Evolution by Natural Selection

Question 1

Define evolution

Answer 1

Change over time

Question 2

Define biological evolution

Answer 2

Genetic changes in a population that are inherited over successive generations due to natural selection and ultimately resulting in the formation of a new species

Question 3

Evidence of evolution (5)

Answer 3

• Fossil records
• Modification by descent
• Biogeography
• Genetics
• Other

Question 4

Define fossil record

Answer 4

The accumulation of all listed and known fossils of different ages

Question 5

Geological timeline (4)

Answer 5

• Archaeozoic
• Palaeozoic
• Mesozoic
• Cenozoic (now)

Question 6

Define modification by decent

Answer 6

How different plant and animal groups were modified to adapt to their different environments

Question 7

Homologous structures

Answer 7

Similar structures with the same body plan that perform different functions

Question 8

Homologous structures in vertebrates

Answer 8

Pentadactyl limb

Question 9

Analogous structure

Answer 9

Body parts that perform the same function, but did not originate from a common ancestor

Question 10

Biogeography

Answer 10

The study of the distribution of plant and animal species in specific geographical regions

Question 11

Genetics

Answer 11

The study of inheritance

Question 12

Genetics evidence (4)

Answer 12

• Closely related organisms have similarities in their DNA
• Explains source of variation
• Shows how changes in genotype/phenotype are transferred
• Explains how gene pools change

Question 13

Other forms of evidence (3)

Answer 13

• Comparative biochemistry
• Vestigial organs
• Comparative embryology

Question 14

Erasmus Darwin’s Theory

Answer 14

Life originated from a common ancestor. One species developed from another over time.

Question 15

Jean Baptiste de Lamarck’s Theory

Answer 15

During their lifetimes, organisms acquire changes in characteristics that are inherited by their offspring

Question 16

Alfred Wallace’s Theory

Answer 16

Worked with Charles Darwin, on natural selection

Question 17

Charles Darwin’s Theory (8)

Answer 17

1. Organisms produce a large number of offspring
2. There is variation in the offspring
3. Some individuals have favourable characteristics that give them an advantage
4. Organisms with favourable characteristics are better adapted to survive
5. Organisms with less favourable characteristics die
6. Survivers reproduce, and pass on favourable characteristics
7. Next generation has higher proportion of favourable organisms
8. Changes lead to formation of new species

Question 18

Define natural selection

Answer 18

The mechanism of evolution where nature selects the fittest individuals for survival

Question 19

Conditions for natural selection (4)

Answer 19

• Variation in population
• Characteristics must be hereditary
• More offspring than necessary
• Changes in environment

Question 20

Define artificial selection

Answer 20

The deliberate breeding of plants and animals for desired characteristics that would not necessarily benefit the survival of the offspring

Question 21

Define speciation

Answer 21

The formation of species increases the range of organisms on earth and thus increases biodiversity

Question 22

Define extinction

Answer 22

The loss of species decreases the range of organisms on earth and thus decreases biodiversity

Question 23

Define reproductive isolation

Answer 23

The type of isolation that develops between the new species and the ancestral species, and prevents inbreeding

Question 24

Causes genetic variation in species (2)

Answer 24

• Genetic recombination

- Mutations

Question 25

Genetic recombination

Answer 25

Occurs during meiosis and sexual reproduction

Question 26

Types of mutations (2)

Answer 26

• Gene mutations

- Chromosome mutations

Question 27

Types of gene mutations (3)

Answer 27

• Harmful mutations
• Neutral mutations
• Beneficial mutations

Question 28

Genotypic variations in populations examples

Answer 28

• Galapagos finches

- White lions

Question 29

Define Inbreeding

Answer 29

The crossing of closely related individuals

Question 30

Advantages of inbreeding (3)

Answer 30

• Produces predictable offspring
• Recessive genes can be isolated
• Undesirable characteristics and be isolated

Question 31

Disadvantages of inbreeding (8)

Answer 31

• Offspring have low resistance to disease
• High mortality rate
• Increased abnormalities
• Recessive genetic diseases evident
• Loss of vigour in offspring
• Decrease in frequency of heterozygous gene pairs
• Offspring can be sterile
• Gene pool is smaller, possibility of extinction

Question 32

Define Outbreeding

Answer 32

The crossing of unrelated individuals resulting in offspring that are genetically different

Question 33

Advantages of Outbreeding (4)

Answer 33

• New characteristics introduces, gene pool enlarges
• Reintroduces lost characteristics
• Increases hybrid offspring
• Individuals still ‘pure’

Question 34

Disadvantages of outbreeding (3)

Answer 34

• Typical characteristics lost
• Loss of separate race, new race develop
• Less predictability in offspring

Question 35

Convergent evolution

Answer 35

Many different, unrelated organisms independently developing adaptation for similar environments

Question 36

Divergent evolution

Answer 36

One common ancestor giving rise to a variety of different, but related organisms

Question 37

Mechanisms of speciation (2)

Answer 37

• Geographic (allopatric) speciation

- Sympatric speciation

Question 38

Allopatric speciation

Answer 38

When a new species arises from an existing species when the populations are separated by a geographical barrier

Question 39

Sympatric speciation

Answer 39

When a new species arises from an existing species in the same geographical area

Question 40

Mechanisms of reproductive isolation (3)

Answer 40

• Temporal/seasonal isolation
• Behavioural isolation
• Mechanical isolation