Subject

Biology

Class

NEET Class 12

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 Multiple Choice QuestionsMultiple Choice Questions

21.

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


C.

If assertion is true but reason is false

In opposite phyllotaxy, two leaves are borne on the opposite sides of a single node e.g., Quisqualis (opposite and superposed) and Calotropis (opposite and decussate). Nerium or Oleander shows whorled type of phyllotaxy and China rose exhibits alternate phyllotaxy.


22.

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


B.

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

Carbohydrates are more suitable for the production ofenergy in the body than proteins and fats, because carbohydrate molecules contain relatively more oxygen than the others, and consequently, require less molecular oxygen for their oxidation. In other words, for each litre of oxygen consumed, carbohydrates yield far more energy than proteins or fats. Carbohydrates are also stored in the. tissues as glycogen for use in the production of energy, when necessary.


23.

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


B.

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

Pili are long and thick tubular outgrowths, which develop in response to F or fertility factor in Gram negative bacteria. They are made up of protein pilin. A donor bacterial cell having fertility factor develops 1-4 pili. Pili are helpful in attaching to recipient cell and forming conjugation tube.


24.

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


C.

If assertion is true but reason is false

CAM plants do not exhibit the structural compartmental as shown by C4 plants which exhibit kranz anatomy. CAM plants fix CO2 at night because their stomata are open at night and remain closed during the day.


25.

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


D.

If both assertion and reason are false

Afferent neurons are sensory that carry nerve impulses from sensory stimuli towards the central nervous system and brain, while efferent neurons are motor neurons that carry neural impulses away from the central nervous system and towards muscles to cause movement.


26.

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


D.

If both assertion and reason are false

Pneumatophore is an aerial root specialized for gaseous exchange. Hydrophytes are aquatic plants that are especially suited for living in aquatic environments. In order to survive, a hydrophyte, also known as an aquatic macrophyte, must either be completely submerged in water or in some cases be allowed to float on the surface of the water.


27.

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


C.

If assertion is true but reason is false

Seeds can last from a few years to centuries, depending on the species and the storage conditions. In general, most seeds stored in cool, dry conditions will survive longer than seeds stored in a wet, warm environment. This is because due to low moisture content and low temperature as it helps in reducing the seed viability.


28.

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.


B.

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

Ctenophores are characterized by eight rows of cilia, which are used for locomotion. The cilia in each row are arranged to form a stack of combs, also called comb plates, ctenes; thus the name ctenophore comes from the Greek, meaning 'Comb bearer'.


29.

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.


30.

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


B.

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

Sphagnum is commonly known as peat moss. Its accumulations can store water, since both living and dead plants can hold large qauntities of water inside their cells. Sphagnum and peat formed does not decay readily because of the phenolic compounds embedded in the moss's cell walls.