Ans: A

Exp:

On the basis of the temperature tolerance, different groups of organisms are defined. Among them, eurythermal and stenothermal animals are two categories.

Statement 1 is correct: Eurythermal animals are those who can tolerate a wide range of temperatures. They are able to function at a wide range of body temperatures. Eurythermal animals show less sensitivity to temperature or they show comparatively low temperature sensitivity. Hence, they are not affected by the temperatures.

Statement 2 is incorrect: Stenothermal animals are those which can tolerate a narrow range of temperature levels. Since stenothermal animals are temperature sensitive, they are greatly affected by the temperature fluctuations. Examples of cryophilic animals include salmon, crustaceans, etc.

Ans: B

Exp:

 Interspecific interactions arise from the interaction of populations of two different species. They could be beneficial, detrimental or neutral (neither harm nor benefit) to one of the species or both.

Pair 1 is correctly matched: Both the species benefit in mutualism and both lose in competition in their interactions with each other. Lichens result from the symbiotic union between fungi and algae or fungi and cyanobacteria. 

Pair 2 is correctly matched: In both parasitism and predation, only one species benefits (parasite and predator, respectively) and the interaction is detrimental to the other species (host and prey, respectively).

The best-known examples of predation involve carnivorous interactions, in which one animal consumes another, such as tiger eating deer. Carnivorous plants, such as the Venus fly trap and the pitcher plant, consume insects are also examples of Predation.

Pair 3 is incorrectly matched: In amensalism, on the other hand, one species is harmed whereas the other is unaffected.  

Pair 4 is incorrectly matched: The interaction where one species is benefitted and the other is neither benefitted nor harmed is called commensalism. commensalism is the remora (family Echineidae) that rides attached to sharks and other fish. 

Ans: C

Exp:

Statement 1 is correct: A niche is the unique functional role or place of a species in an ecosystem. It is a description of all the biological, physical and chemical factors that a species needs to survive, stay healthy and reproduce.Statement 2 is correct: A niche is unique for a species, which means no two species have exact identical niches. While different species may share the same habitat.

Statement 3 is correct: It helps in species conservation programmes as Conservation efforts of species in their natural habitat require knowledge of niche requirements of species.

Ans: B

Exp:

Statement 1 is correct: Many desert plants have a thick cuticles on their leaf surfaces and have their stomata arranged in deep pits (sunken) to minimise water loss through transpiration. Desert plants also have a deep taproot system which allows them to access water deep below the surface of the ground. They also have a special photosynthetic pathway (CAM) that enables their stomata to remain closed during day time. Some desert plants, like Opuntia, have no leaves – they are reduced to spines–and the photosynthetic function is taken over by the flattened stems.

Statement 2 is incorrect: Animals living in colder regions of the world have shorter limbs than those living in warmer regions as an adaptation to control the dissipation of heat. A smaller body surface area helps animals in colder regions stay warm by slowing down the loss of body heat.

Statement 3 is correct: In arid regions, animals adapt to lower their water consumption as low as possible. For example, kangaroo rats conserve water by concentrating their urine, sometimes even excreting solid urine and can live from birth to death without water.

Ans: D

Exp:

Statement 1 is correct: Ecotone is a zone of transition between two or more diverse ecosystems. For e.g. the mangrove forests represent an ecotone between marine and terrestrial ecosystem. Other examples are – grassland, estuary and river bank.

Characteristics of Ecotone

• It may be very narrow or quite wide.
• It has the conditions intermediate to the adjacent eco-systems. Hence it is a zone of tension.
• It is linear as it shows progressive increase in species composition of one in coming community and a simul-taneous decrease in species of the other out going ad-joining community.

Statement 2 is correct: A well-developed ecotones contain some organisms which are entirely different from that of the adjoining communities.

Statement 3 is correct: Few times, the number of species and the population density of some of the species is much greater in this zone than in either community. This is called the edge effect. The organisms which occur primarily or most abundantly in this zone are known as edge species. In terrestrial ecosystems edge effect is especially applicable to birds. For example, the density of birds is greater in the mixed habitat of the ecotone between the forest and the desert.