Test: Our Environment- 1 - UPSC MCQ

• The flow of energy in the ecosystem is unidirectional because the energy lost as heat from the living organisms of a food chain cannot be reused by plants in photosynthesis.
• During the transfer of energy through successive trophic levels in an ecosystem, there is a loss of energy all along the path.

• Organisms occupy a place in the natural surroundings or in a community according to their feeding relationship with other organisms.
• Based on the source of their nutrition or food, organisms occupy a specific place in the food chain that is known as their trophic level.
• Producers belong to the first trophic level, herbivores (primary consumer) to the second and carnivores (secondary consumer) to the third.
• The amount of energy decreases at successive trophic levels

Hence, trophic levels represent energy level as well.

Correct Answer :- b

Explanation : A Non-Biodegradable material can be defined as a kind of substance which cannot be broken down by natural organisms and acts as a source of pollution. ... Non-biodegradable wastes are those who cannot be decomposed or dissolved by natural agents.

Plastic is a non-biodegradable substance.

A food chain is a linear sequence of organisms through which nutrients and energy pass as one organism eats another. 

(i)  At the base of the food chain lie the primary producers. The primary producers are autotrophs and are most often photosynthetic organisms such as plants, algae, or cyanobacteria.

(ii) Primary consumers are the organisms that eat the primary producers. They are usually herbivores, plant-eaters, though they may be algae eaters or bacteria eaters.

(iii) Secondary consumers are the organisms that eat the primary consumers. They are generally meat-eaters called carnivores.

(iv) Tertiary consumers are the organisms that eat the secondary consumers. These are carnivore-eating carnivores, like eagles or big fish.

All the practices mentioned are environment friendly

Mango pulp contains enzymes like polyphenol oxidase which results in its browning and later degrades it and it is mainly absent in other substances. 

Grass, goat and human constitute a food chain. Grass is an autotroph i.e. it produces its own food. Grass is eaten by goat which is a herbivore. Human beings are omnivores (they eat both meat and plant foods) so they eat meat of goat. Hence this is a food chain.

Nylon is a man made fibre it is actually a polymer interconnected by a chain of smaller unit hence the strong intermolecular force between this type of fibre make the bacteria mainly the decomposers to take a long time to decompose this since nylon take a million of year for decomposition it is non biodegradable where as one we talk about wool animal bones tea leaves they all are biodegradable hence the correct option is B

Due to the 10% rule, there is a decrease in energy at every higher trophic level.

Leather belts are biodegradable whereas silver foils, plastic mugs and iron nails are non - biodegradable. It takes leather between 25-50 years to completely decompose.