Question

Which situation is most likely to lead to speciation over time?

	1.	Some members of the same species begin to use a different food source, eventually preferring that food over what the other members of the population are eating
	2.	A population immigrates in large numbers to the territory of a neighboring population of the same species
	3.	A population immigrates in large numbers to the territory of a neighboring population of a differerent species
	4.	Genetic drift severely reduces the population size causing massive inbreeding and reduced fitness

Which situation is most likely to lead to speciation over time?

	1.	Some members of the same species begin to use a different food source, eventually preferring that food over what the other members of the population are eating
	2.	A population immigrates in large numbers to the territory of a neighboring population of the same species
	3.	A population immigrates in large numbers to the territory of a neighboring population of a differerent species
	4.	Genetic drift severely reduces the population size causing massive inbreeding and reduced fitness

A doctor is testing a new drug for treatment of high cholesterol. She uses only male subjects age 44-47 who are in the normal weight range who have no other health problems other than high cholesterol. She gives 50 subjects the new drug and 50 others a fake drug (placebo). Which best describes this experiment.?

	1.	A controlled, double blind study with independent variable only
	2.	The placebo is the dependent variable and the drug is the independent variable
	3.	The drug is the dependent variable and cholesterol lelvel is the independent variable
	4.	A controlled study where cholesterol level is the dependent variable and the drug is the independent variable

How old was the planet when oxygen became an important component of the Earth's atmosphere?

		1 billion years
		2 billion years
		3 billion years
		five billion years

Answer 1

1.The situation that lead to speciation overtime is genetic drift which reduced the population size causing massive inbreeding and reduced fitness. This is due to isolation by adaptation where selection effects the pattern of genetic divergence by reducing the gene flow to the extent that genetic drift takes place at all loci.

2. The experiment best describes(1) a controlled double blind study with independent variable that is Placebo. Double blind study is such that neither the participants nor the experimenters know who is receiving the treatment

3. The age of the planet when oxygen became its important component is 3 billion years