Adapted from Ice-Caves of France and Switzerland by George Forrest Browne (1865)

This account states that the cave is in the county of Thorn, among the lowest spurs of the Carpathians. The entrance, which faces the north, and is exposed to the cold winds from the snowy part of the Carpathian range, is eighteen fathoms high and nine broad; and the cave spreads out laterally, and descends to a point fifty fathoms below the entrance, where it is twenty-six fathoms in breadth, and of irregular height. Beyond this no one had at that time penetrated, on account of the unsafe footing, although many distant echoes were returned by the farther recesses of the cave; indeed, to get even so far as this, much step-cutting was necessary.

When the external frost of winter comes on, the account proceeds, the effect in the cave is the same as if fires had been lighted there: the ice melts, and swarms of flies and bats and hares take refuge in the interior from the severity of the winter. As soon as spring arrives, the warmth of winter disappears from the interior, water exudes from the roof and is converted into ice, while the more abundant supplies which pour down on to the sandy floor are speedily frozen there. In the dog-days, the frost is so intense that a small icicle becomes in one day a huge mass of ice; but a cool day promptly brings a thaw, and the cave is looked upon as a barometer, not merely feeling, but also presaging, the changes of weather. The people of the neighborhood, when employed in field-work, arrange their labour so that the mid-day meal may be taken near the cave, when they either ice the water they have brought with them, or drink the melted ice, which they consider very good for the stomach. It had been calculated that six hundred weekly carts would not be sufficient to keep the cavern free from ice. The ground above the cave is peculiarly rich in grass.

In explanation of these phenomena, Bell threw out the following suggestions, which need no comment. The earth being of itself cold and damp, the external heat of the atmosphere, by partially penetrating into the ground, drives in this native cold to the inner parts of the earth, and makes the cold there more dense. On the other hand, when the external air is cold, it draws forth towards the surface the heat there may be in the inner part of the earth, and thus makes caverns warm. In support and illustration of this view, he states that in the hotter parts of Hungary, when the people wish to cool their wine, they dig a hole two feet deep, and place in it the flagon of wine, and, after filling up the hole again, light a blazing fire upon the surface, which cools the wine as if the flagon had been laid in ice. He also suggests that possibly the cold winds from the Carpathians bring with them imperceptible particles of snow, which reach the water of the cave, and convert it into ice. Further, the rocks of the Carpathians abound in salts, nitre, alum, etc., which may, perhaps, mingle with such snowy particles, and produce the ordinary effect of the snow and salt in the artificial production of ice.

Based on the passage, the primary reason for the lack of full exploration of the cave was that __________.

Adapted from Ice-Caves of France and Switzerland by George Forrest Browne (1865)

This account states that the cave is in the county of Thorn, among the lowest spurs of the Carpathians. The entrance, which faces the north, and is exposed to the cold winds from the snowy part of the Carpathian range, is eighteen fathoms high and nine broad; and the cave spreads out laterally, and descends to a point fifty fathoms below the entrance, where it is twenty-six fathoms in breadth, and of irregular height. Beyond this no one had at that time penetrated, on account of the unsafe footing, although many distant echoes were returned by the farther recesses of the cave; indeed, to get even so far as this, much step-cutting was necessary.

When the external frost of winter comes on, the account proceeds, the effect in the cave is the same as if fires had been lighted there: the ice melts, and swarms of flies and bats and hares take refuge in the interior from the severity of the winter. As soon as spring arrives, the warmth of winter disappears from the interior, water exudes from the roof and is converted into ice, while the more abundant supplies which pour down on to the sandy floor are speedily frozen there. In the dog-days, the frost is so intense that a small icicle becomes in one day a huge mass of ice; but a cool day promptly brings a thaw, and the cave is looked upon as a barometer, not merely feeling, but also presaging, the changes of weather. The people of the neighborhood, when employed in field-work, arrange their labour so that the mid-day meal may be taken near the cave, when they either ice the water they have brought with them, or drink the melted ice, which they consider very good for the stomach. It had been calculated that six hundred weekly carts would not be sufficient to keep the cavern free from ice. The ground above the cave is peculiarly rich in grass.

In explanation of these phenomena, Bell threw out the following suggestions, which need no comment. The earth being of itself cold and damp, the external heat of the atmosphere, by partially penetrating into the ground, drives in this native cold to the inner parts of the earth, and makes the cold there more dense. On the other hand, when the external air is cold, it draws forth towards the surface the heat there may be in the inner part of the earth, and thus makes caverns warm. In support and illustration of this view, he states that in the hotter parts of Hungary, when the people wish to cool their wine, they dig a hole two feet deep, and place in it the flagon of wine, and, after filling up the hole again, light a blazing fire upon the surface, which cools the wine as if the flagon had been laid in ice. He also suggests that possibly the cold winds from the Carpathians bring with them imperceptible particles of snow, which reach the water of the cave, and convert it into ice. Further, the rocks of the Carpathians abound in salts, nitre, alum, etc., which may, perhaps, mingle with such snowy particles, and produce the ordinary effect of the snow and salt in the artificial production of ice.

The passage states that which of the following is true?

Adapted from Rambles in the Mammoth Cave, during the Year 1844 by Alexander Clark Bullitt (1845)

Pensico Avenue averages about fifty feet in width with a height of about thirty feet, and is said to be two miles long. It unites in an eminent degree the truly beautiful with the sublime, and is highly interesting throughout its entire extent. For a quarter of a mile from the entrance, the roof is beautifully arched, about twelve feet high and sixty wide, and formerly was encrusted with rosettes and other formations, nearly all of which have been taken away or demolished, leaving this section of the Cave quite denuded. The walking here is excellent; a dozen persons might run abreast for a quarter of a mile to Bunyan's Way, a branch of the avenue leading on to the river. At this point the avenue changes its features of beauty and regularity, for those of wild grandeur and sublimity, which it preserves to the end. The way, no longer smooth and level, is frequently interrupted and turned aside by huge rocks, which lie tumbled around in all imaginable disorder. The roof now becomes very lofty and imposingly magnificent; its long, pointed, or lancet arches, forcibly reminding you of the rich and gorgeous ceilings of the old Gothic cathedrals, at the same time solemnly impressing you with the conviction that this is a "building not made with hands." No one, not dead to all the more refined sensibilities of our nature, but must exclaim, in beholding the sublime scenes which here present themselves, this is not the work of man! No one can be here without being reminded of the all pervading presence of the great "Father of all."

"What, but God, pervades, adjusts and agitates the whole!"

Not far from the point at which the avenue assumes the rugged features, which now characterize it, we separated from our guide, he continuing his straight-forward course, and we descending gradually a few feet and entering a tunnel of fifteen feet wide on our left, the ceiling twelve or fourteen feet high, perfectly arched and beautifully covered with white incrustations, very soon reached the Great Crossings. Here the guide jumped down some six or eight feet from the avenue which we had left, into the tunnel where we were standing, and crossing it, climbed up into the avenue, which he pursued for a short distance or until it united with the tunnel, where he again joined us. In separating from, then crossing, and again uniting with the avenue, it describes with it something like the figure 8. The name, “Great Crossings,” is not unapt. It was however, not given, as our intelligent guide veritably assured us, in honor of the Great Crossings where the man lives who killed Tecumseh, but because two great caves cross here; and moreover said he, "the valiant Colonel ought to change the name of his place, as no two places in a state should bear the same name, and this being the great place ought to have the preference."

Not very far from this point, we ascended a hill on our left, and walking a short distance over our shoe-tops in dry nitrous earth in a direction somewhat at a right angle with the avenue below, we arrived at the Pine Apple Bush, a large column composed of a white, soft, crumbling material, with bifurcations extending from the floor to the ceiling. At a short distance, either to the right or left, you have a fine view of the avenue some twenty feet below, both up and down. Why this crumbling stalactite is called the Pine Apple Bush, I cannot divine. It stands however in a charming, secluded spot, inviting to repose; and we luxuriated in inhaling the all-inspiring air, while reclining on the clean, soft, and dry saltpeter earth.

Based on the passage, the primary reason the guide wants the Colonel to change the name of his “Great Crossings” is __________.

Adapted from Rambles in the Mammoth Cave, during the Year 1844 by Alexander Clark Bullitt (1845)

Pensico Avenue averages about fifty feet in width with a height of about thirty feet, and is said to be two miles long. It unites in an eminent degree the truly beautiful with the sublime, and is highly interesting throughout its entire extent. For a quarter of a mile from the entrance, the roof is beautifully arched, about twelve feet high and sixty wide, and formerly was encrusted with rosettes and other formations, nearly all of which have been taken away or demolished, leaving this section of the Cave quite denuded. The walking here is excellent; a dozen persons might run abreast for a quarter of a mile to Bunyan's Way, a branch of the avenue leading on to the river. At this point the avenue changes its features of beauty and regularity, for those of wild grandeur and sublimity, which it preserves to the end. The way, no longer smooth and level, is frequently interrupted and turned aside by huge rocks, which lie tumbled around in all imaginable disorder. The roof now becomes very lofty and imposingly magnificent; its long, pointed, or lancet arches, forcibly reminding you of the rich and gorgeous ceilings of the old Gothic cathedrals, at the same time solemnly impressing you with the conviction that this is a "building not made with hands." No one, not dead to all the more refined sensibilities of our nature, but must exclaim, in beholding the sublime scenes which here present themselves, this is not the work of man! No one can be here without being reminded of the all pervading presence of the great "Father of all."

"What, but God, pervades, adjusts and agitates the whole!"

Not far from the point at which the avenue assumes the rugged features, which now characterize it, we separated from our guide, he continuing his straight-forward course, and we descending gradually a few feet and entering a tunnel of fifteen feet wide on our left, the ceiling twelve or fourteen feet high, perfectly arched and beautifully covered with white incrustations, very soon reached the Great Crossings. Here the guide jumped down some six or eight feet from the avenue which we had left, into the tunnel where we were standing, and crossing it, climbed up into the avenue, which he pursued for a short distance or until it united with the tunnel, where he again joined us. In separating from, then crossing, and again uniting with the avenue, it describes with it something like the figure 8. The name, “Great Crossings,” is not unapt. It was however, not given, as our intelligent guide veritably assured us, in honor of the Great Crossings where the man lives who killed Tecumseh, but because two great caves cross here; and moreover said he, "the valiant Colonel ought to change the name of his place, as no two places in a state should bear the same name, and this being the greatplace ought to have the preference."

Not very far from this point, we ascended a hill on our left, and walking a short distance over our shoe-tops in dry nitrous earth in a direction somewhat at a right angle with the avenue below, we arrived at the Pine Apple Bush, a large column composed of a white, soft, crumbling material, with bifurcations extending from the floor to the ceiling. At a short distance, either to the right or left, you have a fine view of the avenue some twenty feet below, both up and down. Why this crumbling stalactite is called the Pine Apple Bush, I cannot divine. It stands however in a charming, secluded spot, inviting to repose; and we luxuriated in inhaling the all-inspiring air, while reclining on the clean, soft, and dry saltpeter earth.

The passage states that which of the following is true?

Adapted from Rambles in the Mammoth Cave, during the Year 1844 by Alexander Clark Bullitt (1845)

Pensico Avenue averages about fifty feet in width with a height of about thirty feet, and is said to be two miles long. It unites in an eminent degree the truly beautiful with the sublime, and is highly interesting throughout its entire extent. For a quarter of a mile from the entrance, the roof is beautifully arched, about twelve feet high and sixty wide, and formerly was encrusted with rosettes and other formations, nearly all of which have been taken away or demolished, leaving this section of the Cave quite denuded. The walking here is excellent; a dozen persons might run abreast for a quarter of a mile to Bunyan's Way, a branch of the avenue leading on to the river. At this point the avenue changes its features of beauty and regularity, for those of wild grandeur and sublimity, which it preserves to the end. The way, no longer smooth and level, is frequently interrupted and turned aside by huge rocks, which lie tumbled around in all imaginable disorder. The roof now becomes very lofty and imposingly magnificent; its long, pointed, or lancet arches, forcibly reminding you of the rich and gorgeous ceilings of the old Gothic cathedrals, at the same time solemnly impressing you with the conviction that this is a "building not made with hands." No one, not dead to all the more refined sensibilities of our nature, but must exclaim, in beholding the sublime scenes which here present themselves, this is not the work of man! No one can be here without being reminded of the all pervading presence of the great "Father of all."

"What, but God, pervades, adjusts and agitates the whole!"

Not far from the point at which the avenue assumes the rugged features, which now characterize it, we separated from our guide, he continuing his straight-forward course, and we descending gradually a few feet and entering a tunnel of fifteen feet wide on our left, the ceiling twelve or fourteen feet high, perfectly arched and beautifully covered with white incrustations, very soon reached the Great Crossings. Here the guide jumped down some six or eight feet from the avenue which we had left, into the tunnel where we were standing, and crossing it, climbed up into the avenue, which he pursued for a short distance or until it united with the tunnel, where he again joined us. In separating from, then crossing, and again uniting with the avenue, it describes with it something like the figure 8. The name, “Great Crossings,” is not unapt. It was however, not given, as our intelligent guide veritably assured us, in honor of the Great Crossings where the man lives who killed Tecumseh, but because two great caves cross here; and moreover said he, "the valiant Colonel ought to change the name of his place, as no two places in a state should bear the same name, and this being the greatplace ought to have the preference."

Not very far from this point, we ascended a hill on our left, and walking a short distance over our shoe-tops in dry nitrous earth in a direction somewhat at a right angle with the avenue below, we arrived at the Pine Apple Bush, a large column composed of a white, soft, crumbling material, with bifurcations extending from the floor to the ceiling. At a short distance, either to the right or left, you have a fine view of the avenue some twenty feet below, both up and down. Why this crumbling stalactite is called the Pine Apple Bush, I cannot divine. It stands however in a charming, secluded spot, inviting to repose; and we luxuriated in inhaling the all-inspiring air, while reclining on the clean, soft, and dry saltpeter earth.

The first paragraph establishes all of the following EXCEPT __________.

Adapted from Common Diseases of Farm Animals by R. A. Craig (1916, 2nd ed.)

The common bot-fly of the horse (G. equi) has a heavy, hairy body. Its color is brown, with dark and yellowish spots. The female fly can be seen during the warm weather, hovering around the horse, and darting toward the animal for the purpose of depositing the egg. The color of the egg is yellow, and it adheres firmly to the hair. It hatches in from two to four weeks, and the larva reaches the mouth through the animal licking the part. From the mouth, it passes to the stomach, where it attaches itself to the gastric mucous membrane. Here it remains until fully developed, when it becomes detached and is passed out with the feces. The third stage is passed in the ground. This takes place in the spring and early summer and lasts for several weeks, when it finally emerges a mature fly.

The bot-fly of the ox (H. lineata) is dark in color and about the size of a honey-bee. On warm days, the female may be seen depositing eggs on the body of the animal, especially in the region of the heels. This seems to greatly annoy the animal, and it is not uncommon for cattle to become stampeded. The egg reaches the mouth through the animal licking the part. The saliva dissolves the shell of the egg and the larva is freed. It then migrates from the gullet, wanders about in the tissue until finally it may reach a point beneath the skin of the back. Here the larva matures and forms the well-known swelling or warble. In the spring of the year it works out through the skin. The next stage is spent in the ground. The pupa state lasts several weeks, when the mature fly issues forth.

The bot-fly of sheep (O. ovis) resembles an overgrown house-fly. Its general color is brown, and it is apparently lazy, flying about very little. This bot-fly makes its appearance when the warm weather begins, and deposits live larvae in the nostrils of sheep. This act is greatly feared by the animals, as shown by their crowding together and holding the head down. The larva works up the nasal cavities and reaches the sinuses of the head, where it becomes attached to the lining mucous membrane. In the spring, when fully developed, it passes out through the nasal cavities and nostrils, drops to the ground, buries itself, and in from four to six weeks develops into the mature fly.

SYMPTOMS OF BOT-FLY DISEASES.—The larvae of the bot-fly of the horse do not cause characteristic symptoms of disease. Work horses that are groomed daily are not hosts for a large number of "bots," but young and old horses that are kept in a pasture or lot and seldom groomed may become unthrifty and "pot bellied," or show symptoms of indigestion.

Cattle suffer much pain from the development of the larva of the H. lineata. During the spring of the year, the pain resulting from the presence of the larvae beneath the skin and the penetration of the skin is manifested by excitement and running about. Besides the loss in milk and beef production, there is a heavy yearly loss from the damage to hides.

The life of the bot-fly of sheep results in a severe catarrhal inflammation of the mucous membrane lining the sinuses of the head, and a discharge of a heavy, pus-like material from the nostrils. The irritation produced by the larvae may be so serious at times as to result in nervous symptoms and death.

Which of the following statements about the bot-fly of the ox is supported by the passage?

Adapted from The Evolutionist at Large by Grant Allen (1881)

I am engaged in watching a brigade of ants out on foraging duty, and intent on securing for the nest three whole segments of a deceased earthworm. They look for all the world like those busy companies one sees in the Egyptian wall paintings, dragging home a huge granite colossus by sheer force of bone and sinew. Every muscle in their tiny bodies is strained to the utmost as they pry themselves laboriously against the great boulders that strew the path, and that are known to our Brobdingnagian intelligence as grains of sand. Besides the workers themselves, a whole battalion of stragglers runs to and fro upon the broad line that leads to the headquarters of the community. The province of these stragglers, who seem so busy doing nothing, probably consists in keeping communications open, and encouraging the sturdy pullers by occasional relays of fresh workmen. I often wish that I could for a while get inside those tiny brains, and see, or rather smell, the world as ants do. For there can be little doubt that to these brave little carnivores here the universe is chiefly known as a collective bundle of odors, simultaneous or consecutive. As our world is mainly a world of visible objects, theirs, I believe, is mainly a world of olfactible things.

In the head of every one of these little creatures is something that we may fairly call a brain. Of course most insects have no real brains; the nerve-substance in their heads is a mere collection of ill-arranged ganglia, directly connected with their organs of sense. Whatever man may be, an earwig at least is a conscious, or rather a semi-conscious, automaton. He has just a few knots of nerve cells in his little pate, each of which leads straight from his dim eye or his vague ear or his indefinite organs of taste; and his muscles obey the promptings of external sensations without possibility of hesitation or consideration, as mechanically as the valve of a steam engine obeys the governor balls. The poor soul's intellect is wholly deficient, and the senses alone make up all that there is of him, subjectively considered. But it is not so with the highest insects. They have something that truly answers to the real brain of men, apes, and dogs, to the cerebral hemispheres and the cerebellum that are superadded in us mammals upon the simple sense-centers of lower creatures. Besides the eye, with its optic nerve and optic perceptive organs—besides the ear, with its similar mechanism—we mammalian lords of creation have a higher and more genuine brain, that collects and compares the information given to the senses, and sends down the appropriate messages to the muscles accordingly. Now, bees and flies and ants have got much the same sort of arrangement, on a smaller scale, within their tiny heads. On top of the little knots that do duty as nerve centers for their eyes and mouths, stand two stalked bits of nervous matter, whose duty is analogous to that of our own brains. And that is why these three sorts of insects think and reason so much more intellectually than beetles or butterflies, and why the larger part of them have organized their domestic arrangements on such an excellent cooperative plan.

We know well enough what forms the main material of thought with bees and flies, and that is visible objects. For you must think about something if you think at all; and you can hardly imagine a contemplative blow-fly setting itself down to reflect, like a Hindu devotee, on the syllable Om, or on the oneness of existence. Abstract ideas are not likely to play a large part in apian consciousness. A bee has a very perfect eye, and with this eye it can see not only form, but also color, as Sir John Lubbock's experiments have shown us. The information that it gets through its eye, coupled with other ideas derived from touch, smell, and taste, no doubt makes up the main thinkable and knowable universe as it reveals itself to the apian intelligence. To ourselves and to bees alike the world is, on the whole, a colored picture, with the notions of distance and solidity thrown in by touch and muscular effort; but sight undoubtedly plays the first part in forming our total conception of things generally.

Which of the following statements about mammals is supported by the passage?

Adapted from Ice-Caves of France and Switzerland by George Forrest Browne (1865)

This account states that the cave is in the county of Thorn, among the lowest spurs of the Carpathians. The entrance, which faces the north, and is exposed to the cold winds from the snowy part of the Carpathian range, is eighteen fathoms high and nine broad; and the cave spreads out laterally, and descends to a point fifty fathoms below the entrance, where it is twenty-six fathoms in breadth, and of irregular height. Beyond this no one had at that time penetrated, on account of the unsafe footing, although many distant echoes were returned by the farther recesses of the cave; indeed, to get even so far as this, much step-cutting was necessary.

When the external frost of winter comes on, the account proceeds, the effect in the cave is the same as if fires had been lighted there: the ice melts, and swarms of flies and bats and hares take refuge in the interior from the severity of the winter. As soon as spring arrives, the warmth of winter disappears from the interior, water exudes from the roof and is converted into ice, while the more abundant supplies which pour down on to the sandy floor are speedily frozen there. In the dog-days, the frost is so intense that a small icicle becomes in one day a huge mass of ice; but a cool day promptly brings a thaw, and the cave is looked upon as a barometer, not merely feeling, but also presaging, the changes of weather. The people of the neighborhood, when employed in field-work, arrange their labour so that the mid-day meal may be taken near the cave, when they either ice the water they have brought with them, or drink the melted ice, which they consider very good for the stomach. It had been calculated that six hundred weekly carts would not be sufficient to keep the cavern free from ice. The ground above the cave is peculiarly rich in grass.

In explanation of these phenomena, Bell threw out the following suggestions, which need no comment. The earth being of itself cold and damp, the external heat of the atmosphere, by partially penetrating into the ground, drives in this native cold to the inner parts of the earth, and makes the cold there more dense. On the other hand, when the external air is cold, it draws forth towards the surface the heat there may be in the inner part of the earth, and thus makes caverns warm. In support and illustration of this view, he states that in the hotter parts of Hungary, when the people wish to cool their wine, they dig a hole two feet deep, and place in it the flagon of wine, and, after filling up the hole again, light a blazing fire upon the surface, which cools the wine as if the flagon had been laid in ice. He also suggests that possibly the cold winds from the Carpathians bring with them imperceptible particles of snow, which reach the water of the cave, and convert it into ice. Further, the rocks of the Carpathians abound in salts, nitre, alum, etc., which may, perhaps, mingle with such snowy particles, and produce the ordinary effect of the snow and salt in the artificial production of ice.

The second paragraph establishes all of the following EXCEPT __________.

Adapted from Taking a Second Look: An Analysis of Genetic Markers in Species Relatedness by Joseph Ritchie (2014)

Phylogenetics is the study of genetic composition in various species and is used by evolutionary biologists to investigate similarities in the molecular sequences of proteins in varying organisms. The amino acid sequences that build proteins are used to construct mathmatical matrices that aid in determining evolutionary ties through the investigation of percentage similarities. The study of these matrices helps to expose evolutionary relationships between species that may not have the same existential characteristics.

Species adapt and evolve based on the pressures that exist in their environment. Climate, food source, and habitat availability are only a few factors that act on species adaptation. These stressors can alter the physical characteristics of organisms. This divergence in evolution has made it difficult to determine the interrelatedness of organisms by analyzing their physical characteristics alone.

For instance, looking only at physical characteristics, the ghost bat resembles a pigeon more than a spider monkey; however, phylogenetics has found that the amino acid sequences that construct the beta hemoglobin molecules of bats are 20% more similar to those of mammalian primates than those of birds. This helps reject the assumption that common physical characteristics between species is all that is needed to determine relatedness. 

Divergent evolution that produces the differences observed in the forest-dwelling, arboreal spider monkey and the nocturnal, airborne ghost bat can be reconciled through homology. Homologous characteristics are anatomical traits that are similar in two or more different species. For instance, the bone structure of a spider monkey’s wrist and fingers greatly resembles that of a bat’s wing or even a whale’s fin. These similarities are reinforced by phylogenetic evidence that supports the idea that physically dissimilar species can be evolutionarily related through anatomical and genetic similarities.

Phylogenetics traditionally investigates which molecular structures?

Adapted from Taking a Second Look: An Analysis of Genetic Markers in Species Relatedness by Joseph Ritchie (2014)

Phylogenetics is the study of genetic composition in various species and is used by evolutionary biologists to investigate similarities in the molecular sequences of proteins in varying organisms. The amino acid sequences that build proteins are used to construct mathmatical matrices that aid in determining evolutionary ties through the investigation of percentage similarities. The study of these matrices helps to expose evolutionary relationships between species that may not have the same existential characteristics.

Species adapt and evolve based on the pressures that exist in their environment. Climate, food source, and habitat availability are only a few factors that act on species adaptation. These stressors can alter the physical characteristics of organisms. This divergence in evolution has made it difficult to determine the interrelatedness of organisms by analyzing their physical characteristics alone.

For instance, looking only at physical characteristics, the ghost bat resembles a pigeon more than a spider monkey; however, phylogenetics has found that the amino acid sequences that construct the beta hemoglobin molecules of bats are 20% more similar to those of mammalian primates than those of birds. This helps reject the assumption that common physical characteristics between species is all that is needed to determine relatedness. 

Divergent evolution that produces the differences observed in the forest-dwelling, arboreal spider monkey and the nocturnal, airborne ghost bat can be reconciled through homology. Homologous characteristics are anatomical traits that are similar in two or more different species. For instance, the bone structure of a spider monkey’s wrist and fingers greatly resembles that of a bat’s wing or even a whale’s fin. These similarities are reinforced by phylogenetic evidence that supports the idea that physically dissimilar species can be evolutionarily related through anatomical and genetic similarities.

What mathematical tool is used in phylogenetics to study species interrelatedness?