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Species originate discontinuously withou...

Species originate discontinuously without intermediate forms according to

A

Lamarck

B

de Vries

C

Darwin

D

Haeckel

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The correct Answer is:
B
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The products of bond breaking, shown below, are not stable, and cannot be isolated for prolonged study. Such species are referred to as reactive intermediate, and are belived to be transient intermediates in many reactions. The general structures and names of four such intermediates are, Charged Intermediates Uncharged Intermediates Carbocations (called carbonium ions in the older literature) are electrophiles and carbananions are nucleophiles. Carbenes have only a valence shell sextet of electrons and are therefore electron deficient. In this sense they are elecrophiles, but the non-bonding electron pair also gives carbenes nucleophilic character. As a rule, the electrophilic character dominates carbene reactivity. Carbon radicals have only seven valence electrons, and may be considered electron deficient, however, they do not in general bond to nucleophilic electron pair, so their chemistry exhibits differences from that of conventional electrophiles. Radical intermediates are often called free radicals. Intermediates are in general stabilised with conjugation, electron donating and electron with drawing groups. Which of the following is relatively an unstable intermediate compared to rest ?

The products of bond breaking, shown below, are not stable, and cannot be isolated for prolonged study. Such species are referred to as reactive intermediate, and are belived to be transient intermediates in many reactions. The general structures and names of four such intermediates are, Charged Intermediates Uncharged Intermediates Carbocations (called carbonium ions in the older literature) are electrophiles and carbananions are nucleophiles. Carbenes have only a valence shell sextet of electrons and are therefore electron deficient. In this sense they are elecrophiles, but the non-bonding electron pair also gives carbenes nucleophilic character. As a rule, the electrophilic character dominates carbene reactivity. Carbon radicals have only seven valence electrons, and may be considered electron deficient, however, they do not in general bond to nucleophilic electron pair, so their chemistry exhibits differences from that of conventional electrophiles. Radical intermediates are often called free radicals. Intermediates are in general stabilised with conjugation, electron donating and electron with drawing groups. Which of the following carbo cations is more stable?

The no.of intermediate formed in the following conversion is

AAKASH SERIES-EVOLUTION-EXERCISE - I (BIOLOGICAL EVOLUTION ( THEORIES OF EVOLUTION & MECHANISM OF EVOLUTION))
  1. Species originate discontinuously without intermediate forms according...

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  2. Lamarck cited the example of giraffe to explain

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  3. In organisms vestigial organs are formed because of

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  4. According to Darwin during the struggle for existence, these organisms...

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  5. A sudden, random, discontinuous and heritable change is

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  6. Hugo de Vries stressed on

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  7. New species arise by sudden jump according to

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  8. There are no intermediate stages in the course of evolution according ...

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  9. According to Darwin, if new variations are to be inherited they should...

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  10. de Vries gave his mutation theory on organic cvolution while working o...

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  11. The most likely reason for the developoment of resistance against pe...

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  12. Which one of the following scientist's name is correctly matched with ...

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  13. Which of the following evidences does not favour the Lmarckian concept...

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  14. The diversity in the ty of veaks of finches adapted to differenn feedi...

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  15. Drawinism explains all the following except

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  16. Given below are four statements (A-D) each with one or two blanks. Sel...

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  17. Single step large mutation leading to speciation is also called

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  18. By the statement 'survival of the fittest', Darwin meant that

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  19. Which of the following are the two key concepts of Darwinian theory of...

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  20. According to Lamrckicm, long necked giraffes evolved because

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