Populations And Evolution

Question 1

Species

Answer 1

An organism that can reproduce to produce fertile offspring

Question 2

Population

Answer 2

All the organisms of one species in one place at one time

Question 3

Community

Answer 3

All the organisms of all the species in one place at one time

Question 4

Gene pool

Answer 4

All the alleles present in a population

Question 5

Allele frequency

Answer 5

How common an allele is in a population

Question 6

Evolution

Answer 6

A change in allele frequency over time and over many generations

Question 7

Differential reproductive success

Answer 7

Organisms with a phenotype better adapted to their environment have a selective advantage and are more likely to survive and reproduce

Question 8

Speciation

Answer 8

The process of forming a new species

Question 9

The hardy weinberg principal

Answer 9

A model predicting the frequency of alleles in a population, that will stay constant over generations providing there is no mutation no selection and it is a large population

Question 10

What are the two equations for hardy Weinberg

Answer 10

p+q=1
p is usually dominant, q is usually ressesive
p2+2pq+q2=1

Question 11

Intraspecific variation

Answer 11

Individuals of the same species have the same genes but different alleles- variation in their phenotype

Question 12

Interspecific variation

Answer 12

Individuals of different species have different genes and live in different environments- variation in their phenotype

Question 13

Continuos variation

Answer 13

Variation is smooth and continuous (not discrete), represented on a line graph e.g weight and height

Question 14

Discontinuous variation

Answer 14

Individuals fall into discrete groups with no intermediates, represented in a bar chart e.g bloody type, controlled by a single gene with a few alleles

Question 15

Mutation, meiosis crossing over/independent seg., random fertilisation

Answer 15

Genetic causes to variation

Question 16

Environmental causes to variation

Answer 16

Environment changes the phenotype, can change over a lifetime e.g accent

Question 17

Both environmental and genetic causes to variation

Answer 17

E.g height, genetic because you have tall parents, environmental because of you childhood nutrition

Question 18

Allopatric speciation

Answer 18

Geographical isolation so reproductive isolation (no gene flow)

Question 19

Sympatric speciation

Answer 19

Not geographically isolated but are reproductively isolated, e.g seasonal reproductivity, behavioural courtship, hybrid sterility

Question 20

Name the steps that occur due to both allopatric and sympatric spectiation

Answer 20

1. Variation exists in pop. due to mutation
2. Different selection pressures
3. Directional selection of different phenotypes
4. Different reproductive success
5. Change in allele frequency over many generations

Question 21

Genetic drift

Answer 21

Change in allele frequency between generations due to random chance e.g random fertilisation

Question 22

What does genetic drift affect

Answer 22

Small populations much more than large ones, changes the allele frequency, does not depend on the environment

Question 23

Directional selection

Answer 23

Individuals with more extreme characteristics are more likely to survive and reproduce e.g antibiotic resistance, change in environment, mean phenotype changes

Question 24

Stabilising selection

Answer 24

Individuals with extreme characteristics are less likely to survive and reproduce e.g human birth weight, stable environment, mean phenotype remains the same

Question 25

Disruptive selection

Answer 25

Both extremes of the phenotype are more likely to survive and reproduce than the mean phenotype, opposite to STABILISING selection, contributes to sympatric speciation

Question 26

Give an example of disruptive selection

Answer 26

The environment is made of black and white rocks and but the genotype is white black and grey, both extremes (white+black) can hide from predators as they blend in

Question 27

Abundance

Answer 27

The number of individuals of a single species in an ecosystem (population)

Question 28

Distribution

Answer 28

Where a species is found in an ecosystem

Question 29

Intraspecific competition

Answer 29

Competition within a species where they occupy the same niche and compete for everything e.g food and mates

Question 30

Carrying capacity

Answer 30

The maximum stable population an ecosystem can support

Question 31

Limiting factor

Answer 31

The factor that limits max population size

Question 32

Interspecific competition

Answer 32

Competition between species, the abundance of one species affects the other, species with a similar niche will compete for resources

Question 33

Predator prey relationship

Answer 33

Increase of prey, increase of predator due to more food, decrease of prey, decrease of predator. Time lag and on a cycle

Question 34

Abiotic factors

Answer 34

Species can tolerate a range of conditions, where conditions are optimal pop size will be biggest, altitude, temp, pH

Question 35

Niche

Answer 35

The role an organism plays in an ecosystem

Question 36

Each species has its own niche

Answer 36

Two species can’t occupy the exact same niche because they both compete fore everything, the abundance will vary depending on the competition, the distribution will vary because an organism can only exist where it’s niche exists