QCE biology Unit 3 and 4 key terms

carrying capacity

the size of the population that can be supported indefinitely on the available resources and services of that ecosystem

clade

a group of organisms that consists of a common ancestor and all its lineal descendants

ecological niche

the role and space that an organism fills in an ecosystem, including all its interactions with the biotic and abiotic factors of its environment

evolution

change in the genetic composition of a population during successive generations, which may result in the development of new species

gene

region/s of DNA that are made up of nucleotides; the molecular unit of heredity

genome

all the genetic material in the chromosomes of an organism, including its genes and DNA sequences

keystone species

a plant or animal that plays a unique and crucial role in the way an ecosystem functions

macroevolution

the variation of allele frequencies at or above the level of species over geological time, resulting in the divergence of taxonomic groups, in which the descendant is in a different taxonomic group to the ancestor

microevolution

small-scale variation of allele frequencies within a species or population, in which the descendant is of the same taxonomic group as the ancestor

polygenic inheritance

when one characteristic is controlled by two or more genes

stratified sampling

a type of sampling in which a sample is taken of each strata of the population

allopatric speciation

The formation of new species in populations that are geographically isolated from one another.

parapatric speciation

speciation pattern in which populations speciate while in contact along a common border

sympatric speciation

The formation of new species in populations that live in the same geographic area

geographic isolation

physical separation of a group of individuals from others of the same species

temporal isolation

form of reproductive isolation in which two populations reproduce at different times

Behavioural isolation

when two populations are capable of interbreeding but have different behaviours such as courtship rituals or feeding.

spatial isolation

individuals from different species do not come in contact with each other

DNA polymerase

Enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule; also proofreads the new strand of DNA

DNA ligase

enzyme that chemically links DNA fragments together

restriction enzymes

Enzyme that cuts DNA at a specific sequence of nucleotides

Biomass

total amount of living tissue within a given trophic level

competitive exclusion principle

Ecological rule that states that no two species can occupy the same exact niche in the same habitat at the same time for an extended period

pioneer species

first species to populate an area during succession; can photosynthesis, fixate nitrogen, germinate rapidly and tolerate extreme conditions

primary succession

An ecological succession that begins in an area where no biotic community previously existed; no soil present

secondary succession

Succession following a disturbance that destroys a community without destroying the soil

Biodiversity

the variety of life in the world or in a particular habitat or ecosystem.

genetic biodiversity

the total number of genetic characteristics in the genetic makeup of a species

autosomal dominant

inheritance pattern of a dominant allele on an autosomal chromosome

sex-linked inheritance

Inheritance of a gene located on the sex chromosomes

multiple alleles

three or more versions of a gene that code for a single trait

genotype

An organism's genetic makeup, or allele combinations.

phenotype

An organism's physical appearance, or visible traits.

divergent evolution

evolution of one or more closely related species into different species; resulting from adaptations to different environmental conditions

convergent evolution

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

mass extinction

event in which many types of living things become extinct at the same time

parallel evolution

Two related species that have made similar evolutionary adaptations after their divergence from a common ancestor in geographically different regions

Zonation

the distribution of plants or animals into specific zones according to such parameters as altitude or depth, each characterized by its dominant species.

Nitrification

Nitrogen gas is changed into a nitrate by bacteria in the soil so that organisms can use it.

denitrifying bacteria

Bacteria that convert the nitrates in soil or water to gaseous nitrogen and release it back into the atmosphere.

carbon cycle

the movement of carbon from the nonliving environment into living things and back (eg. during photosynthesis or burning of fossil fuels)

Linnean Classification System

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Cladistics

classification based on common ancestry, bifurcation & physical change

species richness

the number of different species in a community

species evenness

the relative abundance of each species in a community (abundance of species/total abundance of all species) x 100

Simpson's Diversity Index

a measure of diversity between ecosystems (between 0 & 1)

SDI = 1-(Σn(n-1)/N(N-1) )

N = total number of organisms of all species

n = number of organisms of one species

Lincoln Index

a method for determining population size by marking and recapturing individuals of a population

Percentage cover

An estimate of the area within a quadrat that a particular plant species covers

percentage frequency

The percentage of the total number of quadrats that a species was present in.

Mutualism

A relationship between two species in which both species benefit

Commensalism

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

Parasitism

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

Amensalism

a relationship in which one organism is harmed and the other is unaffected

species distribution pattern

the distribution of individuals within a habitat at a given point in time

biological species concept

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

interspecific hybrid

Organism that is produced by mating two different species but can't reproduce

Microhabitat

a small, particular part of a habitat in which particular organisms live; for example, beneath the bark of a tree within a forest habitat

Ecoregion

A large area of land or water that contains a characteristic and distinct group of natural communities and species

pyramid of biomass

A pyramid that illustrates the total mass of all the organisms in a trophic level.

pyramid of numbers

representation of the number of individual organisms in each trophic level of an ecosystem

pyramid of energy

A pyramid that shows the total amount of energy available at each trophic level.

Population

A group of individuals that belong to the same species and live in the same area

Community

All the different populations that live together in an area

Ecosystem

A biological community of interacting organisms and their physical environment.

population growth rate

the number of offspring an individual can produce in a given time period, minus the deaths of the individual or its offspring during the same period

population change

Increase or decrease in the size of a population. It is equal to (Births + Immigration) - (Deaths + Emigration).

J-curve

a growth curve that depicts exponential growth

S-curve

a curve that depicts logistic growth; shape of an "S." The leveling off of a J-Curve exponential growth.

Quadrat sampling

square frames (usually 1m x1m) used in estimating abundance in plants or slow-moving animals

Line transect

A tape or string laid along the ground in a straight line between two poles as a guide to a sampling method used to measure the distribution of organisms. Sampling is confined to organisms that are touching the line.

Belt transect

Is used in habitats when there is a gradient change from one side of the habitat to the other

point mutation

gene mutation in which a single base pair in DNA has been changed

frameshift mutation

mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide

Transcription

(genetics) the organic process whereby the DNA sequence in a gene is copied into mRNA

Translation

(genetics) the process whereby genetic information coded in messenger RNA directs the formation of a specific protein at a ribosome in the cytoplasm

transcription factors

A regulatory protein that binds to DNA and affects transcription of specific genes.

activators and repressors

bind to DNA close to the promoter and either activate or repress the activity of RNA polymerase

Histones

protein molecules around which DNA is tightly coiled in chromatin

Chromatin

Substance found in eukaryotic chromosomes that consists of DNA tightly coiled around histones

Chromosomes

threadlike structures made of DNA molecules that contain the genes

Karyotype

A picture of all the chromosomes in a cell arranged in pairs

Ploidy changes

an abnormal number of chromosomes

Down Syndrome

a condition caused by an extra chromosome 21 in one's genetic makeup

Prokaryote

A unicellular organism that lacks a nucleus and membrane bound organelles

Eukaryotic

A cell characterized by the presence of a nucleus and other membrane-bound organelles. Eukaryotes can be unicellular (protists) or multicellular (fungi, plants and animals).

complementary base pairing

In DNA, T pairs with A; G pairs with C;

RNA, U pairs with A and G pairs with C

Nucleotide

A building block of DNA, consisting of a sugar bonded to a nitrogenous base and a phosphate group.

RNA

single-stranded nucleic acid that contains the sugar ribose

PCR

(polymerase chain reaction) a method used to rapidly make multiple copies of a specific segment of DNA; can be used to make millions of copies of DNA from a very small amount of DNA

gel electrophoresis

The separation of nucleic acids on the basis of their size and electrical charge, by measuring their rate of movement through an electrical field in a gel.

Helicase

An enzyme that untwists the double helix of DNA at the replication forks.

DNA replication

DNA unzips into two parts and splits with the cell. In it's new home each side of the DNA strand attaches to matching nucleotides to create 2 exact copies. There is a leading strand and a lagging strand.

Meiosis

a type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.

Spermatogenesis

the production of sperm cells