Multiple Choice Questions

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C4 plants have better productivity because

  • C4 plants absorb more light

  • C4 plants absorb more CO2

  • C4 plants lack photorespiration

  • all of these


C.

C4 plants lack photorespiration

Presence of photorespiration is considered as a wasteful and energy consuming process in crop plants which ultimately leads to reduction in final yield of crops. It is estimated that during C4 photosynthesis, upto 50% of the CO2 fixed may have to pass through photorespiratory process, thereby resulting in considerable decrease in photosynthetic productivity. In C4 plants, there is some loss of photosynthetic activity on account of photorespiration which is absent in C4 plants and hence they have better productivity.


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Unidirectional transmission of a nerve impulse through nerve fibre is due to the fact that

  • nerve fibre is insulated by a medullary sheath

  • sodium pump starts operating only at the cyton and then continues into the nerve fibre

  • neurotransmitters are released by dendrites and not by axon endings

  • neurotransmitters are released by the axon endings and not by dendrites.


Wharton's duct is the duct of

  • submandibular salivary gland

  • parotid gland

  • sublingual gland

  • all of these


Assertion: Photorespiration is a wasteful process where there is no synthesis of ATP energy.

Reason: RuBisCO is present in mesophyll cells of C4 plants hence they show more productivity.

  • 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.


Pick the correct group consisting of all genera exhibiting homospory

  • Lycopodium, Psilotum, Selaginella, Equisetum

  • Equisetum, Pteris, Salvinia, Psilotum

  • Salvinia, Pteris, Lycopodium, Selaginella

  • Equisetum, Psilotum, Lycopodium, Pteris


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Achondroplasia is a disease related with the defect in the formation of

  • membrane

  • cartilage

  • mucosa

  • none of these


An artificial pacemaker is implanted subcutaneously and connected to the heart in patients

  • having 90% blockage of the three main coronary arteries

  • having a very high blood pressure

  • with irregularity in the heart rhythm

  • suffering from arteriosclerosis


Pacinian corpuscles occur in the skin of certain parts of body in mammals. These are

  • type of glands

  • pain receptors

  • naked tactile receptors

  • encapsulated pressure receptors.


The checkpoint in cell cycle plays important role in

  • repairing DNA damage

  • apoptosis initiation

  • assessing DNA damage

  • none of these


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Which part of the nephron is impermeable to water

  • Proximal convoluted tubule

  • Distal convoluted tubule

  • Ascending limb of loop of Henle

  • Descending limb of loop of Henle