The fact that bacteria are capable of chemical communication first eme

Question

The fact that bacteria are capable of chemical communication first emerged from investigations into marine bacteria able to glow in the dark. In 1970 Kenneth H. Nealson and John Woodland Hastings of Harvard University observed that luminous bacteria in culture do not glow at a constant intensity. In fact, they emit no light until the population reaches a high density.

Nealson and Hastings knew the light resulted from chemical reactions catalyzed by the enzyme luciferase. They postulated that this enzyme was ultimately controlled not by some mechanism inside each bacterial cell but by a molecular messenger that traveled between cells. Once inside target cells, the messenger, which the researchers called autoinducer, could induce expression of the genes’ coding for luciferase and for the other proteins involved in light production; that is, autoinducer could stimulate synthesis of the encoded proteins and, thus, of light. Their theory met with skepticism at first but has since been confirmed and expanded.    1 
 1. According to the passage, Nealson and Woodland’s research was instrumental in indicating that

A. bacteria communicate through molecular messengers that travel between cells.
B. luminous bacteria glow not at a constant density but at various densities.
C. bacteria are genetically coded by the autoinducer.
D. the molecular messenger luciferase causes bacteria to glow at high densities.
E. the autoinducer, not the enzyme luciferase as was previously believed, produces the luminosity of certain marine bacteria.

2 
 2. Which of the following are characteristics of the autoinducer involved in light production by marine bacteria?

I. It catalyzes chemical reactions in bacterial cells.
II. It stimulates synthesis of certain proteins.
III. It acts as a messenger between enzymes and bacteria.

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

RC Butler 2022  -  Practice Two RC Passages Everyday.   
Passage # 154 Date: 15-Apr-2022
 This question is a part of RC Butler 2022 .  Click here for Details

Source: Cliffs Test Prep

yashvir45 · Answer

E and B in my opinion...lets see what happens

Akki737 · Answer

Yaay I got both the questions right. Here's my understanding:

1. While all the points presented are correct, the question asks for what the study was 'instrumental' in indicating. i.e., something that was hitherto unknown. And that is simply that bacteria communicate chemically through molecular messengers. Hence, option A.

2. This question is regarding, specifically, the autoinducer. 
I. There is nothing about the autoinducer being a catalyst in the passage - it induces the lighting up of the bacteria but not strictly a catalyst - i.e,. doesn't speed up what is already happening. The enzyme is the catalyst. 
II. This is correct as it stimulates the proteins necessary for light production. 
III. This is a bit tricky - please note that the autoinducer acts as a messenger between bacteria. Not between bacterial cells and enzymes.

singhaz · Answer

The fact that bacteria are capable of chemical communication first emerged from investigations into marine bacteria able to glow in the dark. In 1970 Kenneth H. Nealson and John Woodland Hastings of Harvard University observed that luminous bacteria in culture do not glow at a constant intensity. In fact, they emit no light until the population reaches a high density.
Summary: Bacteria are capable of chemical communication as observed by hastings and nealson from HU. Luminous bacteria glow at variable intensity which also depends on population density.

Nealson and Hastings knew the light resulted from chemical reactions catalyzed by the enzyme luciferase. They postulated that this enzyme was ultimately controlled not by some mechanism inside each bacterial cell but by a molecular messenger that traveled between cells. Once inside target cells, the messenger, which the researchers called autoinducer, could induce expression of the genes’ coding for luciferase and for the other proteins involved in light production; that is, autoinducer could stimulate synthesis of the encoded proteins and, thus, of light. Their theory met with skepticism at first but has since been confirmed and expanded.
Summary: lucifrase an enzyme which catalyze chemical reactions through which light emits is controlled by a molecular messange called autoinducer. It induce expression of genes coding and proteins which is involved in light production. This theory by hastings and nealson was met with skepticism at first but then confirmed and expanded.

1. According to the passage, Nealson and Woodland’s research was instrumental in indicating that

A. bacteria communicate through molecular messengers that travel between cells.
Nealson and Hastings knew the light resulted from chemical reactions catalyzed by the enzyme luciferase. They postulated that this enzyme was ultimately controlled not by some mechanism inside each bacterial cell but by a molecular messenger that traveled between cells.
B. luminous bacteria glow not at a constant density but at various densities.
C. bacteria are genetically coded by the autoinducer.
D. the molecular messenger luciferase causes bacteria to glow at high densities.
E. the autoinducer, not the enzyme luciferase as was previously believed, produces the luminosity of certain marine bacteria.

2. Which of the following are characteristics of the autoinducer involved in light production by marine bacteria?

I. It catalyzes chemical reactions in bacterial cells.
done by enzyme luciferase
II. It stimulates synthesis of certain proteins.
Autoinducer role
III. It acts as a messenger between enzymes and bacteria.
Role of enzyme luciferase

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

Devayusssh · Answer

Please explain why A is the answer of first question and not b .

Posted from my mobile device

kop18 · Answer

Hi  Devayusssh

Let me give it a try!

The question asks "Nealson and Woodland’s research was instrumental in indicating that" - I would rephrase and re write this question like this "what was the most important finding of their research?"
Please look at this line of the passage carefully - 
"The   fact that bacteria are capable of chemical communication first emerged   from investigations into marine bacteria able to glow in the dark."
If you look at the highlighted portion it clearly states that before the research by N&W no body knew that bacteria was capable of communication. This fact first emerged with their research. Hence, when we talk about the most important finding of their research I would say that it was the finding of this communication capability. Rest everything is either just a by product or the supporting material used to support this main idea.

Hope this helps!

Sajjad1994 · Answer

(A) is the correct answer  because the passage clearly states that Nealson and Woodland's research indicated that bacteria communicate through molecular messengers that travel between cells. They postulated the existence of a molecular messenger called autoinducer that could induce gene expression in target cells, leading to the synthesis of proteins and, in this case, the production of light. This discovery of chemical communication between bacteria through signaling molecules was a significant contribution to the understanding of bacterial behavior.

(B) is incorrect  because the passage does not focus on the various densities at which luminous bacteria glow. The passage mentions that luminous bacteria do not glow at a constant intensity and emit no light until the population reaches a high density, but this information is not the main point of Nealson and Woodland's research. The central focus of their research was the concept of chemical communication through molecular messengers, not the variation in glow intensity at different densities.

The fact that bacteria are capable of chemical communication first eme

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The fact that bacteria are capable of chemical communication first eme

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