The most popular organic gem is the pearl. A pearl is the response of a marine mollusk
to the presence of an irritating impurity accidentally introduced into its body; a cultured pearl
is the result of the intentional insertion of a mother-of-pearl bead into a live mollusk. Whether
introduced accidentally or intentionally, the pearl-making process is the same: the mollusk
coats the irritant with a substance called nacre. Nacre is composed chiefly of calcium
carbonate. Because very few natural pearls are now on the market, most pearls used in fine
jewelry are cultured. These include "Biwa" pearls and most other freshwater pearls. Cultured
pearls are not easily distinguished from natural pearls except by an expert
11. Which of the following people could tell the difference between a cultured pearl and an organic pearl?
(A) Scuba diver
(B) Fisherman
(C) Jeweler
(D) Clerk
12. In line 2, "impurity" most nearly means
(A) mollusk.
(B) contaminant.
(C) pearl.
(D) diver.
13. In line 5, "irritant" most nearly means
(A) annoyance.
(B) aid.
(C) relief.
(D) jewelry.
14. What is the chief component of nacre?
(A) Sand
(B) Bead
(C) Calcium carbonate
(D) Biwa
15. In line 3, "intentional" most nearly means
(A) deliberate.
(B) accidental.
(C) unconscious.
(D) forceful.
16. A pearl is
(A) a rock.
(B) a gemstone.
(C) a mineral.
(D) an organic gem.
17. The difference between a pearl and a cultured pearl is the nature of the
(A) color.
(B) introduction of the irritating impurity.
(C) coating material.
(D) irritating impurity
18. Nacre is a substance that is
(A) mechanically manufactured.
(B) the result of laboratory testing.
(C) organically secreted by the mollusk.
(D) present in the chemical composition of freshwater pounds.
19. The main idea in this passage is that
(A) most marketable pearls are cultured because nature does not produse enough of its own to satisfy the market.
(B) cultured pearls are of a higher quality than natural pearls.
(C) there are two major methods of pearl-making.
(D) a natural "drought" of pearl production is taking place.
20. A mollusk, while not defined in this passage, must be
(A) any animal.
(B) a land animal.
(C) the water organism which produces the pearl
(D) all the above