The structure of the feet and legs varies greatly among frog species

Question

The structure of the feet and legs varies greatly among frog species, depending in part on whether they live primarily on the ground, in water, in trees, or in burrows. Frogs must be able to move quickly through their environment to catch prey and escape predators, and numerous adaptations help them do so.

Many frogs, especially those that live in water, have webbed toes. The degree to which the toes are webbed is directly proportional to the amount of time the species lives in the water. For example, the completely aquatic African dwarf frog (Hymenochirus sp.) has fully webbed toes, whereas the toes of White's tree frog (Litoria caerulea), an arboreal species, are only a half or a quarter webbed. Arboreal frogs have "toe pads" to help grip vertical surfaces. These pads, located on the ends of the toes, do not work by suction. Rather, the surface of the pad consists of interlocking cells, with a small gap between adjacent cells. When the frog applies pressure to the toe pads, the interlocking cells grip irregularities on the substrate. The small gaps between the cells drain away all but a thin layer of moisture on the pad, and maintain a grip through capillarity. This allows the frog to grip smooth surfaces, and does not function when the pads are excessively wet.

In many arboreal frogs, a small "intercalary structure" in each toe increases the surface area touching the substrate. Furthermore, since hopping through trees can be dangerous, many arboreal frogs have hip joints that allow both hopping and walking. Some frogs that live high in trees even possess an elaborate degree of webbing between their toes, as do aquatic frogs. In these arboreal frogs, the webs allow the frogs to "parachute" or control their glide from one position in the canopy to another.

Ground-dwelling frogs generally lack the adaptations of aquatic and arboreal frogs. Most have smaller toe pads, if any, and little webbing. Some burrowing frogs have a toe extension—a metatarsal tubercle—that helps them to burrow. The hind legs of ground dwellers are more muscular than those of aqueous and tree-dwelling frogs.   1 
 1. Which of the following best characterizes the main idea of the passage?

A. An introduction mentioning the different frog types is followed by a discussion about the structure and use of webbed feet in arboreal and aquatic frogs and brief mentions of other adaptations.
B. After the first paragraph follow details on how to identify the different types of frogs based on their adaptations.
C. Detailed descriptions of the structure and function of frog toe pads explain how some frogs can “parachute” in the canopy.
D. The role of webbed feet in the survival behaviors of three kinds of frogs is detailed.
E. A general discussion of frog adapations leads to a core passage concerning the “intercalary structure” common to all frogs.

2 
 2. Of the following choices, the best title for this passage is

A. Structure and Function of Frog Foot Webbing and Toe Pads
B. Capillarity and Suction in the Webbed Feet of Frogs
C. Muscular Differences Among Frogs
D. Foot Structure in Arboreal, Aquatic, and Ground-Dwelling Frogs
E. Burrowing Behavior in Frogs

3 
 3. According to the passage, webbed feet would most likely be found on which type of frog?

I. arboreal
II. aquatic
III. ground-dwelling

A. I only
B. II only
C. III only
D. I and III only
E. I and II only

4 
 4. A frog with a metatarsal tubercle and highly developed hind legs most likely lives

A. in a burrow; the adaptations help the frog dig
B. in the water; the adaptations allow the frog to swim quickly through its environment to catch prey and avoid predators
C. in the trees, occasionally “parachuting”; the adaptations help the frog make safe landings when moving from one position in the canopy to another
D. in the trees, occasionally walking along the ground to get from tree to tree; theadaptations help the frog move quickly to avoid predators and catch prey
E. in areas with many smooth surfaces or where other toe pad adaptations are likely to get excessively wet

5 
 5. It may be inferred from the passage that capillarity

A. requires plenty of water to function
B. is a type of suction
C. is the term for interlocking cells on the toe pad
D. works only with thin films of water
E. works even better when found in conjunction with an intercalary structure

gloomybison · Accepted Answer

1) Which of the following best characterizes the main idea of the passage?

A An introduction mentioning the different frog types is followed by a discussion about the structure and use of webbed feet in arboreal and aquatic frogs and brief mentions of other adaptations.
- Correct

B After the first paragraph follow details on how to identify the different types of frogs based on their adaptations.
-Although it is true that it mentions different adaptations in different frog species, the passage's main point is to detail these adaptations seen in different species. We are not really concerned or told about how to identify different frogs according to their adaptations

C Detailed descriptions of the structure and function of frog toe pads explain how some frogs can “parachute” in the canopy.
-It is mentioned in passage but it is too Narrow to be the scope.

D The role of webbed feet in the survival behaviors of three kinds of frogs is detailed.
-It is partially the scope but there are also other adaptations mentioned in addition to webbed feet

E A general discussion of frog adaptations leads to a core passage concerning the “intercalary structure” common to all frogs.
-It is mentioned in passage but it is too Narrow to be the scope.

2) Of the following choices, the best title for this passage is

A Structure and Function of Frog Foot Webbing and Toe Pads
Partial Scope, although structure and function is largely described, the main point is not necessarily structure and function but rather how these structures/functions are different in several frog species

B Capillarity and Suction in the Webbed Feet of Frogs
Too Narrow, only mentioned in second paragraph

C Muscular Differences Among Frogs
Too Narrow, only mentioned in the last paragraph

D Foot Structure in Arboreal, Aquatic, and Ground-Dwelling Frogs
 Correct

E Burrowing Behavior in Frogs
Too Narrow, only mentioned in last paragraph

3) According to the passage, webbed feet would most likely be found on which type of frog?

I arboreal
-"an arboreal species, are only a half or a quarter webbed" + "Some frogs that live high in trees even possess an elaborate degree of webbing between their toes"
II aquatic
"the completely aquatic African dwarf frog (Hymenochirus sp.) has fully webbed toes"
III ground-dwelling
"Ground-dwelling frogs generally lack the adaptations of aquatic and arboreal frogs. Most have smaller toe pads, if any, and little webbing"

A I only
Wrong

B II only
Wrong

C III only
Wrong

D I and III only
Wrong

E I and II only
 Correct

4) A frog with a metatarsal tubercle and highly developed hind legs most likely lives

A in a burrow; the adaptations help the frog dig
 Correct 
"Some burrowing frogs have a toe extension—a metatarsal tubercle—that helps them to burrow. The hind legs of ground dwellers are more muscular than those of aqueous and tree-dwelling frogs."

B in the water; the adaptations allow the frog to swim quickly through its environment to catch prey and avoid predators

C in the trees, occasionally “parachuting”; the adaptations help the frog make safe landings when moving from one position in the canopy to another

D in the trees, occasionally walking along the ground to get from tree to tree; the adaptations help the frog move quickly to avoid predators and catch prey

E in areas with many smooth surfaces or where other toe pad adaptations are likely to get excessively wet

5) It may be inferred from the passage that capillarity

A requires plenty of water to function
No in contrary it just needs a thin layer of water "thin layer of moisture"

B is a type of suction
It is not a suction, it is nowhere mentioned as a suction

C is the term for interlocking cells on the toe pad
Trap "the frog applies pressure to the toe pads, the interlocking cells grip irregularities on the substrate. The small gaps between the cells drain away all but a thin layer of moisture on the pad, and maintain a grip through capillarity." Capillarity is the means to maintain a grip on layer of water iti is not the term for a cell on the toe

D works only with thin films of water
 Correct 
"The small gaps between the cells drain away all but a  thin layer of moisture  on the pad, and maintain a grip through capillarity."

E works even better when found in conjunction with an intercalary structure
Trap, This is mentioned in paragraph 3 , this may seem related but they are not really , this new paragraph starts a new discussion, it is not related to capillarity

hellohnfjskfbkse · Answer

For question 1 I want to understand why is option a correct and not d

guddo · Answer

1. Which of the following best characterizes the main idea of the passage?

The passage explains how frog feet and legs vary depending on habitat, and how those adaptations help frogs move, survive, and function in water, trees, on the ground, or in burrows.  The main idea  is that the author gives a broad overview of habitat-based frog adaptations, while spending the most detail on webbing and toe pads in aquatic and arboreal frogs.  So the best answer must capture both the general overview and the heavier focus on certain specific adaptations .

A. An introduction mentioning the different frog types is followed by a discussion about the structure and use of webbed feet in arboreal and aquatic frogs and brief mentions of other adaptations.

This fits best. The first paragraph gives the general idea that frog leg and foot structure varies by habitat. The next paragraphs focus mainly on aquatic and arboreal frogs, especially webbing and toe pads, and then briefly mention other adaptations such as intercalary structure, hip joints, burrowing extensions, and muscular hind legs.

B. After the first paragraph follow details on how to identify the different types of frogs based on their adaptations.

This is not the main idea. The passage is not mainly about identification. It is about how adaptations function in different habitats.

C. Detailed descriptions of the structure and function of frog toe pads explain how some frogs can “parachute” in the canopy.

This is too narrow and also inaccurate in structure. Toe pads are explained in detail, but parachuting is linked to webbing, not to toe pads.

D. The role of webbed feet in the survival behaviors of three kinds of frogs is detailed.

This is too narrow. Webbing is important, but the passage also discusses toe pads, intercalary structures, hip joints, metatarsal tubercles, and muscular hind legs.

E. A general discussion of frog adapations leads to a core passage concerning the “intercalary structure” common to all frogs.

This is wrong. The intercalary structure is not presented as common to all frogs, and it is not the core focus of the passage.

Answer: (A)

The structure of the feet and legs varies greatly among frog species

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The structure of the feet and legs varies greatly among frog species

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