IB HL BIO YR 2 UNIT ONE-B

evolution

change in the heritable characteristics of a population over time

lamark’s theory

organisms acquire traits during lives and pass them down

darwin’s theory

variation exists in a population

nature selects individuals with traits best for survival/reproduction

favorable traits are passed down

theory

explanation of an aspect of the natural world which has been repeatedly tested through observation and experimentation

biomolecules

same genes are present in organisms with common ancestor

differences in base sequences of DNA (and therefore RNA & proteins) are due to mutations

closely related species share more genes

selective breeding

process of humans choosing plants/animals with desirable traits to breed and produce more offspring that also have those traits

ex: wolf→dog→dog breeds, brassica oleracea → cabbage, kale, brussel sprouts, etc

homologous structures

strongly suggest common ancestor

similar in structure but different function

ex: pentadactyl limbs

convergent evolution

evolution of similar structures in species that aren’t related

analogous structures

common function

no common structure/ancestor

ex: wings of birds/bats/insects

speciation

formation of new species through evolution

pre-existing species evolve into different species over time

increase total number of species

Population

a group of individuals of the same species living and interbreeding within a given area in a given time

Species

a group of organisms that can reproduce naturally with one another and create fertile offspring

Extinction

no living members of a species are remaining, decreases total number of species

Reproductive Isolation

the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences

Geographical Isolation

two populations of the same species are prevented from reproducing because of geographical features (rivers, roads, mountains, etc)

Behavioral Isolation

individuals are reproductively isolated due to behavior (mating calls, etc) can lead to sympatric speciation, ex

Temporal Isolation

organisms reproduce at different times, ex

Sympatric Speciation

population divides into different species within the same habitat, due to behavioral/temporal isolation

Allopatric Speciation

population divides into different species within different habitats, due to geographical isolation

Adaptive Radiation

evolution of 1 species into many species, results in divergent evolution, increases biodiversity

Divergent Evolution

species sharing a common ancestry become more distinct due to differential selection pressure which gradually leads to speciation over an evolutionary time period

Hybridization

the process of combining two different parent species to create an offspring that is genetically similar to both parent organisms

Hybrid

offspring of 2 different species, usually sterile (if survives), not considered a species, ex

Prezygotic Barriers

barriers that prevent formation of zygote, ex

Postzygotic Barriers

barriers that are present after formation of zygote, ex

Sterile

unable to produce offspring

Hybrid Inviability

hybrid does not survive past the embryonic stages

Hybrid Infertility

hybrid is not fertile

Hybrid Breakdown

something that happens to the offspring of hybrids rather than to hybrids themselves, over time the hybrids are invisible, infertile, etc

Polyploidy

more than two sets of chromosomes, results from nondisjunction in meiosis

Triploid

diploid gamete fertilized by haploid gamete

Tetraploid

diploid gamete fertilized by diploid gamete

Taxonomy

the classification of living and extinct organisms

Morphology

the study of the size, appearances, and internal relationships of animals, plants, and microbes

Binomial Nomenclature

way to name species, Genus species, ex

Diploid

the presence of two complete sets of chromosomes in an organism's cells

Karyogram

diagram/photo of chromosomes found in a cell

Karyotype

number and type of chromosomes found in a cell, humans have 22 autosomes and 2 sex chromosomes

Genome Sequencing

used to determine the entire genetic makeup of a specific organism or cell type

Genomics

the study of the complete set of DNA an organism

Autosome

any chromosome not considered a sex chromosome

Sex Chromosome

type of chromosome involved in sex determination, X and Y

Telomere

a region of repetitive DNA sequences at the end of a chromosome

Homologous Chromosomes

pairs of chromosomes in a diploid organism that have the same genes (can be different alleles), gene placement, length, and centromere placement

Genome

all genetic information of an organism, provides all information for cell/organism growth and development, human genome = 23 chromosome pairs in nucleus and 1 in mitochondria

Polymorphism

existence of multiple forms of a trait/characteristic within a species, caused by single-nucleotide base substitution mutations

Genome Size

total amount of DNA in a cell, measured by nitrogen base pairs

Asexual Reproduction

a mode of reproduction in which a new offspring is produced by a single parent, offspring are genetically and physically identical to each other and parent

Dichotomous Key

an important scientific tool, used to identify different organisms, based the organism's observable traits

DNA barcodes

a method of species identification using a short section of DNA from a specific gene or genes

Biodiversity

variety of living organisms including plants, animal, and microorganisms

Paradigm

a standard, perspective, or set of ideas

Paradigm Shift

scientific revolutions, changes in scientific beliefs

Mutation

errors in copying the genetic information during DNA replication, results in alleles or other forms of a gene, most are neutral, can be harmful or beneficial

Sexual Reproduction

two parents, union of specialized gametes, one from each parent, offspring are similar but not genetically identical to parents or each other, very expensive in terms of time and energy, fusion of two haploid gametes to form a diploid zygote

Variation

the differences between individuals of the same species

caused by genetic and environmental factors

Genetic Variation

the difference in DNA among individuals

the genetic differences between populations among the same species

Allele

different forms of a gene

Gene

The basic unit of heredity passed from parent to child

Meiosis

type of nuclear division, produces four haploid genetically unique daughter nuclei, forms gametes for sexual reproduction, diploid -> haploid, reduction division, dna replication must occur prior to

Crossing Over

exchange of equivalent segments of DNA between non-sister chromatids, results in sister chromatids that aren't genetically identical

Independent Assortment

thee random orientation of homologous chromosome pairs during metaphase I, allows for the production of gametes with many different assortments of homologous chromosome

Gamete

a reproductive cell of an animal or plant

Carrying Capacity

the maximum population size that a given environment can sustain over a certain period of time, influenced by availability of resources, is dynamic (varies over time)

Biotic Factors

any living thing that has an effect on an ecosystem

Abiotic Factors

any non-living thing that has an effect on an ecosystem

Selection Pressure

factor that leads to differential survival or reproduction, causes a change in genetic composition of a population

Phenotype

an individual's observable traits, such as height, eye color and blood type

Genotype

the genetic makeup of an organism

Density Independent Factors

impact on population size regardless of density, ex

Intraspecific Competition

occurs when members of a species compete for limited resources

can lead to adaptations of individuals, displacement of less competitive individuals, and/or regulation of population size

Sexual Selection

focus is on finding a mate and reproducing

Asexual Reproduction

involves one parent and multiple offspring

seen in bacteria, fungi, many plants, and some animals

different ways to do this

Horizontal Gene Transfer

the movement of genetic information between organisms that aren't parent and offspring

Dichotomous Key

aids in identification of organisms, composed of binomial questions based on physical characteristics

DNA barcodes

a taxonomic method that uses a short genetic marker in an organism's DNA to identify at the species level

Gene Pool

sum total of all the alleles of all the genes present in a population

indicator of the genetic variation that exists in a population

Reproductive Isolation

all barriers that prevent populations of the same species from interbreeding and/or producing fertile offspring

Neo-Darwinism

phenotype is largely a product of the genotype

natural selection increases frequency of beneficial alleles

genetic drift and gene flow can also bring changes in gene frequency of populations

Stabilizing Selection

favors average individuals with intermediate forms of the trait and eliminates the extremes

results in loss of genetic diversity

Directional Selection

favors one extreme form of the trait over all the other forms

most seen when environment changes

Disruptive Selection

both extreme forms of the trait are favored over the intermediate forms

Hardy-Weinberg Equation

p2+2pq+q2=1

Hardy-Weinberg Principle

in a stable population, frequency of alleles would remain constant generation after generation

conditions: No mutations, Random mating, No natural selection, No genes should enter or leave population, Large population

Artificial Selection

similar to natural selection

perpetuated by humans

humans select organisms with desirable traits

Selective Breeding

choosing parents with particular characteristics to breed together and produce offspring with more desirable characteristics

Ecological Niche

the position of a species within an ecosystem, both the range of conditions necessary for survival and ecological role

Biotic

Consisting of living organisms

Abiotic

Consisting of non-living organisms

Obligate Anaerobes

cant survive in presence of oxygen, live in oxygen free environments (ex: waterlogged soils), carry out anaerobic respiration

Facultative Anaerobes

can survive with or without oxygen

carry out anaerobic respiration in absence of oxygen and aerobic respiration in presence of oxygen

Obligate Aerobes

cant survive without oxygen

carry out aerobic respiration

Photosynthesis

the process by which plants and some other organisms use sunlight to synthesize foods from carbon dioxide and water

Prokaryote

organisms whose cells lack a nucleus and other organelles

Autotrophic Nutrition

a mode of nutrition in which organisms produce their own food

ex: photosynthesis, chemosynthesis, etc

Archaea

single-celled microorganisms with structure similar to bacteria

found in wide variety of environments

all produce ATP

Phototrophs

organisms that produce their own food through taking in sunlight

Chemolithotrophs

an organism that is able to use inorganic reduced compounds as a source of energy

live in hydrothermal vents

Organotrophs

organisms that obtain energy from organic compounds

ex: animals

Omnivore

an organism that eats plants and animals