The factor being changed in a controlled experiment is called the

Why is there no external male reproductive organ in a frog?

Living matter is at least sixty percent water. It makes sense, then, that cell membranes are made of phospholipids because A) phosphates dissolve in water. B) the bilayer acts to repel water. C) the lipids form an insoluble barrier.

When DNA is being transcribed into mRNA, The C and G go together. The A in DNA would pair up with what in RNA? X G T U

Which of the following happens to chromosomes during prophase? A They move to opposite sides of the cell. B They become centrioles. They condense. D They disappear.

What happens in commensalism? A. both organisms benefit B. one organism benefits but the other is not harmed C. one organism benefits but the other is harmed D. both organisms work together

A species has homologous chromosomes. what does this say about the species?

Which has the greatest effect on the amount of salt in a salt marsh? These are the choices

The reproductive process that creates genetic variety in a population is

Which statement best describes an ecosystem maintaining a state of approximate equilibrium? (1) Nutrients from decayed organisms are recycled in a forest ecosystem. (2) All the frog species in a South American rain forest become extinct.

Which of these shows the correct pathway through the heart's four chambers after it enters from the vena cava? a. left ventricle - -> right atrium - -> left ventricle - -> left atrium b.