In the eighteenth century the French naturalist Jean Baptiste de Lamar

Question

In the eighteenth century the French naturalist Jean
Baptiste de Lamarck believed that an animal’s use or
disuse of an organ affected that organ’s development in
the animal’s offspring. Lamarck claimed that the
 (5)  giraffe’s long neck, for example, resulted from its
ancestors stretching to reach distant leaves. But
because biologists could find no genetic mechanism to
make the transmission of environmentally induced
adaptations seem plausible, they have long held that
 (10)  inheritance of acquired characteristics never occurs.
Yet new research has uncovered numerous examples of
the phenomenon.

In bacteria, for instance, enzymes synthesize and
break down rigid cell walls as necessary to
 (15)  accommodate the bacteria’s growth. But if an
experimenter completely removes the cell wall from a
bacterium, the process of wall synthesis and
breakdown is disrupted, and the bacterium continues to
grow—and multiply indefinitely—without walls. This
 (20)  inherited absence of cell walls in bacteria results from
changes in the interactions among genes, without any
attendant changes in the genes themselves.

A fundamentally different kind of environmentally
induced heritable characteristic occurs when specific
 (25)  genes are added to or eliminated from an organism. For
example, a certain virus introduces a gene into fruit
flies that causes the flies to be vulnerable to carbon
dioxide poisoning, and fruit flies infected with the virus
will pass the gene to their offspring. But if infected
 (30)  flies are kept warm while they are producing eggs, the
virus is eliminated from the eggs and the offspring are
resistant to carbon dioxide. Similarly, if an Escherichia
coli bacterium carrying a certain plasmid—a small ring
of genetic material—comes into contact with an E. coli
 (35)  bacterium lacking the plasmid, the plasmid will enter
the second bacterium and become part of its genetic
makeup, which it then passes to its offspring. The case
of the E. coli is especially noteworthy for its suggestion
that inheritance of acquired characteristics may have
 (40)  helped to speed up evolution: for example, many
complex cells may have first acquired the ability to
carry out photosynthesis by coming into contact with a
bacterium possessing the gene for that trait, an ability
that normally would have taken eons to develop
 (45)  through random mutation and natural selection.

The new evidence suggests that genes can be
divided into two groups. Most are inherited
“vertically,” from ancestors. Some however, seem to
have been acquired “horizontally,” from viruses,
 (50)  plasmids, bacteria, or other environmental agents. The
evidence even appears to show that genes can be
transmitted horizontally between organisms that are
considered to be unrelated: from bacteria to plants, for
example, or from bacteria to yeast. Some horizontal
 (55)  transmission may well be the mechanism for
inheritance of acquired characteristics that has long
eluded biologists, and that may eventually prove
Lamarck’s hypothesis to be correct.    1 
 1. The passage suggests that many biologists no longer believe which one of the following?

(A) An organ’s use or disuse can affect that organ’s development.
(B) Some but not all genes are inherited horizontally.
(C) All genes are inherited horizontally.
(D) Some but not all genes are inherited vertically.
(E) All genes are inherited vertically.

2 
 2. According to the passage, which one of the following is an acquired characteristic transmitted by altering the interaction among genes rather than be adding or eliminating a gene?

(A) invulnerability to carbon dioxide poisoning
(B) susceptibility to carbon dioxide poisoning
(C) lack of cell walls
(D) presence of cell walls
(E) possession of certain plasmids

3 
 3. The primary purpose of the last paragraph it to

(A) suggest a modification to Lamarck’s hypothesis
(B) demonstrate the correctness of Lamarck’s hypothesis
(C) illustrate the significance of Lamarck’s hypothesis
(D) criticize scientists’ rejection of Lamarck’s hypothesis
(E) explain how recent discoveries may support Lamarck’s hypothesis

4 
 4. Which one of the following, if true, offers the most support for Lamarck’s hypothesis?

(A) Deer have antlers because antlers make deer more likely to survive and reproduce.
(B) Anteaters developed long snouts because the anteater stretches its snout in order to reach ants hidden well below ground.
(C) Potatoes produced from synthetic genes tend to be more resistant to disease than are potatoes produced from natural genes.
(D) Lions raised in captivity tend to have a weaker sense of direction than do lions raised in the wild.
(E) Pups born to wild dogs tend to be more aggressive than are pups born to dogs bred for hunting.

5 
 5. According to the passage, the inheritance of acquired characteristics is particularly significant because this phenomenon

(A) may affect the speed at which photosynthesis occurs
(B) may help to explain the process of natural selection
(C) may occur without affecting the composition of genes
(D) may influence the rate at which evolution progresses
(E) may be changed or stopped under experimental conditions

6 
 6. Which one of the following can be inferred from the passage about the absence of cell walls in some bacteria?

(A) It can be reversed by introducing the appropriate gene.
(B) It can be brought about by a virally introduced gene.
(C) It can be caused by the loss of a cell wall in a single bacterium.
(D) It can be halted, but not reversed, by restoring cell walls to a group of bacteria.
(E) It can be transmitted horizontally to other bacteria.

Source:   LSAT Official PrepTest 34   
 Difficulty Level:   600

RC Butler 2021  -  Practice Two RC Questions Everyday.   
Passage # 209 Date: 27-May-2021
 This question is a part of RC Butler 2021 .  Click here for Details

mSKR · Answer

1. The passage suggests that many biologists no longer believe which one of the following?

(A) An organ’s use or disuse can affect that  organ’s development. 
(B)  Some but not all  genes are inherited horizontally.
(C) All genes are inherited horizontally.
(D)  Some but not all genes  are inherited vertically.
(E) All genes are inherited vertically.

. But
because biologists could find no genetic mechanism to
make the transmission of environmentally induced
adaptations seem plausible, they have long held that
(10) inheritance of acquired characteristics never occurs.

But as per passage , E fits more than C
Hence E is correct answer

2. According to the passage, which one of the following is an acquired characteristic transmitted by altering the interaction among genes rather than be adding or eliminating a gene?

(A) invulnerability to carbon dioxide poisoning
(B) susceptibility to carbon dioxide poisoning
(C) lack of cell walls
(D) presence of cell walls
(E) possession of certain plasmids

This
(20) inherited absence of cell walls in bacteria results from
changes in the interactions among genes, without any
attendant changes in the genes themselves.

C matches with the information given

3. The primary purpose of the last paragraph it to

(A) suggest a modification to Lamarck’s hypothesis
(B) demonstrate the correctness of Lamarck’s hypothesis
(C) illustrate the significance of Lamarck’s hypothesis
(D) criticize scientists’ rejection of Lamarck’s hypothesis
(E) explain how recent discoveries may support Lamarck’s hypothesis

Some horizontal
(55) transmission may well be the mechanism for
inheritance of acquired characteristics that has long
eluded biologists, and that may eventually prove
Lamarck’s hypothesis to be correct.

E matches the context

B and C are close options. I reject B and C because passage brings new evidence to support the hypothesis. But the primary purpose was not to demonstrate or illustrate his hypothesis.

4. Which one of the following, if true, offers the most support for Lamarck’s hypothesis?

(A) Deer have antlers because antlers make deer more likely to survive and reproduce.
(B) Anteaters developed long snouts because the anteater stretches its snout in order to reach ants hidden well below ground.
(C) Potatoes produced from synthetic genes tend to be more resistant to disease than are potatoes produced from natural genes.
(D) Lions raised in captivity tend to have a weaker sense of direction than do lions raised in the wild.
(E) Pups born to wild dogs tend to be more aggressive than are pups born to dogs bred for hunting.

Lamarck believed that an animal’s use or
disuse of an organ affected that organ’s development in
the animal’s offspring

B matches the context/

A was clos e option but on understanding Landamrk hypothesis, B is clear winner.

5. According to the passage, the inheritance of acquired characteristics is particularly significant because this phenomenon

(A) may affect the speed at which photosynthesis occurs
(B) may help to explain the process of natural selection
(C) may occur without affecting the composition of genes
(D) may influence the rate at which evolution progresses
(E) may be changed or stopped under experimental conditions

The case
of the E. coli is especially noteworthy for its suggestion
that inheritance of acquired characteristics may have
(40) helped to speed up evolution

D matches the context.

mSKR · Answer

6. Which one of the following can be inferred from the passage about the absence of cell walls in some bacteria?

(A) It can be reversed by introducing the appropriate gene.
Reject: No such claim is mentioned
(B) It can be brought about by a virally introduced gene.
Reject: It is brought by enzymes not by virtually induced genes
(D) It can be halted, but not reversed, by restoring cell walls to a group of bacteria.
Reject: no such information about reversal mentioned in the passage.

(C) It can be caused by the loss of a cell wall in a single bacterium.
 (E) It can be transmitted horizontally to other bacteria.

C could be option if the loss were replaced by absence. As this absence is done by enzymes and this can affect future bacterium as given in the below text.

his
(20) inherited absence of cell walls in bacteria results from
changes in the interactions among genes, without any
attendant changes in the genes themselves

But E is pretty straightforward from the context that it can be transmitted horizontally and also from the example of above context, so I choose option E.
 however, seem to
have been acquired “horizontally,” from viruses,
(50) plasmids, bacteria, or other environmental agents

mSKR · Answer

Hi  Sajjad1994  :

Please give official explanation for Q1: Why not A? Actually in the passage , it doesn't mention what scientists believe now finally. It is only given why have believed so far. Whether this belief change is not given in argument.

For Q6: please share official explanation why not E ? in C , its not clear this loss means by what. So I choose E over C.
Official explanations would help for Q1 and Q6

Thanks!

GAngstA · Answer

hi expert, plz provide oe because some question oa might be wrong!!!!

Sajjad1994 · Answer

Explanation

1. The passage suggests that many biologists no longer believe which one of the following?

Difficulty Level:   700

Explanation

The repetition of  “horizontally”  and  “vertically”  among the choices means that it’s time to figure out what those terms mean. Most genes, we’re told, are inherited vertically (that is, from ancestors), but  “some…seem to have been acquired ‘horizontally,’”  from outside agents. If so, then  (B)  and  (D)  each represent what scientists believe now, but  (E)  is what they no longer believe, and that’s why  (E)  is correct. As far as we can tell, no one ever believed that all genes are inherited from the outside  (C).

And  (A)  is curious, picking up on wording from  lines 2-3  but leaving out the controversial phrase  “in the animal’s offspring.”  Without that phrase and its connection to genetics, we’re left with the common sense idea that an individual organ’s use or disuse (i.e. doing bicep curls) can affect the development of that organ (i.e. build up the bicep or make it flabby).

Answer: E

6. Which one of the following can be inferred from the passage about the absence of cell walls in some bacteria?

Difficulty Level:   700

Explanation

This time the question stem clues send us to  paragraph 2 , where the absence of bacterial cell walls is discussed. When one bacterium lost its wall, its  “offspring”  continued to do so  (lines 15-19) , and that’s what  (C)  describes.

(A)  and  (B)  are wrong because they bring up the  paragraph 3  idea of introducing a gene. The cell wall example stops short of mentioning a halt to the process,  (D) . And horizontal inheritance,  (E) , is a genetic concept. Genes are inherited vertically or horizontally, not the absence of cell walls.

Answer: C

kntombat · Answer

GAngstA , can you please be more specific about which question you are having trouble with ?

mSKR · Answer

Hi  GMATNinja   Sajjad1994 :
Actually for Q6 , I am still confused for Q6. I find Q6 is directly given in the context :

however,  seem to
have been acquired  “horizontally,” from viruses,
(50) plasmids,  bacteria , or other environmental agents

But in C , loss is not clear. According to passage "absence " is given. But loss doesn't mean absence. loss seems to be bigger set than absence.
(C) It can be caused by the  loss  of a cell wall in a single bacterium.

Some more clarification for C vs E would be helpful.

Thanks!

sting8 · Answer

Sajjad1994   GMATNinja   GMATNinja Two  VeritasKarishma   mikemcgarry

Can anyone please walk through each of the options for Q4 ?

Thanks.

Sajjad1994 · Answer

Explanation

4. Which one of the following, if true, offers the most support for Lamarck’s hypothesis?

Difficulty Level:   500-550

Explanation

Lamarck illustrated his hypothesis with the in-the-trees giraffe example, and  (B)  is a below-the ground example of the same process, in that the development of an organ came about because of its use.

The antlers in  (A)  aren’t explicitly connected to use or disuse, but rather to survival; and  (A)  would work better if we heard about modification of antlers through their use.  (C)  is emphatically an example of genetic differences.

(D)  doesn’t explicitly ascribe the weaker sense of direction to  “the disuse of an organ” ; anyway it’s describing the change of a sense, and not an organ. Aggressiveness  (E) , too, isn’t the change of an organ; aggressiveness is a trait common to both wild and domesticated dogs, as opposed to a trait that changes over time.

Answer: B

narji · Answer

Why can't Question 5 has an answer as option D?

kntombat · Answer

Hey  narji , did you see  mSKR  's post. I think that should answer your question.
If not then someone will definitely help you out here.

Sajjad1994 · Answer

Please double check, the OA of question #5 is indeed D. Or else let me know what you are looking for?

nikitathegreat · Answer

GMATNinja  - Can you please help with Q6 analysis? Also, I am sharing the understanding of each passage. Please let me know if my understanding of the passage is correct. 
The first para talks about what Jean believed - that an animal use or disuse of an organ's development in the animal offspring. But since biologists couldnt find proof of any genetic mechanism/changes, they believed that acquired characteristics are never passed to the off springs. But some new research has shown new examples

The second para provides proof of how removal of cell walls doesn't transform the genes itself. Only the interaction of genes gets transformed. This provides proof of why the earlier biologists were not able to see changes in gene mechanism even though the acquired characteristics were passed onto their off springs.

When genes get added or removed in an organism then a different kind of environmentally induced heritable characteristic occurs. Examples are provided for the same. Occasions on which the virus will get transferred to their offspring's and occasions in which it will not get transferred. Also, an advantage is stated because of inheriting acquired characteristics. It has speed up the evolution process.

The last para talks about that genes are inherited from the ancestors and some can also be passed onto by the parent organism acquiring the character tics horizontally? This horizontally acquired characteristics can somehow also help to answer the biologists question.

Can you help me explain this last para and also how this is linked to the first para? The ones which are inherited from ancestors can also be horizontal?

VerbalBot · Answer

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In the eighteenth century the French naturalist Jean Baptiste de Lamar

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In the eighteenth century the French naturalist Jean Baptiste de Lamar

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