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Zorluk: OrtaInferences from the Text

In Apis mellifera (honeybees), female larvae are genetically identical at hatching, yet develop into morphologically and behaviorally divergent castes—either reproductive queens or sterile workers. For decades, researchers attributed this phenotypic divergence solely to nutritional differences, specifically the presence of royal jelly in the larval diet. However, recent molecular investigations have revealed that epigenetic modifications mediate this developmental bifurcation. In particular, the enzyme DNA methyltransferase 3 (DNMT3) adds methyl groups to cytosine bases in larval DNA, silencing specific genetic programs required for queen development. When researchers experimentally silenced the gene encoding DNMT3 in newly hatched worker-destined larvae fed a standard worker diet, a substantial proportion developed queen-like physiological traits, including functional ovaries and queen-specific mandibular gland secretions. Conversely, larvae provided royal jelly naturally exhibit suppressed DNMT3 activity, permitting the expression of the queen phenotype. These findings demonstrate that worker sterility is actively enforced by DNA methylation rather than being a default physiological state.

Based on the passage, which of the following statements are logically supported? (Select all that apply.)

  1. The physiological development of worker honeybees involves active epigenetic suppression of genetic pathways that would otherwise produce queen characteristics.Cevap
  2. Artificially suppressing the expression of the DNMT3 gene in larvae on a worker diet can yield anatomical traits that normally require a royal jelly diet to emerge.Cevap
  3. C
    Royal jelly contains specialized biochemical compounds that directly stimulate the transcription of worker-suppression genes.
  4. D
    Newly hatched female honeybee larvae already possess distinct underlying DNA sequences corresponding to their eventual caste outcomes.
  5. E
    Experimental inhibition of DNMT3 in honeybee larvae produces reproductive queens across all social insect species.

Cevap

The statements confirming that worker honeybee development involves active epigenetic suppression of queen pathways and that artificial suppression of the DNMT3 gene produces traits normally requiring royal jelly are both logically supported.
The correct selections are logically entailed by the passage. The text explicitly asserts that worker sterility is actively enforced by DNA methylation (mediated by DNMT3) which silences queen-specific genetic programs, justifying the claim about active epigenetic suppression. Furthermore, the passage describes an experiment in which worker-fed larvae with silenced DNMT3 developed functional ovaries and mandibular gland secretions characteristic of queens, directly supporting the claim that artificially suppressing DNMT3 can produce anatomical traits normally dependent on royal jelly.

Adım Adım Çözüm

1
Analyze the passage premises regarding the mechanism of caste differentiation.
Identified that female larvae are genetically identical, DNMT3 silences queen-specific genetic programs, royal jelly naturally suppresses DNMT3, and worker sterility is actively enforced by DNA methylation.
Establishing the core causal chain is necessary to evaluate the validity of each inference.
2
Evaluate the statement concerning active epigenetic suppression in worker development.
Supported directly by the textual conclusion that worker sterility is actively enforced via DNA methylation silencing queen developmental programs.
Confirms the first valid inference.
3
Evaluate the statement regarding experimental suppression of DNMT3 in worker-fed larvae.
Supported directly by the textual evidence showing worker-fed larvae with silenced DNMT3 developed functional ovaries and queen-like gland secretions.
Confirms the second valid inference.
4
Evaluate and eliminate unsupported claims.
Eliminated claims asserting that royal jelly stimulates worker-suppression genes, that larvae have sequence differences at hatching, and that the finding applies universally to all social insects.
Filters out common distractor patterns involving unsupported leaps, misread details, and unjustified scope expansion.

Anahtar Kavram

Drawing Valid Textual Inferences from Epigenetic Mechanisms
Tahmini Süre:1m 30s
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Inferences from the Text

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