CBSE Class 10 Science Chapter 15: Our Environment NCERT Solutions

The correct option is (c) Fruit-peels, cake and lime-juice. Biodegradable items are those that can be decomposed by natural biological processes, such as the action of microorganisms. Fruit-peels, cake, and lime-juice are organic materials that break down easily in the environment. Options (a), (b), and (d) include plastic, which is a non-biodegradable substance, making those groups incorrect.

The correct option is (b) Grass, goat and human. A food chain illustrates the flow of energy from one organism to another. In this chain, grass is a producer (makes its own food), the goat is a primary consumer (herbivore that eats grass), and humans can be secondary consumers (carnivores or omnivores that eat goats). Options (a), (c), and (d) do not represent a typical, sequential flow of energy in a food chain.

The correct option is (d) All of the above. All the listed practices are considered environment-friendly. Carrying cloth bags reduces plastic waste. Switching off lights and fans conserves energy, reducing the demand on power plants which often contribute to pollution. Walking or using eco-friendly transport reduces air pollution and carbon emissions. These actions collectively help in protecting the environment.

If all the organisms in a particular trophic level are eliminated, it will significantly disrupt the ecosystem's balance. The transfer of energy to the next trophic level will cease, potentially leading to starvation for organisms dependent on that level. Conversely, the population of the trophic level below the removed one might experience uncontrolled growth due to the absence of predators. This imbalance can cascade through the food web, causing widespread ecological damage and instability.

Yes, the impact of removing all organisms from a trophic level will differ depending on which level is affected. Removing producers (like plants) would have the most drastic effect, as they form the base of most food chains, leading to the collapse of higher trophic levels. Removing primary consumers (herbivores) would cause starvation for secondary consumers and potentially an overpopulation of producers. Removing organisms from higher trophic levels might have less immediate, but still significant, long-term effects on population dynamics and ecosystem stability. It is not possible to remove organisms from any trophic level without causing some damage to the ecosystem, as all levels are interconnected through food chains and webs.

Biological magnification is the process by which non-biodegradable substances, such as certain pesticides or heavy metals, accumulate and increase in concentration in the tissues of organisms as they move up through successive trophic levels in a food chain. Yes, the levels of magnification will be different and progressively higher at each subsequent trophic level. For instance, if a pollutant is present in low concentrations in producers, it will be found in much higher concentrations in primary consumers, even higher in secondary consumers, and so on. This occurs because organisms consume large quantities of food from the lower trophic level, and the accumulated non-biodegradable substances are not easily excreted or metabolized.