Reading Skill: Main Idea
With Main Idea questions the test makers want to understand how good you are in getting to the gist of the passage. The best strategies to follow are the following:
1) Don't get lost in the details
The most common mistake test takers make is taking time to read the entire passage in detail and trying to understand every miniscule facts mentioned in the passage. This approach is counterproductive. Skip through the details and read through the first and last line in each paragraph. Skim through the rest of the lines.
2) Summarize each paragraph
Once you have read the first and last line in each paragraph summarize each paragraph in one line. The summary of each paragraph should cover the central idea of the paragraph.
3) Paraphrase the main summary
Try to paraphrase the main summary from the summaries of each paragraph. Sometimes the main idea is explicitly mentioned in one of the summaries and sometimes it would be hidden in the summaries.
4) Eliminate and Select
Now go through each answer options and eliminate options that are irrelevant, out of scope or that tries to generalize or classify the summary to a smaller category. Select the answer option which is most close to the paraphrased main summary and voila you cracked the Main Idea question. Now let's apply the strategy for the following.
P1: Until recently, scientists did not know of a close vertebrate analogue to the extreme form of altruism observed in eusocial insects like ants and bees, whereby individuals cooperate, sometimes even sacrificing their own opportunities to survive and reproduce, for the good of others. However, such a vertebrate society may exist among underground colonies of the highly social rodent Heterocephalus glaber, the naked mole rat.
P2: A naked mole rat colony, like a beehive, wasp’s nest, or termite mound, is ruled by its queen, or reproducing female. Other adult female mole rats neither ovulate nor breed. The queen is the largest member of the colony, and she maintains her breeding status through a mixture of behavioral and, presumably, chemical control. Queens have been long-lived in captivity, and when they die or are removed from a colony one sees violent fighting for breeding status among the larger remaining females, leading to a takeover by a new queen.
P3: Eusocial insect societies have rigid caste systems, each insect’s role being defined by its behavior, body shape, and physiology. In naked mole rat societies, on the other hand, differences in behavior are related primarily to reproductive status (reproduction being limited to the queen and a few males), body size, and perhaps age. Smaller non-breeding members, both male and female, seem to participate primarily in gathering food, transporting nest material, and tunneling. Larger non-breeders are active in defending the colony and perhaps in removing dirt from the tunnels. Jarvis’ work has suggested that differences in growth rates may influence the length of time that an individual performs a task, regardless of its age.
P4:Cooperative breeding has evolved many times in vertebrates, but unlike naked mole rats, most cooperatively breeding vertebrates (except the wild dog, Lycaon pictus) are dominated by a pair of breeders rather than by a single breeding female. The division of labor within social groups is less pronounced among other vertebrates than among naked mole rats, colony size is much smaller, and mating by subordinate females may not be totally suppressed, whereas in naked mole rat colonies subordinate females are not sexually active, and many never breed.
HOW TO ANSWER:
P1 Summary: Scientist were not aware of self sacrificing breed of naked mole rat
P2 Summary: Like bees naked mole is ruled by queen and on the later's death heavy infighting erupts to select the new queen.
P3 Summary: Euscoial Insect societies defined by rigid caste system as in Naked Mole Rats but based on different criteria. Jarvi's work suggests correlation between individual growth rate and performance
P4 Summary: Cooperative breeding in other vertebrates are different from naked mole rats.In other vertebrates female mating habits are not as suppressed as in Naked Mole rats.
Summary: Supremacy of queen and similarities of naked mole rats with eusocial insect societies.
Which of the following most accurately states the main idea of the passage?
(A) Naked mole rat colonies are the only known examples of cooperatively breeding
vertebrate societies. Extreme words: “Only Known examples” (Not mentioned in
the passage) Eliminate
(B) Naked mole rat colonies exhibit social organization based on a rigid caste system.
In Euscoial Insect,behaviour is defined by rigid caste system. Eliminate
(C) Behavior in naked mole rat colonies may well be a close vertebrate analogue to
behavior in eusocial insect societies. Close to Main Summary: Maybe
(D) The mating habits of naked mole rats differ from those of any other vertebrate
species. Extreme words: “ Any Other”. Eliminate
Correct Answer : C
The technology of the North American colonies did not differ strikingly from that of Europe, but in one respect, the colonists enjoyed a great advantage. Especially by comparison with Britain, Americans had a wonderfully plentiful supply of wood.
The first colonists did not, as many people imagine, find an entire continent covered by a climax forest. Even along the Atlantic seaboard, the forest was broken at many points. Nevertheless, all sorts of fine trees abounded, and through the early colonial period, those who pushed westward encountered new forests. By the end of the colonial era, the price of wood had risen slightly in eastern cities, but wood was still extremely abundant.
The availability of wood brought advantages that have seldom been appreciated. Wood was a foundation of the economy. Houses and all manner of buildings were made of wood to a degree unknown in Britain. Secondly, wood was used as fuel for heating and cooking. Thirdly, it was used as the source of important industrial compounds, such as potash, an industrial alkali; charcoal, a component of gunpowder; and tannic acid, used for tanning leather.
The supply of wood conferred advantages but had some negative aspects as well. Iron at that time was produced by heating iron ore with charcoal. Because Britain was so stripped of trees, she was unable to exploit her rich iron mines. But the American colonies had both iron ore and wood; iron production was encouraged and became successful. However, when Britain developed coke smelting, the Colonies did not follow suit because they had plenty of wood and besides, charcoal iron was stronger than coke iron. Coke smelting led to technologic innovations and was linked to the emergence of the Industrial Revolution. In the early nineteenth century, the former colonies lagged behind Britain in industrial development because their supply of wood led them to cling to charcoal iron.
What does the passage mainly discuss?
(A) The advantages of using wood in the colonies
(B) The effects of an abundance of wood on the colonies
(C) The roots of the Industrial Revolution
(D) The difference between charcoal iron and coke iron
Answer key: B