5.6 explain how environmental factors act as forces of natural selection
Biotic Factors - caused by other living organismns. Examples are preditation, competition for food and infection by pathogen
Abiotic factors - caused by non living component of
environment. Examples are water supply and nutrient levels
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Industrial melanism
In polluted areas, deposits of soot make tree bark darker. Melanic moths were better able to camouflage than pale ones. Melanic moths were more likely to survive, reproduce and pass on alleles
As air pollution decreased the advantage swung back in favour of pale form of moth again
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Antibiotics inhibit or kill bacteria
Penicillin prevent cell wall formation in bacteria so that will kill entire population of bacteria. But some become resistant to penicillin. Some bacteria produce an enzyme, penicillinase which inactivates penicillin.
So bacteria with penicillinase are not killed. They can survive and reproduce
