Text Chapter 8: Evolution and Natural Selection

Question 1

Observations that Led Darwin to Form his Theory of Evolution

Answer 1

• living organisms resemble extinct fossil organisms
• progressive changes from simpler to more complex organisms can be seen in the fossil record
• different island species resemble each other
• island populations resemble those on nearby islands
• lands with similar climates have unrelated plants and animals
• plants and animals of each continent are distinctive

Question 2

Observations Reached in the Flowchart of Evolutionary Reasoning

Answer 2

• potential for rapid reproduction
• relatively constant resources and population over time
• variability in structures and behaviors
• some variability is inherited

Question 3

Conclusions Reached in the Flowchart of Evolutionary Reasoning

Answer 3

• competition for survival and rapid reproduction
• natural selection- on average, the fittest organisms leave the most offspring
• evolution- the genetic makeup of the population changes over time driven by natural selection

Question 4

Conclusions Reached in the Flowchart of Evolutionary Reasoning

Answer 4

• competition for survival and rapid reproduction
• natural selection- on average, the fittest organisms leave the most offspring
• evolution- the genetic makeup of the population changes over time driven by natural selection

Question 5

Adaptation

Answer 5

a trait that makes a species survival more likely

Question 6

Evolution

Answer 6

a change in the characteristics of organisms over time

Question 7

Natural Selection

Answer 7

the mechanism for evolution, the fittest organism survive

Question 8

Three Conditions Required for Natural Selection

Answer 8

1. variations for a trait- different versions of a trait are found in a population
2. heritability- variations on the trait are passed from parents to offspring
3. differential reproductive success- individuals best adapted to the environment leave the most offspring

Question 9

Three Conditions Required for Natural Selection

Answer 9

1. variations for a trait- different versions of a trait are found in a population
2. heritability- variations on the trait are passed from parents to offspring
3. differential reproductive success- individuals best adapted to the environment leave the most offspring

Question 10

Analogous Structures

Answer 10

superficially similar, do not show a common origin

Question 11

Homologous Structures

Answer 11

same evolutionary origin despite differences in function

Question 12

Directional Selection

Answer 12

increases one extreme

Question 13

Stabilizing Selection

Answer 13

eliminates both extremes

Question 14

Disruptive Selection

Answer 14

increases both extremes

Question 15

Disruptive Selection

Answer 15

increases both extremes

Question 16

Evidence for Evolution after Darwin

Answer 16

• fossil record
• geological (sufficient time for evolution based on age of earth)
• comparative anatomy (analogous, homologous, vestigial structures)
• embryology (similar embryonic patterns of development)
• biochemistry (molecular similarities between different organisms)
• genetics (mutation generates diversity, meiosis and fertilization generate new combinations due to crossing over, alternate patterns of chromosome segregation, unique genotype of fertilizing sperm combined with unique genotype of egg)

Question 17

Evidence for Evolution after Darwin

Answer 17

• fossil record
• geological (sufficient time for evolution based on age of earth)
• comparative anatomy (analogous, homologous, vestigial structures)
• embryology (similar embryonic patterns of development)
• biochemistry (molecular similarities between different organisms)
• genetics (mutation generates diversity, meiosis and fertilization generate new combinations due to crossing over, alternate patterns of chromosome segregation, unique genotype of fertilizing sperm combined with unique genotype of egg)

Question 18

Ways in which Scientists can Observe Natural Selection in Action Today

Answer 18

artificial selection (dog breeds)
-insecticide resistance (in western corn rootworm larvae)

Question 19

Major Sources of Genetic Variability

Answer 19

-mutation generates diversity
-meiosis and fertilization generate new combinations due to:
crossing over, alternate patterns of chromosome segregation, unique genotype of fertilizing sperm combined with unique genotype of egg

Question 20

Describe how Natural Selection Contributes to Evolution

Answer 20

the fittest offspring survive, over time makes organisms best suited to their environment

Question 21

Describe how Natural Selection Contributes to Evolution

Answer 21

the fittest offspring survive, over time makes organisms best suited to their environment

Question 22

Mutation

Answer 22

an alteration in the base-pair sequence in the DNA of an individual’s gamete- producing cells that changes an allele’s frequency

Question 23

Genetic Drift

Answer 23

a random change in allele frequencies, unrelated to any allele’s influence on reproductive success

Question 24

Migration (gene flow)

Answer 24

a change in allele frequencies caused by individuals moving in or out of a population

Question 25

Natural Selection

Answer 25

a change in allele frequencies that occurs when individuals with one version of a heritable trait have greater reproductive success than individuals with a different version of the trait.

Question 26

Describe the types of color and pattern adaptations that can arise as a result of natural selection

Answer 26

organisms adapt to camouflage to their environment to hide from predators, or become brightly colored to ward off predators