B15.1 - B15.10 - Genetics And Evolution✔️ Flashcards
Who was Gregor Mendel and what did he discover/work on?
Austrian monk born in 1822 who worked in monastery gardens and experimented with breeding peas (smooth,wrinkled,green and yellow peas) found the characteristics were inherited in clear and predictable patterns - explaiend how some charcteristics were dominant over others
Significance of Mendels work?
He was ahead of his time as no one knew about genes or chromosomes in 1844 his work was finally accepted and by late 19th century people ha seen chromosomes through a microscope later in the 20th century scientists observed that chromosomes and mendel’s unit of inheritance behaved in very similar ways - helped create the science of genetics
What happed in mid-20th century with DNA?
It was observed that chromosomes and mendel’s units behaved in similar ways - led to idea that units, now called genes were loacted on the chromosomes - in mid 20th centruy the structure of DNA was determined and the mechanism of gen function was worked out
How was Jean-Baptiste Lamark and what did he do?
French biologist he thought all organisms were linked by what he called a ‘fountain of life’ he suggested that individual animials adapted and evolved to suit their enviorment - his idea was every animial evolved from primitive worms and the change was caused by acquired characteristics
What did lamarcks theory propose?
The way organims behaved affected the features of their body - a case or ‘use it or loose it’ if animials used something over a lifetime,Lamarck though the feature would grow and develop and any changes that took place during its lifetime would pass from a parent to its offspring
Issues with Lamarcks theory?
No evidence for his ‘fountain of life’ and people didnt like the idea of being descended from worms - and people could easily see that changes in their body such as a big muscle was not passed to their children
Who was charles darwin?
Famous scientist who set out in 1831 (aged 22) on a 5 year voyage around the world and was amazed by the different variety of species and noticed that they varied from island to island and that they were different and adapted to their local conitions - he collected many specimens and observations and returned to england to work on his ideas for 20 years
3 main ideas of Darwins theory of evolution?
-the individual organisms in a particualr species tend to show a wide range of variation for each characteritsic
-reproduction always gives more offspring than the enviorment can support and only the most suited for the enviorment (‘fittest’) will survive
-when they breed they pass on the characteristics that have enabled them to survive to the next generation
How did Darwin gather evidence?
He used the animials and plants he gatherd on his journey as part of the evidence - carried out breeding programs with pigeons in his home - studdied different types of barnacles and built up a network of friends who helped him
Why was Darwins theory not completely accepted?
-theory of evolution by natural selection changed the belief that God made all of the animials and plants - many people in early victorian britians shared this religious view
-many scientists felt there was not enough evidence for the theory
-now way to explain how variety and inheritance happend - genes and genetics was not known until 50 years after the theory was published
Who was Alfred russel wallace?
Wallace was an ext teacher who set out in 1848 on an expendition with Henry Bates (who provided the money) he had the idea that if species existed in various form, those which were poorly adapted to change were likley to die out,leaving only the better to survive - he sent of a paper to darwin thinking he would help him get it published
Why was there pressure for darwin to publish his theory?
He recieved wallaces paper after 20 years of his own research and was woried someone would publish theirs before him - year after wallace published his papershoint with darwin (which were not widely noticed) darwin published his theory in the book ‘The Origin of species’ - both continued to work in m utual support with great respect for each other
What was Wallaces importance in speciation?
Worked worldwide gathering evidence for evolutionary theory - known for his work on warning colouration in animials and his theory of speciation
Define species?
A species is a group of organisms able to interbreed and produce fertile offspring.
4 factors that can result in the arise of a new species?
genetic variation
natural selection
speciation
Isolation
Explain how genetic variation results in new species?
genetic variation - each population has a wide range of alleles that can control their characteristics
Explain how natural selction reults in new species?
natural selection - the alleles which help an organism to survive are selected in each population
Define speciation
speciation - Speciation is how a new kind of plant or animal species is created. Speciation occurs when a group within a species separates from other members of its species and develops its own unique characteristics
Explain how isolation results in new species?
two populations of a species can become geographically separated because of the environment
Explain how mutations in a location can result in new species?
different mutations can take place in the isolated groups and create different phenotypes within a particular location
Explain how isolation can cause new species?
isolation can prevent interbreeding and the combination of genes within a species
