Biology Intro Unit

Theory

- well-tested explanation that unifies a broad range of observations
- broader than hypothesis

Prokaryote

unicellular organism that lacks a nucleus
- smaller than eukaryotes

eukaryote

organism whose cells contain a nucleus

emergent properties

due to the arrangement and interactions of parts as complexity increases

symbiotic relationships

The relationship between two species that live in close association with each other
- predation, parasitism, herbivory, commensalism, mutualism, competition

commensalism

A relationship between two organisms in which one organism benefits and the other is unaffected

mutualism

A relationship between two species in which both species benefit

parasitism

A relationship between two organisms of different species where one benefits and lives on the host while the other is harmed

competition

the struggle between organisms to survive in a habitat with limited resources

fitness

how well an organism can survive and reproduce in its environment

phenotypic variations

differences in the physiology, anatomy, or behavior of different species or individuals of the same species (physical features)

evidence for evolution

1. Drug resistant pathogens
2. Homology
3. Fossil Record
4. Biogeography

homology

similarity resulting from common ancestry
- Morphological: common physical attributes due to convergent evolution
- Molecular: two organisms share many portions of nucleic acids sequence (molecular homoplasies)

phylogenetic trees/cladograms

represents the history of species divergence

binomial nomenclature (taxonomy)

First: genus -- Second: Species name Ex: Homo Sapiens

convergent evolution

Process by which unrelated organisms independently evolve similarities when adapting to similar environments

molecular homoplasies

in organisms that do not appear to be closely related, the bases that their otherwise very different sequences happen to share may simply be coincidental matches

shared derived character

An evolutionary novelty that is unique to a clade.

maximum parsimony

one should first investigate the simplest explanation that is consistent with the facts.

Molecular clocks

A method for estimating the time required for a given amount of evolutionary change
- based on the observation that some regions of genomes evolve at constant rates.
Unreliable:
- natural selection causes bursts of genome change
- after the fossil record we have nothing to go off of

descent with modification

each living species has descended, with changes, from other species over time

natural selection

A process in which individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits.
Ex: drug-resistant bacteria

vestigial structures

remnants of features that served important functions in the organism's ancestors

analogous structures

Body parts that share a common function, but not structure

homologous features

features with similar structures but (maybe) different functions

biogeography

study of the distribution of organisms around the world

taxonomy

The scientific study of how living things are classified

• domain -> kingdom -> phylum -> class -> order -> family -> genus -> species

basal taxon

a lineage that diverges early in the history of a group

analogy

similarity between organisms due to convergent evolution

taxon

a group of organisms in a classification system

phylogenetic trees represent a \___

hypothesis

clade

A group of species that includes an ancestral species and all its descendants.

monophyletic group

group that consists of a single ancestral species and all its descendants

paraphyletic group

composed of some but not all members descending from a common ancestor

polyphyletic group

an unnatural group that does not include the most recent common ancestor

Three Domains

Bacteria, Archaea, Eukarya

horizontal gene transfer

transfer of genes between cells of the same generation

mutation

random change in an organisms genome

dependent variable

The measurable effect, outcome, or response in which the research is interested. (pillbugs in each chamber)

independent variable

The experimental factor that is manipulated; the variable whose effect is being studied (time)

species

A group of similar organisms that can breed and produce fertile offspring.
- Reproductive Isolation

adaptive radiation

Evolution of many new species from a common ancestor as a result of introduction to new environments. (quickly)

Biology Themes

1. New properties emerge at successive levels of biological organization
2. Life's process involves the expression and transmission of genetic info
3. Life requires the transfer and transformation of energy and matter
4. Organisms interact with other organisms and the physical environment

genetic variation

The variety of different types of genes (DNA) in a species or population.

Consumer levels

Tertiary consumers (ex: humans and orcas) --\> Secondary consumers (eat primary consumers) --\> Primary consumers (ex: worms) --\> Producers (ex: plants)