• Free Practice Test & Review
How would you score if you took the GMAT

Available with Beat the GMAT members only code

• 5-Day Free Trial
5-day free, full-access trial TTP Quant

Available with Beat the GMAT members only code

• 1 Hour Free
BEAT THE GMAT EXCLUSIVE

Available with Beat the GMAT members only code

• Award-winning private GMAT tutoring
Register now and save up to $200 Available with Beat the GMAT members only code • Free Trial & Practice Exam BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE Available with Beat the GMAT members only code • FREE GMAT Exam Know how you'd score today for$0

Available with Beat the GMAT members only code

• 5 Day FREE Trial
Study Smarter, Not Harder

Available with Beat the GMAT members only code

• Magoosh
Study with Magoosh GMAT prep

Available with Beat the GMAT members only code

• Free Veritas GMAT Class
Experience Lesson 1 Live Free

Available with Beat the GMAT members only code

# This topic has 3 expert replies and 0 member replies

AbeNeedsAnswers Master | Next Rank: 500 Posts
Joined
02 Jul 2017
Posted:
192 messages
Followed by:
2 members
1

#### OG All the cells in a particular plant

Sun Sep 17, 2017 3:14 pm
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.

128. According to the passage, the five well-known plant hormones are not useful in controlling the growth of crops because
(A) it is not known exactly what functions the hormones perform
(B) each hormone has various effects on plants
(C) none of the hormones can function without the others
(D) each hormone has different effects on different kinds of plants
(E) each hormone works on only a small subset of a cell's genes at any particular time

192. 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?
(A) plant cell walls
(B) the complement of genes in each plant cell
(C) a subset of a plant cell's gene complement
(D) the five major hormones
(E) the oligosaccharins

103. The passage suggests that which of the following is a function likely to be performed by an oligosaccharin?
(A) to stimulate a particular plant cell to become part of a plant's root system
(B) to stimulate the walls of a particular cell to produce other oligosaccharins
(C) to activate enzymes that release specific chemical messengers from plant cell walls
(D) to duplicate the gene complement in a particular plant cell
(E) to produce multiple effects on a particular subsystem of plant cells

131. The author mentions specific effects that auxin has on plant development in order to illustrate the
(A) point that some of the effects of plant hormones can be harmful
(B) way in which hormones are produced by plants
(C) hierarchical nature of the functioning of plant hormones
(D) differences among the best-known plant hormones
(E) concept of pleiotropy as it is exhibited by plant hormones

132. According to the passage, which of the following best describes a function performed by oligosaccharins?
(A) regulating the daily functioning of a plant's cells
(B) interacting with one another to produce different chemicals
(C) releasing specific chemical messengers from a plant's cell walls
(D) producing the hormones that cause plant cells to differentiate to perform different functions
(E) influencing the development of a plant's cells by controlling the expression of the cells' genes

133. The passage suggests that, unlike the pleiotropic hormones, oligosaccharins could be used effectively to
(A) trace the passage of chemicals through the walls of cells
(B) pinpoint functions of other plant hormones
(C) artificially control specific aspects of the development of crops
(D) alter the complement of genes in the cells of plants
(E) alter the effects of the five major hormones on plant development

Q128:B
Q129:D
Q130:A
Q131:E
Q132:E
Q133:C

### GMAT/MBA Expert

DavidG@VeritasPrep Legendary Member
Joined
14 Jan 2015
Posted:
2667 messages
Followed by:
120 members
1153
GMAT Score:
770
Fri Oct 13, 2017 10:23 am
Quote:
128. According to the passage, the five well-known plant hormones are not useful in controlling the growth of crops because
(A) it is not known exactly what functions the hormones perform
(B) each hormone has various effects on plants
(C) none of the hormones can function without the others
(D) each hormone has different effects on different kinds of plants
(E) each hormone works on only a small subset of a cell's genes at any particular time
In paragraph 2, we get this sentence about plant hormones: The five have so many simultaneous effects that they are not very useful in artificially controlling the growth of crops.

_________________
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save $100 off any live Veritas Prep GMAT Course Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now! ### GMAT/MBA Expert DavidG@VeritasPrep Legendary Member Joined 14 Jan 2015 Posted: 2667 messages Followed by: 120 members Upvotes: 1153 GMAT Score: 770 Fri Oct 13, 2017 10:25 am Quote: 129. 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? (A) plant cell walls (B) the complement of genes in each plant cell (C) a subset of a plant cell's gene complement (D) the five major hormones (E) the oligosaccharins The first line of paragraph 3: The pleiotropy of the five well-studied plant hormones is somewhat analogous to that of certain hormones in animal. We then get a discussion of hypothalamic hormones in animals. The answer is D _________________ Veritas Prep | GMAT Instructor Veritas Prep Reviews Save$100 off any live Veritas Prep GMAT Course

Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now!

### GMAT/MBA Expert

DavidG@VeritasPrep Legendary Member
Joined
14 Jan 2015
Posted:
2667 messages
Followed by:
120 members
1153
GMAT Score:
770
Fri Oct 13, 2017 10:33 am
Quote:
130. The passage suggests that which of the following is a function likely to be performed by an oligosaccharin?
(A) to stimulate a particular plant cell to become part of a plant's root system
(B) to stimulate the walls of a particular cell to produce other oligosaccharins
(C) to activate enzymes that release specific chemical messengers from plant cell walls
(D) to duplicate the gene complement in a particular plant cell
(E) to produce multiple effects on a particular subsystem of plant cells
The second and third sentences of the first paragraph: 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.

The point of the passage is to explain how a plant's regulatory system produces these discrete structures. We learn in the final paragraph the system works as follows: hormones --> enzymes ---> oligosaccharins --> specific effect on target structures. In other words, the oligosaccharins are the answer to the question of who allows cells to differentiate into structures such as roots. The answer is A

_________________
Veritas Prep | GMAT Instructor

Veritas Prep Reviews
Save \$100 off any live Veritas Prep GMAT Course

Enroll in a Veritas Prep GMAT class completely for FREE. Wondering if a GMAT course is right for you? Attend the first class session of an actual GMAT course, either in-person or live online, and see for yourself why so many students choose to work with Veritas Prep. Find a class now!

### Top First Responders*

1 Jay@ManhattanReview 64 first replies
2 GMATGuruNY 59 first replies
3 Rich.C@EMPOWERgma... 34 first replies
4 Brent@GMATPrepNow 24 first replies
5 ceilidh.erickson 6 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

### Most Active Experts

1 Jeff@TargetTestPrep

Target Test Prep

132 posts
2 GMATGuruNY

The Princeton Review Teacher

94 posts
3 Brent@GMATPrepNow

GMAT Prep Now Teacher

88 posts
4 Scott@TargetTestPrep

Target Test Prep

85 posts
5 Max@Math Revolution

Math Revolution

82 posts
See More Top Beat The GMAT Experts