Echolocating bats emit sounds in patternscharacteristic of each

Question

Echolocating bats emit sounds in patterns—characteristic of each species—that contain both frequency-modulated (FM) and constant-frequency (CF) signals. The broadband FM signals and the narrowband CF signals travel out to a target, reflect from its, and return to the hunting bat. In this process of transmission and reflection, the sounds are changed, and the changes in the echoes enable the bat to perceive features of the target.

The FM signals report information about target characteristics that modify the timing and the fine frequency structure, or spectrum, of echoes—for example, the target's size, shape, texture, surface structure, and direction in space. Because of their narrow bandwidth, CF signals portray only the target's presence and, in the case of some bat species, its motion relative to the bat's. Responding to changes in the CF echo's frequency, bats of some species correct in flight for the direction and velocity of their moving prey.   1 
 D 
 1. According to the passage, the information provided to the bat by CF echoes differs from that provided by FM echoes in which of the following ways?

A Only CF echoes alert the bat to moving targets.
 B Only CF echoes identify the range of widely spaced targets.
 C Only CF echoes report the target's presence to the bat.
 D In some species, CF echoes enable the bat to judge whether it is closing in on its target.
 E In some species, CF echoes enable the bat to discriminate the size of its target and the direction in which the target is moving.

2 
 B 
 2. According to the passage, the configuration of the target is reported to the eholocating bat by changes in the

A echo spectrum of CF signals
 B echo spectrum of FM signals
 C direction and velocity of the FM echoes
 D delay between transmission and reflection of the CF signals
 E relative frequencies of the FM and the CF echoes

3 
 E 
 3. The author presents the information concerning bat sonar in a manner that could be best described as

A argumentative
 B commendatory
 C critical
 D disbelieving
 E objective

4 
 A 
 4. Which of the following best describes the organization of the passage?

A A fact is stated, a process is outlined, and specific details of the process are described.
 B A fact is stated, and examples suggesting that a distinction needs correction are considered.
 C A fact is stated, a theory is presented to explain that fact, and additional facts are introduced to validate the theory.
 D A fact is stated, and two theories are compared in light of their explanations of this fact.
 E A fact is stated, a process is described, and examples of still another process are illustrated in detail.

Skywalker18 · Accepted Answer

All correct in 5 mins 30 seconds, including 1 mins 45 seconds to read.
Para 1- Echolocating bats- FM + CF , process of transmission and reflection
Para 2- FM and CF uses

1. According to the passage, the information provided to the bat by CF echoes differs from that provided by FM echoes in which of the following ways?
 D In some species, CF echoes enable the bat to judge whether it is closing in on its target.- Correct
Because of their narrow bandwidth, CF signals portray only the target's presence and, in the case of some bat species, its motion relative to the bat's.

2. According to the passage, the configuration of the target is reported to the eholocating bat by changes in the 
 B echo spectrum of FM signals
The FM signals report information about target characteristics that modify the timing and the fine frequency structure, or spectrum, of echoes—for example, the target's size, shape, texture, surface structure, and direction in space.

3. The author presents the information concerning bat sonar in a manner that could be best described as
 A argumentative- incorrect, there is no argument used
 B commendatory- incorrect
 C critical- incorrect, 
 D disbelieving - incorrect
 E objective- Correct, the author is objective and does not gives his/her own opinions

4. Which of the following best describes the organization of the passage?
 A A fact is stated, a process is outlined, and specific details of the process are described.- Correct, the fact 'Echolocating bats emit sounds in patterns' is stated. The process(how it works) is outlined and then details are presented

Pankaj0901 · Answer

Question 1, why is Option C not right? 
Option C:  Only CF echoes report the target's presence to the bat.

It is clearly stated in P2: "Because of their narrow bandwidth,  CF signals portray only the target's presence  and, in the case of some bat species, its motion relative to the bat's."

bM22 · Answer

Hi  PANKAJ0901 ,

Question is about the difference between CF echoes and FM echoes, now FM echoes also report the target presence to the bat, and that can be inferred from the lines:"The FM signals report information about target characteristics that modify the timing and the fine frequency structure, or spectrum, of echoes—for example, the target's size, shape, texture, surface structure, and direction in space.", All these would imply that FM echoes report that there is a target present. 
Now what CF echoes do that FM echoes don't is : " Responding to changes in the CF echo's frequency, bats of some species correct in flight for the direction and velocity of their moving prey .", they enable the bat to judge whether it is closing in on its target, thus allowing the bat to change its course of flight depending on the velocity of moving prey.

Thus option D is the correct answer.

Hope This Helps.
Thanks.

VerbalBot · Answer

Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.

Echolocating bats emit sounds in patternscharacteristic of each

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Reading Comprehension (RC) Questions

Echolocating bats emit sounds in patternscharacteristic of each

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards