<p>Hi, I have some doubts with the following questions </p>
<p>The following passage is adapted from a biologists discussion of the diversity of life on Earth (first published in 1992).</p>
<p>The most wonderful mystery of life may well be the means by which it created so much diversity from so little physical matter. The biosphere, all organisms combined, makes up only about one part in ten billion of the Earths mass. It is sparsely distributed through a kilometer-thick layer of soil, water, and air stretched over a half billion square kilometers of surface. If the world were the size of an ordinary desktop globe and its surface were viewed edgewise an arms length away, no trace of the biosphere could be seen with the naked eye. Yet life had divided into millions of species, the fundamental units, each playing a unique role in relation to the whole.
For another way to visualize the tenuousness of life, imagine yourself on a journey upward from the center of Earth, taken at the pace of a Leisurely walk. For the first twelve weeks you travel through furnace-hot rock and magma devoid of life. Three minutes to the surface, five hundred meters to go, you encounter the first organisms, bacteria feeding on nutrients that have filtered into the deep water-bearing
Strata of the rock. You breach the surface and for ten seconds glimpse a dazzling burst of life, tens of thousands of species of microorganisms, plants, and animals within horizontal line of sight. Half a minute later almost all are gone. Two hours later only the faintest traces remain, consisting largely of people in airliners who are filled in turn with bacteria.
The hallmark of life is this: a struggle among an immense variety of organisms weighing next to nothing for a vanishingly small amount of energy. Life operates on less than 10 percent of the Suns energy reaching Earths surface, that portion fixed by the photosynthesis* of green plants. That energy is then sharply discounted as it passes through the food webs from one organism to the next: very roughly 10 percent passes to the caterpillars and other herbivores that eat the plants and bacteria, 10 percent of that to the spiders and other low-level carnivores that eat the herbivores, 10 percent of the residue to the warblers and other middle-level carnivores that eat the low-level carnivores, and so on upward to the top carnivores, which are consumed by no one except parasites and scavengers. Top carnivores, including eagles, tigers and sharks, predestined by their perch at the apex of the fox web to be big in size and sparse in number. They live on such a small portion of lifes available energy as always to skirt the edge of extinction and they are the first to suffer when the ecosystem around them starts to erode.
A great deal can be learned about biological diversity by noticing that species in the food are arranged in tow hierarchies. The first hierarchy is the energy pyramid, a straightforward consequence of the law of diminishing energy flow a noted-a relatively large amount of the Suns energy that strikes Earth goes into the plants at bottom. This energy then tapers to a minute quantity for the big carnivores at the top level.
The second hierarchy is a pyramid composed biomass, the weight of organisms. By far the last part of the physical bulk of the living world is contained in plants. The second largest amount belongs to the scavengers and other decomposers, from bacteria to fungi and termites, which together extra the last bit of fixed energy from dead tissue and waste at every level in the food web. These scavengers and decomposers then return degraded nitric chemicals to the plants. Each level above the plant diminishes thereafter in biomass until you compose the top carnivores, which are so scare that the sight of one in the wild is memorable. No one looks twice at a sparrow or a squirrel, or even once at dandelion, but glimpsing a peregrine falcon or a mountain lion is a lifetime experience. And not because of their size (think of a cow) or ferocity (think of a house cat).</p>
<ol>
<li> the reference to ten seconds primarily serves to
A show the consequences of a single action
B suggest the brief life spans of many species
C illustrate the space occupied by most life
D demonstrate the invulnerability of life on Earth
E indicate the frustration of snatching brief insights</li>
</ol>
<p>I chose B but the answer is C</p>
<ol>
<li> the two pyramids described in the passage are similar in which of the following ways?
I Green plants are at the bottom
II Decomposers are at the second level
III Large carnivores are at the top.
A I only
B III only
C I and II only
D I and III only
E I, II, and III.</li>
</ol>
<p>The answer is D but I'm not sure why.</p>
<ol>
<li>The tone of the passage is primarily one of
A detached inquiry
B playful skepticism
C mild defensiveness
D informed appreciation
E urgent entreaty.</li>
</ol>
<p>I chose B the answer is D</p>