Yr 2 Definitions Flashcards
species
A group of organisms that are able to produce fertile offspring
species richness
the number of different species in a community/ecosystem
genetic diversity
number of different alleles of each gene
phylogenetic group
grouped according to evolutionary relationship/ common ancestry
hierarchy
A hierarchal system is one in which larger groups contain smaller groups with no overlap
transcriptional factor
protein/ molecule that moves from cytoplasm to DNA; and binds to a promoter; allowing RNA polymerase to work
codon
Triplet / three bases on mRNA/DNA; that code for an amino acid
ecological niche
The role that an organism plays in its habitat; including its use of resources and its inter-relationships with other species
abiotic factor
A non-living factor
What is succession
change in community over time;
either due to abiotic factors or due to species present
a climax community
a stable community where there is no further succession
negative feedback
where a change triggers a response which reduces the effect of a change
homeostasis
maintaining a constant internal environment
DNA probe
Single-stranded DNA; with base sequence complementary to DNA to be identified; which is radioactively / fluorescent labelled so that it can be detected
phenotype
Appearance due to genotype and the environment
gene pool
all the alleles in a population
codominant alleles
both alleles expressed in the phenotype if present
dominant allele
is always expressed in the phenotype
community
all of the populations in an area
recessive allele
only expressed in phenotype when homozygous
ecosystem
a system in which all organisms interact with physical environment
population
population is the total number of individuals of a species in an area
sex-linked gene
gene located on X / Y sex chromosome
sympatric speciation
The formation of new species; from a population living in the same area / without geographical isolation
allopatric speciation
new species form from different populations; in different areas
epigenetics
heritable changes in gene function; without changes to the base sequence of DNA
vector
it carries DNA into another organism
recombinant DNA
DNA which contains genes from two species
gene therapy
The introduction of healthy gene to ‘replace’ a defective gene
Epistasis
Interaction between two non linked genes which causes one gene to mask the expression of the other in the phenotype
