CH10 changing population characteristics

Question 1

Steps of natural selection

Answer 1

1 organisms within a species show variation in their characteristics that are caused by differences in genes
2 organisms whose characteristics are best adapted to a selection pressure have an increased chance of survival and successfully reproducing
3 successful organisms pass the allele encoding the advantageous characteristics onto their offspring
4 process is repeated for every generation, and over time the proportion of individuals with advantageous characteristic becomes more common

Question 2

What is a selection pressure

Answer 2

• factors that affect the organisms chances of survival or reproductive success

Question 3

Antibiotic resistant bacteria

Answer 3

• bacteria reproduce rapidly, and when replicate their dna can be altered
• mutation that occurred in some s aureus provided resistance to methicillin
• when exposed to antibiotics, resistant survived and non resistant died

Question 4

Peppered moths

Answer 4

• before industrial revolution, most were pale coloured and blended in with light bark trees
• after industrial revolution, many trees became darker and darker moths were better adapted to survived and reproduced

Question 5

Sheep blowflies

Answer 5

• lay eggs un faecal matter around sheeps tail, which hatch and cause sores
• pesticide diazinon was used to kill blowflies and prevent thus
• blowflies developed high level of resistance, and survived to pass on

Question 6

Flavobacterium

Answer 6

• strain of bacteria found living in waste water from factories that produce nylon 6
• strain of bacteria evolved to digest nylon and is therefore beneficial to humans as help clear up factory waste