Assertion :Nematodes exhibit 'eutely'. Reason: In nematodes cell divisions case near the end of embryonic development so that the number of the cells of the adult is constant.

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

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Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

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Assertion is correct but Reason is incorrect.

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Both Assertion and Reason are incorrect.

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Solution

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
Eutely occurs when the initial embryonic cells each come with a limit for total divisions. After this limit is reached, the organism can only become larger due to cell enlargement rather than cell division. Eutelic organisms have a fixed number of somatic cells when they reach maturity, the exact number being constant for any one species. Development proceeds by cell division until maturity; further growth occurs via cell enlargement only. In nematodes, the number of nuclei is also constant; there is growth in size of the body but this is due to the growth in the size of the cells (hypertrophy). Most eutelic organisms are microscopic. Examples include the rotifers, many species of nematodes, tardigrades, larvacea and dicyemida.

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Similar questions

Q. Assertion: The compressibility factor for

H_{2}

and

H e

(1 + \frac{P b}{R T})

Reason: The compressibility factor for

H_{2}

and

H e

can be derived from Van der Waal's equation.

Assertion (A) Order of the reaction can be zero or fractional.

Reason (R) We cannot determine order from balanced chemical equation.

(a) Both assertion and reason are correct and the reason is correct explanation of assertion
(b) Both assertion and reason are correct, but reason does not explain assertion.
(c) Assertion is correct, but reason is incorrect
(d) Both assertion and reason are incorrect
(e) Assertion is incorrect but reason is correct.

Assertion (A) Order and molecularity are same.

Reason (R) Order is determined experimentally and molecularity is the sum of the stoichimetric coeffcient of rate determining elementary step.

Assertion (A) Rate constant determined from Arrhenius equation are fairly accurate for simple as well as complex molecules.

Reason (R) Reactant molecules undergo chemical change irrespective of their orientation during collision.

ASSERTION: n-Pentane and n-Hexane belong to a homologous series.

REASON: n-Pentane and n-Hexane belong to the same class of hydrocarbons and they differ by a - $C H_{2}$ - group.

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