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Kleptoplasty (from the Greek kleptes, meaning thief) is a phenomenon
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09 May 2023, 23:53
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Kleptoplasty (from the Greek kleptes, meaning “thief”) is a phenomenon whereby host organisms ingest a chlorophyll-utilizing species, typically algae, and use the energy-producing organelles called chloroplasts contained within the consumed species to help meet their own metabolic needs. In this way, kleptoplasty is an example of symbiosis, a close relationship between two different species. Further, it is an endosymbiosis, such that one of the species resides completely within another. Unlike the example of mitochondria, thought to have once been fully separate bacteria that came to live within animal cells and perform a mutualistic metabolic function, the algae are only partially utilized; most of the organism is digested and discarded, leaving only the chloroplasts to be retained by the host. Most kleptoplastic species are unicellular ciliates or dinoflagellates. The only known members of the animal kingdom that practice kleptoplasty are several species of sarcoglossan sea slugs. These “solar-powered” sea slugs incorporate whole chloroplasts into their body cells, where the stolen plastids can convert sunlight into useful energy for as long as ten months in some species.
Chloroplasts produce energy by using sunlight to power a series of reactions that result in sugars that can be used as a food source for the host organism. Algae have genes that encode proteins that act as enzymes that support this process. PRK, for example, is an enzyme that is responsible for the regeneration of ribulose-1,5-bisphosphate, an organic molecule used in the reductive pentose phosphate pathway (RPPP) of photosynthesis. Sea slugs lack the PRK gene, so for many kleptoplastic species, once the raw materials within the chloroplasts are exhausted, photosynthesis ceases and new chloroplasts must be obtained. As a result, until recently it remained a mystery how some sarcoglossan sea slug species were able to sustain chloroplast function for many months.
Genome sequencing revealed the answer. Polymerase chain reaction (PCR) analysis of the genome of individual sarcoglossan sea slugs of species Elysia chlorotica that had been exposed to chlorophyll-utilizing algae revealed that these individuals did in fact have the PRK gene, whereas individuals that had not been exposed to algae lacked the gene. Radioactive labeling confirmed the surprising result: E. chlorotica incorporates genes from the algae into its own genome. This process, known as horizontal gene transfer, is common in bacteria and unicellular eukaryotes but is rare to find in more complex species.
Question 1
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According to the passage, the main difference between the sarcoglossan sea slug species discussed in paragraph 1 and other sea slug species is that
A they can incorporate the PRK gene into their genome, whereas other sea slugs cannot B they obtain energy primarily by digesting only certain components of algae, whereas other sea slugs obtain their energy from digesting the entire organism C they obtain at least some of their metabolic energy from chloroplasts, whereas other sea slugs do not D they lack the enzyme to regenerate compounds necessary for photosynthesis, whereas other sea slugs produce this enzyme E they lack mitochondria to perform metabolic functions, whereas other sea slugs utilize mitochondria as their primary source of energy
Question 2
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Which of the following best expresses the main point of the passage?
A Until recently, scientists found it difficult to understand the exact mechanisms of kleptoplasty due to misconceptions about the relationship between sea slugs and algae. B Elysia chlorotica incorporates algal genes into its own genome, solving a problem that would leave it unable to survive in the wild. C Ribulose-1,5-bisphosphate is an organic compound used in photosynthesis that kleptoplastic species lack the ability to produce on their own. D Kleptoplasty is unusual compared to other forms of symbiotic relationships in that the species that practice it derive some benefit from horizontal gene transfer. E Kleptoplastic species not only use the biochemical machinery of another species to meet their own metabolic needs but can also incorporate genetic material to facilitate this process.
Question 3
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Considering all that apply
The passage provides support for which of the following statements about E. chlorotica?
A In the absence of algae, E. chlorotica typically lacks the ability to synthesize ribulose-1,5-bisphosphate. B Some of the characteristics of E. chlorotica are not commonly found within the animal kingdom. C E. chlorotica is the only sarcoglossan sea-slug species that incorporates the PRK gene into its genome.
Re: Kleptoplasty (from the Greek kleptes, meaning thief) is a phenomenon
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14 May 2023, 04:00
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QUESTION #1
C The necessary reference occurs at the end of paragraph 1: the sarcoglossan sea slugs are “[t]he only known animals that practice kleptoplasty.” The correct answer must match this idea by saying, in some way, that the sarcoglossan sea slugs obtain and get energy from chloroplasts, while other sea slugs do not. (C) is a match. (A) may be tempting, but the passage does not state that other slugs are incapable of incorporating the PRK gene into their genome, nor is it ever stated that all of the kleptoplastic species can. (In fact, it can be inferred that many do not since the passage says that many kleptoplastic species quickly run out of the enzymes needed to maintain photosynthesis.) (B) is also very close, since the passage mentions that the kleptoplastic slugs do digest most of the algae rather than incorporating them, but they do not use this digestion as their primary food source; it is instead the incorporation of whole chloroplasts that is their primary source of energy from the algae. It is not stated that other sea slugs produce the PRK enzyme, so (D) can be eliminated. Similarly, while the passage mentions that the symbiosis that led to incorporation of mitochondria as being different from the partial symbiosis of algae, the passage does not state that kleptoplastic sea slugs lack mitochondria, ruling out (E).
Re: Kleptoplasty (from the Greek kleptes, meaning thief) is a phenomenon
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14 May 2023, 04:00
1
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QUESTION #2
E The passage as a whole defines what kleptoplasty is and describes a surprising experimental result. Choice (E) summarizes both the definition and the result and is therefore correct. (A) is a distortion of the author’s point. The mechanisms of kleptoplasty itself were well understood, even though the nature of its longevity in certain species were not. Both (B) and (C) are too specific. (B) focuses on paragraph 3 and includes information that the author never mentions; it is never stated that E. chlorotica cannot survive without incorporating the PRK gene. (C) focuses on a mere detail from paragraph 2. Finally, choice (D) is not actually mentioned in the passage at all. It is not stated that horizontal gene transfer is unique to kleptoplastic species when compared to “other forms of symbiotic relationships,” nor is it stated that all kleptoplastic species use horizontal gene transfer.
Re: Kleptoplasty (from the Greek kleptes, meaning thief) is a phenomenon
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14 May 2023, 04:00
1
Expert Reply
QUESTION #3
A, B E. chlorotica is mentioned in paragraph 3 as being an example of a kleptoplastic species that incorporates the PRK gene into its genome when exposed to another organism that has this gene. (A) is supported with information from paragraph 2; in the absence of algae, E. chlorotica lacks the PRK gene, which is responsible for producing the PRK enzyme that synthesizes ribulose-1,5-bisphosphate. (B) is likewise supported, since both kleptoplasty and horizontal gene transfer are described as being rare among animals. Regarding choice (C), the passage describes E. chlorotica as an example of a species that can incorporate the PRK gene. Indeed, the scientists were surprised to find that gene transfer was the cause of the longevity of the chloroplasts used by E. chlorotica, but to say that it is the only such species is extreme; it is mentioned in paragraph 2 that other species can maintain the reaction for prolonged periods of time, so it is plausible that they use the same mechanism.
Re: Kleptoplasty (from the Greek kleptes, meaning thief) is a phenomenon
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15 May 2023, 03:16
How do we remember the content in these kind of passages which have lot of information in each paragraph. Its like I am getting lost the info once I am in 2nd paragraph
Re: Kleptoplasty (from the Greek kleptes, meaning thief) is a phenomenon
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15 May 2023, 10:03
1
Expert Reply
Midhilesh489 wrote:
How do we remember the content in these kind of passages which have lot of information in each paragraph. Its like I am getting lost the info once I am in 2nd paragraph
The best strategy is NOT to skim the passage or delve and remember every single detail. especially in such short amount of time.
The best is to read the entire passage sentence by sentence, at a constant pace, understand the overall picture for the main idea and WHERE the most important details are located. A sort of sign spots to go where we have to reply the inference questions.
remember that on the GRE we do have essentially two types of questions: main idea and inference
So
1) read all passage 2) Try to grasp the essence or main idea of the passage 3) Understand the most important details and the connection among them 4) read once from the beginning of the end 5) reply all the questions right away 6) take notes or just something that helps you to remember the key points
Re: Kleptoplasty (from the Greek kleptes, meaning thief) is a phenomenon
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15 May 2023, 11:19
1
Expert Reply
This what I do basically
1) Start reading very carefully but not to slow 2) write down some words as notes to keep in mind 3) I usually just read and NOT take notes at all. All in my mind but this is quite difficult. You need a lot of practice and a well understanding of the standard English language to achieve that. It is just a matter of practice though. Nothing that you cannot achieve on your own
Kleptoplasty (from the Greek kleptes, meaning “thief”) is a phenomenon whereby host organisms ingest a chlorophyll-utilizing species, typically algae, and use the energy-producing organelles called chloroplasts contained within the consumed species to help meet their own metabolic needs.
Simple: the K (something - no need to remember the entire name just K) eat something to have energy to produce something else
In this way, kleptoplasty is an example of symbiosis, a close relationship between two different species.
Important sentence: two species work both to help each other: K hosts algae and from them , though, take nutrients
Further, it is an endosymbiosis, such that one of the species resides completely within another.
Moreover, it is not only symbiosis but also endosymbiosisone of the species resides completely within another.
Unlike the example of mitochondria, thought to have once been fully separate bacteria that came to live within animal cells and perform a mutualistic metabolic function, the algae are only partially utilized; most of the organism is digested and discarded, leaving only the chloroplasts to be retained by the host.
Here we have a specific phenomenon the algae are just used and discarded in the sense that the host only retain the plastic NOT the algae itself
Most kleptoplastic species are unicellular ciliates or dinoflagellates.
Just detail
The only known members of the animal kingdom that practice kleptoplasty are several species of sarcoglossan sea slugs.
Several animals do this process about the plastic
These “solar-powered” sea slugs incorporate whole chloroplasts into their body cells, where the stolen plastids can convert sunlight into useful energy for as long as ten months in some species.
Just detail the sea slugs use solar power to do the same process
Chloroplasts produce energy by using sunlight to power a series of reactions that result in sugars that can be used as a food source for the host organism.
How the plastic from algae makes energy ? producing in the end sugar that is used by the host that incorporate algae
Algae have genes that encode proteins that act as enzymes that support this process.
Detail: algae uses enzymes
PRK, for example, is an enzyme that is responsible for the regeneration of ribulose-1,5-bisphosphate, an organic molecule used in the reductive pentose phosphate pathway (RPPP) of photosynthesis.
Enzyme PRK is just an example
Sea slugs lack the PRK gene, so for many kleptoplastic species, once the raw materials within the chloroplasts are exhausted, photosynthesis ceases and new chloroplasts must be obtained.
Sea slugs lack of this enzyme but nonethless they start the process all over again
As a result, until recently it remained a mystery how some sarcoglossan sea slug species were able to sustain chloroplast function for many months.
we do not know yer how sea slugs can do this lacking of thr PRK
Polymerase chain reaction (PCR) analysis of the genome of individual sarcoglossan sea slugs of species Elysia chlorotica that had been exposed to chlorophyll-utilizing algae revealed that these individuals did in fact have the PRK gene, whereas individuals that had not been exposed to algae lacked the gene.
Ahhhhhhhhhh: now is clear. The sea slugs in the end have the PRK because they have a symbiosis with the algae
Radioactive labeling confirmed the surprising result: E. chlorotica incorporates genes from the algae into its own genome. This process, known as horizontal gene transfer, is common in bacteria and unicellular eukaryotes but is rare to find in more complex species.
Now we know how is possible. Simple................
Re: Kleptoplasty (from the Greek kleptes, meaning thief) is a phenomenon
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15 May 2023, 12:39
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Expert Reply
According to the passage, the main difference between the sarcoglossan sea slug species discussed in paragraph 1 and other sea slug species is that
A they can incorporate the PRK gene into their genome, whereas other sea slugs cannot
Not really. they had from algae so some can incorporate and some no is false
B they obtain energy primarily by digesting only certain components of algae, whereas other sea slugs obtain their energy from digesting the entire organism
not true. they digest the entire algae and that's it
C they obtain at least some of their metabolic energy from chloroplasts, whereas other sea slugs do not
Yes this is true. The only known members of the animal kingdom that practice kleptoplasty are several species of sarcoglossan sea slugs.
D they lack the enzyme to regenerate compounds necessary for photosynthesis, whereas other sea slugs produce this enzyme
no one can produces the enzyme
E they lack mitochondria to perform metabolic functions, whereas other sea slugs utilize mitochondria as their primary source of energy
not really we are talking about metabolic function
Re: Kleptoplasty (from the Greek kleptes, meaning thief) is a phenomenon
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15 May 2023, 12:41
1
Expert Reply
Main idea is the overall essence of the passage: not too strict and not too broad
Which of the following best expresses the main point of the passage?
A Until recently, scientists found it difficult to understand the exact mechanisms of kleptoplasty due to misconceptions about the relationship between sea slugs and algae. No we found the solution
B Elysia chlorotica incorporates algal genes into its own genome, solving a problem that would leave it unable to survive in the wild. no survivalism into the wild is mentioned
C Ribulose-1,5-bisphosphate is an organic compound used in photosynthesis that kleptoplastic species lack the ability to produce on their own.
too specific answer
D Kleptoplasty is unusual compared to other forms of symbiotic relationships in that the species that practice it derive some benefit from horizontal gene transfer.
no comparison in the passage among symbiosis
E Kleptoplastic species not only use the biochemical machinery of another species to meet their own metabolic needs but can also incorporate genetic material to facilitate this process.
09 May 2023, 23:53
35% (02:46) correct
