QCAA Biology Define Unit 3+4

Biology

clade

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

ecological niche

the role and space that an organism fills in an ecosystem

keystone species

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

carrying capacity

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

genome

all the genetic material in the chromosomes of an organism

gene

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

polygenic inheritance

when one characteristic is controlled by two or more genes

evolution

change in the genetic composition of a population during successive generations

microevolution

small-scale variation of allele frequencies within a species or population

macroevolution

the variation of allele frequencies at or above the level of species over geological time

stratified sampling

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