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Heredity and Evolution — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10ScienceHeredity and Evolution1 Mark
MCQ
For two statements are given $-$ one labelled Assertion $(A)$ and the other labelled Reason $(R)$. Select the correct answer to these questions from the codes $\ce{(a), (b), (c)}$ and $(d)$ as given below :
Assertion : ln grasshoppers, females are hetero gametic and males are homo gametic.
Reason : ln grasshoppers, male has only one sex chromosome $(XO)$ whereas the female has sex chromosomes $(XX).$
  • A
    Both $A$ and $R$ are true, and $R$ is correct explanation of the assertion.
  • B
    Both $A$ and $R$ are true, but $R$ is not the correct explanation of the assertion.
  • C
    $A$ is true, but $R$ is false.
  • ✓
    $A$ is false, but $R$ is true.
✓

Answer

Correct option: D.
$A$ is false, but $R$ is true.
ln grasshoppers, the male has only one sex chromosome $\ce{(XO)}$ whereas the female has two sex chromosomes i.e., homo gametic. This type of sex determination mechanism is called $\ce{XX-XO}$ mechanism.

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