Heliophytes are those plants which grow in strong light so are commonly called Sun plants e.g. sunflower, while sciophytes are those plants which prefer to grow in lower light intensities or shade loving plants e.g. money plant, fir etc. 

(a) Curve 'a'
(b) It is not realistic as resources become limiting sooner or later.

Population. A population is a unit of biotic community made up of near permanent group of interbreeding individuals of a species found in a geographical area or space at a particular time.
Community. It is a grouping of different but independent and interacting populations of different species which live in a specific locality, e.g., pond community.

 Vertebrates like bear undergo hibernation, to escape in time.
Angiosperms produce seeds and certain other vegetative structures to tide over unfavourable conditions in the habitat.

(i) In summer, we sweat profusely; the evaporation of sweat causes a cooling and brings down the body temperature.
(ii) In winter, we shiver, and that produces heat to raise the body temperature.

The eggs of koel have evolved to resemble the eggs of host bird in colour and size, to reduce chances of the host bird detecting the foreign egg and throwing them out.

Seals have thich layer of fat, called blubber below their skin.
The blubber acts as an insulator and reduces loss of body heat.

(i) Some organisms have evolved a constant internal environment and are able to maintain homeostasis by physiological or behavioural means.
(ii) Many animals and nearly all plants change their internal environment of the body with tho e of the external environment, i.e. they are conformers.
(iii) Some organisms move away temporarily from the stressful conditions in their habitats and return when the stressful period is over.
(iv) Some animals suspend their metabolic activities and avoid stress by escaping in time; hibernation and aestivation are examples of such suspension.

When an organism cannot maintain a constant internal environment, but changes the temperature, osmotic concentration of body fluids, etc. with those of the ambient environment, it is called a conformer, e.g. freshwater fishes maintain the osmolarity of their body fluid.

It is \(37^{ \circ }C\)( or \(98.4^{ \circ }F\))
During summer, when the outside temperature is higher than our body temperature, we sweat profusely.

Desert lizards cope with the temperature variations in their habitat by behaviour means.
They bask in the sun and absorb heat when their body temperature drops below the comfort zone.
They move into the shade when the temperature starts increasing.

It is a case of mutualism because both the fig tree and the wasp are benefitted by this interaction.
The female wasp uses the ovary as a site for oviposition and the developing seeds within the fruit for nourishing the larvae.
The fig inflorescence is pollinated while the wasp is searching for the suitable place for egg-laying.

The monarch butterfly is highly distasteful to its predators because of a chemical present in its body.
It has acquired it at the caterpillar stage by feeding on a poisonous weed.