The key structural difference between DNA and RNA is A. RNA is a protein, while DNA is a nucleic acid. B. RNA is a polymer, but DNA is not. C. DNA contains a different sugar than RNA. D. RNA is a double helix, but DNA is not. E. All the bases in DNA differ from those in RNA.

 Living organisms are characterized by: A. adapting to the environment.B. evolving over time.C. displaying homeostatic controls.D. all of the choices pertain to living organisms.

Which of the following concepts is NOT one of the unifying theories of biology? A. All organisms are composed of cells.B. Life may arise through spontaneous generation.C. Life comes only from life.D. Organisms contain coded information that dictates their form, function, and, at times, behavior.E. All living things have a common ancestor and are adapted to a particular way of life

If a segment of DNA has 20% adenine in its base composition, what percent thymine is there? A. 20%B. 80%C. 60%D. 30%

A community of organisms along with their physical environment constitutes a(n)A) biosphere.B) ecosystem.C) population.D) habitat.E) community.

Choose the correct statement about proteins and their structure. A)Hydrogen bonding rarely occurs in proteins. B)Most proteins are made from a short chain of amino acids. C)A denatured protein is equally effective as the protein in its original shape .D)A protein’s conformation determines its function.

 All cells have these two characteristics: A. contain DNA in the nucleus and have a plasma membraneB. produce a cell wall outside of the plasma membraneC. contain mitochondria and chloroplastsD. have a plasma membrane and ribosomes in the cytoplasm

.Match the items below with their descriptions:

Which of the following elements is NOT one of the six most common in living organisms? A. carbonB. oxygenC. ironD. nitrogenE. hydrogen

The ______ of water molecules determines its chemistry and thus the chemistry of life. A.closeness B.cohesiveness C.wetness D.polarity