Exam 2 Study Guide

Question 1

What is systematics? Taxonomy?

Answer 1

systematics: discipline of biology that characterizes and classifies the relationships of all organisms on earth.

taxonomy: science of describing, naming, and classifying organisms

Question 2

What are the 8 categories of taxonomic hierarchy (in order from species upward to broader classifications)? What are the three domains of life?

Answer 2

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
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Archaea, bacteria, eukarya

Question 3

What are the two parts of any Latinized binomial name?

Answer 3

Genus species

Question 4

What are the three different types of phylogenetic groups?

Answer 4

1. monophyletic: common ancestors and all its descendants
2. paraphyletic: common ancestor but some of its descendants
3. polyphyletic: groups with different common ancestors

Question 5

What is a phylogenetic tree and what is it used for (or what is phylogeny)?

Answer 5

graphical summary that describes the evolutionary relationships among various species

Question 6

What are the two ways a new species can be formed?

Answer 6

cladogenesis: species diverge into two or more species

anagenesis: a species evolves into a different species

Question 7

What is Homology?

Answer 7

similarities among various species

Question 8

What does cladistics compare?

Answer 8

classification of species based on evolutionary relationships to produce phylogenetic trees or cladograms

Question 9

What is the difference between a primitive character and a derived character?

Answer 9

primitive character: shared by two or more taxa from an older common ancestor

derived character: shared by two or more species from the latest common ancestor

Question 10

What is the Principle of Parsimony?

Answer 10

the preferred hypothesis is the most simplest phylogenetic tree

Question 11

What is the definition of evolution? What are the 2 mechanisms of evolution?

Answer 11

heritable changes in characteristics of a population from one generation to the next
- genetic variation and natural selection

Question 12

Define Natural Selection.

Answer 12

subset of individuals that survive best and produce the most offspring

Question 13

What 2 observations the theory of natural selection based off of? What conclusion (inference) can be made from these two observations?

Answer 13

1. All species tend to produce excessive numbers of offspring.
2. Organisms vary, and much of this variation is heritable.

Question 14

Identify and explain the 5 pieces of evidence for evolution we discussed in class.

Answer 14

1. fossil record: show morphological changes are apparent
2. biogeography: played key role in revolution of new species from isolated habitats
3. convergent evolution: two species from different lineages independently evolved similar characteristics because they occupy similar habitats
4. selective breeding: domesticating species, breeder chooses parents not natural selection
5. natural selection: alters populations in response to environmental changes

Question 15

What is the transitional form when found as a fossil?

Answer 15

intermediate state between ancestral form and form of its descendants

Question 16

What are the 3 types of homologies that are seen among species?

Answer 16

1. Anatomical (vestigial structures): anatomical features that have no current function but resemble structures of presumed ancestors.
2. developmental: species that differ in adult stage but have similarities during the embryonic phase (temporary)
3. molecular: similarity between organisms at the molecular level due to descent from a common ancestor or interrelated ancestors.

Question 17

What does endemic mean and provide an example?

Answer 17

plants and animals that are naturally found in a particular location
- ex: Galapagos finches

Question 18

Explain a gene pool.

Answer 18

all alleles for every gene in a given population

Question 19

What is the symbol for the dominant allele frequency in a population? What about the recessive?

Answer 19

dominant allele frequency: P
recessive allele frequency: q

Question 20

What are the ultimate sources for all genetic variation?

Answer 20

1. new genetic information: mutations, gene duplications, exon shuffling, horizontal gene transfer
2. evolutionary mechanisms: natural selection, genetic drift, migration, random mating

Question 21

What is the Hardy-Weinberg formula? How can it be used?

Answer 21

describes the relationship between allele and genotype frequencies in a population

Question 22

What are the conditions for Hardy-Weinberg Equilibrium?

Answer 22

• no new mutations
• no natural selection
• large population
• no migration
• random mating

Question 23

Understand, and explain the four general outcomes (patterns) of natural selection.

Answer 23

1. directional selection: extreme phenotypic range have greater reproductive success in a particular environment
2. stabilizing selection: favors intermediate phenotypes
3. diversifying (disruptive) selection: favors extreme values of the trait
4. balancing selection: maintains genetic diversity in a population

Question 24

What is genetic drift? How can it influence allele frequencies in a population? What size populations are most susceptible to genetic drift?

Answer 24

changes in allele frequency due to random chance
- favors either elimination or fixation of an allele in a population
- greater effect in smaller populations

Question 25

What is gene flow? Does it increase or decrease genetic differences between populations?

Answer 25

transfer of alleles into and out of a population when individuals move to a population with different allele frequencies - reduce differences in allele frequencies between neighboring populations - increase genetic diversity within a population

Question 26

What is the difference between microevolution and macroevolution?

Answer 26

microevolution: small scale of changes in allele frequencies n macroevolution: produce new species and groups of species

Question 27

What are the different species concepts and how do they differ from each other?

Answer 27

biological species concept: individuals that interbreed and produce viable offspring in nature, can't interbreed with other species evolutionary lineage concept: each new species is the direct result of speciation from an immediate ancestral species morpho species concept: evolutionary independent lineages by different size, shape, or other morphological features

Question 28

What is the difference between allopatric and sympatric speciation? Be able to identify and give examples of each.

Answer 28

allopatric speciation: when a population becomes isolated from other populations and evolves into one or more species- may involve a geographic barrier sympatric speciation: when members of a species within the same range diverge into two or more different species even though there are no physical barriers

Question 29

What are prezygotic barriers? Give examples of each (5 pre and 3 post).

Answer 29

habitat isolation: species occupy different habitats temporal isolation: species have different mating or flowering seams or times of day behavioral isolation: differences in behavior or physiology mechanical isolation: incompatible genitalia gametic isolation: gametes fail to unite with each other

Question 30

What are postzygotic barriers? Give examples of each (5 pre and 3 post).

Answer 30

hybrid inviability: fertilized egg fails to develop past the early embryonic stages hybrid sterility: hybrid survives but it is sterile hybrid breakdown: the F1 hybrid is viable and fertile but the succeeding generations become inviable

Question 31

Be able to explain and put in a time frame some of the major episodes in the history of life on earth.

Answer 31

13.7 bya: big bang 4.6 bya: solar system 4.55 bya: Earth was formed 4 bya: Earth's outer layer cooled and oceans formed 4-3.5 bya: first life emerged as single-celled microbes

Question 32

What is the Cambrian Explosion?

Answer 32

due to high oxygen levels species highly diversified, used new habitats and defense mechanisms

Question 33

What organisms, and process they perform, would be responsible for the accumulation of atmospheric oxygen about 2.8 billion years ago?

Answer 33

- increased in animal body size associated with increased in O2 levels through aerobic respiration

Question 34

Explain the two-stage hypothesis for the origin of Eukaryotic cells, what organelles provide evidence for and be able to define endosymbiosis.

Answer 34

1. individual cells aggregated to form a colony 2. single cels divides and resulting cells adhere endosymbiosis: smaller organism lives inside a larger organism - nucleus, mitochondria, and chloroplast

Question 35

What is the fossil record?

Answer 35

a window into the history of Earth

Question 36

We talked about several things that could affect the fossil record & create bias, be able to identify and explain these factors.

Answer 36

1. anatomy: hard body parts are more likely to be preserved 2. size: larger organism are more likely to be found 3. number: greater numbers are more likely to be preserved 4. environment: inland species are less likely to become fossilized than marine environment 5. time: lived relatively recent or existed for a long time are more likely to be fossilized 6. geological processes: certain organisms are more likely to be preserved due to chemical composition 7. paleontology: certain types of fossils may be more interesting compared to others

Question 37

How many mass extinctions have been identified in the fossil record?

Answer 37

five mass extinctions

Question 38

What three important principles found among multicellular organisms did volvocine algae elucidate?

Answer 38

1. multicellular organisms arise from a single cell that divides to produce daughter cells that adhere 2. daughter cells have different fates- produce different cell types 3. as organisms get larger, they have a greater proportion of somatic cells