Bio Quiz

A culture of spirogyra (an autotrophic alga) 1s maintained in a water solution containing dissolved carbon dioxide and a source of phosphates but lacking nitrogen compounds. A researcher determines the rates of synthesis of several organic compounds found in the Spirogyra before and after several weeks in the water solution. Which of the following graphs best illustrates a likely result of the experiment?

B

Scientists examined the folded structure of a purified protein resuspended in water and found that amino acids with

nonpolar R groups were primarily buried in the middle of the protein, whereas amino acids with polar R group: were primarily on the surface of the protein. Which of the following best explains the location of the amino acids 1r the folded protein?

C

A mutation in the gene coding for a single-polypeptide enzyme results in the substitution of the amino acid serine which has a polar R group, by the amino acid phenylalanine, which has a nonpolar R group. When researchers test

the catalvss of the normal enzyme and the mutated enzme. they lind that the mutated enzme has much lowe activity than the normal enzyme does.

B

Cholinesterase is an enzyme that catalyzes the hydrolysis of the signaling molecule acetylcholine. Which of the following best explains how cholinesterase carries out its function:

A

Which of the following best describes the effect of a greater number of cysteine amino acids on the stability of the proteins?

B

Which of the following best explains the reactions of these enzymes?

B

Which of the following best describes the hyddrolosis of carbohydrates.

C

Which of the following best explains why hydrogenation converts liquid lipids to solid lipids?

A

Based on Figure 1, the amino acids in region A are most likely to have which of the following characteristics?

A

Which of the following best describes the process by which gas from the atmosphere is obtained by plants and used to build lipids

C

The synthesis of protein or carbohydrate polymers always produces which of the following as a byproduct?

Water (E)

Humans produce sweat as a cooling mechanism to maintain a stable internal temperature. Which of the following best explains how the properties of water contribute to this physiological process?

B