(i) A-conformers         
(ii) B-Regulators

1. The tropical latitudes has more biodiversity as compared to polar region.
2. The large tropical Amazonian rain forest in South America has the greatest biodiversity on earth.
Reasons 1. Tropical latitudes have remained undisturbed for million of years, thus lead a long evolutionary time for species biodiversity.
2. Tropical environments are less seasonal, relatively more constant and predictable. Such constant environments promote niche specialisation and leads to greater species diversity.
3. There is more solar energy available.

(a) Competition is an interaction between organism for the life requirements(nutrition, shelter, sunlight, etc.). It is of two types: intraspecific and interspecific. Efforts of a tiger and a leopard for a prey is an interspecific competition. In general, it is believed that competition occurs among closely related species when they compete for the same resources that are limited.
(b) But it is found to be not true always for the following reasons:
(i) Completely unrelated species can also compete for the same sources. e.g., In certain shallow lakes of South America, the visiting flamingoes and the native fishes compete for the same zooplankton as their food.
(ii) Resources need not be limiting for competition to occur, the feeding efficiency of one species might be reduced due to the interfering and inhibitory presence of the other species, even if resources are plenty.
e.g., Abinddon tortoise in Galapagos island became extinct within a decade after goats were introduced into the island: this was due to the fact that the goats had greater browsing efficiency than the tortoise.
(c) Another evidence for competition is competitive release, a phenomenon in which a species whose distribution is restricted to a small geographical area due to the presence of a competitively superior species, expands its distributional range when the competing species is experimentally removed.
(d) Gause's competitive exclusion principle
states that two closely related species competing for the same resources cannot exist together as the competitively inferior one will be eliminated, but this is true only when the resources are limiting and not otherwise.
They have also pointed out that species facing competition might evolve mechanisms that promote co-existence, rather than exclusion.
(e) Mac Arthur had shown that five closely related species of warblers living on the same tree were able to avoid competition and co-exist to behavioural differences in their foraging activities.

(a) In some shallow lakes of South America, the visiting flamingoes and the resident fishes compete for their common food, the zooplanktons in the lake
b) In interference competition.the feeding efficiency of one species is reduced by the interfering and inhibitory presence of the other species, even if the resources are abundant and not limiting e.q. the Abingdon tortoise in Galapagos island became extinct within a decade after goats were introduced into the island.
(c) Work hard and equip yourself to be successful in this competitive world.

(a) Commensalism
(b) (i) Orchids grow as epiphytes on mango tree or other fruit trees.
Orchids are benefitted by getting a shelter, while the tree is neither benefitted nor damaged.
(ii) Barnacles growing on the whale are benefitted to move where food is available.
(iii) The cattle egrets always forage near to where the cattle animals graze; the cattle animals stir up the ground and the insects are flushed out from the vegetation and make it easy for the egrets to catch them.
(iv) The clown fish living among sea anemones get protection from their predators, which stay away from the stinging tentacles of the sea anemone:
(c) Amensalism
Roots of certain plants secrete chemicals, which are harmful to the soil organisms.
The antibiotics secreted by certain soil fungi are harmful to soil fungi bacteria. (anyone)
(d) Interactions should be beneficial to all concerned. Avoid selfish or selfcentered people.

The chemical composition and pH of water are important to affect the animals.
Some animals can tolerate only a narrow range of salinity and are called stenohaline.
Some animals can tolerate a wide range of salinity and are called euryhaline.
Many freshwater fishes can not live for long in sea water and vice versa, because of the osmotic problems, they would face in such waters.
(b) (i) The leaves are reduced to spines.
(ii) The stem is green, flattened, spongy and takes over the function of photosynthesis .
(iii) A thick cuticle prevents loss of water.
(iv) They have a special photosynthetic mechanism (CAM), that enables their stomata to remain closed during day and open during night.
(c) Water is the most precious resource, use it judiciously and think of programs for its conservation.

(a) The factors include
(i) The rotation of the earth around the sun and the tilt of its axis cause annual variation in the intensity and duration of temperature, which affects distinct reasons.
(ii) Annual variation in precipitation.
(b) (i) Scorching deserts of Rajasthan.
(ii) Rain-soaked Meghalaya forests
(iii) Deep ocean trenches.
(iv) Tropical rain forests
(v) High mountain tops. (any four)
(c) Interactions are necessary; they should be beneficial to all.

(a) Commensalism:
It is the interspecific interaction, where one species is benefitted by the association while the other is neither benefitted nor harmed, e.g. Sucker fish attached to a shark.
(b) Parasitism:
It is the interspecific interaction, where one species (called parasite) takes food and shelter from another living species (host) and damages the host in due course of time; the parasite is benefitted and the host is harmed,e.g. Tapeworm in the intestine of man.
(c) Camouflage:
It is an adaptation, where the animal (organism blends with the surroundings to escape detection by the predator, e.g. Frogs have olive green skin with patches of chromatophores to camouflage with the grasses.
(d) Mutualism:
It is the interspecific interaction, where both the interacting species are mutually benefitted, e.g. An alga and a fungus in a lichen. Rhizobium and legume plant.
(e) Interspecific competition: It is an interspecific interaction, where organisms of two different species compete with each other for certain resources, e.g. Flamingoes and fishes competing for their common food, i.e. zooplanktons. 

The population can grow exponentially for a certain period of time and then assumes a steady state as the resource availability becomes limiting at some point of time.  

Every environment has resources to support a particular maximum number of individuals, called its carrying capacity; beyond that there is no increase in the size/density of a population.
A population showing logistic growth shows a sigmoid curve, when the number of individuals is plotted as a function of time.
It is described by the equation,
dN/dt = \(rN\left( \frac { K-N }{ K } \right) \), 
Where, N = Population density at time t.
r = Intrinsic rate of natural increase.
K = Carrying capacity.
This growth model is more realistic in nature because no population can sustain the exponential growth indefinitely.

(I) When resources are limiting, the population growth curve is sigmoid and it is represented by the equation:
\(dN/dt=rN\left( \frac { K-N }{ K } \right) \), where
N = population density at time t
r = intrinsic rate of natural increase
K = carrying capacity
When resources are not limiting, the growth curve is J shaped and is represented by the equation: dN/dt = rN 
\(N_{ t }={ N }_{ 0 }^{ e^{ rt } },where\)
\(N_{ t }\) =population density after time t
\(N_{ 0 }\)= population density at time zero
r = intrinsic rate of natural increase
e = the base .of  natural logarithm (2.71828)