Comprehension I
Listen to part of a university lecture on agriculture.
Professor:
Good afternoon, class. We’ve been looking at various of the world’s population problems and their possible solutions over our last few classes, and today I’d like us to take a quick look at one of the solutions to the growing problem of supplying enough food for us all. It’s called “dry land farming”.
Dry land farming is a, a set of agricultural practices, agricultural techniques, that should be, or need to be, used to produce profitable crops in areas where the rainfall- or the snowfall- is slight, is erratic, or is very seasonal, and is generally less than about fifty centimeters a year. All over the world, there are countries that must use these less-than-optimal lands to grow their food- the North American prairies, the South American pampas, the Russian steppes, the Middle East- all these areas have marginal rainfall, precipitation. Almost half of India’s arable- cultivatable- land, 47 out of a total of 108 million hectares, is dry land, as opposed to land fed by adequate rainfall. Originally, these lands were covered with well-adapted grasses, but today much of the natural cover is gone, and these vast plains are seen as, potentially at least, our global breadbasket.
Now, dry land farming is something that must be practiced in places where the land is inherently only barely suited for food production in the first place, and you can’t make a silk purse out of a sow’s ear, but there’re a number of things you can do that can improve the situation, the conditions, for successful farming.
Water is of course a key, or the key, requirement, and the little precipitation that does fall must be captured and conserved and used sparingly. Providing windbreaks, and providing some slight shade, and leaving residues from previous crops can often save water, keep it from evaporating so quickly. And weeding can save the water that the weeds would otherwise drink up. If the countryside is hilly, terracing can be used, and this goes along with contour plowing to prevent run-off. In some areas, it may even be feasible to build cisterns so that rainwater can be collected and stored. Also, planting the seeds carefully, with consideration- choosing precisely the right time to plant them, choosing the optimum seed depth, and so forth, can help use the available moisture most efficiently.
Mentioning seeds brings me to the next point: crop choice. Drought-resistant varieties, heat-tolerant varieties, of wheat or corn, for instance, must be chosen or developed. Varieties that can stand hot, dry conditions, whose seeds will germinate in such adverse conditions, and which have growth cycles, life cycles, that are fitted to the conditions they must face. With careful attention to these choices and to these practices we are talking about here, even crops like watermelons have been grown successfully in dry lands!
So, conserving and carefully distributing what rainfall is available and choosing crops that can best tolerate dry conditions are key factors for success. And the soil itself is also a key factor.
Dry land soils are, as you might expect, relatively poor in nutrients, because dry conditions allow a lot of topsoil to be blown away. So the quality of the thin topsoils must be preserved and maintained as carefully as possible. The most obvious help here is fertilizers, but other techniques like mulching- putting a protective cover over the field, like old vegetable matter, plant stalks and leaves, for instance, or plastic sheeting- and minimal tillage, minimal plowing, help solve this problem of soil deterioration, as well as the other main soil problem, erosion. Erosion can also be fought with windbreaks and strip-farming, which is the planting of alternate strips of land each growing season.
As I said before, dry lands by their nature are not very good, relatively speaking, for growing our food, and part of that is that they are more susceptible to low crop yields or complete crop failures. This is something that dry land farmers must always keep in mind and must always plan for, be ready to deal with.
If the year turns ugly, if it is even dryer and colder or hotter than usual, the farmer must be ready and willing to abandon his effort for that year, and in that way to save his fertilizers and his seeds and his energies. On the other hand, in promising years, where the weather is boding fair, the farmer should be quick to take advantage of it- by boosting yields with extra or broader plantings, by extending his growing cycle, and so on- and of course by working longer and harder at it.
With such approaches as these- and others we develop- the productivity of such marginal dry lands may be able to help us keep up with our irresistibly growing populations. We can at least take hope in the thought that the natives of the arid American southwest- the Hopi, the Zuni, the Navajo- survived for hundreds of years on dryland farming, in an area with a rainfall of less than twenty-five centimeters a year.
Now answer the following questions. You may use your notes to help you.
1). How has the professor organized his lecture?
(A) By geographical regions
(B) By seasonal changes
(C) By agricultural zones
(D) By key elements
2). The professor mentions watermelons as an example of what?
(A) A typical dry land product
(B) A drought-resistant seed
(C) An unusual success
(D) An inappropriate crop choice
3). According to the lecture, which is NOT true of dry land agriculture?
(A) It is a collection of methods.
(B) It is practiced in half of Russia’s arable lands.
(C) It requires a water source.
(D) It suffers erratic productivity.
4). The severity of the Dust Bowl storms of the 1930s in the south-central US were evidence of which dry land characteristic?
(A) Excessive evaporation
(B) Excessive erosion
(C) Inadequate precipitation
(D) Marginal productivity
5). Nature has produced thousands of species of edible plants. Which of the following plants would probably NOT be feasible for dry land farming?
(A) Plants with short life cycles
(B) Plants with spreading or deep root systems
(C) Plants that store water in their tissues
(D) Plants with large, spreading leaves
Answers: 1:D 2:C 3:B 4:B 5:D
Comprehension II
Read a transcript of a part of a university lecture by a professor of Paleontology.
Professor:
For more than a hundred years after the first dinosaur fossils were dug up, paleontologists just assumed that dinosaurs were cold-blooded animals, like modern lizards and snakes are. Dinosaurs were big, and they were slow, and they were stupid- and none of these characteristics are consistent with small, active, intelligent, warm-blooded animals like birds and mammals.
But in the late 1960s, two youngYale scientists, Robert Bakker and John Ostrum, came out with the hypothesis that dinosaurs were in fact faster, smarter and more energetic organisms than science previously thought. This radical idea caused an immediate stir, and the controversy about dinosaur physiology is still continuing today.
First, here are some of the arguments put forth for warm-bloodness, or endothermism, in dinosaurs. ‘Endothermism’ means ‘inside heat’, and an endothermic organism is one that generates heat with its own body in order to counteract a colder environment to keep itself at a constant internal temperature. The arguments for endothermic dinosaurs include:
One- many dinosaurs actually moved pretty quickly- as those of you who have seen Jurassic Park already know- and that would require a high metabolic rate and an internal heater.
Two- the dinosaurs evolved alongside mammals and competed with them for 170 million years, so they must have been competitive with other warm-blooded species.
Three- some dinosaurs had very large bodies and very long necks, so they would need a four-chambered heart and a lot of energy to move their blood those distances.
And four- the structure of dinosaur bone is more similar to bird and mammal bone than it is to typical reptile bone, so they were probably more closely related to the endothermic groups.
Those are some of the arguments that are used to support the idea that dinosaurs were warm-blooded. Of course, none of them prove that these animals were endotherms- they’re just theories- but scientists are continuing their research in order to come up with some more solid data. For instance, Doctor Herman Pontzer and his team of British researchers have recently determined that the energy cost of animal movement, of locomotion, is proportional to the length of their legs and to their leg muscle volume. Pontzer first calculated this with 98 percent accuracy in a wide range of living land animals, and then he applied it to dinosaur measurements. He discovered that a dinosaur’s energy requirements were simply too high for cold-blooded animals to be able to produce.
But overall, there’s still no incontestable evidence for endothermy, and other researchers offer strong arguments for the opposite view- for the old idea of ectothermy in dinosaurs. ‘Ectothermy’, as you should be able to guess now, is the opposite of ‘endothermy’. ‘Ectothermy’ means ‘outside heat’, and it’s used for organisms like reptiles and insects that rely on their environment or on their behaviour to regulate their body heat. They cannot produce heat themselves; they’re cold-blooded, but they can lie in the sun to get warmer or hide in shade to cool down.
As evidence that dinosaurs were ectothermic, more traditional paleontologists suggest such ideas as these-
One- dinosaurs were so big that they didn’t need to be endotherms; they could’ve been what’s called ‘inertial homeotherms’. And now, ‘homeothermy’ should be easy for you to figure out- it means ‘similar heat’. Homeotherms can maintain a relatively constant body temperature with or without producing internal heat. A very large animal, because it has a massive body volume, warms up and cools down very slowly, so that its behaviour can keep it at a relatively constant temperature all day and night.
Two- or there’s a simpler probability: the climate in the Mesozoic Era, the dinosaur era, was much warmer worldwide than now, so cold temperatures were just not a problem.
Three- another clue is that some dinosaur bones show lines of arrested growth, or LAGs, indicating that they grew seasonally, like trees- as many ectotherms, but not endotherms, do.
And four- all warm-blooded animals today have what are called ‘respiratory turbinates’, which are folded bones in the nose area used to minimize water loss when they breathe out warm air. But dinosaur fossils don’t show these respiratory turbinates.
Well, they are all thoughtful ideas, and so the controversy of warm-blooded dinosaurs versus cold-blooded dinosaurs goes on, with strong supporters on both sides, and with no final solution in sight. It’s one of the most interesting problems of evolution, actually. And in fact, the real answer may be something else- some sort of intermediate physiology. Remember that dinosaurs were not reptiles or any other kind of animals that are alive today, so all we have to rely on are for evidence are fossils in stone. This problem may never be solved. Or maybe one day, one of you will help solve this mystery of dinosaur physiology.
Now answer the following questions. You may use your notes to help you.
1). What is this lecture mainly about?
(A) Recent research on dinosaurs
(B) An insoluble problem about dinosaurs
(C) An ongoing argument about dinosaurs
(D) The characteristics of dinosaurs
2). An organism that generates internal heat is called what?
(A) Ectothermic
(B) Endothermic
(C) Homeothermic
(D) Poikilothermic
3). How has the professor organized his lecture?
(A) By listing opposing viewpoints
(B) By suggesting new theories
(C) By describing dinosaur evolution
(D) By defining physiological terms
4). Who found the energy cost of locomotion?
(A) John Ostrum
(B) Charles Darwin
(C) Robert Bakker
(D) Herman Pontzer
5). Which fact suggests that dinosaurs were cold-blooded creatures?
(A) Fossil dinosaurs have been found at high elevations (Alaska and Antarctica, for instance).
(B) Dinosaurs were scaly- they were covered with scales, not hair or fur.
(C) Dinosaurs were the direct ancestors of birds.
(D) Theropod and Ornithopod dinosaurs had larger-than-normal brains.
6). Which best expresses the lecturer’s probable opinion on the current state of dinosaur research?
(A) Dinosaurs were most probably cold-blooded animals.
(B) Dinosaurs had some sort of intermediate physiology.
(C) Dinosaurs were actually warm-blooded creatures.
(D) Paleontologists remain divided on this issue.
Answer: 1:C 2:B 3:A 4:D 5:B 6:D
Comprehension III
Read a transcript of a part of a university lecture by a professor of Natural History
Professor:
Now, as a part of our study of biological evolution and evolutionary processes, let’s look for a few minutes at an extraordinary group of bird species, the Birds of Paradise. You may’ve seen pictures of some of these fantastic birds– I think there’s one in the next chapter of our textbook. The male Birds of Paradise are incredibly beautiful creatures. They have extremely elongated and very elaborate sets of many-colored feathers arising from their head and tail and wings, and when the males display for the females during courtship, they can erect and manipulate these feather tracts, waving or shaking or twirling or wiggling these feathers. And at the same time they often assume very odd postures or do acrobatics- so they put on quite incredible performances to attract females.
In fact, the male plumage is so gorgeous that Bird of Paradise skins have been highly valued trade items for hundreds, if not thousands, of years. The Birds of Paradise are restricted almost entirely to the tropical jungles of the New Guinea archipelago, to the large island of Papua-New Guinea and its surrounding islands. Not only have the Papuan men traditionally adorned themselves with Bird of Paradise feathers since before history, but these feathers appeared as rare and valuable trade goods in other parts of Asia as long as two thousand years ago.
However, they weren’t discovered by the Western world until the sixteenth century. In 1520, the famous Portuguese explorer, Ferdinand Magellan, was given several Bird of Paradise skins by the Sultan of Batchian- in the Moluccan Islands- and they created quite a sensation back in Europe. As exploration expanded, more and more skins were sent to the United States and Europe, and the beauty of the feathers resulted, of course, in their becoming fashionable decorations for ladies’ hats. By the end of the nineteenth century, thousands of trade skins had been exported from New Guinea. Through London alone, between the years 1904 and 1908, 155,000 skins were imported.
Luckily, it was about this time that groups like the Audubon Society and the Royal Society for the Protection of Birds were becoming active defenders of wildlife, and from 1908, laws banning the import of bird feathers were beginning to be passed in many countries. In 1955, the government of Nepal was having difficulty getting new Bird of Paradise plumes for the Royal Nepali crown for the coronation of their new King, Mahendra, until they finally arranged for replacements from an illegal shipment of skins that had earlier been confiscated by the US Customs Service.
At last, in 1990, Indonesia itself passed a law banning the trade in Bird of Paradise skins. Incredibly, none of the Birds of Paradise are Endangered species today, although several are on the Vulnerable list and on the Near Threatened list. Today, only sustainable hunting for ceremonial purposes is permitted to the local native tribes.
There’s about forty species of Birds of Paradise, and they’re really outstanding examples of the evolutionary phenomenon of species radiation from a single ancestor, because each isolated mountain range in the New Guinea archipelago has its own unique, endemic species- species that’re found nowhere else in the world. The Birds of Paradise are all very closely related-actually, they’re all closely related to our common crows!- but each species has evolved in isolation into something that looks and behaves very different from its relatives on the next mountain or in the next valley. In fact, elevation is probably the single most important ecological sorting mechanism for the adaptive radiation of these birds into so many different, unique forms.
On top of their extraordinary plumage, these birds have also developed a whole range of breeding strategies. A few species are monogamous- which means that one male and one female mate and raise young. But most species are polygamous, where the males try to attract and mate with as many females as possible, and the females raise the young birds alone. Some of these polygamous males perform single, non-territorial displays when they find a female. In other cases, the single male frequents some sort of regular display ground, called a ‘court’, where he may clear a space and perform for passing females. And in yet other species, the males gather at distinctive, traditional, communal display grounds called ‘leks’. Here, many males will compete for female attention and perform as energetically as they can, because the females choose the ones who put on the best show. The native Papuans call these performances ‘sakaleli’ or ‘dancing parties’, and they are truly amazing exhibitions. Just picture a dazzling gold-white-and-green Greater Bird of Paradise, who leans forward and downward, and lowers his open wings to display his large, lacy, golden flank feathers raised above his back and over his head like Japanese fans. Or the immaculate black-and-turquoise Blue Bird of Paradise, who hangs completely upside-down and flexes his legs slowly and rhythmically to vibrate his long, thin tail feathers for the ladies.
This big, sequential radiation of behaviors and plumages- as well as similar sequential variations in morphology and feeding habits- is a really rich source of research opportunities for graduate students, and I hope that some of you will have the chance to participate in Bird of Paradise research during your careers, because they are amazingly beautiful birds with fascinating habits.
Now answer the following questions. You may use your notes to help you.
1). According to the lecturer, why do Birds of Paradise have amazing plumages?
(A) To exploit habitats
(B) To differentiate species
(C) To defend territories
(D) To attract females
2). Why does the lecturer mention King Mahendra?
(A) He gave Magellan some Bird of Paradise skins.
(B) He banned the export of Bird of Paradise feathers.
(C) He needed some Bird of Paradise feathers.
(D) He authorized research on Birds of Paradise.
3). Based on the information in this lecture, which is NOT true?
(A) Some species of Birds of Paradise are Endangered.
(B) Some species of Birds of Paradise are Vulnerable.
(C) Some species of Birds of Paradise are Extinct.
(D) Some species of Birds of Paradise are Near Threatened.
4). When did Indonesia ban trade in Bird of Paradise feathers?
(A) 1908
(B) 1919
(C) 1955
(D) 1990
5). According to the lecturer, which factor was the main cause of the differences among Bird of Paradise species?
(A) Altitude
(B) Islands
(C) Tropical forest
(D) Breeding strategy
6). Which would make the best title for this lecture?
(A) Adaptive Radiation
(B) The Skin Trade
(C) The Birds of New Guinea
(D) Endangered Species
Answers: 1:D 2:C 3:A 4:D 5:A 6:A