b14 genetics and evolution Flashcards
the theory of evolution by natural section is now?
widely accepted
evidence for Darwin’s theory is now available. Why?
it has been shown that characteristics are passed on to offspring in genes
there is further evidence in?
the fossil record and the knowledge of how resistance to antibiotics evolve in bacteria.
there is further evidence in?
the fossil record and the knowledge of how resistance to antibiotics evolve in bacteria.
what does the theory of evolution by natural selection state?
all species of living things have evolved from simple life forms that first developed more than three billion years ago
what is evolution?
the change in the inherited characteristics of a population over time through the process of natural selection
what is natural selection?
different organisms have different alleles for different characteristics
there could be a change in environment, and the organisms with the best-suited characteristics are more likely to survive and go on to reproduce.
Their children also inherit same alleles and are also more likely to survive and reproduce.
over generations this inherited allele become more common for populations
what are fossils?
fossils are the ‘remains’ of organisms from millions of years ago,which are found in rocks
fossils may be formed in three ways. give one way
fossils may be formed from parts of organisms that have not decayed because one or more of the conditions needed for decay are absent
give another way fossils may be formed
when parts of the organism are replaced by minerals as they decay
fossils may also be formed as
preserved traces of organisms,such as footprints, burrows and rootlet traces
what were early forms of life? And what does this mean?
early forms of life were soft-bodied, which means that they have left few traces behind
what happened to the traces there were?
what traces there were have been mainly destroyed by geological activity. This is why scientists cannot be certain about how life began on earth
what can we learn from fossils?
we can learn from fossils how much or how little different organisms have changed as life developed on earth
fossils can form when parts of organisms have not decayed when the conditions needed for decay are absent. Give examples of conditions
if the temperature is too cold
if there is not enough oxygen
or if there is not enough water
when is a species extinct?
when there are no remaining individuals of that species still alive
why can species become extinct?
due to a catastrophic event. For example, asteroid colliding with the earth eventually led to the instinction of dinosaurs
species can also become extinct when the environment changes. Give an example
change in weather patterns
why else could species become extinct?
new disease or new predator could kill all of the individuals of a species and make it extinct
-if a new more successful species evolve and compete with it(e.g for food or scarce water)
why can bacteria evolve rapidly?
because they reproduce at a fast rate
what do mutations of bacterial pathogens produce?
new strains
why are some strains not killed?
some strains might be resistant to antibiotics
what happens to the strains that may be resistant to antibiotics?
they survive and reproduce so the population of the resistant strain rises
why will the resistant then spread?
because people are not immune to it and there is no effective treatment
what do antibiotics do?
kill bacteria
why are antibiotics used in farming?
to prevent animals from developing bacterial diseases
what is one strain of antibiotic resistant bacteria called?
MRSA
in any population of an organism, there will be genetic variations due to?
mutations
what can a mutation do?
make bacteria resistant to antibiotics
what happens to the antibiotic strain when antibiotics are consumed?
antibiotic strain survives and reproduces without any competition from other bacteria and over time the resistant strain rises.
give one way to reduce the rate of development of antibiotic-resistant strains
(doctors)
doctors should not prescribe antibiotics inappropriately, such as treating non-serious or viral infections
way to reduce the rate of development of antibiotic-resistant strains
(patients)
patients should complete their course of antibiotics so all bacteria are killed and none survive to mutate and from resistant strains
way to reduce the rate of development of antibiotic-resistant strains
(Agricultural)
the agricultural use of antibiotics should be restricted
the development of new antibiotics is costly and slow. What does this mean?
it is unlikely to keep up with the emergence of new resistant strains
traditionally, living things have been classified into groups. what does this depend on?
their structure and characteristics in a system developed by Carl linnaeus
what did Linnaeus classify living things into? (king Phillip came over for good soup-neumonic)
kingdom, phylum, class, order, family, genus and species
organisms are named by?
the binomial system of genus and species
why did evidence of internal structures become more developed?
due to improvements in microscopes
as evidence of internal structures became more developed and the understanding of biochemical processes progressed what were proposed?
new models of classifcation
due to evidence available from chemical analysis what is there now?
a ‘three-domain system’ developed by Carl Woese.
in this system organisms are divided into:
-archaea
-bacteria
-eukaryota
archaea
primitive bacteria usually live in extreme environments)
bacteria
true bacteria, kind that lives in the human digestive system
Eukaryota
which includes protists,fungi,plants and animals
what are evolutionary trees?
evolutionary trees are a method used by scientists to show how they believe organisms are related
what do evolutionary trees use?
current classification data for living organisms and fossil data for extinct organisms
why is using fossil records a problem?
fossil records of many species are incomplete
