Bio Exam 2

Question 1

Natural Selection

Answer 1

The process by which individuals with certain heritable traits tend to produce more surviving offspring than do individuals without those traits, often leading to a change in the genetic makeup of the population. A major mechanism of evolution. The only evolutionary process that produces adaptation.

Question 2

Genetic Drift

Answer 2

Any change in allele frequencies due to chance. Causes allele frequencies to drift up and down randomly over time, and eventually can lead to the fixation or loss of alleles.

Question 3

Gene flow

Answer 3

The movement of alleles between populations; occurs when individuals leave one population, join another, and breed.

Question 4

Mutation

Answer 4

Any permanent change in the hereditary material of an organism (DNA in most organisms, RNA in some viruses). The only source of new alleles in populations.

Question 5

Hardy-Weinberg Principle

Answer 5

A principle of population genetics stating that genotype frequencies in a large population do not change from generation to generation in the absence of evolutionary processes (e.g., mutation, gene flow, genetic drift, and selection), and nonrandom mating.

Question 6

Gene pool

Answer 6

All the alleles of all the genes in a certain population.

Question 7

Inbreeding Depression

Answer 7

The decline in average fitness that takes place when homozygosity increases and heterozygosity decreases in a population due to inbreeding; results from the exposure of deleterious recessive alleles to selection

Question 8

Directional selection

Answer 8

A mode of natural selection that favors one extreme phenotype with the result that the average phenotype of a population changes in one direction. Generally reduces overall genetic variation in a population. Compare with disruptive selection and stabilizing selection.

Question 9

Stabilizing selection

Answer 9

A mode of natural selection that favors phenotypes near the middle of the range of phenotypic variation. Reduces overall genetic variation in a population. Compare with disruptive selection and directional selection.

Question 10

Disruptive selection

Answer 10

A mode of natural selection that favors extreme phenotypes at both ends of the range of phenotypic variation. Increases overall genetic variation in a population. Compare with stabilizing selection and directional selection.

Question 11

Balancing Selection

Answer 11

A mode of natural selection in which no single allele is favored over time and across locations, on average. An overall balance of fitness and frequency is maintained among alleles.

Question 12

Founder effect

Answer 12

A change in allele frequencies that often occurs when a new population is established from a small group of individuals (founder event) due to sampling error (that is, the small group is not a representative sample of the source population).

Question 13

Genetic bottleneck

Answer 13

A reduction in the diversity of alleles in a population resulting from a sudden decrease in the size of that population (population bottleneck) due to a random event

Question 14

Hardy-Weinberg Equilibrium

Answer 14

Allele frequencies will not change if there is:
1. No mutation
2. No gene flow (no immigration/emigration)
3. No genetic drift (large population size)
4. No natural selection
5. Random mating

Question 15

Gene pool equation

Answer 15

p + q = 1

Question 16

Offspring genotype equation

Answer 16

p^2 + 2pq + q^2 = 1

Question 17

Offspring allele equation

Answer 17

fr(A) = p^2 + pq
fr(a) = q^2 +pq

Question 18

H-W formula

Answer 18

1. Genotype frequencies
2. Calculate observed alleles frequencies fr(A) = p + ½(pq) and fr(a) = q +½(pq)
3. Calculate expected genotype frequencies f(AA)= p^2 from p value above, f(Aa)=2pq, f(aa)= q^2
4. Compare observed vs. Expected –> if supports H-W no evolution

Question 19

Genetic Isolation

Answer 19

Something causes a population to separate – remove gene flow

Question 20

Allopatric Speciation

Answer 20

live in different areas

Question 21

Sympatric Speciation

Answer 21

live in different areas

Question 22

Genetic divergence

Answer 22

Mechanisms of change lead to
genetic and phenotypic differences.

Question 23

Biological Species concept

Answer 23

The definition of a species as a population or group of populations that are reproductively isolated from other groups. Members of a species have the potential to interbreed in nature to produce viable, fertile offspring but cannot interbreed successfully with members of other species.

Question 24

Morphological Species concept

Answer 24

The definition of a species as a population or group of populations that have measurably different anatomical features from other groups.

Question 25

Phylogenetic Species concept

Answer 25

The definition of a species as the smallest monophyletic group in a phylogenetic tree.

Question 26

Hybridization

Answer 26

Mix between two things

Question 27

Clade/lineage

Answer 27

An evolutionary unit that includes an ancestral population and all of its descendants but no others

Question 28

Phylogenetic tree

Answer 28

A branching diagram that depicts the evolutionary relationships among species or other taxa

Question 29

Nodes

Answer 29

In a phylogenetic tree, the point where two branches diverge, representing the point in time when an ancestral group split into two or more descendant groups; also called fork.

Question 30

Outgroup

Answer 30

Any taxon that is not part of the taxonomic group being studied; researchers often select one or more outgroups that are closely related to the ingroup to help root phylogenetic trees and to determine the direction of character changes

Question 31

Ancestral Trait

Answer 31

A trait found in the ancestors of a particular group.

Question 32

Derived Trait

Answer 32

A trait that is a modified form of an ancestral trait, found in a descendant

Question 33

Monophyletic Group

Answer 33

An evolutionary unit that includes an ancestral population and all of its descendants but no others. Also called a clade or lineage

Question 34

Homology

Answer 34

Similarity among organisms of different species due to shared ancestry. Features that exhibit such similarity (e.g., DNA sequences, proteins, body parts) are said to be homologous.

Question 35

Homoplasy

Answer 35

Similarity among organisms of different species due to reasons other than common ancestry, such as convergent evolution

Question 36

Synamorphies

Answer 36

A shared, derived trait found in two or more taxa that is present in their most recent common ancestor but is missing in more distant ancestors. Useful for inferring evolutionary relationships

Question 37

Parsimony

Answer 37

The principle that the most likely explanation of a phenomenon is the most economical or simplest. When applied to comparison of alternative phylogenetic trees, it suggests that the one requiring the fewest character changes is most likely.

Question 38

Convergent Evolution

Answer 38

The independent evolution of similar traits in different species due to adaptation to similar environmental conditions and a similar way of life.

Question 39

Cuticle

Answer 39

A protective coating secreted by the outermost layer of cells of an animal or a plant; often functions to reduce evaporative water loss.

Question 40

Stomata

Answer 40

Generally, a pore or opening. In plants, a microscopic pore on the surface of a leaf or stem through which gas exchange occurs; typically surrounded by specialized cells that open the pore.

Question 41

Vascular tissue

Answer 41

In plants, tissue that transports water, nutrients, and sugars. Made up of the complex tissues xylem and phloem, each of which contains several cell types

Question 42

Embryophyte

Answer 42

A plant that nourishes its embryos inside its own body. All land plants are embryophytes.

Question 43

Gametangia

Answer 43

(1) The gamete-forming structure found in all land plants except angiosperms. Contains a sperm-producing antheridium and an egg-producing archegonium. (2) The gamete-forming structure of some chytrid fungi.

Question 44

Spores

Answer 44

In eukaryotes, a single haploid cell produced by meiosis; it is distinct from a gamete, however, in being able to grow into a multicellular, haploid organism through mitotic divisions directly (no fertilization required).

Question 45

Pollen

Answer 45

a fine powdery substance, typically yellow, consisting of microscopic grains discharged from the male part of a flower or from a male cone. Each grain contains a male gamete that can fertilize the female ovule, to which pollen is transported by the wind, insects, or other animals.

Question 46

Seeds

Answer 46

A plant reproductive structure consisting of an embryo, associated nutritive tissue (endosperm), and an outer protective layer (seed coat). In angiosperms, develops from the fertilized ovule of a flower

Question 47

Flowers

Answer 47

seed-bearing part of a plant, consisting of reproductive organs (stamens and carpels) that are typically surrounded by a brightly colored corolla (petals) and a green calyx (sepals)

Question 48

Fruit

Answer 48

In flowering plants (angiosperms), a mature, ripened plant ovary (or group of ovaries), along with the seeds it contains and any adjacent fused parts; often functions in seed dispersal. See aggregate fruit, multiple fruit, and simple fruit.

Question 49

Green Algae

Answer 49

A paraphyletic group of photosynthetic organisms that contain chloroplasts similar to those in land plants. Often classified as protists, green algae are the closest living relatives of land plants and form a monophyletic group with them

Question 50

Non-Vascular plants

Answer 50

Non-vascular plants are plants without a vascular system consisting of xylem and phloem. Instead, they may possess simpler tissues that have specialized functions for the internal transport of water.

Question 51

Seedless vascular plants

Answer 51

Seedless vascular plants are ancient land plants that have tubes to transport water and nutrients, but no seeds or flowers to reproduce (rely on spores)

Question 52

Gymnosperms

Answer 52

A vascular plant that makes seeds but does not produce flowers. The gymnosperms include five lineages of green plants (cycads, ginkgoes, redwoods, pines, and gnetophytes). Compare with angiosperm.

Question 53

Angiosperms

Answer 53

A flowering vascular plant that produces seeds within mature ovaries (fruits). The angiosperms form a single lineage