T3.3 - Biodiversity

Question 1

State what is meant by the term biodiversity

Answer 1

The variety of organisms living in an area

Question 2

Biodiversity can be assessed at what three levels?

Answer 2

Habitat
Species
Genetic

Question 3

State what is meant by the term habitat.

Answer 3

The place where an organism lives

Question 4

State what is meant by habitat biodiversity

Answer 4

The number of habitats in an area.
The UK has large habitat biodiversity e.g. deciduous forest, fen, heathland, sand dunes, moorland, marshland, peat bog, grassland etc.
The Antarctic has has very low habitat biodiversity

Question 5

Explain the importance of habitat biodiversity to maintaining species biodiversity

Answer 5

Specific habitats are occupied by different organisms.
-The greater the number of habitats, the greater the species diversity.
- So habitat protection is important to maintain species biodiversity.
- Habitat loss is one of the biggest threats to biodiversity and the most common cause of extinction.

Question 6

Give examples of habitat destruction

Answer 6

Deforestation
Ploughing natural meadows for agriculture
Draining wetlands and peat lands
creating dams

Question 7

What two factors determine species biodiversity?

Answer 7

Species richness and evenness

Question 8

What data is required to compare biodiversity of two sites?

Answer 8

Species richness and evenness of both areas

Question 9

State what is meant by the term species richness

Answer 9

The number of different species found in the habitat

Question 10

Why is species richness limited as a measure of biodiversity?

Answer 10

Species richness is the number of different species found in the habitat
It does not take into account relative abundance of each species

Question 11

State what is meant by the term species eveness

Answer 11

The relative abundance of individuals of each species in a habitat

Question 12

Name the formula used to measure biodiversity

Answer 12

Index of diversity

Question 13

Simpson’s index - What is N, n, and Σ?

Answer 13

N = total number of organisms
n = number of individuals of a single species
Σ = sum of

Question 14

What sampling method would you use to estimate the population of each species found in a habitat?

Answer 14

Random sampling using quadrants

Question 15

What is the significance of a high value of D?

Answer 15

High values of D signify:
high biodiversity
Many different species + many organisms
Environment is not stressed, with more ecological niches
Complex food webs
Habitat is stable - able to withstand change

Question 16

What is the significance of a low value of D?

Answer 16

low values of D signify
Low biodiversity
Few different species
Environment is stressed, with fewer ecological niches
Simple food webs
Habitat is unstable - small changes cause more damage

Question 17

Explain why extinction will reduce biodiversity

Answer 17

Biodiversity depends on the number of species.
Extinction will reduce the number of species as well as ones that depend on them

Question 18

What are keystone species?

Answer 18

A species which has a disproportionately large effect on ecosystem stability relative to its abundance due to their role in the ecosystem e.g an apex predator

Question 19

Explain what is meant by the term endemic

Answer 19

The ecological state of a species being unique to a defined geographic location (having evolved there)

Question 20

State what is meant by the term invasive species

Answer 20

A species that has been introduced (non-indigenous) into an environment and typically causes ecological or economic harm

Question 21

Explain what effect invasive species have on biodiversity

Answer 21

Causes either competition or predation so reduces biodiversity

Question 22

Explain why higher genetic diversity results in lower chance of extinction

Answer 22

Species that contain greater biodiversity are more likely to be able to adapt to changes in the environment, because there is more likely to be some individuals that carry an advantageous allele, which enables them to survive the altered condition

Question 23

Explain how genetic diversity can be increased

Answer 23

● Mutations in DNA create new alleles
● Gene flow/migration transfers of alleles between populations due to interbreeding between individuals of different populations.

Question 24

Explain how genetic diversity can be decreased

Answer 24

● Selective breeding increases the frequency of the allele coding for the desired traits, decreasing frequency of allele coding for undesirable traits
● Natural selection selects against alleles coding for less
advantageous characteristics, which are lost from population
● Gene bottlenecks – few individuals survive an event or change (disease, natural disaster etc), thus reducing the gene pool. Only alleles in surviving population can be passed on.
● Founder effect– small no of individuals create new colony, geographically isolated from rest, so gene pool of new population is low.

Question 25

Explain the effects of low genetic diversity

Answer 25

Species is less able to respond to environmental change, as it is less likely an individual has an advantageous allele, this is results in a higher risk of extinction.
There is an increase in genetic disorders and infertility due to inbreeding.

Question 26

How is genetic biodiversity measured?

Answer 26

Measure the proportion of polymorphic genes.

Question 27

What are polymorphic genes?

Answer 27

Genes that have more than one allele

Question 28

How is the proportion of polymorphic genes calculated?

Answer 28

Number of polymorphic gene loci / total number of gene loci.

Question 29

Explain the economic reasons for maintaining biodiversity

Answer 29

Ecosystem services are provided by bio diverse ecosystems e.g. regulation of atmosphere and climate, formation and fertilisation of soil so we can grow food, recycling of nutrients, growth of timber, food and fuel, safe and stable water supplies.
There would be additional costs to humanity if we had to provide these services without the help of natural, healthy ecosystems.

Question 30

Explain the ethical reasons for maintaining biodiversity

Answer 30

Species become extinct as a result of human action.
Humans have a responsibility to maintain species, ecosystems and habitats for future generations.
All organisms have a right to survive and live in the way to which they have become adapted.

Question 31

List some human activities that reduce biodiversity

Answer 31

Hunting
Agriculture (monoculture, farming)
Diverting water
Mining resources
Over-harvesting
Agriculture
Pesticides
Habitat destruction e.g. deforestation
Introducing invasive species
Combustion of fossil fuels as causing global warming

Question 32

Explain how different agricultural practices (farming methods) reduce biodiversity

Answer 32

Woodland clearance - done to increase area of farmland - it directly reduces the number of trees and different tree species, which also destroys habitats, shelter and food sources for other species.

Hedgerow removal - done to increase area of farmland (by turning lots of small fields into fewer large fields) - it directly reduces the number of trees and different tree species, which also destroys habitats, shelter and food sources for other species.

Pesticides - used to kill pests that feed on crops - this directly kills the pests and reduces a food source for consumers that feed on them, reducing their number too.

Herbicides - used to kill unwanted plants (weeds) - this
reduces plant diversity and could reduce numbers of herbivores that feed on them.

Mono culture - when farmers only grow one type of plant species - this reduces biodiversity directly and will support fewer organisms (e.g. as a habitat or food source).

Question 33

State what is meant by the term endangered species

Answer 33

Species that have such small numbers that they are at risk of extinction
Little genetic variability leaves them susceptible to genetic and infectious diseases

Question 34

State what is meant by the term conservation

Answer 34

The protection and management of a species and habitats in order to maintain biodiversity

Question 35

State what is meant by in situ conservation

Answer 35

Protection of species within their native habitat by conservation of natural habitats and ecosystems; involves active management of nature reserves or national parks.

Question 36

Describe the advantages of in situ conservation

Answer 36

● Species left in the protected area have access to their natural resources and breeding sites
● Species will continue to develop and evolve in their natural habitat thus conserving their natural behaviours
● Allows conservation of a greater number of species at once.
● Animals have more space than in captivity.
● Preserves unrecognised (undiscovered) species
● Protects larger breeding populations
● Active management controls invasive species
● Can control human exploitation
● legal protection for endangered species
● Opportunities for research
● restoration of degraded areas
● less expensive and requires fewer specialised facilities than captive breeding.

Question 37

Give some examples of active management strategies

Answer 37

● Culling alien or damaging species
● Fire-clearing areas to kill invasive species
● Legal measures against human impacts
● Legal protection for endangered species
● Replanting or reintroducing endangered species

Question 38

Describe the disadvantages of in-situ conservation

Answer 38

● Controlling human exploitation is difficult
● Habitats that shelter in-situ populations may need extensive restoration, including pest eradication and ongoing control.
● Populations may continue to decline during restoration.
● There may not be enough suitable habitat to maintain wild populations e.g. due to habitat destruction by humans, or large territory requirements (e.g. tigers).
● Human-wildlife conflict, especially in rural Africa; animals may still be hunted in-situ (poaching) even in national parks and reserves, as human populations grow they come into conflict as farms border
natinal parks and animals destroy crops / use same water sources, putting animals and humans in danger.

Question 39

State what is meant by ex situ conservation

Answer 39

Protection of species outside their natural habitat;
Animals are cared for in zoos
Plants are cared for in botanical gardens/seed banks

Question 40

When is ex-situ conservation used?

Answer 40

When a species has become critically low in numbers (critially endangered) or when in-situ methods have been unsuccessful.

Question 41

Describe the role of botanical gardens like Kew Gardens in London in conserving plants species

Answer 41

They collect seeds from the wild, store the seeds and germinate them in protected conditions, increasing the number of individuals of a species very quickly.

Question 42

State the role of seed banks in conserving plant species.

Answer 42

Store seeds from an endangered plants in dormant state

Question 43

Explain why seeds instead of whole plants are stored

Answer 43

● Less space is required so more species can be held in the available space
● Most plants produce large numbers of seeds so collecting small samples is unlikely to damage the wild population
● They are easier to store because they are dormant
● It is more cost effective

Question 44

Explain how seed banks are operated

Answer 44

1) Seeds are collected from a number of individual plants - to ensure high genetic diversity
2) Seeds are x-rayed to check for fully formed embryos - to ensure only viable seeds are stored.
3) Seeds are dried to remove water - to increase storage time.
4) Seeds are stored in the cold e.g. -20°C - to increase storage time.
5) Some seeds are periodically germinated to check for viability - to check systems are working and take action if not.

Question 45

Explain the advantage of selecting differently sized seeds

Answer 45

Different sized seeds are likely to have more chance of having different alleles
Genetic diversity means there is less chance of all being susceptible to the same diseases as there is a higher chance of an advantageous allele being present

Question 46

Describe the roles that zoos play in conserving animals.

Answer 46

1) Protection - protect animals from poachers / hunting / predators, they are protected from disease as have access to vet care including vaccinations and medicines, they have a safe habitat, food and water.

2) Re population - increase numbers of species using breeding and reintroduction programmes.

3) Education - they increase public awareness of endangered species and conservation.

4) Research - increase knowledge of breeding & life cycles, better nutrition and health, and develop genetic databases.

Question 47

Describe the disadvantages of zoos

Answer 47

● Animals suffer stress and boredom due to confinement
● Change behaviour as habitat differs
● Certain species favoured e.g. lions but not rodents!
● Captive breeding programs may not successfully release animals back into the wild
● Removing individuals from the wild will further endanger the wild population
● People can observe wildlife in the wild or visit a sanctuary
● Conservation more successful in situ / in a reserve

Question 48

Describe how zoos use captive breeding programmes to help conserve rare species.

Answer 48

● They increase the number of individuals of endangered species
● Studbooks are used to monitor births, deaths, select individuals for mating, keep a record of breeding events and any transfer of individuals
● Animals are selected to prevent breeding between closely related individuals to prevent inbreeding depression
● Animals / gametes are exchanged between zoos to maintain heterozygosity in offspring

Question 49

Explain how breeding programmes in zoos maintain the genetic diversity of captive populations.

Answer 49

● Studbooks are used to monitor births, deaths, select individuals for mating, keep a record of breeding events and any transfer of individuals
● Animals are selected to prevent breeding between closely related individuals to prevent inbreeding depression
● Animals / gametes are exchanged between zoos to maintain heterozygosity in offspring

Question 50

What are the issues with reintroduction programmes?

Answer 50

● Need to release into protected natural habitat e.g. National Parks otherwise dangers still exist e.g. habitat destruction, lack of resources, poaching
● Captive bred animals show behaviour that may make them unable to compete in the wild e.g. unable to hunt / find food
● Low numbers in wild lead to inbreeding depression
(E.g. Borneo - habitat destruction continues, only 2% forest protected. Will only support limited no. of orangutans. Increased competition for food. Dangers of poaching and hunting remain)