Multiple Choice Questions

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Assertion : Atmospheric nitrogen gas is always fixed by nitrogen-fixing micro-organisms.

Reason : Decomposers release nitrogen gas from dead bodies of plants and animals.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


D.

If both assertion and reason are false

Nitrogen fixation is a process by which nitrogen in the Earth's atmosphere is converted into ammonia (NH3) or related nitrogenous compounds. Nitrogen- fixing bacteria is a  micro- organisms which is capable of transforming atmospheric nitrogen into fixed nitrogen. More than 90 percent of all nitrogen fixation is effected by these organisms, which thus play an important role in the nitrogen cycle. Decomposers are the organisms that break down dead or decaying organisms. They use organic substrates in order to obtain their energy, carbon and nutrients for growth and development.


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Assertion : Carbohydrates are more suitable for the production of energy in the body than proteins and fats.

Reason : Carbohydrates can be stored in the tissues as glycogen and can be used for the production of energy, whenever necessary.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


Assertion : In opposite phyllotaxy two leaves are borne on the opposite sides of a single node.

Reason : Opposite phyllotaxy is seen in China rose and Oleander.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


Assertion : Pili are tubular structures present in bacteria which help in conjugation.

Reason : Formation of pili is controlled by F+  or fertility factor.

  • If both assertion and reason are true and reason is the correct explanation of assertion.

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false

  • If both assertion and reason are false


Assertion : Sphagnum is slowly carbonised, compressed and fossilised over thousands of years to produce a dark spongy mass called peat.

Reason : Peat helps to keep soil porous and it also improves water holding capacity of the soil.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


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Assertion : Presence of pneumatophores is a special adaptation of hydrophytes.

Reason Pneumatophores are positively geotropic shoots that have lenticels and help in gaseous exchange.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


Assertion : In Pleurobrachia, eight comb like ciliary plates called comb plates are present on the body that help in locomotion.

Reason : Pleurobrachia reproduces sexually and its life cycle includes cydippid larva.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false.


Assertion : All motor neurons are efferent neurons.

Reason : Motor neurons conduct nerve impulses from the spinal cord to the brain.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false.

  • If both assertion and reason are false


Assertion : CAM plants lack structural compartmentation of leaf as found in C4 plants.

Reason : Stomata of CAM plants are open during the day.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion

  • If assertion is true but reason is false

  • If both assertion and reason are false


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Assertion : Storage of seeds at low temperature is possible.

Reason : Respiration and anzymatic activity of seeds are very high at low temperature.

  • If both assertion and reason are true and reason is the correct explanation of assertion

  • If both assertion and reason are true but reason is not the correct explanation of assertion.

  • If assertion is true but reason is false

  • If both assertion and reason are false