Reading Passage Question
A freshwater lake's summertime ecology is significantly affected by a phenomenon known as the thermocline. In a typical deep-water impoundment in the southern United States, the water temperature measures a uniform 38-42 degrees in late winter after any surface ice has melted. Wave action stirs oxygen into the water at the lake's surface, and the temperature uniformity allows distribution of this dissolved oxygen to all depths. With oxygen plentiful, many of the reservoir's fish species, both predator and forager, are found throughout the water column.
As the lake's surface temperature increases in early spring, that water expands. A layer of warmer water builds at the surface of the lake, resting like a pillow on the mass of colder water below. The pillow of warm surface water slowly increases in thickness, as heat is transferred into the depths by the limited stirring of wave action. By early summer, a sharp boundary separates two independent bodies of water within the lake. The boundary is a temperature gradient called the thermocline, and it acts as a barricade to prevent any further mixing of oxygen into the chilly depths. The temperature barrier prevents oxygen from circulating downward from the surface, as it does in the winter, to replace the oxygen consumed by fish and dying zooplankton. In order to survive, fish are forced upward into the relatively narrow zone between the thermocline and the surface.
The cold nights of autumn cool the surface to the point that it is heavier than the water below the thermocline. In a process known as the turnover, a current of richly oxygenated water plunges to the bottom of the reservoir, forcing stagnant water back to the surface. The lake reaches equilibrium by early winter and remains there until the process repeats itself the following spring.
“A freshwater lake's summertime ecology is significantly affected”- is a GMAT reading comprehension passage with answers. Candidates must have a solid grasp on English GMAT reading comprehension. There are four comprehension questions in this GMAT Reading Comprehension section. GMAT Reading Comprehension questions are designed to evaluate candidates' abilities to comprehend, analyze, and apply information or concepts. Candidates can actively prepare by answering GMAT Reading Comprehension Practice Questions.
Solutions and Explanation
- The passage suggests that which one of the following can be inferred about dissolved oxygen in a lake?
(A) The colder the water, the less dissolved oxygen it can hold.
(B) There is always more dissolved oxygen within six feet of the surface than at 60 feet beneath the surface.
(C) The formation of ice can completely block the supply of dissolved oxygen.
(D) Dissolved oxygen is not necessary for organisms other than fish and zooplankton.
(E) Wave action at the surface increases dissolved oxygen levels in the lake.
Answer: (E)
Explanation: The first paragraph of the passage makes a crucial point about dissolved oxygen. The lake's surface is oxygenated by wave action. The lake's uniform temperature makes it possible for this dissolved oxygen to reach all depths. The statement in the final option can correspond to this description and is therefore the right answer.
- The passage suggests that the effects of temperature stratification
(A) would be relevant to the interests of fisheries managers
(B) on an individual lake cannot be predicted
(C) represent the most important factor influencing a lake's ecology
(D) become more pronounced as a lake gets older
(E) are most severe in the lakes of the southern United States
Answer: (A)
Explanation: The first option is the correct answer. This is due to the inference that the fisheries could profit from information of temperature stratification. Since they would be familiar with the distribution of fish along the various layers of the lake that were formed during various seasons, this can be assumed.
- Which one of the following is not mentioned in the passage as a step in the yearly lake stratification process?
(A) Fish congregate in the water layer above the thermocline in the summer.
(B) Water temperatures achieve a general uniformity by late winter.
(C) The thermocline reaches its maximum depth by early summer.
(D) Oxygen levels decline in the layer beneath the thermocline.
(E) The fall turnover replaces stagnant water in the depths with oxygen-rich water.
Answer: (C)
Explanation: The third option states that by early summer. The thermocline has reached its deepest point. This cannot be inferred with the passage as it is uncertain whether it will reach its maximum depth by summer or spring. Therefore the third option is the right answer. The remaining options are all wrong answers as the statements in them are clearly mentioned in the passage.
- The author is primarily interested in discussing
(A) the effect of fish and other aquatic organisms on a phenomenon known as the thermocline
(B) the relationship between a lake's ecology and water purity
(C) the contribution of the thermocline to overfishing in Southern lakes
(D) an effect of the seasonal warming and cooling of water in freshwater lakes
(E) the changes in a lake's water temperature caused by fluctuating oxygen levels
Answer: (D)
Explanation: The author defines the term thermocline/temperature gradient, explains what it is. Then talks about how the process affects the lake's ecology. The statement given in the fourth option is in correspondence with this pre-thinking and is therefore the right choice. The rest of the options are all wrong answers as the statements in them have distorted or irrelevant information.
Suggested GMAT Reading Comprehension Samples
- In his 1976 study of slavery in the United States, Herbert Gutman GMAT Reading Comprehension
- Great comic art is never otherwordly, it does not seek to mystify us GMAT Reading Comprehension
- Early models of the geography of the metropolis were unicellular GMAT Reading Comprehension
- Many Native Americans view the archaeological excavation and museum display of ancestral skeletal GMAT Reading Comprehension
- With their recognition of Maxine Hong Kingston as a major literary figure GMAT Reading Comprehension
- The recurring theme of equality in the United States has flared into a fervent moral issue at crucial stages GMAT Reading Comprehension
- In the year 1885, the Eiffel firm, which was named after the French engineer and architect Gustave Eiffel and which had extensive experience in structural engineering GMAT Reading Comprehension
- In the history of nineteenth-century landscape painting in the United States, the Luminists are distinguished GMAT Reading Comprehension
- The principle of selection solved the riddle as to how what was purposive GMAT Reading Comprehension
- The painter Roy Lichtenstein helped to define pop art GMAT Reading Comprehension
- Henry Varnum Poor, editor of American Railroad Journal, drew the important elements GMAT Reading Comprehension
- Antonia Castañeda has utilized scholarship from women's studies and Mexican-American history to examine nineteenth-century literary portrayals of Mexican women GMAT Reading Comprehension
- Premillennialism - a type of eschatology (the study of the last things) based on a literal GMAT Reading Comprehension
- Recent studies on Native American languages point towards an alarming problem in the United States today GMAT Reading Comprehension
- Thomas Hardy’s impulses as a writer, all of which he indulged in his novels, were numerous and divergent GMAT Reading Comprehension
- The Establishment Clause and the Free Exercise Clause of the First Amendment to the US Constitution GMAT Reading Comprehension
- Many critics of Emily Brontë’s novel Wuthering Heights see its second part as a counter-point GMAT Reading Comprehension
- James Porter (1905-1970) was the first scholar to identify the African influence on visual art in the Americans GMAT Reading Comprehension
- There is substantial evidence that by 1926, with the publication of The Weary Blues, Langston Hughes had broken with two well-established traditions in African American literature GMAT Reading Comprehension
- The struggle to obtain legal recognition of aboriginal rights is a difficult one GMAT Reading Comprehension
Comments