Why is evolution considered a theory?

A. It was proposed by a scientist.

B. It cannot be proven.

C. It is a guess about what happened.

D. It is backed up by scientific evidence.

What would happen if the valves separating the chambers in a person's heart did not close? The volume of blood pumped from the atria to the body would be reduced because blood would backflow into the ventricles.

Answer the following questions about Ebola: Where did they occur? How did they start? How did they spread? How deadly are they? Is there a vaccine? Find out if the virus is gone, or is it still a problem.

Why do a chicken embryo and a cow embryo look very similar even though the adults do not? a. They are not related, but still have similar development. b. They are distantly related, so their development is similar. c.

Charles darwin, after observing variability among plant and animal species in various locations, proposed an explanation for what he saw.

Which organism would more closely resemble it's parent, one produced by asexual reproduction, or one produced by sexual reproduction? why?

Which of the following represents the treatment option most likely to avoid the evolution of drug-resistant HIV (assuming no drug interactions or side effects) ?

Which of the following connective tissues is richly vascularized and consists of more cells than extracellular matrix? A) Adipose b) Dense regular C) Areolar D) Hyaline cartilage

Humans and apes have five fingers they can use to grasp objects. do you think these are analogous or homologous structures? explain your answer.

During which two minute time period is the temperature of the water changing fastest?

The human body is made up of: nucleus absorption cells neurons