levels: (from melting ice caps + thermal expansions of oceans), could flood low lying land, reducing available terrestrial habitats, killing biodiversity in them, saltwater in rivers = reduces freshwater habitats gtoo, killing biodiversity of freshwater animals
• higher temps + less rainfall: kills some plant species, so xerophytes would become more dominant, loss of non-drought resistant plants would cause loss of some animal species reliant on them for food source, lowering biodiversity
• changing of insect lifecycles + pops to adapt to climate change: if happens, could affect lives of plants, as insects are their key pollinators, causing extinction, so loss of plant biodiversity

Question 31

Describe the aesthetic reasons for maintaining biodiversity.

Answer 31

• presence of diff plants + animals enriches our lives
• natural world provides inspiration for certain professions e.g. Musicians / writers, who then provide pleasure for people
• studies show patients recover more rapidly when supported by plants + a natural environment

Question 32

Describe the economical reasons for maintaining biodiversity.

Answer 32

• to avoid economic dependence on other nations to feed people, due to inability to grow crops as result of soil erosion + desertification, caused by deforestation
• important to conserve all organisms we use to make things, as removal of them could lead to collapse of an industry, once all raw material lost, = not economically viable to continue industry
• species w/ potential economic importance could be existing before discovered, due to large scale habitat + biodiversity loss
• continuous monoculture = soil depletion, reduction in diversity of soil nutrients
• high biodiversity = protection against abiotic stresses + disease

Question 33

Describe the ecological reasons for maintaining biodiversity.

Answer 33

• all organisms interdependent on others for survival, removal of one species may have significant effects on others
• ‘keystone species’ play key role in maintains structure of an ecological community, so if removed, habitat is drastically changed

Question 34

Describe conservation.

Answer 34

The preservation and careful management of epithet environment and of natural resources.

Two types:

• In Situ Conservation: within the natural habitat
• Ex Situ Conservation: out of the natural habitat

Question 35

Describe some In Situ conservation methods.

Answer 35

• Legislation / Controlled Poaching: passing laws on banning hunting, giving legal protection to endangered species
• Wildlife Reserves: establishing protected areas e.g. National parks, restricting urban development, industrial development + farming in these areas to protect habitats + species, active management techniques then used (e.g. controlled grazing + poaching, restricted human access, feeding animals, reintroduction of species)
• Marine Conservation Zones: vital in preserving species rich areas e.g. coral reefs
• Repopulation / Captive Breeding Programs: aim to create stable, healthy pop of species + then reintroduce species back into natural habitat
• Environmental Stewardship Scheme: to make conservation part of normal farming + land management practice e.g. by sustaining diversity of landscape

Question 36

Describe the advantages of In Situ Conservation.

Answer 36

• maintains genetic diversity of species + evolutionary adaptions, enabling them to adapt to changing environmental conditions
• preserved interdependent relationships in a habitat
• so interlinked species may also be present
• generally cheaper than ex situ conservation
• chances of pop recovering are greater than w/ ex situ methods

Question 37

Describe the disadvantages of In Situ conservation.

Answer 37

• can be diff to control some factors threatening species e.g. poaching / predators / disease
• endangered habitats may be fragmented so area may not be large enough to ensure survival of these species
• genetic diversity may have already been decreased

Question 38

Describe some Ex Situ conservation methods.

Answer 38

• Botanic Gardens: plant species actively managed here to provide them w/ best resources to grow
• Seed banks: example of a gene bank - store of genetic material, seeds carefully stored so new plants may grow in future, stored below -20 to slow down rate they lose ability to germinate
• Zoos

Question 39

Describe the advantages of Ex Situ Conservation.

Answer 39

• can be used to protect individual animals in controlled environment, so issue like predation + hunting can be monitored easier
• can be used to reintroduce species that have left an area

Question 40

Describe the disadvantages of ex situ conservation.

Answer 40

• usually only a small no. of individuals can be cared for
• can be diff + expensive to create + sustain right environment
• usually less successful type of conservation as many species can’t breed success you in captivity / don’t adapt to new environment when moved to new location
• animals used to human contact more prone to catching human diseases

Question 41

Describe The Rio Convention conservation agreements made to protect species and habitats.

Answer 41

• Convention on Biological Diversity (CBD): requires countries to develop national strategies for sustainable development, to ensure maintenance of biodiversity
• The United Nations Framework Convention on Climate Change (UNFCCC)
• The United Nations Convention to Combat Desertification (UNCCD)

Question 42

Describe the International Union for the Conservation of Nature to protect species and habitats.

Answer 42

• IUCN assist in securing agreements between nations, + involved w/ Conservation on International Trade in Endangered Species (CITES)
• CITES: regulates international trade of wild plants + animal specimens + their products
• as trade in wild animals + plants crosses country borders, effort to regulate it requires international cooperation, to safeguard species from over-exploitation

Question 43

Describe how to use frame quadrats.

Answer 43

• three main ways: Density, Frequency, Percentage Cover (used for speed as much data can be collected quickly)

Method:

• take samples as numerous points for more reliable results
• calculate mean or individuals quadrat results to get average value for an organism per metre squared (sum of individual quadrats / no. of samples taken)
• work out total pop of an organism in an area sampled by multiplying mean val / m^2 by total area

Question 44

Describe how to estimate a population size using the mark and recapture method.

Answer 44

• capture as many organisms as poss, mark, then release (C1)
• leave time for organisms to redistribute themselves in habitat, then collect another sample (C2)
• no. of marked individuals in C2, = C3, is compared w/ no. of unmarked in C2, so scientists can estimate a population size
• the greater the no. of marked recaptured = the smaller the pop

Total pop size = (C1 x C2) / C3