The incentives for developing vaccines for plants have never been

Question

The incentives for developing vaccines for plants have never been greater. The world’s farmers are spending about $25 billion per year on chemical sprays, yet diseases still destroy about twelve
(5) percent of the total harvest of food. When we want to protect children against disease, we use vaccines that stimulate their immune systems, but plants we simply douse in noxious chemicals. Spraying chemical agents to kill off crop diseases is so central
(10) to modern agriculture that the idea of vaccinating a plant seems thoroughly alien. However, biologists are now learning how to stimulate the natural biochemical mechanisms by which plants defend themselves from disease.

(15) A variety of “resistance genes” enable plants to detect particular infectious agents. A plant having the appropriate resistance gene will respond by instructing cells near the site of infection to die off. Cells around the infection die rapidly, depriving the
(20) invader of food, while cells immediately outside the dead area produce chemicals that thicken their walls. In a few days, the infection is isolated by a layer of dead cells. Plants will also actively attack infectious agents by producing compounds toxic to invading
(25) organisms or by producing enzymes that degrade the invader’s cell walls. Plants that do not possess resistance genes against a particular infectious organism can still, like animals, acquire immunity through being exposed to
(30) the organism. Unlike animals, plants infected with one disease can also acquire immunity to a wide range of other diseases. Immunologists have demonstrated that infecting cucumber seedlings with a controlled anthracnose fungus infection protected the seedlings
(35) against more severe infections for up to six weeks, radically reduced damage from subsequent anthracnose infections, and protected plants against twelve other bacterial, viral, and fungal diseases. The treatment did not, however, protect against powdery
(40) mildew. Unfortunately, immunization can also inhibit plant growth, presumably because defense mechanisms divert food resources. When deployed too vigorously, defense mechanisms may also damage the plant
(45) itself. Some substances made in response to disease are toxic to the plants that produce them, as well as to infectious organisms. Biologists will have to overcome these side effects if immunization is going to replace chemical spraying.     1 
 1. According to the passage, an unwanted side effect of plant immunization is that immunized plants

A. become more susceptible to certain infections, such as powdery mildew
B. become more vulnerable to uncontrolled infections from the same infectious agent used to immunize the plants
C. produce substances that are toxic to organisms that are beneficial to the plant
D. produce enzymes that can degrade the plants’ cell walls
E. focus their resources on fighting invading organisms, thereby impeding other plant processes

2  
 2. According to the passage, biologists can immunize a plant against an infectious organism by doing which of the following?

A. Manipulating the plant’s genetic code in order to give it the appropriate resistance genes
B. Exposing the plant to a controlled infection of the organism
C. Killing off cells near the site of the infection
D. Applying enzymes to the infectious organism in order to degrade its cell walls
E. Treating the plant with chemicals that thicken the plant’s cell walls

3 
 3. Which of the following best states the function of the first paragraph?
 
A. It presents an example to help illustrate a problem.
B. It discusses the history of a problem and its present implications.
C. It describes a situation and introduces a possible solution.
D. It reconciles two conflicting solutions to a problem.
E. It evaluates a possible solution to a problem.

Legallyblond · Answer

whats the source of this passage?

BhardwajS · Answer

Legallyblond  This is from official guide 2026-27

Bunuel · Answer

Please check the tags: https://gmatclub.com/forum/download/file.php?id=88619 GMAT-Club-Forum-w09vrm74.png

guddo · Answer

1. According to the passage, an unwanted side effect of plant immunization is that immunized plants

The passage says plant immunization can protect plants from disease, but it can also inhibit plant growth because the plant’s defense mechanisms divert food resources.  So the unwanted side effect is that the plant may use resources for defense instead of normal growth .

A. become more susceptible to certain infections, such as powdery mildew

This is incorrect. The passage says the treatment did not protect against powdery mildew, not that it made plants more susceptible to it.

B. become more vulnerable to uncontrolled infections from the same infectious agent used to immunize the plants

This is not stated. The controlled anthracnose infection protected the plants against more severe anthracnose infections.

C. produce substances that are toxic to organisms that are beneficial to the plant

This is not stated. The passage says some substances are toxic to infectious organisms and to the plants themselves, not to beneficial organisms.

D. produce enzymes that can degrade the plants’ cell walls

This is incorrect. The enzymes degrade the invader’s cell walls, not the plant’s own cell walls.

E. focus their resources on fighting invading organisms, thereby impeding other plant processes

This is correct. The passage says immunization can inhibit plant growth, presumably because defense mechanisms divert food resources. This matches the idea that  defense comes at a cost to normal plant growth .

Answer: (E)

guddo · Answer

2. According to the passage, biologists can immunize a plant against an infectious organism by doing which of the following?

The passage says plants without resistance genes can still acquire immunity by being exposed to the infectious organism. It then gives the cucumber example: seedlings were protected after being exposed to a controlled anthracnose infection.  So plant immunization can be done through controlled exposure  to the relevant  infectious organism .

A. Manipulating the plant’s genetic code in order to give it the appropriate resistance genes

This is incorrect. The passage mentions resistance genes, but it does not say biologists immunize plants by adding those genes.

B. Exposing the plant to a controlled infection of the organism

This is correct. The passage says plants can acquire immunity through exposure, and the cucumber seedlings were protected by a controlled anthracnose infection.

C. Killing off cells near the site of the infection

This is incorrect. That is part of the plant’s own defense response, not the method biologists use to immunize the plant.

D. Applying enzymes to the infectious organism in order to degrade its cell walls

This is incorrect. The passage says plants may produce such enzymes as a defense; it does not say biologists apply them to immunize plants.

E. Treating the plant with chemicals that thicken the plant’s cell walls

This is incorrect. Thickening cell walls is another part of the plant’s defense response, not the immunization method described.

Answer: (B)

guddo · Answer

3. Which of the following best states the function of the first paragraph?
 
The first paragraph explains the problem: farmers spend huge amounts on chemical sprays, yet crop diseases still destroy a significant part of the harvest. It then introduces the alternative idea of using plant “vaccines” by stimulating plants’ own defenses.  So the paragraph describes a situation and introduces a possible solution .

A. It presents an example to help illustrate a problem.

This is too narrow. The paragraph does not mainly give one example; it sets up the broader problem and introduces plant vaccination.

B. It discusses the history of a problem and its present implications.

This is incorrect. The paragraph does not trace the history of crop disease or pesticide use.

C. It describes a situation and introduces a possible solution.

This is correct. The situation is the heavy use of chemical sprays despite continuing crop losses, and the possible solution is  stimulating plants’ natural defenses .

D. It reconciles two conflicting solutions to a problem.

This is incorrect. The paragraph contrasts chemical spraying with plant vaccination, but it does not reconcile them.

E. It evaluates a possible solution to a problem.

This is incorrect. The detailed evaluation of plant immunization comes later, especially when the passage discusses its limits and side effects.

Answer: (C)

The incentives for developing vaccines for plants have never been

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The incentives for developing vaccines for plants have never been

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