If a stimulus, several times greater than the threshold stimulus

Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

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1.

If a stimulus, several times greater than the threshold stimulus is provided to a muscle fibre, it will

  • contract with a larger force

  • contract with a smaller force

  • contract with the same force

  • undergo tetany.


C.

contract with the same force

A muscle fibre would contract only when it receives stimulation of certain intensity called threshold stimulus. Response of a muscle fibre to a stimulus is not proportional to its intensity. It is absent when the intensity is subliminal. Muscle fibre contracts to the maximum whether the stimulus has threshold value or supraliminal value.


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2.

During the cell cycle, DNA content is doubled in the

  • G1 phase

  • S phase

  • G2 phase

  • end of M phase


3.

Barr body is found in the cytoplasm during

  • interphase in cell of female mammal

  • interphase in cell of male mammal

  • prophase in cell of female mammal

  • prophase in cell of male mammal


4.

The respiratory centre in the brain is stimulated by

  • CO2 concentration in venous blood

  • O2 concentration in artery blood

  • CO2 concentration in artery blood

  • O2 concentration in venous blood


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5.

Which of these are considered most essential in the origin of life?

  • Enzymes

  • Nucleic acids

  • Carbohydrates

  • Proteins


6.

Wooden doors swell up and get stuck during the rainy season. This is due to the phenomenon of

  • imbibition

  • endosmosis

  • capillarity

  • deplasmolysis


7.

Which of these are most widely used in genetic engineering?

  • Plastid

  • Plasmid

  • Mitochondrion

  • Ribosome


8.

Which floral family has (9) + 1 arrangement or anthers in the androecium ?

  • Malvaceae

  • Rutaceae

  • Fabaceae

  • Caesalpinaceae


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9.

Porous wood has abundance of 

  • vessels

  • fibres only

  • tracheids

  • sieve tubes


10.

A human RBC is placed in 1.5% salt solution. It will

  • swell up

  • shrink

  • remain unaffected

  • burst


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