21.
Early blight of potato spreads and becomes serious when the season begins with

28.
The megaspore mother cell nucleus after dividing meiotically forms four haploid megaspores which are arranged in a linear tetrad, of which the lower most megaspore is functional in case of

29.
Which of the following methods is based on the act that tissue will not gain or lose water to the atmosphere when the vapour pressure of air corresponds to the water potential of the tissue?

30.
Assertion (A) The lenticel is meant for gaseous exchange.
Reason (R) Lenticel checks excessive evaporation of water.