module 7 Flashcards
what is a species
a group of organisms with similar characteristics that can interbreed to produce fertile offspring
what is a population
all individuals of a particular species in a particular place
what is community
all the population of different species in a particular place
what is a habitat
the place where organisms lives
what is an ecosystem
a mix of different communities and habitats and how they interact based on abiotic and biotic factors
what is ecological niche
an organisms role/position in an ecosystem- in terms of its interaction with abiotic and biotic factors
why can 2 different species not occupy the same ecological niche
interspecific competition will take place for the limiting factors/resources (abiotic/biotic factors)- better adapted species will out compete the other= competitive exclusion principle
how to sample plant species over large area
-obtain a map of the area
-divide map into grids
-select a large number of coordinates using running mean
-select a random set of coordinates using random number chart
-in each coordinate place a quadrat
-measure abundance of the plant species in each quadrat= frequency or percentage cover
- calculate average for the whole area
how to sample plants species along a path
use a transect
place a tape along the path, count number of plants touching tape
OR
place a tape along a path and at regular intervals place a quadrat, measure abundance within the quadrat ( belt transect)
phenotype
the expression of the genetic constitution and its interaction within the environment
chromosome
a thread like structure made of protein and dna and contains the genetic information
allele
an alternate version of a gene
genotype
the genetic constitution of an organism
locus
the position of a gene on a chromsome
genome
the complete set of genes in a cell
gene
a selection of dna that codes for a polypeptide
diploid
cells where the nucleus contains 2 sets of chromosomes
proteome
the full range of proteins that a cell is able to produce
homozygous
condition in which the alleles of a particular gene are identical
haploid
a cell with only 1 set of chromosomes
heterozygous
condition in which the alleles of a particular gene are different
dominant allele
an allele that is always expressed in the phenotype
co-dominance allele
both alleles of 1 gene in a heterozygous organism are expressed in the phenotype
recessive allele
the allele is only expressed if 2 copies are present
allopatric speciation
result of geographical isolation. eg, mountains
sympatric speciation
no geographical barrier. eg, same plants start flowering at different times of the year due to mutation
formation of species generic mark scheme
in each population there is variation caused by mutation
in each population the environments differ
‘’ there is competition
‘’ the best adapted to survive and reproduce
pass on advantageous alleles
frequency of allele increases
2 populations are now different species and cannot reproduce successfully
evolution definition
how a species becomes better adapted to its environement
genetic variation
mutation
crossing over
independent assortment
random fertilisation
( all produce new combinations of alleles)
genetic variation
mutation
crossing over
independent assortment
random fertilisation
(All produce new combinations of alleles)
environmental factors of variation
eg sunlight
influences the way an organism gene to be expressed
evolution generic mark scheme
competition (preditation and disease) results
in some individuals better adapted
those individuals with advantageous phenotypes are more likely to survive and reproduce and pass on the alleles
frequency of these alleles will increase
3 types of pf selection
directional
stabilising
disruptive
pedigree charts
this shows the inheritance of a particular gene through a number of generations
(Never write skipped generation in an exam)
hardy Weinburg equation
p+q=1
p^2 + 2pq + q^2 = 1
monohybrid cross
Monohybrid inheritance is when a phenotype or trait is controlled by a single gene
3:1 ratio
dihybrid cross
Dihybrid inheritance is when two characteristics are studied and is determined by two different genes that are present on two different chromosomes at the same time
9:3:1:1
recessive epistasis
Recessive epistasis occurs when the presence of
a recessive allele prevents the expression of
another allele at a second locus. Recessive
epistasis gives the ratio of 9:3:4
dominant epistasis
Dominant epistasis is when a dominant allele at one locus completely masks the alleles at a second locus. Dominant epistasis gives a ratio of
12:3:1
hardy Weinburg principle
The Hardy-Weinberg Equation can be used to estimate the frequency of alleles in a
population and to see whether a change in allele frequency is occurring in a population over time
in order for hardy Weinburg equation to work the following must be true
no mutation
large population size
mating must be random
no migration
no selection
