Unit 3 (KA7-8)

Question 1

Biodiversity (biological diversity)

Answer 1

The total variation that exists among all living things on Earth.

Refers to the number of species, genetic variation within species and variability of ecosystems.

There are around 2 million known species, there could be 5-20 million in unexplored and inaccessible ecosystems.

Question 2

Biodiversity databases

Answer 2

There are several biodiversity databases, but ideally one central global one is needed.

This would require international co-operation and a huge level of funding.

Every new species would have to be checked and verified by experts, to avoid incorrect classification.

Question 3

Reasons for conserving biodiversity

Answer 3

The world’s biodiversity is a natural store of different genes.

Many species have not been tested for potential uses and may become extinct before their value is discovered.

Essential to preserve the wonder and beauty of our planet.

To prevent extinction of species by giving them time to adapt to change.

To maintain a rich variety of resources for the future.

Question 4

Why measure biodiversity?

Answer 4

Needed to provide conservationists with information so biodiversity can be preserved.

Identifies species and ecosystems in need of protection.

Used to measure environmental change and pollution.

Question 5

Genetic diversity

Answer 5

Results from variation in the number and frequency of all the alleles of all the genes in a population.

Question 6

Species diversity

Answer 6

There are 2 aspects :

species richness

abundance of different species

Question 7

Species richness

Answer 7

Number of different species present in an ecosystem.

Question 8

Relative abundance

Answer 8

The proportion of each species in an ecosystem.

Question 9

Communities with one dominant species…

Answer 9

..such as wheat, may have the same number of species (species richness) but are less diverse than an area with a more even balance of species.

Question 10

Ecosystem diversity

Answer 10

The number of distinct ecosystems present in a defined area.

Scotland is a small country with a high ecosystem diversity.

Question 11

Island biogeography

Answer 11

The study of factors affecting the distribution and diversity of species on islands.

Species richness is related to island size and distance from the mainland.

Fewer species colonise an island a large distance away from the mainland.

Large islands have higher immigration rates and lower extinction rates (as they have more food and other resources).

Question 12

Island

Answer 12

True islands are surrounded by water.

Habitat islands are surrounded by dissimilar habitat.

Question 13

Overexploitation

Answer 13

Overexploit = remove individuals faster than they can be replaced by reproduction. eg. overfishing.

Overexploitation is not sustainable.

Question 14

Exploitation

Answer 14

To make the best use of a natural resource

Question 15

Causes of overfishing

Answer 15

Rapid decline in fish stocks as a result of uncontrolled fishing using large nets and sonar to locate shoals.

Question 16

Preventing overfishing

Answer 16

Fishing quotas, fewer boats, restricted time at sea and restricted fishing areas.

Question 17

Monitoring harvest species

Answer 17

Harvested species can be monitored using PCR and gel electrophoresis to identify them.

Question 18

Over exploitation - whaling

Answer 18

Commercial whaling with modern harpoons and boats caused a dramatic decline in global whale populations.

Question 19

Whaling moratorium

Answer 19

1986 - International Whaling Commission imposed a moratorium (ban) on commercial whaling, allowing limited numbers to be caught for research only.

This has reversed the decline in whale numbers

Question 20

Bottleneck effect

Answer 20

Causes a reduction in the genetic diversity of a species.

Occurs when a large proportion of a population is wiped out at random by a natural disaster or by hunting.

Rarer alleles may be lost, and even if populations recover their numbers, there is less genetic variation in the surviving population.

Loss of genetic diversity can lead to inbreeding and may reduce the ability of a population to adapt to change.

Question 21

Fragmentation

Answer 21

Natural ecosystems are broken up by roads, or are cleared for agriculture.

The total surface area of the combined fragments is less than the original habitat.

Degradation of fragment edges leads to further habitat loss, and an increase in the ratio of edge : interior.

This favours edge species over interior species, which need undisturbed habitats.

Small fragments support smaller populations with a lower genetic diversity.

Question 22

Habitat corridors

Answer 22

Used to link isolated fragments with a corridor or ‘stepping stones’ of quality habitat.

Allows species to move between isolated fragments to feed, mate and recolonise after a local extinction.

Question 23

Problems with habitat corridors

Answer 23

They do not solve the problem of loss of interior habitat.

They may spread disease or invasive species between fragments.

Question 24

Introduced species

Answer 24

Foreign species are accidentally or intentionally introduced to an area which they did not previously inhabit.

Occurs as a result of plant collecting, the pet trade, commercial shipping, tourism or biological control.

Question 25

Naturalised species

Answer 25

Establish themselves in the wild community and live and breed within it without affecting it too much.

Question 26

Invasive species

Answer 26

Spread rapidly in the wild community and eliminate native species.

They prey on or outcompete native species, and may hybridise with them.

They have no natural predators, pathogens or parasites to control their numbers in their new environment.

Question 27

Characteristics of invasive species

Answer 27

Characteristics include rapid growth and reproduction rates, high dispersal rates, tolerance and adaptability.

Question 28

Invasive species - effects on the economy

Answer 28

Japanese knotweed was introduced as an ornamental plant.

It has no natural parasites, pathogens or grazers in the UK.

It can grow rapidly through the foundations of buildings, regenerates from tiny fragments and is becoming herbicide resistant.

Millions of pounds are spent every year trying to remove it.

Question 29

Invasive species - effects on health

Answer 29

Giant hogweed was introduced as a garden plant but has become invasive.

It has poisonous sap which causes burns and blisters.

Question 30

Invasive species - effects on biodiversity

Answer 30

Invasive species affect biodiversity by :

• outcompeting native species and spreading disease (grey/red squirrels)
• preying on native species (mink/water voles)
• hybridising with native species (domestic cat/Scottish wildcat)