Some antibiotics prevent protein synthesis by targeting the ribosome. Ribosomes in eukaryotes have a different structure to prokaryotes.
In no more than 50 words, explain why these types of antibiotics can be used to treat bacterial infections without effecting human cells.

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

hope this .. .

but there is no

i guess you forgot putting it.

if you know your abc's you should be able to get your answer or just use google