Answer: Option B. -> Red algae
:
B
The blue-greenlight have short wavelength and penetrates deep into the water.Red algaeare commonly found in the depths ofoceansas they contain pigments such as phycobilins that can utilise short wavelength blue light that can penetrate deeper than other wavelengths of light.

Answer: Option B. -> Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
:
B
Predation is a complexinterspecific interaction with a feeding strategy i.e., one specieseatsanother. The population of the prey is regulated by the number of predators, but if the population of the prey drop heavily, the predator population also drops because they run out of food. Thus predatorand their prey maintain fairly stable population through time and one population does not becomeabundant or scarce, without affecting the other. However, population size of the prey or the predator does not explain the predatory interaction, therefore the two statements are not related, and Reason does not explain Assertion.

Answer: Option B. -> Closely related species growing in the same habitat
:
B
When the species are closely related they tend to require the same resources, the same habitat and food, this leads to high competition between them, whereas two distantly related species in the same habitat, will have different food requirements and different shelter requirements and therefore do not compete for the same resources or atleast will have different modes to acquire these resources, thereby decreasing competition between them. Species occupy different ecological niches to apportion resources between them and to decrease the competition between them. Ecological niche can be defined as the role of an organism in its environment. Therefore closely related species that occupy different niches, do not compete heavily.

:
Commensalism benefits one organism and does not harm the other. For example, epiphytic orchids. This interaction benefits orchids as it allows them to grow on top of the trees. This prevents the orchids from being walked on or eaten by ground-dwelling organisms. It also allows the orchids to receive more sunlight for photosynthesis. Since, the orchids receive nutrients from the air and compost on the trees, they do not harm nor benefit the plants on which they grow.

Answer: Option C. -> A is correct but R is incorrect
:
C
Stenothermal organisms are those which can thrive only within a limited temperature range. They could be further categorised into two groups- thermophiles and cryophiles. The former refers to those organisms which can thrive only in high temperatures (at least above ${20}^{\circ }C$) while the latter includes organisms which can thrive only in lower temperatures (below ${20}^{\circ }C$). Corals, some insects and a majority of the reptiles are thermophiles. Arctic crustaceans are examples of cryophiles.

Answer: Option B. -> Tundra and Desert
:
B
The desert and the nonforest biome (tundra) are the two biomes that receive the least amount of rainfall during the year.The tundrareceives very little precipitation about 6-10 inches annually, mostly in the form of snow, and the desert receives less than 9.9 inches per year.

Answer: Option A. -> A is more recent and shows slight reduction in the growth rate
:
A
Interpretation (a) is correct.
The Diagram A shows reduction in the number of males and females of the population. As you can see the 0-9 bar shows a total of 15 individuals in the digram B and the 0-9 bar in diagram A shows only 12 individuals. So Figure Ashows slight reduction in the growth rate.

Answer: Option A. -> -,- and -,0
:
A
Competition is an interspecies interaction that is not beneficial to both the organisms involved, therefore it is a -,-. Ammensalism is an interaction that is harmful to one and does not affect the other, therefore it is a -,0.

Answer: Option D. -> All of these
:
D
India is a tropical country and it has evergreen rainforests in theAndaman and Nicobar Islands,the Western Ghats,and the greater Assam region in the north-east. Deciduous forests are found in the north eastern states of Jharkhand, West Orissa and Chhattisgarh. Desert is the Thar desert of Rajasthan and sea-coast on either side of the Indian peninsula and around the islands.

Answer: Option B. -> f
:
B
Mutualism is where both the organisms benefit from the interaction.
Commensalism is where one organism benefits, while the other is not affected.
Parasitism is where one organism benefits by colonizing the host, but the host is harmed because of this interaction.
Predation is where one organism is killed by the other for food.
Column I
Column II
Mutualism
Hermit crab and sea anemone
Commensalism
Sucker fish and shark
Parasitism
Cuscuta on Citrus
Predation
Tiger and Deer