Speciation has occurred when:
A. divergent populations evolve to the point where interbreeding does not produce viable, fertile offspring.
B. mutations in a population reach 100% of the organisms in that population.
C. organisms from a single species are separated by a physical barrier.
D. a DNA sequence is changed, resulting in an altered protein product.
E. an alteration in an organism's genetic material is made permanent.

When explaining dominant and recessive traits to a younger family member, they respond, "well chances are i can probably taste ptc, since dominant traits are more common." how might you address this misconception?

The activity of the modern sample is 1.10 bq . how long does that measurement take?

Lactase is essential for digesting lactose in milk. this enzyme is specific for this sugar. why? molecules and active sites vary in size; only properly sized molecules can fit. there is a precise compatibility between the active site and the lactose molecule. specificity refers to the action of the enzyme, such as hydrolysis, and relatively few molecules can be hydrolyzed. reaction-specific enzymes assume a fit by folding around the most numerous substrate molecules.