Variation, evolution and classification

Discontinuous variation + example

Controlled by a single gene and result in distinct trait and characteristics

Blood group

Continous variation + example

Controlled by many genes and results in a large range of values

Height - skin colour

Non-heritable variation

Environment influenced phenotype but have little evolutionary significance as they are not passed on

How is a variety of gene expression created

Random cross fertilisation

Crossing over during prophase 1

Random assortment during metaphase 1

Mutation

A random change in the amount, arrangement to structure of DNA

Increase variation

2 types of competition between organisms

Intra-specific - between the same species basis or origin of natural selection

Inter-specific - between different species predator prey relationships

Selection pressure + example

Something that causes the death of an organism

Disease

How selection pressure works

When selection pressure present individuals with traits that help them survive are more successful

These traits get passed on through generations

Over time can lead to evolution

Gene pool

All the alleles of all the genes of all the individuals in a population at any one time

What happens to the gene pool in a stable environment

Proportion of dominant and recessive alleles remains constant

What happens to a gene pool in a changing environment

Some phenotypes become advantageous and selected for while others may be disadvantaged and selected against

Genetic drift

Random variation in allele frequencies (red and yellow counters)

Founder effect

When a small group of individuals break off form the main population to form a new one

Some alleles may be under/ over represented or not at all

Deme breeding sub-units

Group of interbreeding individuals

Reproductive isolation

When a population becomes isolated into 2 groups and can no longer interbreed to produce fertile offspring

Behavioural isolation

Different mating behaviours

Mechanical isolation

Incompatible genitalia

Gametic isolation

Sperm and egg can’t fuze

Temporal isolation

Reproduce at different times

Ecological isolation

Live in different habitat or niches

Hybrid sterility

Produces offspring that is infertile

Sympatric speciation

New species arising due to a behavioural or reproductive barrier causing reproductive isolation

Allopatric speciation

New species arising due to physical geographical barrier causing reproductive isolation

Hardy Weinberg principle

Allele frequencies in a population will remain constant unless acted upon by external forces

What is the equation for Hardy-Weinberg

P + Q = 1

p2 + q2 + 2pq =1

In a Hardy-Weinberg what is the P2 and P

Dominant percentage

Number of alleles

In a Hardy-Weinberg what is the Q2 and Q

Recessive percentage

Number of recessive alleles

In a Hardy-Weinberg what does the 2PQ represent

Number of carriers (heterozygous)

What does it mean to accept the null hypothesis

When your value is less than critical value

Difference between groups is likely due to chance

What does it mean to reject the null hypothesis

When your value is more than the critical value

significant difference in data

Heritable variation

Gained through sexual reproduction

Necessary conditions for hairy Weinberg equilibrium (5)

No immigration + emigration

Large pollution size

No selection pressures

Random mating

No new mutation

Natural selection (4)

Variation due to mutations

Individuals have selected advantage

Pass on advantageous alleles to the next generation

Allele frequency increases in the population

Speciation

Formation of a new species from an existing one

Biodiversity

Number of species and number of individuals in each species in a given environment

Classification

Organisation of organisms intro groups according to shared similarities

What is the modern classification system

Phylogenetic hierarchy

How to remember classification system (taxa)

Dirty king Philip comes over for good sex

Domain kingdom phylum class order family genus species

Species

Group of organisms that can interbreed to produce fertile offspring and are reproductively isolated form other groups

What are the 5 kingdoms

Animalia

Plantae

Prokaryote

Protoctista

Fungi

3 domains

Eubacteria

Archaea

Eukarya - plants, animals, fungi, protists

Halophiles

Areas where salinity is high

(dissolved salt in water)

Where does evidence for domains come from

Studies on ribosomal RNA

Prokaryotae

70s ribosomes

No membrane bound organelles

Both hetero and autotrophic

Animalia

No cell walls

Heterotrophs

eukaryotes

Plantae

Autotrophs

Cellulose cell walls

Fungi

Eukaryotes

Chitin cell walls

Heterotroph

Protoctista

eukaryotes

some have cell walls

both hetero and autotrophic

Binomial name

First capitalised genus

second lowercase species

Where do fragments of dna move and what does it show during gel electrophoresis

Smaller fragments move further from negative to positive electrode

Produced banning pattern called DNA fingerprinting

Homologous structures

Similar structure that have different functions

Common ancestors

(5 fingered limb in humans and whales)

Analogous structures

From convergent evolution

Same function however origin is different

No evolutionary relationship

Where does biodiversity increase to and from

From poles to the equator

polymorphism

When a species has a number of different forms (snails)

Difference between physiological and anatomical

Physio - way in which body processes

Ana - structural differences

Testing DNA hybridisation

Single strands of DNA from 2 different species join together

This is heated to separate

Higher temp = more hydrogen bonds to break = more related closeness