Genetic Diversity And 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 (same locus)→ different DNA base sequence
● Arise by mutation

Question 3

What is a population?

Answer 3

A group of interbreeding individuals of the same species.

Question 4

Explain the importance of genetic diversity

Answer 4

● 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 (increased chances of survival and reproductive success)

Question 5

What is evolution?

Answer 5

● Change in allele frequency (how common an allele is) over many generations in a population
● Occurring through the process of natural selection

Question 6

Explain the principles of natural selection in the evolution of populations

Answer 6

Mutation Random gene mutations can result in [named] new alleles of a gene
2. Advantage In certain [named] environments, the new allele might benefit its possessor
[explain why]→ organism has a selective advantage
3. Reproductive success Possessors are more likely to survive and have increased reproductive success
4. Inheritance Advantageous allele is inherited by members of the next generation (offspring)
5. Allele frequency Over many generations, [named] allele increases in frequency in the population

Question 7

Describe 3 types of adaptations

Answer 7

● 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 8

Example of directional selection

Answer 8

Directional selection
Antibiotic resistance in bacteria
Organisms with an extreme variation of a trait eg. bacteria with high level of resistance to a particular antibiotic
Yes, usually eg. antibiotic introduced
• Increased frequency of organisms with / alleles for extreme trait
• Normal distribution curve shifts
towards extreme trait

Question 9

Example of stabilising selection

Answer 9

Stabilising selection
Human birth weight
Organisms with an average / moda variation of a trait eg. babies with ai average weight
No, usually stable
• Increased frequency of organism with / alleles for average trait
Normal distribution curve similar, less variation around the mean

Question 10

What is a species?

Answer 10

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

Question 11

Suggest why 2 different species are unable to produce fertile offspring

Answer 11

● Different species have different chromosome numbers → offspring may have odd chromosome number
● So homologous pairs cannot form → meiosis cannot occur to produce gametes

Question 12

Explain why courtship behaviour is a necessary precursor to successful
mating

Answer 12

● Allows recognition of members of same species → so fertile offspring produced
● Allows recognition / attraction of opposite sex
● Stimulates / synchronises mating / production / release of gametes
● Indicates sexual maturity / fertility
● Establishes a pair bond to raise youn

Question 13

Describe a phylogenetic classification system

Answer 13

● Species (attempted to be) arranged into groups, called taxa, based
on their evolutionary origins (common ancestors) and relationships
● Uses a hierarchy:
○ Smaller groups are placed within larger groups
○ No overlap between group

Question 14

Name the taxa in the hierarchy of classification

Answer 14

Domain (largest / broadest)→ kingdom → phylum → class → order → family → genus → species (smallest)

Question 15

How is each species universally identified?

Answer 15

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

Question 16

Suggest an advantage of binomial naming

Answer 16

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

Question 17

How can phylogenetic trees be interpreted?

Answer 17

● Branch point = common ancestor
● Branch = evolutionary path
● If two species have a more recent common
ancestor, they are more closely related (eg. C & D)

Question 18

Describe two advances that have helped to clarify evolutionary
relationships between organisms

Answer 18

1. Advances in genome sequencing → allowing comparison of DNA base sequences
   ● More differences in DNA base sequences → more distantly related / earlier common ancestor
   ● As mutations (change in DNA base sequences) build up over time
2. Advances in immunology → allowing comparison of protein tertiary structure (eg. albumin)
   ● Higher amount of protein from one species binds to antibody against the same protein from
   another species → more closely related / more recent common ancestor
   ● As indicates a similar amino acid sequence and tertiary structure
   ● So less time for mutations to build up

Question 19

What is biodiversity?

Answer 19

● Variety of living organisms (species, genetic and ecosystem diversity)
● Can relate to a range of habitats, from a small local habitat to the Earth

Question 20

What is a community?

Answer 20

All populations of different species that live in an area.

Question 21

What is species richness?

Answer 21

A measure of the number of different species in a community

Question 22

What does an index of diversity do?

Answer 22

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 23

Suggest why index of diversity is more useful than species richness

Answer 23

● Also takes into account number of individuals in each species
● So takes into account that some species may be present in small or high numbers

Question 24

What is the formula for index of diversity?

Answer 24

d= N(N-1)
————-
Σ n (n -1)

N = total number of organisms of all species
n = total number of organisms of each species, Σ = the sum of
Σ

Question 25

List the steps involved in calculating an index of diversity

Answer 25

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. Add up all the values of n(n - 1) to get Σn(n - 1) 5. Divide N(N - 1) by Σn(n -

Question 26

Describe how index of diversity values can be interpreted

Answer 26

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

Question 27

Explain how some farming techniques reduce biodiversity

Answer 27

Removal of woodland and hedgerows Monoculture (growing one type of crop) Use of herbicides to kill weeds All leads to reduced variety of plants, less habitats, and less variety of food sources Use of pesticides to kill pests - predator population of pests decreases

Question 28

Explain the balance between conservation and farming

Answer 28

● Conservation required to increase biodiversity ● But when implemented on farms, yields can be reduced, reducing profit / income for farmers ○ Eg. by reducing land area for crop growth, increasing competition, increasing pest population ● To offset loss, financial incentives / grants are offered ●

Question 29

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

Answer 29

● Reintroduction of field margins and hedgerows (where farmers only grow one type of crop) ● Reduce use of pesticides ● Growing different crops in the same area (intercropping) ● Using crop rotation of nitrogen fixing crops instead of fertilisers

Question 30

● Reintroduction of field margins and hedgerows (where farmers only grow one type of crop) ● Reduce use of pesticides ● Growing different crops in the same area (intercropping) ● Using crop rotation of nitrogen fixing crops instead of fertilisers

Answer 30

● 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 mRN

Question 31

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

Answer 31

● 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 32

Explain the change in methods of investigating genetic diversity over time

Answer 32

● 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 33

Explain the key considerations in quantitative investigations of variation within a species

Answer 33

● Collect data from random samples (use a random number generator)→ removes bias ● Use large sample size (or sample until stable running mean)→ representative of whole population ● Ethical sampling (where applicable)→ must not harm organism / allow release unchanged ● Calculate a mean value of collected data and standard deviation of that mean ● Interpret mean values and their standard deviations (S.D) ○ S.D shows spread of values about the mean → higher S.D = higher variation ○ If standard deviations overlap, causing values of two sets of data to be shared, any difference between the two may be due to chance / not significant ● Use [named] statistical test → analyse whether there is a significant difference between populations