genetic and evolution Flashcards
explain gregor mendels experiment
Gregor Mendel cross-bred peas and found that characteristics were inherited in clear and predictable patterns
He explained this by discovering that some traits were dominant over others and they never mixed together
Lamarck’s theory of evolution - french guy:
Lamarck’s theory of evolution - french guy:
1. thought that all organisms were linked by what is called a “fountain of life”
2.suggested that individual animals evolved to suit their environment
3. his theory proposed that the way organisms behaved affected the features of their body –> if animals used something a lot over their lifetime this feature would grow and develop
Darwin’s main ideas of evolution:
Darwin’s main ideas of evolution:
1. Individual organisms in a particular species tend to show a wide range of variation for each characteristic
2. Reproduction always gives more offspring than the environment can support. The better adapted (fittest) are more likely to survive and breed.
3. When breeding, they pass on characteristics that allowed them to survive
Today we know it is the alleles that control the characters of the advantageous phenotypes that are passed on in natural selection
Reasons it took so long for Darwin’s theories to be accepted
Reasons it took so long for Darwin’s theories to be accepted:
1. It challenged the belief that God made everything on Earth
2. Many scientists felt like there wasn’t enough evidence to convince them of his theories
3. There was no mechanism for them to understand how these traits can be inherited –> genetics had not been discovered yet
steps of speciation
Speciation:
1. two groups of one species become separated
2. different natural selection takes place in each group
3. when they become so different they are no longer able to interbreed to produce fertile offspring, they become new species
what are the Most common form of isolation
Most common form of isolation = geographical isolation –> when two populations become physically isolated by a geographical feature (e.g. a new mountain range, new river or an area of land becoming an island
what is enviromental isolation
environmental isolation = when the climate changes in one area where an organism lives but not the other areas (e.g. if the climate changes breeding times of plants + animals linked with them will change
what are fossils
fossils = remains of organisms from millions of years ago found preservedin rocks, ice and other places
Conditions needed for decay?
Conditions needed for decay:
1. oxygen
2. bacteria
3. relatively temperature
what happens when some of conditions for decaying are not met
when one or more of these conditions aren’t there, the organisms don’t decay but are preserved in almost its original form (mostly in ice or peat)
what do scientists extract from fossils
scientsits can extract DNA and compare it to modern organisms
Reasons that fossil record is not complete?
Reasons that fossil record is not complete:
1. many of the earliest forms of life are soft-bodied organisms –> they’ve left little fossil trace. Most of the fossils created have been destroyed by geographical activity
2. most organisms that died did not become fossilised –> conditions for fossil formations were rare
3. there are many fossils still to be found
explain mould fossils
Mould fossils = when an impression of an organism is made in mud, then becomes fossilised
explain cast fossils
Cast fossils = when a mould is filled in
what is extinction
Extinction = the permanent loss of all the members in a species
