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Zorluk: ZorExplicit Detail Retrieval

In her 1905 monograph on germ cell development in Coleoptera, cytologist Nettie Stevens examined spermatogenesis in the mealworm beetle Tenebrio molitor, challenging the prevailing view held by Edmund Beecher Wilson that chromosomal size variations were incidental cellular anomalies. Stevens documented that somatic cells in female beetles consistently contained twenty large chromosomes, whereas male somatic cells possessed nineteen large chromosomes paired with a single markedly smaller element. She demonstrated that during meiotic division in males, this smaller chromosome paired directly with a large counterpart before segregating into distinct spermatozoa, resulting in two equal classes of male gametes: one carrying twenty large chromosomes and the other carrying nineteen large chromosomes plus the small element. Because fertilizations involving the latter produced exclusively male offspring, Stevens concluded that the small chromosome played a deterministic role in sex specification. Although Wilson independently published similar findings regarding Hemiptera shortly thereafter, his initial communications attributed sex determination primarily to environmental and metabolic factors within the egg cytoplasm, acknowledging the chromosomal dimorphism only after reviewing Stevens's unequivocal cytological evidence.

According to the passage, which of the following statements regarding Stevens's findings or Wilson's research is explicitly supported? Consider each of the three choices separately and select all that apply.

  1. Male Tenebrio molitor beetles produce two distinct types of spermatozoa in equal proportions with respect to their chromosomal composition.Cevap
  2. B
    Wilson's initial communications on Hemiptera attributed sex determination primarily to chromosomal dimorphism before he reviewed Stevens's research.
  3. Female somatic cells in Tenebrio molitor were observed to contain twenty large chromosomes rather than the smaller chromosomal element found in male cells.Cevap

Cevap

The statements explicitly supported by the text are that male Tenebrio molitor produce two equal classes of spermatozoa differing in chromosomal composition, and that female somatic cells contained twenty large chromosomes while lacking the smaller chromosome found in male cells.
The passage provides explicit factual support for two statements. First, it directly states that meiotic division in males resulted in 'two equal classes of male gametes' with distinct chromosomal contents (twenty large vs. nineteen large plus one small element). Second, it explicitly contrasts female somatic cells (which 'consistently contained twenty large chromosomes') with male somatic cells (which contained nineteen large chromosomes plus a small element). In contrast, the option asserting that Wilson initially attributed sex determination to chromosomal dimorphism misreads the explicit details; the text specifies that he initially attributed it to environmental and metabolic factors in the egg cytoplasm.

Adım Adım Çözüm

1
Scan the passage for explicit details regarding male gamete production in Tenebrio molitor.
The text explicitly notes that meiotic division in males produces 'two equal classes of male gametes' differing by the presence or absence of the small chromosome.
This directly confirms the statement regarding male beetles producing two distinct types of spermatozoa in equal proportions.
2
Scan the passage for Wilson's initial view on sex determination.
The text states that Wilson's initial communications attributed sex determination to 'environmental and metabolic factors within the egg cytoplasm' and that he acknowledged chromosomal dimorphism only after reading Stevens's work.
This reveals that the statement asserting Wilson initially favored chromosomal dimorphism is a misread reversal of the explicit text.
3
Scan the passage for the chromosomal makeup of female somatic cells.
The text explicitly records that female somatic cells 'consistently contained twenty large chromosomes, whereas male somatic cells possessed nineteen large chromosomes paired with a single markedly smaller element.'
This confirms that female cells contained twenty large chromosomes and lacked the smaller element present in male cells.

Anahtar Kavram

Identifying explicitly stated factual details and distinguishing them from inverted conditional or timeline statements.
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Konular

Explicit Detail Retrieval

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