IB Bio SL Y1 Unit 2

variation

differences within a species

sexual reproduction

leads to more variation

asexual reproduction

leads to less variation

morphological species concept

defines a species as a group that shares physical characteristics

ignores reproductive isolation

biological species concept

defines a species as having the ability to interbreed and produce fertile and viable offspring

doesn’t apply to asexual organisms

ex: mules

bacterial conjugation

allows for inter-species breeding

binomial nomenclature

genus name, species name

genome

all of the genes in an organism

single nucleotide polymorphisms (SNPs)

the replacement of one nucleotide with another

creates variation within a species

haploid

1 copy of each chromosome

diploid

two copies of each chromosome

chromosome fusion

chromosome 12 and 13 from chimpanzees fused to make chromosome 2 in humans

karyogram

number, size, and shape of chromosomes (karyotype)

aneuploidy

abnormal number of chromosomes

monosomy

only 1 copy of a specific chromosome

trisomy

having 3 copies of a specific chromosome

trisomy 21

three copies of chromosome 21

down syndrome

homologous chromosomes

matched pairs of chromosomes

autosomes

chromosomes that aren’t sex chromosomes

locus/loci

the location of a gene/chromosome

alleles

genes

dichotomous key

used to identify unknown organisms or objects by observing their characteristics

taxonomy

naming, classifying, and describing organisms based on shared characteristics

carl woese

defined the archaea domain through the taxonomy of 60S ribosomal dna

kingdom eubacteria

bacteria domain, prokaryotic, unicellular, rigid cell wall with peptidoglycan, autotroph, asexual, can move, lives everywhere

autotroph

creates its own food

kingdom archaebacteria

domain archaea, prokaryotic, unicellular, rigid cell wall without peptidoglycan, chemautotroph, asexual, some mobile with flagellum, survives in extreme habitats

chemautotroph

creates food from organic compounds

kingdom animalia

domain eukarya, eukaryotic, multicellular, no cell wall, heterotroph, sexual, can move, terrestrial and aquatic

heterotroph

creates food from other organisms

kingdom plantae

domain eukarya, eukaryotic, multicellular, cell wall made of cellulose, autotrophic, asexual and sexual, cannot move, terrestrial or aquatic

kingdom fungi

domain eukarya, eukaryotic, multicellular, cell wall made of chitin, heterotrophic, sexual and asexual, can’t move, terrestrial or aquatic

kingdom protista

domain eukarya, eukaryotic, unicellular or multicellular, some cell wall, autotrophic or heterotrophic, sexual and asexual, aquatic

cladogram

a way to represent the evolutionary relationship between species based on shared traits and/or genetic evidence

clade

a group of species with a single common ancestor and a set of common traits

node

root

common ancestor shared by whole cladogram

outgroup

most distantly related species in the cladogram

figwort family

recently reclassified using cladistics

evolution

change in the heritable characteristics of a population over time

mechanisms of evolution

natural selection, gene flow, genetic drift, mutation

natural selection

organisms with successful selections will survive

sexual selection

direct competition in attracting a mate

gene flow

when organisms from one area move to another

genetic drift

change in gene frequencies due to chance

bottleneck effect

when an event drastically reduces the size of a population, leading to less genetic diversity

founder effect

when a new population is created by a small number of individuals, leading to less genetic diversity

mutation

any changes in the gene frequencies of an organism

often caused by mistakes in DNA copying

evidence of evolution

molecular data, selective breeding, comparative anatomy, embryology, biogeography, and fossil record

molecular data

analyzing dna and amino acid sequences

molecular clock

molecular clock

an estimation of the length of time since speciation occurred

comparative anatomy

homologous structures, analogous structures, and vestigial structures

homologous structures

structures inherited from a single common ancestor

analogous structures

structures that have similar functions but are not related

vestigial structures

structures that have lost their original purpose

embryology

studying organisms from the start of fertilization

biogeography

the branch of biology that deals with the geographical distribution of plants and animals.

convergent evolution

when different species independently evolve similar traits due to similar environments

divergent evolution

when organisms that share a common ancestor develop different traits due to different environments

adaptive radiation

rapid diversification of a single ancestral species due to environment

fossil record

the totality of all fossils collected and arranged in chronological order, forming a historical account of life on Earth

law of superposition

the oldest layers of sedimentary rock are at the bottom

radiometric dating

how scientists determine the age of rocks and fossils

transitional fossils

show intermediate traits between an ancestral form and its descendants

speciation

the process by which two species split creating a new species

allopatric speciation

speciation that occurs in different location

sympatric speciation

speciation that occurs in the same location

process of speciation

one species becomes reproductively isolated from the other, then the two populations become different species

prezygotic barrier

obstacle to mating/fertilization

geographic isolation

physical barrier separating populations

the congo river

chimpanzees and bonobos got separated, becoming two different species

temporal isolation

different mating seasons/times/days

behavioral isolation

different mating behaviors

mechanical isolation

different structures

postzygotic barrier

prevents offspring from developing properly

reduced hybrid fertility

hybrids aren’t fertile

reduced hybrid viability

hybrids aren’t viable

hybrid breakdown

the first generation of hybrids are fertile, but subsequence generations are sterile

gradualism

gradual speciation

punctuated equilibrium

sudden/quick speciationx

polyploidy

more than 2 copies of each chromosome

lamarck’s theory of evolution

acquired traits are passed down to your offspring

darwin’s theory of evolution

natural selection

elements of natural selection

mutation/variation, competition, fitness, and adaptation

competition

organisms fight for mates/resources

fitness

a measure of reproductive success

survival of the fittest

only those with favorable traits will survive

adaptation as a process

over time, populations change so there is a higher percentage of organisms with favorable traits

adaptation as a characteristic

any variation that helps an organism survive

structural adaptation

variations in the body of an organism

behavioral adaptation

variations in the behavior of an organism

physiological adaptation

variations in the metabolic processes of an organism

selective pressures

choose what traits are beneficial/detrimental

stipulations of natural selection

individuals don’t evolve, populations do
only works on traits where variation exists

must be studied in context

relies on differential reproductive success

birds of paradise

bright feathers to attract a mate (sexual selection)

gene pool

all of the genes within a species

neo-darwinism

evolution occurs gradually due to natural selection and genetic variation

directional selection

one extreme is favored over the other

disruptive selection

both extremes are favored

stabilizing selection

the middle is favored over both extremes