Chapter 11: The Evolution of Life on Earth Flashcards
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
taxonomy
a branch of systematics that creates a classification scheme for organisms
Carl Linnaeus
the inventor of the Binomial Nomenclature system
clade
an evolutionary branch in a phylogenetic tree, which represents a divergence between species
cladogram/phylogenetic tree
a graphic representation of the evolutionary relationship between characteristics organisms
phenetics
the data-driven field of systematics
cladistics
the phylogenetic approach to systematics
phylogeny
the evolutionary history of a species or a group of related species
homologies
equivalent structures resulting from a shared ancestry
general homology
a trait shared by all organisms in question
special homology
a trait shared by some organisms in question
homoplasy
the occurrence of homoplastic/analogous structures which perform similar functions, but do not share a recent common ancestry
derived traits
traits which only occur in descendants, not in the ancestor
outgroup
a species or group of species that are more closely related to each other than to other species in their clade
homeotic genes
master controls genes for other genes (ex: genes which determine segmental growth)
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
photoautotrophic
an organism that extracts energy from light to fix the carbon from carbon dioxide
photoheterotrophic
an organism that extracts energy from light but must rely on other organisms as a source of carbon
obligate anaerobes
anaerobes which cannot switch between aerobic and anaerobic
nitrogen fixation
the process of splitting molecular nitrogen and making it biologically available as ammonia (NH3)
enteric
pertaining to the gut
peptidoglycan
a lipopolysaccharide found in the cell wall of Bacteria
protists
a generic word describing single-celled eukaryotes
mixotroph
an organism that can act as both a heterotroph and autotroph
dessication
drying out
coevolution
how the evolution of one species affects the evolution of another, and vice versa
xylem and phloem
vascular tissues involved in conducting water and nutrients
spore
a single, haploid (n) cell that can give rise to an entire organism
seed
a plant embryo enclosed in a protective coat
tracheophytes
vascular plants
sori
structures on the underside of fern leaves that contain sporangia
hermaphroditic
having both male and female sexual structures
homosporous
having one type of spore that develops into a bisexual gametophyte (hint: ferns)
heterosporous
having two types of spores that give rise separately to male and female gametophytes (hint: seed plants)
dioecious
having male and female reproductive structures on separate plants
monoecious
having both male and female reproductive structures on the same plant
fruit
plant structures that contain seeds
cotyledons
the seeds leaves of an angiosperm embryo
meristem
the region of plant tissue where cells are dividing allowing for the plant to grow
fungi
generally multicellular heterotrophs that absorb nutrients using extracellular digestion
colonial
a group of cells that are physically adjoining, but not dependent on each other
divergent evolution
the division of an ancestral group into two or more lineages that share homologous structures or patterns of development
cephalization
the aggregation of sensory organs at one end of an organism; the development of a head
germ layers
concentric layers of undifferentiated cells in an embryo which will give rise to the various tissues and organs of the body
coelom
a body cavity
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.
totipotency
the ability for each cell of an embryo to have the potential to form all parts of an organism
amplexus
a type of controlled, external fertilization where the male fertilizes a specific female’s eggs
amniotic egg
a type of egg that has a hard outer shell and inner membranes which allow for respiration while preventing water loss
monophyletic
having one common ancestor
diploblastic
having two cell layers
sessile
resting on the bottom
alternation of generations
the alternation of haploid and diploid stages in the life cycle of sexual organisms
acoelomate
an animal which lacks a cavity between the outer body wall and the gut
pseudocoelomate
an organism with a body cavity derived from endoderm on one side and mesoderm on the other
schizocoelous
the formation of the coelom from the splitting of the mesoderm
blastopore
the opening of the archenteron in the gastrula
enterocoelous
development in which the coelom is formed from gut tissue
zooplankton
the community of small animals suspended in the water column of marine and freshwater habitats
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
axial skeleton
skeletal features of the head, neck, and trunk
appendicular skeleton
skeletal features of the appendages
superclass
an informal taxonomic division above the level of class and below the level of the phylum
polyspermy
the fertilization of an egg by more than one sperm
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
zygote
a fertilized egg that is diploid
blastocoel
the cavity inside of the blastula
gastrula
the three-layered structure that results after the blastula undergoes gastrulation
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
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
F1
first filial generation, the progeny of a cross between two parents
F2
F2: second filial generation, the progeny of the cross between F1 offspring
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
morphogen
a diffusable substance that by its concentration gradient will determine the pattern of development in an organism
gap genes
genes that are responsible for gross subdivision of the embryo, or groups of adjacent segments in the developing embryo
pair-rule genes
genes that are responsible for whole sets of alternate segments
segment-polarity genes
genes that control the anterior-posterior polarity of every segment
homeotic genes
genes whose mutations cause one part of a body to develop as if it were in another part of the body
