FREE Reading Comprehension Practice Problems for CAT

Tips on how to approach CAT Reading Comprehension passages
  • Don’t get into the minor details of the passage; just focus on what each paragraph has to say
  • As you read, create a map of the passage; you must remember what thing is located where in the passage
  • Once you read the question, come back to the part of the passage that is likely to have the answer
  • Compare the options and eliminate the incorrect choices based on the evidence that you see in the passage
  • Choose the answer once you are convinced of the right choice

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Reading Comprehension Practice Passage

All of the cells in a particular plant start out with the same complement of genes. How then can these cells differentiate and form structures as different as roots, stems, leaves, and fruits? The answer is that only a small subset of the genes in a particular kind of cell are expressed, or turned on, at a given time. This is accomplished by a complex system of chemical messengers that in plants include hormones and other regulatory molecules. Five major hormones have been identified: auxin, abscisic acid ), cytokinin, ethylene, and gibberellin. Studies of plants have now identified a new class of regulatory molecules called oligosaccharins.

Unlike the oligosaccharins, the five well-known plant hormones are pleiotropic rather than specific; that is, each has more than one effect on the growth and development of plants. The five has so many simultaneous effects that they are not very useful in artificially controlling the growth of crops. Auxin, for instance, stimulates the rate of cell elongation, causes shoots to grow up and roots to grow down, and inhibits the growth of lateral shoots. Auxin also causes the plant to develop a vascular system, to form lateral roots, and to produce ethylene.

The pleiotropy of the five well-studied plant hormones is somewhat analogous to that of certain hormones in animal. For example, hormones from the hypothalamus in the brain stimulate the anterior lobe of the pituitary gland ) to synthesize and release many different hormones, one of which stimulates the release of hormones from the adrenal cortex . These hormones have specific effects on target organs all over the body. One hormone stimulates the thyroid gland, for example, another the ovarian follicle cells, and so forth. In other words, there is a hierarchy of hormones. Such a hierarchy may also exist in plants. Oligosaccharins are fragments of the cell wall released by enzymes: different enzymes release different oligosaccharins. There are indications that pleiotropic plant hormones may actually function by activating the enzymes that release these other, more specific chemical messengers from the cell wall.

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Question: According to the passage, the five well-known plant hormones are not useful in controlling the growth of crops because

it is not known exactly what functions the hormones perform
each hormone has various effects on plants
none of the hormones can function without the others
each hormone has different effects on different kinds of plants
each hormone works on only a small subset of a cell’s genes at any particular time

Question: The passage suggests that the place of hypothalamic hormones in the hormonal hierarchies of animals is similar to the place of which of the following in plants?

Plant cell walls
The complement of genes in each plant cell
A subset of a plant cell’s gene complement
The five major hormones
The oligosaccharins

Question: The passage suggests that which of the following is a function likely to be performed by an oligosaccharin?

To stimulate a particular plant cell to become part of a plant’s root system
To stimulate the walls of a particular cell to produce other oligosaccharins
To activate enzymes that release specific chemical messengers from plant cell walls
To duplicate the gene complement in a particular plant cell
To produce multiple effects on a particular subsystem of plant cells

Question: The author mentions specific effects that auxin has on plant development in order to illustrate the

point that some of the effects of plant hormones can be harmful
way in which hormones are produced by plants
hierarchical nature of the functioning of plant hormones
differences among the best-known plant hormones
concept of pleiotropy as it is exhibited by plant hormones

Question: According to the passage, which of the following best describes a function performed by oligosaccharins?

Regulating the daily functioning of a plant’s cells
Interacting with one another to produce different chemicals
Releasing specific chemical messengers from a plant’s cell walls
Producing the hormones that cause plant cells to differentiate to perform different functions
Influencing the development of a plant’s cells by controlling the expression of the cells’ genes

Question: The passage suggests that, unlike the pleiotropic hormones, oligosaccharins could be used effectively to

trace the passage of chemicals through the walls of cells
pinpoint functions of other plant hormones
artificially control specific aspects of the development of crops
alter the complement of genes in the cells of plants
alter the effects of the five major hormones on plant development

Question: The author discusses animal hormones primarily in order to

introduce the idea of a hierarchy of hormones
explain the effects that auxin has on plant cells
contrast the functioning of plant hormones and animals hormones
illustrate the way in which particular hormones affect animals
explain the distinction between hormones and regulatory molecules

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