Bio MCAS

acquired characteristics

a change in an organism during the lifetime of an individual due to use, disuse, or enviroinmenal effects. This type of characteristic is not inherited.

adaptation

inherited characteristic that increases an organism's chance of survival

allele frequency

how often a form of a gene appears in a gene pool

analogous structure

features of different species that are similar in function but not necessarily in structure and which do not derive from a common ancestral feature

cladogram

diagram that shows the evolutionary relationships among organisms based on derived characters; resembles a timeline

common ancestor

the most recent ancestor of a set of different organisms

common descent

principle that all living things have a common ancestor

comparative anatomy

the study of body structures of different species of animals in order to understand their differences and similarities

comparative embryology

the study of embryos of different species of animals in order to understand their relation to each other

convergent evolution

the process by which distantly related organisms independently evolve similar traits

directional selection

a type of natural selection in which the phenotype of the species tends toward one extreme rather the mean phenotype or the opposite extreme phenotype

disruptive selection

a type of natural selection in which extreme values for a trait are favored over intermediate values.

divergent evolution

pattern of evolution in which two species become more and more dissimilar, or "diverge" from each other

evolution

change over time; process by which modern organisms descended from ancient organisms

fitness

ability of an organism to survive and reproduce in its environment

fossil

preserved remains of an ancient organism

gene flow

the movement of genes into or out of a population

gene pool

combined genetic information of of all the members of a population

genetic diversity

the range of different inherited traits within a species. In a species with high genetic diversity, there would be many individuals with a wide variety of different traits.

genetic variation

the variation in the DNA sequence in each of our genomes.

geographical isolation

the physical separation of members of a population which can reduce gene flow

homologous structure

structures that have different mature forms but develop from the same embryonic tissues

natural selection

individuals that are better suited to their environment survive and reproduce most successfully; survival of the fittest

natural variation

differences among individuals of a species; results from mutation and sexual reproduction

phylogenetic tree

diagram showing evolutionary relationships of organisms with a common ancestor; resembles a tree

speciation

formation of a new species as a result of reproductive isolation

species

two organisms that are so similar they can interbreed in nature and produce fertile offspring

species

two organisms that are so similar they can interbreed in nature and produce fertile offspring

stabilizing selection

a type of natural selection in which intermediate (average) values for a trait are favored over others

struggle for existence

competition between organisms for food and space

survival of the fittest

individuals that are better suited to their environment survive and reproduce most successfully; natural selection

temporal isolation

type of reproductive isolation in which two organisms reproduce at different times

variation

a different or distinct form or version of something

vestigial organ

organ so reduced in size, it does not serve an important function; may be homologous to structures in other organisms

allele

one of two or more versions of DNA sequence (a single base or a segment of bases) at a given location on DNA strand

asexual reproduction

a type of reproduction that does not involve the combination of gametes. offspring are often unicellular organisms

codominance

a type of inheritance in which both alleles are simultaneously expressed.

codon

a sequence of three nucleotides which together form a unit of genetic code in a DNA or RNA molecule

crossing over

the exchange of DNA between pairs of chromosomes and occurs during meiosis. This allows for an increase of variation of traits.

diploid

a cell that contains two complete sets of chromosomes - one from each parent

dominant

When two copies of a gene are present a dominant allele will result in the that phenotype being expressed

gamete

a haploid cell that fuses with another haploid cell during fertilization - sperm or egg cells

genetics

the study of the inheritance of traits

genotype

the genetic makeup of an organism

haploid

a cell that contains one complete set of chromosomes - from one parent - or half the total amount of genetic material of a body cell.

heredity

the process of passing on genetic characteristics from one generation to another.

heterozygous

having two different alleles for one gene

homozygous

having two of the same alleles for one gene

incomplete dominance

a form of inheritance in which one allele for a specific trait is not completely expressed over its paired allele. This results in a third phenotype in which the expressed physical trait is a combination of the phenotypes of both alleles. Ex. some white type flowers and red type flowers will produce a pink type flower.

law of independent assortment

the rule of heredity that states that the allele a gamete receives for one gene does not influence the allele received for another gene

law of segregation

When an organism makes gametes, each gamete receives just one gene copy, which is selected randomly

meiosis

a type of cell division that creates games - sex cells

mutation

a change in the structure of a gene - the sequence of DNA base pairs

nucleotide

the monomer of a nucleic acid

pedigree chart

a diagram that shows the frequency and appearance of phenotypes of a particular gene from one generation to another

phenotype

physical characteristics of an organism

polygenic traits

a characteristic, such as height or skin color, that is influenced by two or more genes.

probability

likelihood an event will occur

Punnett Square

a diagram used to predict the genotypes of a particular cross of individuals

pure dominant

a genotype where both alleles are the dominant form

pure recessive

a genotype where both alleles are the recessive form

purebred

also known as homozygous

recessive

trait that will only appear in the phenotype if organism inherits two of them; covered up by the dominant gene

segregation

separation of alleles during meiosis or gamete formation

sex cell

a gamete - sperm or egg cell

sex-linked trait

trait related to a gene that is found on the X or Y chromosomes

sexual reproduction

the production of an individual organism by combining genetic information from two individuals of different types/sexes

trait

specific characteristic that varies from one individual to another

true-breeding

inherited two identical alleles for a trait; homozygous or purebred

x-chromosome

one of two sex chromosomes in humans

y-chromosome

one of two sex chromosomes in humans

zygote

a diploid cell resulting from the fusion of two haploid cells or gametes

10% rule

When energy passes from one trophic of the food chain to the next only 10% of that energy is received by the next organism.

abiotic factor

non-living factor that affects an ecosystem

aquatic

relating to water

atmosphere

A layer of gas or layers of gases that envelope a planet, and is held in place by the gravity of the planet.

autotroph

organism that makes its own food using sunlight or chemicals; producer

bacteria

Small single-celled organisms. Bacteria are found almost everywhere on Earth and are vital to the planet's ecosystem

behavioral isolation

type of reproductive isolation in which two organisms have different mating rituals that prevent them from interbreeding

binomial nomenclature

two part scientific name for an organism; its genus is listed first, followed by its species

biodiversity

variety of organisms that exist in the biosphere

biogeochemical cycle

process in which nutrients are recycled through the biosphere, ex. carbon, nitrogen, and phosphorous

biomass

the total mass of organisms in a given area or volume.

biome

a large community of flora and fauna occupying a major habitat, e.g. forest or tundra.

biosphere

part of Earth that living organisms inhabit

biotic factor

living factors or organisms that affect an ecosystem

birth rate

the amount of births of a specific organism over a period of time

carbon cycle

" The process in which carbon atoms continually travel from the atmosphere to the Earth, into and out of organisms, and then back into the atmosphere."

carnivore

consumer that eats animals or meat

carrying capacity

largest number of individuals of a population that the environment can support

cellular respiration

A metabolic pathway that breaks down glucose and produces ATP in cells

climate

the long-term weather pattern in an area, typically averaged over 30 years

climate change

Climate change refers to long-term shifts in temperatures and weather patterns. These shifts may be natural, or human caused.

combustion

a chemical reaction between substances, usually including oxygen and usually accompanied by the generation of heat and light

commensalism

symbiotic relationship in which one organism benefits and the other organism is not affected

community

populations of different organisms living in a defined area

competition

an interaction between organisms or species in which both the organisms or species are harmed. Limited supply of at least one resource (such as food, water, and territory) used by both can be a factor.

consumer

organism that relies on other organisms for food; heterotroph

decomposer

organism that breaks down and absorbs nutrients from dead organisms

denitrification

conversion of nitrates in the soil by bacteria into nitrogen gas