31. The phrase "smooth operation" in line 1 is closest in meaning to
(A) daily activity
(B) effective functioning
(C) delicate balance
(D) permanent location

27. Based on the information in the passage, it can be inferred that low-fire clays are MOST appropriate for making objects that (A) must be strong (B) can be porous (C) have a smooth texture (D) are highly decorated

28. The phrase "account for" in line 22 is closest in meaning to (A) reduce (B) explain (C) combine with (D) list all of

29. The passage supports which of the following conclusions? (A) Clay deposits are only found deep in the Earth. (B) If clay contains too much iron it will melt when fired. (C) Only certain types of clay are appropriate for making china teacups. (D) If sufficient heat is applied, all clay will become nonporous.

30. What aspect of ants does the passage mainly discuss? (A) The relationship between the queen and the worker ants (B) Ways in which ants use chemical signals (C) Methods ants use to identify food sources (D) The importance of respiration in the production of ant pheromones

32. According to the passage, carbon dioxide serves which of the following functions for fire ants? (A) It protects the queen. (B) It attracts other ant species. (C) It informs workers of possible danger. (D) It encourages the ants to gather together.

33. The word "cluster" in line 4 is closest in meaning to (A) organ (B) activity (C) group (D) cycle

34.According to the passage, each nest has a distinct odor that allows its inhabitants to (A) find the location of the nest in the dark (B) distinguish worker ants from other ants (C) distinguish foreign ants from resident ants (D) signal other inhabitants when foreign ants attack

35. The word "alert" in line 13 is closest in meaning to (A) allow (B) transport (C) ware (D) provide

36. What is the role of pheromones in the mass migrations of ants? (A) Pheromones are used to create a trail that directs the ants during migrations. (B) Pheromones signal the ants that the nest has been invaded and must be abandoned. (C) Pheromones control the speed at which ants move from one location to another. (D) Pheromones enable scouts to identify suitable areas for establishing a new nest.

37. The word "scurrying" in line 16 is closest in meaning to (A) agreeing (B) appearing (C) competing (D) rushing