1. Heat loss or heat gain is a function of surface area.
2. Since small animals (like humming birds) have a larger surface area relative to their volume, they tend to lose body heat very fast, when it is cold outside.
3. They spend more energy to generate body heat through metabolism; considering the cost and benefit of mai ntaining a constant internal temperature, small animals (e.g. humming birds) are not found in polar regions.

a) Commensalisms
b) Competition
c) Amensalism
d) Mutualism

Evolution of the flowers & its pollinator species
Ex. Fig species can be pollinated only by its partner wasp species and no other species. In turn female fly uses the fruit for laying its egg as well as nourishment of its larvae from the developing speed.

To minimize heat lose. This is called the Allen's Rule.

It enables their stomata to remain closed during day time to prevent transpiration, but open during night for intake of air (O2).

Adaptation: Reduce wastage and maximize bio-availability of water from the reserves.
a) By its internal fat oxidation in which water is a by product
b) Ability to concentrate its urine.

Adapting to the ambient environment by sweating in summer and by shivering or doing physical work in winter.

Such flowers depend mainly on fragrance; also the white colour has reflective effect so it becomes visible during night.

Orchid is an epiphytic plant that grows on a mango tree branch and they together show commensalism. In this interaction, orchid is benefitted and the mango tree is neither harmed nor benefitted at all.

The termite provides shelter and space for the protozoan Trichonympha to live. The protozoan present in gut digests the wood, which termite feeds upon.
In the absence of Trichonympha, the termite is unable to digest wood and hence dies. Thus, the association of two given animal species represents mutualism.