21) Butter, which is made from milk fat, tends to be harder at room temperature than most margarines. If you wanted to make a butter that is softer at room temperature, you should consider:

A) making the fatty acid chains longer.

B) making fatty acid chains with fewer kinks.

C) creating more double bonds in the fatty acid chains.

D) saturating the fatty acid chains.

E) adding more than three fatty acid chains to the triglycerides.

22) What is a triglyceride?

A) a lipid made of one glycerol and two fatty acids

B) a lipid made of two glycerols, a fatty acid, and a phosphate group

C) a lipid made of one glycerol and three fatty acids

D) a carbohydrate made of three sugars

E) a polypeptide made of three amino acids

23) You notice that water is running off the feathers of a bird in the rain. The reason is probably that the bird has coated the feathers with ________, which keeps the water out of them.

A) proteins

B) polysaccharides

C) lipids

D) nucleic acids

24) What do wax and testosterone have in common?

A) They are both hormones.

B) They are both proteins.

C) They are both steroids.

D) They are both lipids.

25) Which of the following lipids is the primary component in cell membranes?

A) triglycerides

B) steroids

C) phospholipids

D) glycerol

26) Which of the following is true of steroids?

A) Steroids exist naturally in humans as hormones.

B) Some amino acids are steroids.

C) If people inject male steroid hormones, they can build muscle mass with no side effects.

D) Steroids contain a central, single-ring carbon structure.

E) Steroids are polymers.

27) Which of the following is an example of a lipid?

A) cholesterol

B) cellulose

C) keratin

D) chitin

28) If you removed the cuticle from the skin of an apple, the:

A) apple would absorb moisture and get soggy.

B) apple would lose water and dehydrate.

C) seeds of the apple would die.

D) apple would be inedible.

29) Unsaturated fatty acids:

A) have one or more double bonds between the carbons.

B) are usually found in animal fats.

C) have long been linked with heart disease.

D) contain the maximum number of hydrogen atoms possible.

30) The hydrogenation of vegetable oil results in:

A) an increase in the number of double bonds between the carbon atoms.

B) the oil becoming more liquid at room temperature.

C) a decrease in the number of double bonds between the carbon atoms.

D) the conversion of monounsaturated fatty acids into polyunsaturated fatty acids.

E) a decrease in the number of hydrogen atoms in the oil molecule.