1. The simple of these is the carbon dioxide from the respiration of an ant cluster, a chemical that acts pheromone to promote aggregation.
The word "cluster" is closest in meaning to which of following?
(A) organ
(B) activity
(C) group
(D) cycle
2. Fire ants also make use of an alarm pheromone to alert workers to an emergency, and their scouts lay down a trail pheromone as a guide during mass migrations.
The word "alert" is closest in meaning to which of following?
(A) allow
(B) transport
(C) warn
(D) provide
3. A fire ant queen emits a chemical signal that identifies her to the colony's workers. They respond by scurrying to gather around her. The decomposing corpse of a dead ant also generates a signal, to which workers respond by eliminating the corpse from the nest.
The word "scurrying" is closest in meaning to which of following?
(A) agreeing
(B) appearing
(C) competing
(D) rushing
4. Rivers also reveal clay along their banks, and erosion on a hillside may make clay easily accessible.
The word "accessible" is closest in meaning to which of following?
(A) buried
(B) improved
(C) available
(D) workable
5. Variations of clay composition and the temperatures at which they are fired account for the differences in texture and appearance between a china teacup and an earthenware flowerpot.
The phrase "account for" is closest in meaning to which of following?
(A) reduce
(B) explain
(C) combine with
(D) list all of
