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
