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Assertion Directional selection operates...

Assertion Directional selection operates in response to gradual changes in enviromental conditions
Reason Stabilising selection operates when phenotypic features coincide with the optimal environmental conditions

A

Both Assertion and Reason are true, but Reason is the correct explanation of Assertion

B

Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion

C

Assertion is true, but Reason is false

D

Assertion is false, but reason is true

Text Solution

Verified by Experts

The correct Answer is:
B
Directional selection operates in response to gradual changes in environment condition it operates on the range of phenotype existing with in the population and exerts selection pressure which moves the mean phenotype towards one phenotypic features coincide with the optimal environment conditions and competition is not serve it occurs in all populations and tends to eliminate extremes from the population
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Read the passage given below and answer the following questions: Reduction of carboxylic acids and their derivatives plays an important role in organic synthesis, in both laboratory and industrial processes. Traditionally, the reduction is performed using stochiometric amounts of hydride reagents, generating stochiometric amounts of waste. A much more attractive, atom-economical approach is a catalytic reaction using H_2 , however, hydrogenation of carboxylic acid derivatives under mild conditions is a very challenging task, with amides presenting the highest challenge among all classes of carbonyl compounds. Very few examples of the important hydrogenation of amides to amines, in which the C-O bond is cleaved with the liberation of water (Scheme 1), were reported. C-O cleavage of amides can also be affected with silanes as reducing agents. We have now prepared the new, dearomatized, bipyridine-based pincer complex 3, catalyst 3(Here refered as Cat. 3). Remarkably, it efficiently catalyzes the selective hydrogenation of amides to form amines and alcohols (eq 1). The reaction proceeds under mild pressure and neutral conditions, with no additives being required. Since the reaction proceeds well under anhydrous conditions, hydrolytic cleavage of the amide is not involved in this process. (Balaraman, E., Gnanaprakasam, B., Shimon, L. J., & Milstein, D. (2010). Direct hydrogenation of amides to alcohols and amines under mild conditions. Journal of the American Chemical Society, 132(47), 16756-16758.) In the following questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices on the basis of the above passage. Assertion: Use of hydride catalyst or hydrogen brings about cleavage of C-O bond in amides. Reason: Hydride catalyst or hydrogen cause to reduction of amides.

Read the passage given below and answer the following questions: Reduction of carboxylic acids and their derivatives plays an important role in organic synthesis, in both laboratory and industrial processes. Traditionally, the reduction is performed using stochiometric amounts of hydride reagents, generating stochiometric amounts of waste. A much more attractive, atom-economical approach is a catalytic reaction using H_2 , however, hydrogenation of carboxylic acid derivatives under mild conditions is a very challenging task, with amides presenting the highest challenge among all classes of carbonyl compounds. Very few examples of the important hydrogenation of amides to amines, in which the C-O bond is cleaved with the liberation of water (Scheme 1), were reported. C-O cleavage of amides can also be affected with silanes as reducing agents. We have now prepared the new, dearomatized, bipyridine-based pincer complex 3, catalyst 3(Here refered as Cat. 3). Remarkably, it efficiently catalyzes the selective hydrogenation of amides to form amines and alcohols (eq 1). The reaction proceeds under mild pressure and neutral conditions, with no additives being required. Since the reaction proceeds well under anhydrous conditions, hydrolytic cleavage of the amide is not involved in this process. (Balaraman, E., Gnanaprakasam, B., Shimon, L. J., & Milstein, D. (2010). Direct hydrogenation of amides to alcohols and amines under mild conditions. Journal of the American Chemical Society, 132(47), 16756-16758.) In the following questions, a statement of assertion followed by a statement of reason is given. Choose the correct answer out of the following choices on the basis of the above passage. Assertion: The use of catalyst 3 is an efficient method of preparation of primary amines Reason: Use of catalyst 3 is a step down reaction.