Positively photoblastic seeds germinate only in presence of

$A$ : Antarctic fishes have blubber to withstand sub zero temperatures.
$R$ : Blubber are proteins which allow the freezing of body fluids.

Distinguish between the following:

$(a)$ Hibernation and Aestivation

$(b)$ Ectotherms and Endotherms

$I.$ Biochemical adaptation are seen in organisms living in great depth of the ocean to face crushing pressure

$II.$ Allen's rule is explain mammals living in colder climates

$III.$ Altitude sickness is caused because of body not getting enough oxygen due to low atmospheric pressure at high altitude

$IV.$ Desert lizards lack behavioural means to manage to their body temperature

Choose the correct option for above adaptations

People who have migrated from the planes to an area adjoining Rohtang Pass about six months back

Why do submerged plants receive weaker illumination than exposed floating plants in a lake ?