Natural Selection and GM Flashcards
(32 cards)
what were the first organisms on earth like
simple and single celled (unicellular)
how many species do we estimate are on this planet
10 million
what is evolution
the change of an organisms characteristics over generations
what is the most widely accepted theory of evolution
the theory of evolution by natural selection from Charles Darwin
what is the theory of natural selection
- individuals in a population show genetic variation, caused by different alleles arriving through mutations
- selection pressures affect an organisms chance of surviving and reproduction
- individuals with characteristics suited to selection pressures are more likely to survive and breed successfully
- these successful alleles are more likely to be passed on and become more common in the population over time
selection pressure
things like predation, competition for resources, disease etc.
alleles
different forms of the same gene
mutation
rare, random change in gene/chromosome
what did charles darwin do
spent 5 years on hms beagle, noticed variation in individuals of same species and those with characteristics most suited to the environment were more likely to survive with characteristics passed on to offspring.
published his theory of evolution by natural selection in 1859 in origin of species
what did alfred russel wallace do
worked at same time as darwin. also came up with nautral selection indepent of darwin, both published papers on evolution together, acknowledged each others work. Wallace’s observations provided lots of evidence to support this theory
how does antibiotic resistance in bacteria support darwins theory of evolution
example of natural selection taking place.
what are the 2 ways fossils can be dated
stratigraphy and through radiometric dating
stratigraphy
study of rock layers within which fossils are found. Older fossils usually in the lower rock layers
radiometric dating
method of dating rocks using radioactive isotopes, usually potassium-argon.
why are fossils useful as evidence for evolution
they are a trace of an organism that lived many years ago, and by arranging them in chronological order, gradual changes can be observed
what is a pentadactyl limb
a limb with 5 digits
how does the pentadactyl limb show evidence for evolution
many modern day vertebrates have a complete pentadactyl with the same bone structure, it makes it likely that they all evolved from a common ancestor
anatomy of a pentadactyl ling
humerus at the top, radius on left, ulna right, carpal underneath radius and ulna, phalanges on bottom
5 kingdoms in classification
animals, plants, fungi, prokaryotes, protists
classification ladder
kingdom
phylum
class
order
family
genus
species
what did Carl Linnaeus do
published classification system in 1735. used genus and species to give organism its binomial name
what did Carl Woese find
using rna sequencing, he found out that some members of prokaryotes were not as closely related, and split the kingdom into 2 groups called Bacteria and Archae, and changed the classification system into 3 domains
3 domain classification system
Eukarya, Archaea, Bacteria are 3 domains, then subdivided into classification ladder.
why are dna sequences useful
scientists can compare organisms dna sequence to compare relationships between organisms.
