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Living Earth Semester 2 > Unit 7 > Flashcards

Unit 7 Flashcards

1
Q

What is Evolution?

A

a process by which modern organisms have descended from ancient organisms

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2
Q

What is a theory?

A

a well-supported testable explanation of phenomena occurring in the natural world

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3
Q

What are fossils?

A

the preserved remains of ancient organisms

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4
Q

What is artificial selection?

A

the process by which humans select the desired variation and breed together the best possible combination in order to produce it

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5
Q

What is the struggle for existence?

A

a process by which members of each species compete regularly to obtain food, living space, and other necessities of life

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6
Q

What is fitness?

A

the ability of an individual to survive and reproduce in its specific environment

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7
Q

What is Adaptation?

A

any inherited characteristic that increases an organism’s chance of survival (physiological processes, functions, or even behavior)

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8
Q

What is Survival of the Fittest?

A

the idea that individuals with characteristics that are not well suited to their environment will die or leave few offspring, whilst the better adapted ones will survive and reproduce the most successfully

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9
Q

What is Natural Selection?

A

the process by which favorable traits become more common and unfavorable traits fade out

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10
Q

What is Descent with Modification?

A

The idea that over a long periods of time, natural selection produces different structures, establishes niches, and abilities to occupy different habitats, resulting in descendents looking different from ancestors (therefore being modified with descent)

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11
Q

What is Common Descent?

A

The principle that states that all species were derived from common ancestors

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12
Q

What are Homologous structures?

A

structures that have different mature forms but develop from the same embryonic tissues

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13
Q

What are Vestigial Organs?

A

organs that do not affect an organisms’ ability to survive and reproduce (natural selection does not eliminate or increase their likelihood of appearance) (ex. Wisdom teeth, coccyx, or appendix in humans)

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14
Q

What is an Allele?

A

a version of a gene (ie blue eye allele vs brown eye allele)

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15
Q

What is a Population?

A

a group of individuals of the same species that interbreed

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16
Q

What is a Gene Pool?

A

a common group of genes including all the different genes and alleles that are present in a population

17
Q

What is Relative Frequency?

A

the relative frequency of an allele is the number of times other alleles for the same gene occur

18
Q

What is a Mutation?

A

a random change in a sequence of DNA

19
Q

What is a Single-Gene Trait?

A

a trait controlled by a single gene with two alleles (therefore there are only two possible phenotypes; ex. Presence of Widow’s peak/dimples)

20
Q

What is a Polygenic Trait?

A

a trait controlled by two or more genes (therefore resulting in a spectrum of genotypes and phenotypes; ex. height)

21
Q

What is Directional Selection?

A

one extreme is more fit than the other extreme or the center

22
Q

What is Stabilizing Selection?

A

the center is the most fit; both extremes are less fit

23
Q

What is Disruptive Selection?

A

both extremes are more favorable than the average

24
Q

What is Genetic Drift?

A

a random change in allele frequency (happens by chance)

25
Q

What is the Founder Effect?

A

a situation where allele frequencies change due to migration of a subgroup of a population (small group of individuals becomes isolated, reducing genetic variation in the main population and in extreme cases taking a step towards speciation)

26
Q

What is the Hardy-Weinberg Principle?

A

allele frequencies in a population will remain constant unless one or more factors cause those frequencies to change

27
Q

What is Genetic Equilibrium?

A

the situation in which allele frequencies remain constant

28
Q

What is Speciation?

A

formation of new species

29
Q

What is Reproductive Isolation?

A

the point at which members of two populations can no longer interbreed and produce viable, fertile offspring

30
Q

What is Behavioral Isolation?

A

when two populations are capable of interbreeding, but have different courtship behaviors or reproductive strategies (ex. song)

31
Q

What is Geographical Isolation?

A

when two populations are separated by geographic barriers and therefore genetic changes in one population no longer impacts the other population (does not guarantee new species if they can still interbreed)

32
Q

What is Temporal Isolation?

A

when two populations reproduce at different times of year even if they live in the same habitat

33
Q

What is Divergent Evolution?

A

the diversification of an ancestral group into two or more species

34
Q

What is Adaptive Radiation?

A

when divergent evolution involves the formation of a large number of species to occupy different niches

35
Q

What is Sequential Evolution?

A

the accumulation of genetic changes that over time result in a new species

36
Q

What is Punctuated Equilibrium?

A

species are stable for most of their existence and formation of a new species is rapid (the stimulus being environmental change)

37
Q

What is Phyletic Gradualism?

A

theory that populations diverge slowly by accumulating adaptive features in response to different selective pressures

38
Q

What are the conditions for genetic equilibrium?

A 
Random mating
Large population
No migration in or out of population
No mutation
No natural selection
39
Q

What is the pathway of speciation?

A

Population splits - gene flow is common - gene flow is rare (offspring die quickly) - separate species

Living Earth Semester 2 (6 decks)

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