Chapter 11: The Evolution of Life on Earth Flashcards Preview

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Flashcards in Chapter 11: The Evolution of Life on Earth Deck (78):
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systematics

the study of the diversity of life forms which categorizes species based on phylogenetic relationships determined by concepts such as evolutionary history, genetics, and anatomy

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taxonomy

a branch of systematics that creates a classification scheme for organisms

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Carl Linnaeus

the inventor of the Binomial Nomenclature system

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clade

an evolutionary branch in a phylogenetic tree, which represents a divergence between species

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cladogram/phylogenetic tree

a graphic representation of the evolutionary relationship between characteristics organisms

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phenetics

the data-driven field of systematics

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cladistics

the phylogenetic approach to systematics

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phylogeny

the evolutionary history of a species or a group of related species

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homologies

equivalent structures resulting from a shared ancestry

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general homology

a trait shared by all organisms in question

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special homology

a trait shared by some organisms in question

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homoplasy

the occurrence of homoplastic/analogous structures which perform similar functions, but do not share a recent common ancestry

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derived traits

traits which only occur in descendants, not in the ancestor

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outgroup

a species or group of species that are more closely related to each other than to other species in their clade

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homeotic genes

master controls genes for other genes (ex: genes which determine segmental growth)

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domain

the highest-level taxonomic category, superior to kingdom. It was proposed by Woese, Kandler, and Wheelis in 1990 in order to reflect the relationships of organisms suggested by molecular data

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photoautotrophic

an organism that extracts energy from light to fix the carbon from carbon dioxide

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photoheterotrophic

an organism that extracts energy from light but must rely on other organisms as a source of carbon

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obligate anaerobes

anaerobes which cannot switch between aerobic and anaerobic

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nitrogen fixation

the process of splitting molecular nitrogen and making it biologically available as ammonia (NH3)

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enteric

pertaining to the gut

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peptidoglycan

a lipopolysaccharide found in the cell wall of Bacteria

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protists

a generic word describing single-celled eukaryotes

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mixotroph

an organism that can act as both a heterotroph and autotroph

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dessication

drying out

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coevolution

how the evolution of one species affects the evolution of another, and vice versa

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xylem and phloem

vascular tissues involved in conducting water and nutrients

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spore

a single, haploid (n) cell that can give rise to an entire organism

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seed

a plant embryo enclosed in a protective coat

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tracheophytes

vascular plants

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sori

structures on the underside of fern leaves that contain sporangia

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hermaphroditic

having both male and female sexual structures

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homosporous

having one type of spore that develops into a bisexual gametophyte (hint: ferns)

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heterosporous

having two types of spores that give rise separately to male and female gametophytes (hint: seed plants)

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dioecious

having male and female reproductive structures on separate plants

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monoecious

having both male and female reproductive structures on the same plant

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fruit

plant structures that contain seeds

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cotyledons

the seeds leaves of an angiosperm embryo

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meristem

the region of plant tissue where cells are dividing allowing for the plant to grow

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fungi

generally multicellular heterotrophs that absorb nutrients using extracellular digestion

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colonial

a group of cells that are physically adjoining, but not dependent on each other

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divergent evolution

the division of an ancestral group into two or more lineages that share homologous structures or patterns of development

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cephalization

the aggregation of sensory organs at one end of an organism; the development of a head

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germ layers

concentric layers of undifferentiated cells in an embryo which will give rise to the various tissues and organs of the body

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coelom

a body cavity

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cleavage

a rapid series of mitotic divisions that creates a solid ball of cells called the morula. By the end of this process, the morula has transformed into a blastula, a hollow ball of cells.

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totipotency

the ability for each cell of an embryo to have the potential to form all parts of an organism

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amplexus

a type of controlled, external fertilization where the male fertilizes a specific female's eggs

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amniotic egg

a type of egg that has a hard outer shell and inner membranes which allow for respiration while preventing water loss

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monophyletic

having one common ancestor

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diploblastic

having two cell layers

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sessile

resting on the bottom

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alternation of generations

the alternation of haploid and diploid stages in the life cycle of sexual organisms

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acoelomate

an animal which lacks a cavity between the outer body wall and the gut

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pseudocoelomate

an organism with a body cavity derived from endoderm on one side and mesoderm on the other

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schizocoelous

the formation of the coelom from the splitting of the mesoderm

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blastopore

the opening of the archenteron in the gastrula

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enterocoelous

development in which the coelom is formed from gut tissue

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zooplankton

the community of small animals suspended in the water column of marine and freshwater habitats

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notochord

a) a cartilaginous structure that establishes a dorsal axis in a developing embryo and may later take part in the formation of the vertebrae
b) a flexible rod running the length of the body in the embryos of all chordates

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axial skeleton

skeletal features of the head, neck, and trunk

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appendicular skeleton

skeletal features of the appendages

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superclass

an informal taxonomic division above the level of class and below the level of the phylum

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polyspermy

the fertilization of an egg by more than one sperm

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depolarization

an electrical charge which occurs when the inside of a cell is made less negative than the outside of the cell compared to its resting membrane potential

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zygote

a fertilized egg that is diploid

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blastocoel

the cavity inside of the blastula

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gastrula

the three-layered structure that results after the blastula undergoes gastrulation

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model organism

an organism that is intensively studied by many researchers asking many different questions and that is chosen to provide information that can direct research in other less-studied species

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maternal cytoplasmic factors

molecules of mRNA or protein in an egg that are the products of the mother's genome, are distributed to the egg's cytoplasm by follicle cells, and direct traits expressed in the offspring

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F1

first filial generation, the progeny of a cross between two parents

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F2

F2: second filial generation, the progeny of the cross between F1 offspring

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maternal-effect gene

a gene whose phenotype is expressed in offspring of the mother possessing it, through provisioning of the egg cytoplasm with maternal mRNA or protein

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morphogen

a diffusable substance that by its concentration gradient will determine the pattern of development in an organism

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gap genes

genes that are responsible for gross subdivision of the embryo, or groups of adjacent segments in the developing embryo

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pair-rule genes

genes that are responsible for whole sets of alternate segments

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segment-polarity genes

genes that control the anterior-posterior polarity of every segment

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homeotic genes

genes whose mutations cause one part of a body to develop as if it were in another part of the body