B15 Genetics and Evolution Flashcards
how did Darwin develop his theory of evolution by natural selection?
he studied many fossils, animal specimines and plants
he then discussed and experimented and came up with his theory
what is present within any species for any characteristic
wide range of genetic variation
what does ‘survival of the fittest’ mean?
individuals with the characteristics most suited to the environment are more likely to survive and reproduce
what happens to beneficial characteristics
they are passed on to the next generation
why did many people disagree with Darwin’s theory?
- it challenged the belief that God made all the plants and animals on the earth
- many scientists felt that Darwin did not have enough evidence to back up his theory
- there was no understanding of how characteristics were inherited as genetics was not understood until 50 years after Darwin’s publication
what was Lamarck’s theory?
he suggested that when a characteristic is regularly used, it becomes more developed
the strengthened characteristic is then passed on to the offspring
what was the problem with Lamarck’s theory?
changes that occur in an organism’s lifetime, cannot be passed on to the offspring
what is speciation?
the process by which two species evolve from a single original species by natural selection
how does speciation occur?
- a geographical area contains a population of organisms which can all interbreed so a beneficial mutation is spread through the whole population
- a geographical barrier separates the one population into two separate groups
- no interbreeding now takes place between the two groups
- over time, natural selection will favour different alleles in each of the two groups
- mutations cannot be spread between the two groups as no interbreeding takes place . this means that the two populations will begin to change over many generations
- if the two populations mix again, their phenotypes are so different that they can no longer breed to produce fertile offspring
what is a species?
a group of organisms which can breed together to produce fertile offspring
what did Mendel investigate and study?
he looked at the different characteristics of pea plants and how they transferred from plant to plant
what did Mendel discover?
He said that characteristics are determined by inherited units (genes) and the units are not changed when passed on to descendants
he also showed that characteristics could be masked and reappear in later generations (recessive alleles)
What is are fossils?
Remains of organisms from millions of years ago that can be found in rocks, ice and other places
How can fossils be formed?
- when an organism does not decay after it died
- mineralisation of the harder parts of the organism
- preserved traces
Why is the fossil record incomplete?
- early life forms were soft bodied
- most organisms that died did not become fossilised
- many fossils are still to be found
how does decay not happen when a fossil is formed?
the conditions for decay are absent
what do fossils show?
large amount of species have become extinct
what does extinct mean?
when there are no remaining members of a species alive
what can cause a species to become extinct?
- catastrophic event
- when the environment changes
- new disease
- new predator
- new more successful competitor
why can bacteria evolve rapidly?
because they reproduce at a very high rate
what does antibiotic resistant mean?
when a bacteria is no longer killed by antibiotics
how does antibiotic resistance occur in bacteria?
- in a population of bacteria, it is possible that a bacterium develops a mutation making it resistant to bacteria.
- the rest of the bacteria are killed by the antibiotic, leaving the resistant bacterium to reproduce without any competition.
- the population of the resistant bacteria increases and spreads rapidly as there is no treatment or immunity.
what are the ways to reduce antibiotic resistance?
- not prescribe antibiotics inappropriately
- complete the course of antibiotics to kill all the bacteria so none can survive to mutate
- restrict the use of antibiotics in farming
what is the problem with developing new antibiotics?
it takes a long time and is expensive
what are the two kingdoms of Linneaus’ classification system?
plants
animals
what are the categories of Linneaus’ classification system?
kingdom
Phylum
Class
Order
Family
Genus
Species
(King Phillip Came Over For Good Soup)
where does an organism’s binomial name come from?
their genus and species
what is Linneaus’ classification system based on?
characteristics that you can see
what can be used to classify an organism?
physical features
biochemistry
internal structures
these are compared to other species for similarities
what are archae?
another domain for classification which is a primitive type of bacteria
what are the three domains for classification?
archae
true bacteria
eukaryota
what types of organisms are eukaryota?
plants, animals, fungi and protists
what data is used to make evolutionary trees?
classification data from living organisms
fossil records
what is the problem with using fossils for evolutionary trees?
the fossil record is incomplete
