B5.2 Flashcards
What is evolution
What do scientists believed we evolved from
Evolution is the GRADUAL CHANGE In species over time
1) from unicellular aquatic organisms that lived over three billion years ago, that over time eve loved to Mut,I cellular organisms and variety like us
Natural selection
1) there is variation in the population of species
2) Random mutations can occur, giving more variation
3) organisms with characteristics that are advnatgeius and help them survive survive and successfully breed. Then their genes are passed down to the next generation.
4) those without the characteristics will eventually die. This is called ‘survival of the fittest”
5) the next generation will have a greater proportion of organisms with advantageous characteristics. As more and more generations go by, eventually the entire population will have these two.
6) if the two ‘species’ have changed so much that if they were to breed they could not produce fertile offspring, then they are two separate species now, which happens after millions of years.
When does evolution produce two different species
What does rate of evolution depend on?
When a natural barrier arises and separates tow populations of the same species, over time, the conditions on these two areas may be different. Natural selection takes place and over millions of years the two Orginal populations will have different characteristics that they can’t produce fertile offspring
2) how quick it takes for an organism to reproduce. The faster it is, the more likely a random mutation will occur that is advantageous and pass down genes more quickly too. Humans slow but bacteria in this way are fast…
How are fossils formed?
1) the organism dies
2) over time the flesh will rot away, exposing the skeleton or hard substance in the organism
3) over time, mud and clay can build over the skeleton
4) over more time, the skeleton can mineralise and turns to ROCK
What does the fossil record tell us?
Advantage and disadvantage
- the deeper the rock, the older the fossil
- scientists have found simpler organism such as bacteria in deep rock and complex ones like vertebrates in higher one’s. This shows the theory that life fame from simple organisms becoming gradually complex
- plant fossils appear before animal fossils- showing that animals needed plants to survive
- CLOSELY RELATED ORGANISMS COME FROM THE SAME ANCESTOR. By studying similarities in things like bone anatomy, it shows modern day animals and where they evolved from- proving evolution. Also you can make assumptions on why a animal may have evloeved.
However there are still gaps
- some fossils destroyed due to volcanoes
- some haven’t found yet
- some decompose quicker then it can become a fossil, so the entire story can’t be traced .
How is anti biotic resistant bacteria evidence for evolution?
- they replicate rapidly, and can study how an advantageous characteristic such as antibiotic resistance arises. The fact that they are resistant shows evolution happened
Scientists expose bacteria to anti resistant drug. Because bacteria divide quick, a chance for a random mutation to occur increases. If this mutation happens to counteract the anti biotic resistance, then eventually all the bacteria will become reistant , and the others die out. This is proof evolution in bacteria occurs
Extinction evidence for evolution?
Scientist say that species that didn’t evolve have died out, and that is 99% of all species (such as species we find in fossils, not alive today- why).
What about molecular comparison?
WHY CAN DNA BE COMPARED BETWEEN ANY TWO ORGANISMS?
Closely related species should have closely related dna
because all dna have the same 4 bases
What three reasons scientists use bacteria instead of animals for experiments in evolution?
- asexually divide, so only one parent is needed
- bacteria reproduces much more quickly then animals
# ethical reasons on testing in animals - take up little space
- much more cheaper
Darwin and Wallace how was theory if evolution occur
Darwin went to Galápagos Islands
- on the way there he read a book called “principles of geology by Lyell” which states fossils were evidence for evolution years ago. Got him thinking
- there he studied finches and made conclusions. This involved different islands had different finches in terms of beaks and claws. He concluded that these design if beaks were linked to FOOD available on each island, and those with beaks better suited for a specific type of beak would be more likely to survive, and so it would have more offspring, eventually all the finches would have that characteristic - called it natural selection
2) at the same time, wallade was making his own theory up, after observing moths and warning signs in BORNEO . He sent his ideas for peer review to Darwin and because ideas so similar they jointly pubslished their ideas in a conference.
3) HOWEVER, a year after, Darwin published his own book called ‘ON THE ORIGIN IF SPECIES”, and this is when people caught on to the idea, which is why he is more remembered
Why was evolution controversial back then and why not now?
3 things
Back then people believed god made everything. There wasn’t enough EVIDENCE, and they believed in lamarck’s theory of squired characteristics, where an animal will acquire characteristics based on something they did their life, like stretching neck.
2) now, there is more evidence like fossil records, dna studies, extinction and bacteria.
Classification
Natural
Artificial
The process of organisms ,Irving organisms into groups
1) natural is organising organisms based on phylogenetic links , so dna and grouping organisms based off a common ancestor . Closed the dna, the closer related they are.
2) artificial is process of organisms organisms based on observable features. Not always necessary accurate because a rose has 5 petals, doesn’t mean all flowers with 5 petals are roses.
Binomial nomenclature and taxonomic levels
Binomial nomenclature is the method in which all species are named. All species have a Latin America consisting of the GENUS AND THEN THE SPECIES .
TAXONIC LEVEKS are kingdom phylum class order family genus species.
Ends ins species , which is different for each species., smallest unit if classification. Contains only one organism
Dna sequencing
Comparing sequences of bases to see how similar organisms are
To prove artifical wrong?
Amphibians
