Chapter 27 Terms Of _Inquiry Into Life_

Front 1

Evolution

Back 1

all the changes that have occurred in living things since the beginning of life

Front 2

Transitional links

Back 2

a fossil that shows an organism in the middle of evolution from one species to another

Front 3

Biogeography

Back 3

the study of the distribution of plants and animals throughout the world

Front 4

Homologous structures

Back 4

structures that are similar because they were inherited from a common ancestor

Front 5

Analogous structures

Back 5

Structures that are similar because they have been developed for adaptations, but are structurally unrelated

Front 6

Vestigial structures

Back 6

anatomical features that are fully developed in one group of organisms but reduced and maybe even nonfunctional in similar groups

Front 7

Protocell

Back 7

a structure that came before the cell which had a plasma membrane and organic molecules inside it

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RNA-first hypothesis

Back 8

suggests that only the macromolecule RNA was neededat this time to progress toward formation of the first cell or cells

Front 9

protein-first hypothesis

Back 9

states that amino acids in water formed into proteinoids, which formed into microspheres in water

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Proteinoids

Back 10

small polypeptides that have some catalytic properties

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Microspheres

Back 11

structures composed only of protein that have many of the properties of a cell

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Heterotroph

Back 12

an organism that takes in preformed food

Front 13

Autotrophs

Back 13

organisms that make their own food

Front 14

Liposomes

Back 14

droplets formed by phospholipid molecules

Front 15

Population

Back 15

all members of a single species occupying a particular area at the same time

Front 16

Gene pool

Back 16

the various alleles of all the gene loci in all the members

Front 17

Mutations

Back 17

the raw material for evolutionary change

Front 18

Genetic drift

Back 18

changes in the allele frequencies of a gene pool due to chance

Front 19

Founder effect

Back 19

when a few individuals found a colony, and only a fraction of the total genetic diversity is represented in these few individuals

Front 20

Bottleneck effect

Back 20

when a natural catastrophe occurs which wipes out the majority of the population, leaving only a few individuals with only a fraction of the genetic diversity of the gene pool's to survive and reproduce

Front 21

Gene flow

Back 21

the movement of alleles between populations

Front 22

Nonrandom mating

Back 22

when individuals pair up, not by chance, but according to their genotypes or phenotypes

Front 23

Natural selection

Back 23

the process by which populations become adapted to their environment

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Fitness

Back 24

the measurement of how many fertile offspring an individuals has had

Front 25

Stabilizing selection

Back 25

when an intermediate phenotype is favored

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Directional selection

Back 26

when an extreme phenotype is favored

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Disruptive selection

Back 27

when two or more extreme phenotypes are favored over any intermediate phenotype

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Species

Back 28

a group of interbreeding subpopulations that share a gene pool and are isolated reproductively from other species

Front 29

Premating isolating mechanisms

Back 29

when reproduction is never attempted because of a difference in phenotypes

Front 30

Postmating isolating mechanisms

Back 30

when reproduction may be attempted but is not successful

Front 31

Allopatric speciation

Back 31

when there is a geographic barrier which prevents two populations from interbreeding, resulting in reproductive isolation

Front 32

Sympatric speciation

Back 32

when one population divides into two reproductively isolated groups without the need for geographic isolation

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Adaptive radiation

Back 33

the proliferation of a species by adaptation to different ways of life

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Gradualism

Back 34

slow and steady evolutionary change

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Punctuated equilibrium

Back 35

sudden and quick speciation

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Phylogeny

Back 36

the evolutionary relationship among organisms

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Cladistics

Back 37

the arranging of species and higher classification categories into clades

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Clade

Back 38

a portion of a cladogram

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Cladogram

Back 39

a diagram that contains a common ancestor and all its descendant species - the common ancestor is presumed and not identified