Homeostasis, an animals maintenance of certain internal variables

Question

Homeostasis, an animal’s maintenance of certain internal variables within an acceptable range, particularly in extreme physical environments, has long interested biologists. The desert rat and the camel in the most water-deprived environments, and marine vertebrates in an all-water environment, encounter the same regulatory problem: maintaining adequate internal fluid balance.

For desert rats and camels, the problem is conservation of water in an environment where standing water is nonexistent, temperature is high, and humidity is low. Despite these handicaps, desert rats are able to maintain the osmotic pressure of their blood, as well as their total body water content, at approximately the same levels as other rats. One countermeasure is behavioral: these rats stay in burrows during the hot part of the day,thus avoiding loss of fluid through panting or sweating, which are regulatory mechanisms for maintaining internal body temperature by evaporative cooling. Also, desert rats’ kidneys can excrete a urine having twice as high a salt content as seawater.

Camels, on the other hand, rely more on simple endurance. They cannot store water, and their reliance on an entirely unexceptional kidney results in a rate of water loss through renal function significantly higher than that of desert rats. As a result, camels must tolerate losses in body water of up to 30 percent of their body weight. Nevertheless, camels do rely on a special mechanism to keep water loss within a tolerable range: by sweating and panting only when their body temperature exceeds that which would kill a human, they conserve internal water.

Marine vertebrates experience difficulty with their water balance because though there is no shortage of seawater to drink, they must drink a lot of it to maintain their internal fluid balance. But the excess salts from the seawater must be discharged somehow, and the kidneys of most marine vertebrates are unable to excrete a urine in which the salts are more concentrated than in seawater. Most of these animals have special salt-secreting organs outside the kidney that enable them to eliminate excess salt.   1 
 1. Which of the following most accurately states the purpose of the passage?

(A) To compare two different approaches to the study of homeostasis
(B) To summarize the findings of several studies regarding organisms’ maintenance of internal variables in extreme environments
(C) To argue for a particular hypothesis regarding various organisms’ conservation of water in desert environments
(D) To cite examples of how homeostasis is achieved by various organisms
(E) To defend a new theory regarding the maintenance of adequate fluid balance

2 
 2. It can be inferred from the passage that some mechanisms that regulate internal body temperature, like sweating and panting, can lead to which of the following?

(A) A rise in the external body temperature
(B) A drop in the body’s internal fluid level
(C) A decrease in the osmotic pressure of the blood
(D) A decrease in the amount of renal water loss
(E) A decrease in the urine’s salt content

3 
 3. It can be inferred from the passage that the author characterizes the camel’s kidney as “entirely unexceptional” (line 26) primarily to emphasize that it

(A) functions much as the kidney of a rat functions
(B) does not aid the camel in coping with the exceptional water loss resulting from the extreme conditions of its environment
(C) does not enable the camel to excrete as much salt as do the kidneys of marine vertebrates
(D) is similar in structure to the kidneys of most mammals living in water-deprived environments
(E) requires the help of other organs in eliminating excess salt

Sajjad1994 · Accepted Answer

Official Explanation

2. It can be inferred from the passage that some mechanisms that regulate internal body temperature, like sweating and panting, can lead to which of the following?

Difficulty Level:   Medium

Explanation

An inference is drawn from stated information. To answer this question, look at the information about sweating and panting in  lines   (One countermeasure is behavioral: these rats stay in burrows during the hot part of the day, thus avoiding loss of fluid through panting or sweating)  and  Lines   (As a result, camels must tolerate losses in body water of up to 30 percent of their body weight. Nevertheless, camels do rely on a special mechanism to keep water loss within a tolerable range) .

The passage states that desert rats avoid loss of fluid through panting or sweating, which are regulatory mechanisms for maintaining internal body temperature by evaporative cooling. These mechanisms reduce internal body temperatures. Additionally, camels conserve internal water  (line 35 mechanism to keep water loss within a tolerable range)  when they avoid sweating and panting, except at very high body temperatures. Therefore, they must lose internal water when they do sweat and pant.

A.  The passage does not discuss external body temperature; sweating and panting lower internal body temperature, and there is no reason to infer external body temperatures might rise.

B. Correct.  Sweating and panting lead to loss of fluid. Desert rats avoid sweating and panting by staying in burrows, and camels do not employ these mechanisms except at very high body temperatures (lines  (As a result, camels must tolerate losses in body water of up to 30 percent of their body weight. Nevertheless, camels do rely on a special mechanism to keep water loss within a tolerable range) .) and thus conserve internal water.

C.  The passage states that desert rats are able to maintain the osmotic pressure of their blood, as well as their total body-water content  (lines Despite these handicaps, desert rats are able to maintain the osmotic pressure of their blood)  and does not connect changes in osmotic pressure to temperature regulating mechanisms such as sweating and panting.

D.  While the passage does discuss renal water loss, it does not relate this to temperature-regulating mechanisms like sweating and panting.

E.  The passage does not relate body temperature regulators like sweating and panting to changes in the urine’s salt content.

The correct answer is B.

Hope it helps

Aiena · Answer

1. Which of the following most accurately states the purpose of the passage?

(A) To compare two different approaches to the study of homeostasis
(B) To summarize the findings of several studies regarding organisms’ maintenance of internal variables in extreme environments
(C) To argue for a particular hypothesis regarding various organisms’ conservation of water in desert environments
(D) To cite examples of how homeostasis is achieved by various organisms
(E) To defend a new theory regarding the maintenance of adequate fluid balance

The first line of the passage says that biologists are  INTERESTED  in homeostasis. The author does not talk about any  studies . So, option B is incorrect.

Summary of the four paragraphs-

PARAGRAPH 1: What is homeostasis? Examples of three animals that maintain internal fluid balance.

PARAGRAPH 2: Explains how   desert rats   maintain fluid balance.

PARAGRAPH 3: Explains how   camels   maintain their fluid balance.

PARAGRAPH 4: Talks about water balance in   marine vertebrates  .

Hence, option D is the correct answer.

I hope this helps.

Aiena.

LakerFan24 · Answer

1. Which of the following most accurately states the purpose of the passage?

(A) To compare two different approaches to the study of homeostasis
  -   Incorrect . What are the two different approaches? Each animal / species has a different way of achieving homeostasis, so if we were to be technical, it should say *multiple* approaches
 
 (B) To summarize the findings of several studies regarding organisms’ maintenance of internal variables in extreme environments
  -   Incorrect . How do we know there are *SEVERAL* studies whose findings we are summarizing? What if these are just observations that experts have discussed? There is no way we can infer the info in this passage came from studies.
 
 (C) To argue for a particular hypothesis regarding various organisms’ conservation of water in desert environments
  -   Incorrect . There is no "particular" hypothesis that is favored here. Also, this passage not only talks about desert environments, but aquatic ones as well.

(D) To cite examples of how homeostasis is achieved by various organisms
  -   Correct . This passage cites several examples of how different organisms achieve homeostasis (i.e. desert rats, camels & marine vertebrates). No flaw here

(E) To defend a new theory regarding the maintenance of adequate fluid balance 
-   Incorrect . What is this "new theory"? When was this mentioned?

aragonn · Answer

P1 - about H, examples are given.
P2 - H in terms of desert rats exemplified.
P3 - H in terms of desert camel exemplified.
P4 - H in terms of Marine vertebrates exemplified.

Main point - about H, examples are given. and each one of them is described.
Tone - informative, modrate

1. Which of the following most accurately states the purpose of the passage?

(A) To compare two different approaches to the study of homeostasis - No
(B) To summarize the findings of several studies regarding organisms’ maintenance of internal variables in extreme environments - Close but no, D is better with use of the word such as example. It is more like p1 only
(C) To argue for a particular hypothesis regarding various organisms’ conservation of water in desert environments - No
(D) To cite examples of how homeostasis is achieved by various organisms - Correct.
(E) To defend a new theory regarding the maintenance of adequate fluid balance - No

-----------------------------------------

2. It can be inferred from the passage that some mechanisms that regulate internal body temperature, like sweating and panting, can lead to which of the following?

lines to read - Nevertheless, camels do rely on a special mechanism to keep water loss within a tolerable range: by sweating and panting only when their body temperature exceeds that which would kill a human, they conserve internal water.

(B) A drop in the body’s internal fluid level - yes

-----------------------------------------

3. It can be inferred from the passage that the author characterizes the camel’s kidney as “entirely unexceptional ” (line 26) primarily to emphasize that it

pre-think - Not much helpful for camels.

(A) functions much as the kidney of a rat functions - no
(B) does not aid the camel in coping with the exceptional water loss resulting from the extreme conditions of its environment - yes
(C) does not enable the camel to excrete as much salt as do the kidneys of marine vertebrates - No
(D) is similar in structure to the kidneys of most mammals living in water-deprived environments - NO
(E) requires the help of other organs in eliminating excess salt - no

100mitra · Answer

RC#8 long passage {10 mins 3/3 correct}

Pharaphasing  
  Para 1:   “Homeostasis” is the state of steady internal, physical, and chemical conditions maintained by living systems
 Challenge:  Maintaining adequate internal fluid balance.
 3 examples how "Homeostasis" is maintained below 
  Para 2:    Desert Rats : behavioral - in the most water-deprived environments
- burrows during the hot part of the day to avoid fluid loss
- can excrete a urine having twice as high a salt content as seawater.
  Para 3:    Camels : simple endurance - in the most water-deprived environments
- by sweating and panting only when their body temperature exceeds 
- they conserve internal water (fluid loss)
  Para 4:    Marine vertebrates : in an all-water environment
- the excess salts from the seawater 
- special salt-secreting organs outside the kidney that enable them to eliminate excess salt.

1. Which of the following most accurately states the purpose of the passage?  
(A) To compare two different approaches to the study of homeostasis
  Wrong:   Passage has two different examples of different living being behave to maintain homeostasis.
 
(B) To summarize the findings of several studies regarding organisms’ maintenance of internal variables in extreme environments
  Wrong:   Tricky! I kept this option on hold, checking next option, returning back, with best of 2 between D and B, I realized that, it’s not summarized of several studies regarding organisms, in fact, in passage a statement is quoted, followed by 3 examples to explain how homeostasis is maintained by different organs for different living species.
 
(C) To argue for a particular hypothesis regarding various organisms’ conservation of water in desert environments
  Wrong:   No argue to any a supposition or proposed explanation made on the basis of limited evidence as a starting point for further investigation

(D) To cite examples of how homeostasis is achieved by various organisms
  Correct: the author has mentioned 3 examples 2 from terrestrial and 1 from Marine vertebrates, how homeostasis is achieved.

(E) To defend a new theory regarding the maintenance of adequate fluid balance
  Wrong:   Easy elimination, there is no any mention of theory.

2. It can be inferred from the passage that 
some mechanisms that regulate internal body temperature, 
like sweating and panting, can lead to which of the following?  
  Explanation:   as mentioned in the passage in para 2 
“camels do rely on a special mechanism to keep water loss within a tolerable range: by sweating and panting 
only when their body temperature exceeds that which would kill a human, 
 they conserve internal wate r”

(A) A rise in the external body temperature   – No   
  (B) A drop in the body’s internal fluid level - Yes  
(C) A decrease in the osmotic pressure of the blood   – No  
(D) A decrease in the amount of renal water loss   – No  
(E) A decrease in the urine’s salt content   – No

3. It can be inferred from the passage that 
the author characterizes the camel’s kidney as “entirely unexceptional” (line 26) 
primarily to emphasize that it

(A) functions much as the kidney of a rat functions
  Wrong:   as mentioned in passage para 3 “They cannot store water, and their reliance on an entirely unexceptional kidney results in a rate of water loss through renal function significantly higher than that of desert rats” there is contrast between camel and desert rat kidney
(B) does not aid the camel in coping with the exceptional water loss resulting from the extreme conditions of its environment
  Correct: Exactly, since camel kidney does not aid, due to sweating and patting huge liquid loss occurs with camel in extreme conditions to maintain internal temperature balance   
(C) does not enable the camel to excrete as much salt as do the kidneys of marine vertebrates
  Wrong:   No such information is mentioned in passage 
(D) is similar in structure to the kidneys of most mammals living in water-deprived environments
  Wrong:   mammals living in water deprived environments have additional organ apart from kidney to eliminate excess salt.
(E) requires the help of other organs in eliminating excess salt
  Wrong:   Camel kidney does not have additional organ to eliminate salt from body.

Sajjad1994 · Answer

Official Explanation

1. Which of the following most accurately states the purpose of the passage?

Difficulty Level:   Easy

Explanation

Main idea

To answer this question, look at the passage as a whole. The first paragraph defines homeostasis and names three animals that must maintain internal fluid balance in difficult circumstances. The topic of the second paragraph is how desert rats maintain fluid balance. The third paragraph discusses how camels maintain fluid balance, while the final paragraph describes maintenance of water balance in marine vertebrates. Thus, the overall purpose is to give three examples of how homeostasis is achieved.

A.  Examples of homeostasis are given, but different approaches to studying it are not discussed.

B.  The passage describes examples, but it does not summarize studies.

C.  While the passage does discuss two desert animals, it does not present any argument for a particular hypothesis.

D.  Correct.   The passage discusses the examples of desert rats, camels, and marine vertebrates to show how these organisms are able to achieve homeostasis.

E.  The passage describes how three organisms maintain water balance, but it presents no theory about it.

The correct answer is D.

Sajjad1994 · Answer

Official Explanation

3. It can be inferred from the passage that the author characterizes the camel’s kidney as “entirely unexceptional” (line 26) primarily to emphasize that it

Difficulty Level:   Easy

Explanation

Inference

To answer this question, look at the phrase entirely unexceptional in the context of the passage. Desert rats and camels share the problem of conserving water in an environment where water is lacking, temperature is high, and humidity is low (lines 10–12). Desert rats have as part of their coping mechanisms exceptional kidneys that produce urine with a high salt content. The author compares camels’ kidneys to those of desert rats and shows that the camels have ordinary kidneys that do not help the camels conserve water.

A.  Since a contrast is drawn between the kidneys of camels and those of desert rats, the two must function differently; the passage makes no reference to the kidneys of other rats.

B.  Correct.   The camel’s kidney does nothing special to help the camel cope
with its difficult environment.

C.  No comparison between the kidneys of camels and the kidneys of marine vertebrates is made.

D.  There is no information given about the kidney structure of most mammals in desert environments so this conclusion is not justified.

E.  Marine vertebrates have other organs that help eliminate extra salt; camels do not.

The correct answer is B.

VerbalBot · Answer

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Homeostasis, an animals maintenance of certain internal variables

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