The concept of continental drift, continents drifting over the ocean floors, was proposed by Alfred Wegner in 1915. This concept was replaced by the theory of plate tectonics in the 1960s. Changes from the continental drift concept to the plate tectonics theory required which of the following?

strong earthquakes occurring along fault zones

data and ideas being shared among scientists

a scientific law being passed by Congress

teachers beginning to teach the newer theory

Duchenne muscular dystrophy is a serious condition caused by a recessive allele of a gene on the human x chromosome. the patients have muscles that weaken over time because they have absent or decreased dystrophin, a muscle protein. they rarely live past their twenties. how likely is it for a woman to have this condition? a) women can never have this condition.b) one-fourth of the daughters of an affected man would have this condition.c) one-half of the daughters of an affected father and a carrier mother could have this condition.d) only if a woman is xxx could she have this condition.

Which direction does the energy flow in this energy pyramid ?

How does secondary succession differ from primary succession?