Unit 3 KA7-KA8

Question 1

Components of biodiversity

Answer 1

There are 3 measurable components of biodiversity:-
 Genetic diversity
 Species diversity
 Ecosystem diversity

Question 2

Genetic diversity

Answer 2

Genetic diversity is the number and frequency of all the alleles in a population.
Lack of genetic diversity is an issue – if one population of a species dies out, then the species may have lost some genetic diversity. This may limit its ability to adapt to changing environmental conditions in the future.

Question 3

species diversity

Answer 3

Species diversity comprises the number of different species in an ecosystem and the proportion of each species in the ecosystem .

Question 4

Ecosystem diversity

Answer 4

Ecosystem diversity is the number of distinct ecosystems within a defined area.
A region with a wide variety of ecosystems will have a greater species diversity than an area with only a few ecosystems.

Question 5

Exploitation

Answer 5

Humans exploit natural resources for food, raw materials and so on.
Over-exploitation involves resources being used at a rate greater than they can be replaced. A common example of over-exploitation is over-fishing.
With overexploitation, populations can be reduced to a low level, but may still recover

Question 6

Bottleneck effect

Answer 6

This is when small populations may lose the genetic variation necessary to enable evolutionary responses to environmental change.
In small populations, this loss of genetic variation can be critical for many species, as inbreeding can result in poor reproductive rates.

Question 7

Habitat fragmentation

Answer 7

This occurs when a habitat is divided into several smaller habitats.
Fragmentation occurs when humans build roads or clear forests for agriculture or housing.
Fragmentation causes a decrease in species richness
This results in competition between them and the interior species and biodiversity decreases further.
More isolated fragments and smaller fragments exhibit lower species diversity.

Question 8

Habitat corridors

Answer 8

To remedy widespread habitat fragmentation, isolated fragments can be linked with habitat corridors.
This allows animals to move between habitat fragments for increased access to food and choice of mate. This may lead to recolonization of small fragments after local extinctions.

Question 9

Introduced species

Answer 9

An introduced species is a non-native species which has been moved by humans intentionally or accidentally to a new geographical location.

Question 10

Naturalised species

Answer 10

A naturalised species is an introduced species that has become established within a wild community.

Question 11

Invasive species

Answer 11

Invasive species are naturalised species that spread rapidly and eliminate native species, therefore reducing species diversity.

Invasive species may be free from natural predators, parasites, pathogens and competitors which limited their population numbers in their native habitat
Invasive species may threaten indigenous (native) species by preying on them, out-competing them for resources or hybridising with them.