Biodiversity

Question 1

What is genetic diversity?

Answer 1

Number of different alleles of genes in a population

Question 2

What are alleles and how do they arise?

Answer 2

Variations of a particular gene
Arise by mutation

Question 3

Explain the importance of genetic diversity

Answer 3

Enables natural selection to occur
As in certain environments, a new allele of a gene might benefit its possessor
By resulting in a change in the polypeptide (protein) coded for that positively changes its properties
Giving possessor a selective advantage

Question 4

What is evolution?

Answer 4

Change in allele frequency over many gens occurring through natural selection

Question 5

Explain the principles of natural selection in the evolution of populations

Answer 5

Mutation can cause new alleles
Organism has a selective advantage
Posessors more likely to reproduce
Advantageous allele is inherited by next generation
Allele frequency increases

Question 6

Describe 3 types of adaptations

Answer 6

Anatomical - structural / physical features that increase chance of survival

Physiological - processes / chemical reactions that increase chance of survival

Behavioural - ways in which an organism acts that increase chance of survival

Question 7

What is a species?

Answer 7

A group of organisms that can (interbreed to) produce fertile offspring

Question 8

Suggest why 2 different species are unable to produce fertile offspring

Answer 8

Different species have different chromosome numbers
So homologous pairs cannot form → meiosis cannot occur to produce gametes

Question 9

Explain why courtship behaviour is a necessary precursor to successful mating

Answer 9

Allows recognition of members of same species → so fertile offspring produced
Allows recognition / attraction of opposite sex
synchronises mating
Indicates sexual maturity / fertility
Establishes a pair bond to raise young

Question 10

Describe a phylogenetic classification system

Answer 10

Species arranged into groups, called taxa, based on their common ancestors and relationships

Hierarchy - small groups within larger with no overlap

Question 11

Name the taxa in the hierarchy of classification

Answer 11

1.Domain (largest / broadest)
2. Kingdom
3. Phylum
4. Class
5. Order
6. Family
7. Genus
8. Species (smallest)

Question 12

How is each species universally identified?

Answer 12

binomial consisting of the name of its genus and species, eg. Homo sapiens

Question 13

Suggest an advantage of binomial naming

Answer 13

Universal so no confusion as many organisms have more than one common name

Question 14

How can phylogenetic trees be interpreted?

Answer 14

Branch point = common ancestor
Branch = evolutionary path
If two species have a more recent common
ancestor, they are more closely related

Question 15

What is biodiversity?

Answer 15

Variety of living organisms
Can relate to a range of habitats,

Question 16

What is a community?

Answer 16

All populations of different species that live in an area

Question 17

What is species richness?

Answer 17

A measure of the number of different species in a community

Question 18

What does an index of diversity do?

Answer 18

Describes the relationship between:
1. The number of species in a community (species richness)
2. The number of individuals in each species (population size)

Question 19

Suggest why index of diversity is more useful than species richness

Answer 19

Also takes into account number of individuals in each species

Question 20

List the steps involved in calculating an index of diversity

Answer 20

1. Calculate the total number of organisms (N), if not given
2. Multiply N by (N - 1)
3. For each species, multiply the number of organisms (n) by (n - 1)
4. Addupallthevaluesofn(n-1)togetΣn(n-1) 5. DivideN(N-1)byΣn(n-1)

Question 21

Describe how index of diversity values can be interpreted

Answer 21

High → many species present (high species richness) and species evenly represented
Low → habitat dominated by one / a few species

Question 22

Explain how some farming techniques reduce biodiversity

Answer 22

Removal of woodland and hedgerows, use of herbicides to kill weeds - Reduces variety of plant species, so fewer habitats and niches
and less variety of food sources

Use of pesticides to kill pests, predator population of pest decreases

Question 23

Explain the balance between conservation and farm

Answer 23

Conservation required to increase biodiversity

Question 24

Give examples of how biodiversity can be increased in areas of agriculture

Answer 24

Reduce use of pesticides
Growing different crops in the same area (intercropping)
Using crop rotation of nitrogen fixing crops instead of fertilisers

Question 25

How can genetic diversity within or between species be measured?

Answer 25

Comparing frequency of measurable or observable characteristics Comparing base sequence of DNA Comparing base sequence of mRNA Comparing amino acid sequence of a specific protein encoded by DNA and mRNA

Question 26

Explain how comparing DNA, mRNA and amino acid sequences can indicate relationships between organisms within a species and between species

Answer 26

More differences in sequences → more distantly related / earlier common ancestor As mutations (change in DNA base sequences) build up over time More mutations cause more changes in amino acid sequences

Question 27

Explain the change in methods of investigating genetic diversity over time

Answer 27

Early estimates made by inferring DNA differences from measurable or observable characteristics ○ Many coded for by more than one gene → difficult to distinguish one from another ○ Many influenced by environment → differences due to environment not genes ● Gene technologies allowed this to be replaced by direct investigation of DNA sequences

Question 28

Explain how data should be collected when investigating variation within a species quantitatively

Answer 28

Collect data from random samples ○ Use a grid / divide area into squares ○ Use a random number generator to obtain random coordinates Use same method of measurement each time Use a large sample size / measure a large number of organisms → so representative of population Calculate a running mean and sample until number becomes (fairly) constant (Where applicable) ensure sampling is ethical → must not harm organism / must allow release unchanged