Unit 9: Evolution

Question 1

Natural selection

Answer 1

Individuals whose traits enable them to better obtain food, escape predators or tolerate physical conditions will survive and reproduce more successfully than those without those traits

Question 2

Why is environment the driving force behind natural selection, and therefore evolution?

Answer 2

Organisms must adapt their characteristics to the environment they are in so that they can survive

Question 3

Biogeography

Answer 3

Geographic distribution of species

Question 4

3 keys points about natural selection

Answer 4

1. Natural selection occurs through interactions between individual organisms and their environment
2. Natural selection can only amplify or diminish heritable traits
3. Natural selection is the result of environmental factors that vary from place to place

Question 5

How does biogeography provide evidence for evolution?

Answer 5

Organisms evolve from ancestral species. Organisms migrate and adapt to their new environment, eventually creating a new species

Question 6

Homologous structures

Answer 6

Features that often have different functions but are structurally similar because of common ancestry

Question 7

Vestigial organs

Answer 7

Structures of marginal or no importance to the organisms

Question 8

How does molecular biology provide evidence for Darwin’s claim that all life forms are related?

Answer 8

Similarities in genes or DNA sequences/proteins reflect evolutionary relationship

Question 9

Population

Answer 9

A group of individuals of the same species living in the same place at the same time

Question 10

Gene pool

Answer 10

Total collection of genes in a population at any one time

Question 11

How do new alleles arise in a gene pool?

Answer 11

Mutations

Question 12

What is the importance of sexual reproduction?

Answer 12

It causes variation in a population

Question 13

Hardy-Weinberg equilibrium

Answer 13

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Question 14

Required conditions to be in equilibrium

Answer 14

1. Very large population
2. No gene flow between population
3. No mutations
4. Random mating
5. No natural selection

Question 15

Hardy-Weinberg equation

Answer 15

P^2 + 2pq + q^2=1

Question 16

Genetic drift. How can it occur?

Answer 16

Change in gene pool population due to chance

It can occur though the bottleneck effect or founder effect

Question 17

Bottleneck effect

Answer 17

Drastic reduction in population size

Question 18

Founder effect

Answer 18

Differences in gene pool of the larger population left

Question 19

Stabilizing selection

Answer 19

Favors intermediate phenotypes. It typically occurs in relatively environments (ex. Human broth weight)

Question 20

Directional selection

Answer 20

Shifts the overall makeup of the population by acting against individuals at one of the phenotypic extremes. Most common during periods of environmental change

Question 21

Disruptive selection

Answer 21

Typically occurs when environmental conditions are varied in a way that favors individuals at both extremes of a phenotypic range. Can lead to two or more contrasting phenotypes in a population

Question 22

Sexual dimorphism

Answer 22

Distinction in appearance where a male and female of an animal species have different characteristics (lions mane, peacock feathers, antlers)

Question 23

Sexual selection

Answer 23

Form of natural selection in which individuals with certain characteristics are more likely than other individuals to obtain mates

Question 24

How does penicillin usually work?

Answer 24

Prevents the formation of bacterial cell wall

Question 25

What makes some bacteria resistant to penicillin?

Answer 25

Contains a gene that codes for a protein to break down penicillin

Question 26

Heterozygotes advantage

Answer 26

Heterozygotes have a greater reproductive success than homozygotes, resulting in 2 or more alleles for a character are maintained in a population

Question 27

4 reasons why natural selection does not create perfect organisms

Answer 27

1. Selection can act only on existing variations
2. Evolution is limited by historical constraints
3. Adaptations are often compromises
4. Chance, natural selection and the environment interact

Question 28

Neutral mutation

Answer 28

A mutation with no effect

Question 29

How does stabilizing selection impact variation?

Answer 29

There is less variation

Question 30

How does directional selection impact variation?

Answer 30

There is no more/less variation

Question 31

How does disruptive selection impact variation?

Answer 31

There is more variation

Question 32

Artificial selection

Answer 32

Humans selecting traits

Question 33

4 components of Charles Darwin’s theory of evolution

Answer 33

1. Variation
2. Inheritance
3. High rate of population growth
4. Differential survival and reproduction

Question 34

Inheritance of acquired characteristics

Answer 34

Traits acquired during an organism’s lifetime will be passed on to offspring (not true)

Question 35

Use vs. disuse

Answer 35

Using a trait will strengthen it, not using it will make it go away over time

Question 36

Micro evolution

Answer 36

Change in allele frequency

Question 37

Macro evolution

Answer 37

Change in phenotype

Question 38

Analogous structures

Answer 38

Organisms in similar environments acquire certain traits

Question 39

Intersexual selection

Answer 39

2 organisms of the same sex compete and the opposite sex chooses the mate

Question 40

Intrasexual selection

Answer 40

2 organisms of the same species compete and the winner gets the mate

Question 41

Why does it take longer for recessive alleles to reach fixation rather than dominant alleles?

Answer 41

More of the species has the dominant allele, due to homozygous dominants and heterozygotes