(4) Biodiversity

Question 1

Biodiversity

Answer 1

The variety of living organisms in an area

Question 2

Biodiversity at different levels

Answer 2

Habitat diversity - the number of different habitats in an area.
Examples: sand dunes, woodland, meadows, streams.

Species diversity - number of different species (species richness) and the abundance of each species in an area (species evenness) - comparison of the numbers of individuals of each species in a community.

Genetic biodiversity - the variety of genes/alleles that make up a species. Leads to different characteristics being exhibited.
Example: variation in alleles in dogs results in different breeds.

Question 3

Using sampling to measure biodiversity

Answer 3

Used to estimate the number of organisms in a habitat without having to count them all.
Also useful to measure a particular characteristic.

Question 4

How sampling can be carried out

Answer 4

Random - to avoid bias, can use measuring tapes, random number generators and coordinates. Also randomly selecting the organism you will study using random number generators or tables.

Non random - more useful if there is lots of variety in the distribution of species in the habitat and you want to make sure that all the different areas are sampled.
Systematic - samples taken at fixed intervals,
Opportunistic - samples are chosen by the investigator because it is simple to carry out, but baised,
Stratified - different areas of a sample are identified and sampled separately in proportion to their part of the habitat as a whole.

Question 5

Sampling techniques for animals

Answer 5

Pooter trap - used to trap small insects, sucking into a mouthpiece and insects are drawn into the chamber, a filter prevents them being sucked into the mouth.

Sweep nets - catch insects in long grass.

Pitfall traps - catch small crawling invertebrate, hole is dug into the ground which is deep enough so the insect cannot get back out, then the hole is covered to prevent it filling with rainwater.

Tree beating - takes samples of invertebrates living in a tree, large cloth is stretched out under the tree and then it is shaken or beaten, animals will fall onto sheet.

Kick sampling - studies organisms in a river, riverbed is kicked to disturb the substrate and a net is held downstream to catch any of the organisms released into flowing water.

Question 6

Sampling techniques for plants.

Answer 6

Using quadrats.
Point quadrats - frame with a horizontal bar where long pins can be pushed through, each species that touches the pin is recorded.

Frame quadrat - divided into grid, type and number of species in each square is recorded.

Question 7

Measuring species richness and evenness.

Answer 7

Richness - using a combination of techniques and using an identification key.

Question 8

How to calculate biodiversity

Answer 8

Simpsons index

Question 9

how to calculate genetic diversity

Answer 9

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

Question 10

Factors affecting biodiversity - human population growth

Answer 10

Destroying habitats (deforestation) - decreases habitat diversity.
Over exploitation - greater demand for resources and being used up faster than they can be replenished - decreased species diversity.
Urbanisation - can isolate species, so populations are less likely to interbreed - decreasing genetic diversity.
Pollution

Question 11

Factors affecting biodiversity - agriculture

Answer 11

Large areas of land developed into monoculture (growing of a single variety of a single crop).
Habitats are destroyed for large fields - reducing habitat diversity.
Naturally occurring plants and animals are seen as weeds and pests so are destroyed with pesticides and herbicides - reducing species diversity.
Traditional varieties of crops are lost because they dont make enough money, so are not planted anymore - decreases species diversity

Question 12

Factors affecting biodiversity - climate change

Answer 12

Variation in earth’s climate - changes in temperature and rainfall patterns. Increase in greenhouse gasses, produced by human activity, cause global warming.

Most species need a particular climate to survive - may cause a habitat to become uninhabitable - causing an increase or decrease in the range of some species which could increase or decrease biodiversity.
Some species may be force to migrate to a more suitable area - causing a change in species distribution, decreasing the biodiversity in the area they move from and the increase in the area they move to.
If there isnt a suitable habitat to move to (or if a plant cant migrate) they will become extinct - decreasing biodiversity

Question 13

Reasons for maintaining biodiversity - aesthetic reasons

Answer 13

Provides an attractive environment which can also be good for mental health. By maintaining biodiversity we protect these landscapes.

Question 14

Reasons for maintaining biodiversity - economic reasons

Answer 14

Continuous monoculture (planting the same crop in the same field without interruption). This can cause soil depletion because nutrient required by the plant are gradually used up, they are no recycled because the crop has been harvested. Making the ecosystem more fragile. Leads to increased spending on fertilisers and decreased yield, long term.
Also could impact a country’s ability to grow crops causing economical independence on other countries.

Large scale habitat loss means species with potential economic importance are lost - chemically or medically useful.

Question 15

Reasons for maintaining biodiversity - ecological reasons

Answer 15

Protecting keystone species - organisms in an ecosystem are interdependent (depend on each other to survive). Disruption of food chains - loss of prey. Disruption of nutrient cycles - decomposers improve the quality of the soil by recycling nutrients, if decomposers decline this will affect the growth of plants and the amount of food available.
Keystone species play a key role in maintaining the the structure of an ecological community (often predators). If removed, all other species may be affected in some way and some may disappear altogether.

To maintain genetic resources - material from plants, animals or microorganisms, containing genes that we find valuable. Food and drink, clothing (fibres and fabrics made from plants and animals), drugs, fuels (renewable fuels like biogas) and other industrial materials (wood, oils, pesticides).
Important to the global economy - products are traded on a global scale. They allow us to adapt to changes in the environment.

Question 16

Conservation

Answer 16

Careful management of the environment and resources.
In situ - within the natural habitat
ex situ - out of the natural habitat

Conservation is used to try and prevent extinction.

Question 17

In situ conversation methods

Answer 17

Wildlife reserves are established and active management is required.
Controlled grazing - only allowing grazing in a certain area or for a certain period of time.
Restricting human access (paths to prevent plants being trampled).
Controlling poaching (creating defences to minimise access or fines)
Feeding animals
Reintroduction of species.
Removal of invasive species.
Halting succession in some places which can be done by controlled grazing.

Marine conservation zones.
Protecting species rich areas such as coral reefs, which are destroyed by non sustainable fishing.
Creates areas of refuge which populations can build up and repopulate adjacent areas.
Large areas of sea are often required because the organism they are protecting often move long distances.

Question 18

Ex situ conservation methods

Answer 18

Botanic gardens - plant species are grown successfully here, they are actively managed to provide them with the best resources to grow.

Seed banks - stores genetic material. Seeds are stored carefully so the new plants can be grown in the future, providing a back up against the extinction of wild plants. Seeds are dried and frozen to prevent germination, seeds of most tropical rainforests cannot survive these conditions.

Captive breeding programmes - produce offspring or species in a human controlled environment, often run and managed by zoos and aquatic centres. Aim to create a stable, healthy population of a species, the gradually reintroduce the species back into its own natural habitat.
Maintaining genetic diversity can be difficult, those born in captivity may be more susceptible to disease and not as much behaviour can be learnt from others and experience.

Question 19

International conservation agreements.

Answer 19

Convention of International Trade of Endangered Species (CITES) - increasing international cooperation in regulating trade in wild animal and plant species. Member countries all agreed to make it illegal to kill endangered species. Limits trade through licensing and makes it illegal to trade products from endangered animals. Safe guarding certain species from over exploitation

Rio Convention on Biological Diversity (CBD) - requires countries to develop national strategies for sustainable development. Stating conserving biodiversity is everyone’s responsibility. Addressing interdependent issues.

Question 20

Local conservation agreements

Answer 20

Countryside Stewardship Scheme - offered governmental payments to farmers and other land managers to enhance and conserve the English landscape (leaving grassy borders or regenerating hedgerows) Restoring neglected land and conserving historic features, sustaining the beauty and biodiversity of a landscape. Improving, extending and creating wildlife habitats.