$A$ treeless biome is

$I.$ Many xerophytic plants have thick cuticle on leaf epidermis and sunken stomata.
$II.$ Some xerophytic plants have a special photosynthetic pathway $(CAM)$ that enables their stomata to close during the day.
$III.$ $Opuntia$ has spines (modified leaves) and a photosynthetic phylloclade (stem).
$IV.$ All adaptations are genetically fixed in all organisms.
Choose the combination of correct statements.

Why do mammals of colder regions generally have shorter ears and limbs?
$I.$ To minimize their surface area to volume ratio
$II.$ To minimize heat loss
$III.$ To maximize their surface area to volume ratio
$IV.$ To maximize heat loss
Choose the correct combination from the given options:

Small animals have a $......P.......$ surface area relative to their volume, so they lose body heat $.....Q.....$ when it is cold outside.

An elephant has very few hairs,while a bear has thick fur because the bear:

$A$ genetically adapted population to a particular habitat is called: