Chapter Four: Evolution

Question 1

Evolution

Answer 1

The gradual development of organisms over time.

Question 2

Common Descent (3)

Answer 2

1. All organisms are composed of cells
2. All take in chemicals and energy from the environment
3. All reproduce, respond to stimuli, and evolve

Question 3

Fossil

Answer 3

The preservation of the general shape of an organism. Formed when minerals in the earth harden over it’s body upon its death

Question 4

Transition Fossil

Answer 4

A fossil representing an evolutionary link in the fossil record, indicating a common ancestor

Question 5

Strata

Answer 5

Layers of the earth representing geological periods of time.

Question 6

Relative Dating

Answer 6

• Fossil dating method using layers of strata to determine which era it came from. The lower the strata, the older the fossil
• Only accurate if the strata has not been twisted or upturned from natural processes

Question 7

Radiometric/Absolute Dating

Answer 7

Dating method which uses the half-lives of isotopes present in the fossil to determine its age. In organic fossils, carbon is typically used.

Question 8

Mass Extinction

Answer 8

Event that extinguishes a large number of organisms in a short period of time. This causes only the most well-adapted organisms to survive.

Question 9

What is an example of a mass extinction?

Answer 9

The Cretaceous period; a large number of meteorites hit the earth and the debris blocked the sunlight. Many plants and animals died.

Question 10

Biogeographical Evidence for Evolution

Answer 10

• Study of the distribution of plants and animals
• continental drift shown through distribution of similar fossils on different continents: evolving species unable to migrate

Question 11

Homologous Structure ( + example)

Answer 11

Has same function and basic structure, indicates a common ancestor
ex) A human arm and a whale forelimb

Question 12

Analogous Structure ( + example)

Answer 12

Same basic function but different origin

ex) bird’s wing and bee wing

Question 13

Vestigial Structure ( + example)

Answer 13

Anatomical structure fully functional in one group and reduced or nonfunctional in another
ex) Human coccyx (tailbone)

Question 14

Biochemical Evidence for Evolution

Answer 14

• All organisms have the same three basic biochemical molecules: DNA, ATP, and general enzymes
• The degree of similarity between DNA base sequences and amino acid sequences indicate the degree of relatedness

Question 15

Evolution of micromolecules

Answer 15

Earth’s early atmosphere according to Miller was full of methane, hydrogen, and ammonia
-when applied with enough each (ex lightning) these molecules could form organic compounds and amino acids

Question 16

Miller Experiment

Answer 16

Simulated conditions of early earth (methane, hydrogen, and ammonia) and applied an electric spark. Yielded amino acids without the use of oxygen.

Question 17

Macromolecules: RNA first hypothesis

Answer 17

RNA functioned both as an enzyme and a substrate. Some viruses use RNA as their genetic material

Question 18

Macromolecules: Protein first hypothesis

Answer 18

Sidney Fox’s experiments

• amino acids can form polypeptides when exposed to dry heat
• amino acids collected in puddles and formed proteinoids within microspheres

Question 19

Microsphere

Answer 19

A chemical reaction separated from its environment

Question 20

Macromolecules: Cairnes-Smith hypothesis

Answer 20

• Proteins and RNA at the same time: Clay attracted small organic molecules, which served as inorganic catalysts for polypeptide formation
• Fueled by energy from radioactive decay

Question 21

The Protocell

Answer 21

• Proposed structure of a protein-lipid membrane which carried on an energy metabolism
• Microspheres were exposed to lipids, created a coacervate with a protein-lipid membrane
• the phospholipid automatically formed a liposome

Question 22

Coacervate

Answer 22

Microscopic spontaneously formed spherical collection of lipid molecules, held together by electrostatic forces

Question 23

Liposome

Answer 23

A spherical structure with at least one lipid bilayer

Question 24

The Heterotroph Hypothesis

Answer 24

• Since nutrition was plentiful in the ocean, the first organism was probably a heterotroph
• used ATP first; was a fermentative process
• Had a catalytic ability like microspheres and took in available enzymes (beginning of glycolysis)

Question 25

The True Cell (RNA first hypothesis)

Answer 25

-First true cell had RNA genes; reverse transcriptase produced DNA from RNA

Question 26

Reverse Transcriptase

Answer 26

An enzyme that generates complimentary DNA from an RNA template. Requires DNA polymerase and a nucleus

Question 27

The True Cell (Protein-first hypothesis)

Answer 27

Complex enzymatic processes may have been necessary for the formation of DNA and RNA - requires proteins

Question 28

The True Cell (Cairnes-Smith hypothesis)

Answer 28

RNA genes could replicate because proteins present for catalysm. Once protocells could replicate, they became true cells

Question 29

Order of the Evolution of the Cell (5)

Answer 29

1. Micromolecules 2. Macromolecules 3. The Protocell 4. The Heterotroph 5. The True Cell

Question 30

Microevolution

Answer 30

A change in the gene frequency of a population

Question 31

Population

Answer 31

All members of a species occupying a particular area

Question 32

Hardy-Weinberg Law

Answer 32

Equilibrium of allele frequencies in a gene pool will remain constant in each generation of a large sexually reproducing population, as long as certain conditions are met.

Question 33

Hardy-Weinberg Equation

Answer 33

p2 + 2pq + q2

Question 34

Agent of Evolutionary Change: Mutations

Answer 34

Only source of new alleles in a population; can also be an adaptive variation.

Question 35

Gene Pool

Answer 35

the sum total of all alleles in a population

Question 36

Agent of Evolutionary Change: Genetic Drift

Answer 36

Change in allele frequency due to chance

Question 37

Founder Effect

Answer 37

A few individuals found a colony and their collective genes represent a small fraction of the original gene pool

Question 38

Bottleneck Effect

Answer 38

Population is subjected to near extinction by a disaster and only a few genotypes contribute to the next generation

Question 39

Agent of Evolutionary Change: Gene Flow

Answer 39

Movement of alleles between populations, keeps the gene pools of two or more populations similar

Question 40

Agent of Evolutionary Change: Nonrandom Mating

Answer 40

Individuals pair up according to genotype and phenotype. Increases frequency of recessive abnormalities (ex. inbreeding)

Question 41

Agent of Evolutionary Change: Natural Selection

Answer 41

Process by which populations adapt to their environment.

Question 42

Requirements for Natural Selection (4)

Answer 42

1. Variation 2. Inheritance 3. Differential Adaptiveness (some differences have a survival benefit) 4. Differential Reproduction (better adapted individuals survive to reproduce more offspring)

Question 43

Fitness

Answer 43

Measured by the number of fertile offspring produced by an individual. Variations occur from mutations, crossing over, and independent assortment.

Question 44

Stabilizing Selection

Answer 44

An intermediate, or average, phenotype is favoured. Improves adaption of a population to a stable environment.

Question 45

Directional Selection

Answer 45

An extreme phenotype is favoured. Distribution curve shifts in that direction.

Question 46

Species

Answer 46

A group of interbreeding sub populations that share a gene pool

Question 47

Premating Isolation Mechanisms (4)

Answer 47

Reproduction never attempted 1. Habitat Isolation 2. Temporal Isolation 3. Behavioral Isolation 4. Mechanical Isolation

Question 48

Premating Isolation Mechanism: Habitat Isolation

Answer 48

Species at same locale occupy different habitats

Question 49

Premating Isolation Mechanism: Temporal Isolation

Answer 49

Species reproduce at different seasons or different times of day

Question 50

Premating Isolation Mechanism: Behavioral Isolation

Answer 50

Courtship behaviour differs; species respond to different songs, calls, pheromones, or other signals

Question 51

Premating Isolation Mechanism: Mechanical Isolation

Answer 51

Genitalia unsuitable for one another

Question 52

Postmating Isolation Mechanisms (4)

Answer 52

Reproduction may take place but it does not produce fertile offspring 1. Gamete Isolation 2. Zygote Mortality 3. Hybrid Sterility 4. F2 Fitness

Question 53

Postmating Isolation Mechanism: Gamete Isolation

Answer 53

Sperm cannot reach or fertilize egg

Question 54

Postmating Isolation Mechanism: Zygote Mortality

Answer 54

Fertilization occurs, but zygote dies

Question 55

Postmating Isolation Mechanism: Hybrid Sterility

Answer 55

Hybrid survives but is sterile and cannot reproduce

Question 56

Postmating Isolation Mechanism: F2 Fitness

Answer 56

Hybrid is fertile, but F2 has reduced fitness

Question 57

Allopatric Speciation

Answer 57

Geographical barriers separate a population into two groups

Question 58

Sympatric Speciation

Answer 58

Separation occurs without any geographical barriers. Two subgroups of a population becomes reproductively isolated.

Question 59

Phyletic Gradualism

Answer 59

Change of species is slow but steady after a divergence

Question 60

Punctuated Equilibrium

Answer 60

Stasis is punctuated by speciation, occurs too rapidly to fossilize

Question 61

Cladogram

Answer 61

A branching, tree-like diagram with successive points of divergence from a common ancestor

Question 62

Cladistic

Answer 62

A branch of a cladogram

Question 63

Clad

Answer 63

The specific trait of analyzed in a cladogram