With the evolution of terrestrial life about 400 million years ago,

Question

With the evolution of terrestrial life about 400 million years ago, wind replaced water as the primary vector by which plants moved male sex cells. Wind pollination has traditionally been viewed as a reproductive process dominated by random events—the vagaries of wind and weather. Pollen loss through happenstance is compensated for in wind-pollinated plants by pollen-to-ovule ratios that greatly exceed those of insect-pollinated species. Unlike the sticky pollen grains of plants pollinated by insects, the pollen grains of wind-pollinated plants are smooth and dry, to avoid clumping and precipitating, and the stigma of the female plant is large and sticky, the better to catch any floating pollen grains. Similarly, wind-pollinated plants typically evolved to grow in stands, such as cornfields, grasslands, or other large, near-monocultural populations.

While wind pollination is usually considered a “primitive” feature by textbooks, recent research has, in fact, shown that several remarkably sophisticated mechanisms for dispersal and capture are characteristic of wind-pollinated plants. Pollen release is often tied to the recognition of unambiguous environmental clues; thus, many plants will not release pollen when wind speeds are low or while humid conditions exist, which might cause pollen grains to clump and fall. The devices that operate to prevent self-pollination are also at times extremely intricate.

Recent findings have revealed another intricacy that compensates for wind pollination’s inefficiency—the physics of pollen motion. The rate at which pollen settles is dictated principally by the size and density of the grain. The slower the settlement rate, the greater the dispersal range. Numerous species reduce the density of pollen grains with air cavities in their walls. There is a limit, however, to the lower range of pollen size.    1 
 1. According to the author, pollen grains that would have the greatest dispersal range would have which of the following characteristics?

I. Small size
II. Dryness
III. Low-density

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

2 
 2. If rainfall levels in a particular growing season were abnormally high, it is most reasonable to conclude, based on the passage, that the

A. amount of pollen released by wind-pollinated species would be less than normal because of sophisticated mechanisms tied to environmental clues
B. amount of pollen released by wind-pollinated species would be greater than normal to compensate for the greater resulting pollen loss
C. pollen-to-ovule ratios of wind-pollinated species would be unaffected by the change in weather
D. amount of seed produced and released by wind-pollinated species would be greater than normal 
E. amount of pollination carried by insect pollinators would remain unchanged

3 
 3. According to the passage, all the following mechanisms serve to reduce pollen loss in wind-pollinated plants EXCEPT:

A. development of a large specially shaped stigma
B. retention of pollen within the male organ when weather conditions are not conducive to dispersal
C. growth of plants in large populations with few species
D. development of intricate mechanisms to prevent self-pollination
E. efficient design of the airborne pollen grain

4 
 4. The author’s attitude towards textbooks that describe wind pollination as “primitive” is best described as one of

A. reasoned rejection
B. tempered uncertainty
C. vehement disagreement
D. mild displeasure
E. complete support

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Passage # 57 Date: 10-Feb-2021
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41396302717 · Answer

1. D
2. A
3. D
4. A

Hoping for the best

arya251294 · Answer

For question 1 - 
 Para 1 mentions:   Unlike the sticky pollen grains of plants pollinated by insects, the pollen grains of wind-pollinated plants are smooth and dry, to avoid clumping and precipitating 
So I believe dryness is another characteristic of pollen grains required for better dispersal, therefore I choose (E).

Question 2 -
As mentioned in Para 2  Pollen release is often tied to the recognition of unambiguous environmental clues; thus, many plants will not release pollen when wind speeds are low or while humid conditions exist,  the pollen release will be less in humid/rainy conditions. therefore option (A)

Also, for the 3rd question -
 Para 2 mentions:   The devices that operate to prevent self-pollination are also at times extremely intricate. 
So we can't choose D as the answer because of this reasoning but para 2 also talks about this - 
 thus, many plants will not release pollen when wind speeds are low or while humid conditions exist, which might cause pollen grains to clump and fall. 
which means that plants don't release the pollens but they fall therefore there is no retention, I go with option (B) here.

Question 4 - Para 2 starts with the word  while  and thus shows us some form of contrast and going forward in the para 2, the author provides us with the reasoning as to why he/she feels that there are other  remarkably sophisticated mechanisms . Therefore option (A)

Ranasaymon · Answer

1. According to the author, pollen grains that would have the greatest dispersal range would have which of the following characteristics?

...the pollen grains of wind-pollinated plants are smooth and  dry , to avoid clumping and precipitating,
 The rate at which pollen settles is dictated principally by the  size and density  of the grain. The slower the settlement rate, the greater the dispersal range. Numerous species  reduce the density of pollen grains  with air cavities in their walls.There is a limit, however, to the lower range of pollen size. ( greatest dispersal is related with small size and low density)

I. Small size
II. Dryness
III. Low-density

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

2. If rainfall levels in a particular growing season were abnormally high, it is most reasonable to conclude, based on the passage, that the

Pollen release is often tied to the recognition of unambiguous environmental clues; thus, many plants will not release pollen when wind speeds are low or while  humid conditions exist ,

A. amount of pollen released by wind-pollinated species would be less than normal because of sophisticated mechanisms tied to environmental clues  -> More rain-> humid condition-> less pollen release
B. amount of pollen released by wind-pollinated species would be greater than normal to compensate for the greater resulting pollen loss
C. pollen-to-ovule ratios of wind-pollinated species would be unaffected by the change in weather
D. amount of seed produced and released by wind-pollinated species would be greater than normal
E. amount of pollination carried by insect pollinators would remain unchanged

3. According to the passage, all the following mechanisms serve to reduce pollen loss in wind-pollinated plants EXCEPT:

A. development of a large specially shaped stigma -> mentioned in the last part of the first paragraph
 B. retention of pollen within the male organ when weather conditions are not conducive to dispersal  -> There is nothing about male organ in the passage 
C. growth of plants in large populations with few species ->mentioned in the last part of the first paragraph
D. development of intricate mechanisms to prevent self-pollination -> mentioned in the last part of the second paragraph
E. efficient design of the airborne pollen grain -> mentioned in the middle part of the second paragraph

4. The author’s attitude towards textbooks that describe wind pollination as “primitive” is best described as one of

While  wind pollination is usually considered a “primitive” feature by textbooks, recent research has, in fact, shown that several remarkably sophisticated mechanisms for dispersal and capture are characteristic of wind-pollinated plants.

A. reasoned rejection 
B. tempered uncertainty (No uncertainty, there is direct contrast present in second paragraph)
C. vehement disagreement ->Extreme
D. mild displeasure 
E. complete support -> Completely opposite
Between options A and D, I choose option A, as the use of different tone in second paragraph shows us contrast.

41396302717 · Answer

I still feel that in 3rd question, option D is the most suitable because "development of intricate mechanisms to prevent self-pollination" is used just as an example of an intricate mechanism while on the other hand there is a statement in the passage that says the pollens are released only when the conditions are conducive. Also there is an instance in the passage where it states "plants moved male sex cells",
That is why I have my fair share of doubts on option B.

arya251294 · Answer

But retention does not take place at all. All we know is that voluntarily the plant avoids the release of pollens in X condition but they fall therefore retention doesn't take place.

Ranasaymon · Answer

Check the very first sentence,  With the evolution of terrestrial life about 400 million years ago, wind replaced water as the primary vector by which plants moved male sex cells  Water was the primary vector through which plants moved,not retained males sex cells. Now, Wind is the primary vector.

Now check this,   many plants will not release pollen when wind speeds are low or while humid conditions exist , which might cause pollen grains to clump and fall. The devices that operate to prevent  self-pollination  are also at times extremely intricate . What is the self pollination? It is a process given in the highlighted part. And it is not an example, rather it tells us about the feature, intricacy, of pollination.

road740 · Answer

My solutions 
 
 1. According to the author, pollen grains that would have the greatest dispersal range would have which of the following characteristics?

I. Small size ( "The rate at which pollen settles is dictated principally by the  size and density of the grain . The slower the settlement rate, the greater the dispersal range. Numerous species  reduce the density of pollen grains  with air cavities in their walls. There is a limit, however, to the lower range of pollen size." )

II. Dryness (In passage 1 the author states:  "Unlike the sticky pollen grains of plants pollinated by insects, the pollen grains of wind-pollinated plants are smooth and dry"  However, he does not say anything about how this characteristic might be influencing the  dispersal range  of the pollen)

III. Low-density (see I.)

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

2. If rainfall levels in a particular growing season were abnormally high, it is most reasonable to conclude, based on the passage, that the...

A. amount of pollen released by wind-pollinated species would be less than normal because of sophisticated mechanisms tied to environmental clues  
( "many plants will not release pollen when wind speeds are low or while humid conditions exist"  rain = (more than) humid condition)

B. amount of pollen released by wind-pollinated species would be greater than normal to compensate for the greater resulting pollen loss
C. pollen-to-ovule ratios of wind-pollinated species would be unaffected by the change in weather
D. amount of seed produced and released by wind-pollinated species would be greater than normal 
E. amount of pollination carried by insect pollinators would remain unchanged

3.According to the passage, all the following mechanisms serve to  reduce pollen loss  in wind-pollinated plants EXCEPT:

A. development of a large specially shaped stigma
-->  "and the  stigma  of the female plant is  large and sticky , the better to catch any floating pollen grains"

B. retention of pollen within the male organ when weather conditions are not conducive to dispersal
-->  "many plants  will not release  pollen when wind speeds are low or while humid conditions exist" 
--> we can assume that the male organ would release these pollen

C. growth of plants in large populations with few species
-->  "...other large, near-monocultural populations." 
--> "large populations" is specifically mentioned, while "near-monocultural" refers to the fact that there are "few species"

D. development of intricate mechanisms to prevent self-pollination  
-->  "The devices that operate to prevent self-pollination  are also  at times extremely intricate." 
--> This is not a mechanism to reduce pollen loss. The text only says that there are also devices, that operate to prevent slf-pollination.

E. efficient design of the airborne pollen grain
-->  "the pollen grains of wind-pollinated plants are  smooth and dry, to avoid clumping and precipitating "

4. The author’s attitude towards textbooks that describe wind pollination as “primitive” is best described as one of

A. reasoned rejection  
-->  "recent  research has, in fact, shown that  several remarkably sophisticated mechanisms"  
--> he does not "vehemently" disagree or expresses displeasure; rather he rejects the term by reasoning, more specifically here with a "recent research"

B. tempered uncertainty
C. vehement disagreement
D. mild displeasure
E. complete support

Akarshkhan86 · Answer

I am bit confused with the Question 3

It mentions: " Pollen release is often tied to the recognition of unambiguous environmental clues; thus, many plants will not release pollen when wind speeds are low or while humid conditions exist, which might cause pollen grains to clump and fall. "

Doesn't it makes sense that this mechanisms serve for pollens to fall and loss, how does this reduce pollen loss in wind-pollinated plants ?

Doesn't it supports answer option B.  Sajjad1994

VerbalBot · Answer

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With the evolution of terrestrial life about 400 million years ago,

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