Ans: B

Exp:

The standing crop is the amount of living matter present at any given time at each trophic level. The mass of living things (biomass), or the quantity in a given area, is used to measure the standing crop. A species’ biomass is measured in terms of fresh or dry weight. It is more accurate to measure biomass in terms of dry weight.

Ans: A

Exp:

Allen’s rule: American naturalist Joel Asaph Allen discovered that certain extremities of animals living in colder regions have shorter limbs (smaller body surface) as an adaptation to control the dissipation of heat. Generally speaking, “extremities” refers to the limbs, legs, ears, and snout or nose. Hence, option a is correct

Gause’s law: According to Gause’s Law, often known as the “competitive exclusion principle,” two species vying for the same resource are unable to coexist at stable population levels. Competition between two species either results in the extinction of the weaker competitor or causes one or both species to undergo evolutionary or behavioural change, allowing them to start utilising at least slightly different ecological niches. Hence, option b is incorrect.

Bergmann’s rule: According to Bergmann’s Rule, geographic races of a species are found in the warmer portions of its distribution and races with greater body sizes in the cooler ones.  Ec: Raccoon and procyon lotor in Mexico’s tropical Yucatan . Hence, option c is incorrect.

Gloger’s rule: According to Gloger’s Rule, races of animals living in warm, humid environments have an increase in dark pigments. Of course, humans are one of the animal species that adhere to this “rule”. Hence, option d is incorrect

Ans: B

Exp:

Statement 1 is correct: Phosphorus is an essential nutrient for living processes. It is a major component of nucleic acids and phospholipids, and, as calcium phosphate, it makes up the supportive components of our Phosphorus is often the limiting nutrient (necessary for growth) in aquatic, particularly freshwater, ecosystems. Phosphorus occurs in nature as the phosphate ion (PO43-) and enters the cycle from erosion and mining activities. The phosphate rock has its origins in the ocean. Phosphate-containing ocean sediments form primarily from the bodies of ocean organisms and from their excretions.

Statement 2 is correct: The biogeochemical cycle of water, or the hydrological cycle describes the way that water (Hydrogen Dioxide or H2O) is circulated and recycled throughout Earth’s systems. The hydrologic cycle is the continuous circulation of water in the earth-atmosphere system which is driven by solar energy. All living organisms, without exception, need water to survive and grow, making it one of the most important substances on Earth. On a geographical level, the biogeochemical cycle of water is responsible for weather patterns. As water in its various forms (vapor, liquid and ice) interacts with its surroundings and it alters the temperature and pressure of the atmosphere, creating wind, rain and currents, and is responsible for changing the structure of earth and rock through weathering.

Statement 3 is incorrect: Sulphur is important for the functioning of proteins and enzymes in plants, and in animals that depend upon plants for sulphur. Plants absorb sulphur when it is dissolved in water. Animals consume these plants, so that they take up enough sulphur to maintain their health. Most of the earth’s sulphur is tied up in rocks and salts or buried deep in the ocean in oceanic sediments. Sulphur can also be found in the atmosphere. It enters the atmosphere through both natural and human sources. Atmospheric sulphur is found in the form of sulfur dioxide (SO2), which enters the atmosphere in three ways: first, from the decomposition of organic molecules; second, from volcanic activity and geothermal vents; and, third, from the burning of fossil fuels by humans.

Ans: B

Exp:

Statement 1 is correct : These ecosystems are characterised by distinct layers of vegetation at various heights.

• Forest Floor: The lowest layer with minimal light and decomposing matter
• Understory Layer: Comprising small trees and shrubs adapted to low light.
• Canopy Layer: The primary layer, a lush treetop canopy teeming with diverse species.
• Emergent Layer: Some rainforests have towering trees rising above the canopy.

     Ebony, mahogany, rosewood, rubber and cinchona are some important tree species.

Statement 2 is correct: They have been described as ‘deserts covered by trees’ due to their astounding biodiversity contrasted with nutrient-poor soils. This paradox is due to the intense competition among plants, which has led to specialised adaptations and a rich diversity of species. Despite heavy rainfall causing maximum nutrient leaching from the soil, efficient nutrient recycling through decomposition keeps these rainforests lush and vibrant.

Statement 3 is incorrect: Tropical rainforests are known for their remarkable biodiversity, making them among the most biodiverse terrestrial habitats on the planet. But coral reefs are believed by many to have the highest animal phyla biodiversity of any ecosystem on the planet—even more than a tropical rainforest. Occupying less than one percent of the ocean floor, coral reefs are home to more than 25% of all marine life.

Ans:D

Exp:

Statement 1 is incorrect: Forest cover and tree cover have not shown a declining trend in the last two years.The total forest and tree cover of the country is 80.9 million hectare which is 24.62 percent of the geographical area of the country. As compared to the assessment of 2019, there is an increase of 2,261 sq km in the total forest and tree cover of the country. 

Statement 2 is incorrect: In terms of forest cover as a percentage of total geographical area, the top five States are Mizoram (84.53%), Arunachal Pradesh (79.33%), Meghalaya (76.00%), Manipur (74.34%) and Nagaland (73.90%). Area-wise, Madhya Pradesh has the largest forest cover in the country, followed by Arunachal Pradesh, Chhattisgarh, Odisha and Maharashtra.