UPSC Static Quiz – Environment : 19 July 2025

Solution: B

Statement 2 is incorrect.

There are many plants in which parts like the root, stem and leaves develop into new plants under appropriate conditions. This property of vegetative propagation is used in methods such as layering or grafting to grow many plants like sugarcane, roses, or grapes for agricultural purposes. Plants raised by vegetative propagation can bear flowers and fruits earlier than those produced from seeds. Such methods  also make possible the propagation of plants such as banana, orange, rose and jasmine that have lost the capacity to produce seeds. Another advantage of vegetative propagation is that all plants produced are

genetically similar enough to the parent plant to have all its characteristics.

Solution: D

• Ecological pyramids represent the structure of ecosystems by illustrating the distribution of energy, biomass, or number of organisms across various trophic levels. This visual model is crucial for understanding ecological balance and helps in ecosystem conservation by revealing how energy flows and matter cycles.
• Statements 1 and 2 are correct — knowledge of the pyramid helps track bioaccumulation, where toxic substances like heavy metals accumulate in organisms at lower trophic levels, and biomagnification, where these toxins become more concentrated at higher trophic levels. This understanding is vital for monitoring ecosystem health and taking corrective actions to protect apex consumers.
• However, statement 3 is incorrect — ecological pyramids do not directly help identify invasive species, as these models do not distinguish between native and non-native species.

Solution: C

Commensalism is a type of symbiotic relationship between organisms in which one organism benefits without harming the other.

Many birds form a commensal relationship with some species of ants like the army ants. A great number of army ants trail on the forest floor, and while moving, stir up many insects lying in their path. The birds follow these army ants and eat up the insects that try to escape from them. The birds benefit by catching their prey easily, while the army ants are totally unaffected.

Solution: B

Nitrous oxide emissions occur naturally through many sources associated with the nitrogen cycle, which is the natural circulation of nitrogen among the atmosphere, plants, animals, and microorganisms that live in soil and water.

Nitrous oxide is actually removed from the atmosphere when it is absorbed by certain types of bacteria or destroyed by ultraviolet radiation or chemical reactions.

A natural source of nitrogen oxides occurs from a lightning stroke. The very high temperature in the vicinity of a lightning bolt causes the gases oxygen and nitrogen in the air to react to form nitric oxide. The nitric oxide very quickly reacts with more oxygen to form nitrogen dioxide.

Solution: A

Only option 2 is correct.

Epiphytic (plants growing on other plants including those growing on rock boulders and often termed lithophyte),

Terrestrial (plants growing on land and climbers)

Mycoheterotrophic (plants which derive nutrients from mycorrhizal fungi that are attached to the roots of a vascular plant).