Reading Passage Question
Desert plant populations have evolved sophisticated physiological behavioral traits that aid survival in arid conditions. Some send out long, unusually deep taproots; others utilize shallow but widespread roots, which allow them to absorb large, intermittent flows of water. Certain plants protect their access to water. The creosote bush produces a potent root toxin which inhibits the growth of competing root systems. Daytime closure of stomata exemplifies a further genetic adaptation; guard cells work to minimize daytime water loss, later allowing the stomata to open when conditions are more favorable to gas exchange with the environment. Certain adaptations reflect the principle that a large surface area facilitates water and gas exchange. Most plants have small leaves, modified leaves (spines), or no leaves at all. The main food-producing organ is not the leaf but the stem, which is often green and non-woody. Thick, waxy stems and cuticles, seen in succulents such as cacti and agaves, also help conserve water. Spines and thorns (modified branches) protect against predators and also minimize water loss.
“Desert plant populations have evolved sophisticated physiological behavioral traits that aid survival in arid conditions.” - this is a GMAT reading comprehension passage with answers. Candidates need a strong knowledge of English GMAT reading comprehension.
This GMAT Reading Comprehension consists of 4 comprehension questions. The GMAT Reading Comprehension questions are designed for testing candidates’ abilities in understanding, analyzing, and applying information or concepts. Candidates can actively prepare with the help of GMAT Reading Comprehension Practice Questions.
Solution and Explanation
- The passage refers to the spines and thorns of desert plants as
- genetically evolved structural adaptations that protect against predation
- genetic modifications that aid in the reduction of water loss
- structures that do not participate directly in food production
(A) I only
(B) III only
(C) I and II only
(D) II and III only
(E) I, II and III
Answer: E
Explanation: The author focuses on structural and behavioral adaptations of desert plants in the passage. The word “genetic” is mentioned in the last sentence of the first paragraph. We see that many of these modifications are genetic. This helps to reduce water loss. Spines and thorns, modified as leaves and branches, are genetic adaptations. We can confirm option iii from the third sentence of the second paragraph. Most of a desert plant’s food is produced in its stem, not in its leaves. This means that spines and thorns are not related to food production. Since all the options are mentioned, E is the correct answer.
- The author suggests that the guard cells of desert plants act to do which of the following?
- Facilitate gas and water exchange between the plants and their surroundings
- Cause the stomata of desert plants to remain closed during daytime hours
- Respond to sudden, heavy rainfalls by forcing the plants’ stomata to open
(A) I only
(B) II only
(C) III only
(D) I and II only
(E) I, II, and III
Answer: D
Explanation: We need to focus on the functioning of guard cells. This is mentioned in the sentence that concludes the first paragraph. This sentence mentions two related plant features: the stomata and the guard cells. We see that daytime closing of the stomata is an adaptation which helps to minimize daytime water loss. The second half of the sentence implies that it’s the guard cells that control this opening and closing of the stomata. The first two options are correct, making D the correct answer.
- The passage suggests that which of the following weather-related conditions would most benefit plants with shallow root systems?
(A) An unusually prolonged drought
(B) A windstorm
(C) A flash flood
(D) A light spring rain
(E) A winter snowfall
Answer: C
Explanation: We see that the shallow root systems are mentioned in the second sentence. The point is that these specially adapted roots allow desert plants to take advantage of heavy, irregular flows of water. The author also provides examples like very heavy or torrential downpours. This also means flash flood. Flash floods result from unexpected, torrential rainfall. Hence, C is the correct answer.
- The adaptations of desert plants to their environment would tend to support the statement that
(A) the rate of genetic evolution is greater in the desert than in more temperate surroundings
(B) structures in a plant which usually perform one function may, under certain conditions, perform different functions
(C) while the amount of leaf surface area is critical for a desert plant, it is much less so for plants in most other environments
(D) desert plants do not have many physiological and behavioral traits in common with other plants
(E) desert plants could probably adapt to life in a variety of harsh ecosystems
Answer: B
Explanation: As per the passage, the main food-producing organs are not the leaf but the stem. This is often green and non-woody. This means that food is not produced by leaves but by my stem. Modified leaves and branches serve other purposes - protect against predators and minimize water loss. So some structures in a plant which usually perform one function may, under certain conditions, perform different functions is correct. Hence, B is the correct option.
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