Chapter 3

A glucose molecule is to starch as (Explain your answer.) a. a steroid is to a lipid. b. a protein is to an amino acid. c. a nucleic acid is to a polypeptide. d. a nucleotide is to a nucleic acid.

Cows can derive nutrients from cellulose because a. they produce enzymes that recognize the shape of the glucose-glucose bonds and hydrolyze them. b. they re-chew their cud to break down cellulose fibers. c. their digestive tract contains microorganisms that can hydrolyze the bonds of cellulose. d. they convert cellulose to starch and can digest starch.

Of the following functional groups, which is/are polar, tending to make organic compounds hydrophilic? a. carbonyl b. amino c. hydroxyl d. all of the above

Unsaturated fats a. have double bonds in their fatty acid chains. b. have fewer fatty acid molecules per fat molecule. c. are associated with greater health risks than are saturated fats. d. are more common in animals than in plants.

A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture a. DNA. b. proteins. c. cellulose. d. sucrose.

Which structural level of a protein would be least affected by a disruption in hydrogen bonding? a. primary structure b. secondary structure c. tertiary structure d. quaternary structure

Most proteins are soluble in the aqueous environment of a cell. Knowing that, where in the overall three-dimensional shape of a protein would you expect to find amino acids with hydrophobic R groups?

Explain the role of complementary base pairing in the functions of nucleic acids.

What are the two types of secondary structures found in polypeptides, and what maintains them? What stabilizes the tertiary structure of a polypeptide?

The diversity of life is staggering. Yet the molecular logic of life is simple and elegant: Small molecules common to all organisms are ordered into unique macromolecules. Explain why carbon is central to this diversity of organic molecules. How do carbon skeletons, chemical groups, monomers, and polymers relate to this molecular logic of life?

Given that the function of egg yolk is to nourish and support the developing chick, explain why egg yolks are so high in fat, protein, and cholesterol.