Q23 / 180 · AIIMS 2007 · Botany

Assertion : Conifer trees produce a large quantity of wind borne pollen grains. Reason : The pollen grains have wings.

  • Correct answer
    A
    If both assertion and reason are true and reason is the correct explanation of assertion
  • B
    If both assertion and reason are true but reason is not the correct explanation of assertion
  • C
    If assertion is true but reason is false
  • D
    If both assertion and reason are false.

Solution

Conifer or Pinus is a heterosporous plant producing mega and microspores inside megasporangium and micro-sporangium respectively. Each microsporangium is a small, sessile and elongated sac like structure having two layered wall. Inside the wall lie tapetum which is a nourishing layer. Inside the cavity are large number of dusty and two winged microspores present. On maturity the microsporangium wall bursts from the upper side forming a longitudinal slit. A large number of yellow pollen grains are liberated which are carried by wind due to the presence of wings.

Hence, the correct answer is option: 'A'.

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