4A Biodiversity

Question 1

Biodiversity definition

Answer 1

The variety of living organisms in an area

Species diversity- the number of different species and their abundance in an area
Genetic diversity- the variation of alleles within a species

Question 2

What is endemism

Answer 2

When a species is only found in one place in the world

Question 3

How to measure species diversity

Answer 3

Count the number of different species to find out species richness
count the number of different species and their abundance to calculate an index of diversity

Question 4

How to measure genetic diversity

Answer 4

Using phenotype- the larger the number of different phenotypes for the same characteristic eg eye colour, the greater the genetic variation
using genotype- Sequencing DNA samples allows for identifications of similarities and differences in alleles. the larger the number of different alleles the greater the genetic diversity.
The heterozygosity index can also be used

Question 5

Heterozygosity index

Answer 5

H= no of heterozygotes/ number of individuals

Question 6

Niche

Answer 6

The role of a species within its habitat including interactions with both biotic and abiotic factors.
a niche can only be occupied by one species as if there are more than one they will have to compete until only one is left

Question 7

Types of adaptations

Answer 7

Behavioural- ways an organism acts to improve survival eg playing dead
Physiological- processes inside an organism that increase survival eg hibernation
Anatomical/ structural- Structural features of the body that increase survival eg thick fur

Question 8

Evolution by natural selection

Answer 8

Mutations occur introducing new alleles into population which may be advantageous
A selection pressure eg predation means individuals without the advantageous allele do not survive
Individuals with the allele are more likely to survive allowing them to reproduce
The allele is passed onto the offspring and over time the allele becomes more common in the population

Question 9

Speciation

Answer 9

The development of a new species
occurs when populations of the same species become reproductively isolated due to seasonal, mechanical or behavioural changes.
This can happen due to geographical isolation where two populations are divided by a physical barrier eg floods earthquakes