NCERT MCQ Solutions for Class 10 Science Chapter 13 Our Environment

A pond is a natural ecosystem where organisms interact with each other and the environment without human control. It includes producers, consumers and decomposers maintaining ecological balance and nutrient cycling.

Producers like green plants and some algae use sunlight, carbon dioxide and water to perform photosynthesis and create organic food which supports all other trophic levels in an ecosystem.

Decomposers like bacteria and fungi break down dead organisms into simpler substances returning nutrients to the soil which are reused by plants for growth ensuring nutrient cycling.

An aquarium is an artificial aquatic environment created and maintained by humans to house selected aquatic organisms often under controlled conditions unlike natural ecosystems.

Herbivores feed directly on producers and are placed at the second trophic level in a food chain which is the first level of consumers in the energy flow.

Out of total solar energy received by Earth only about 1% is captured by green plants through photosynthesis to produce food for the entire ecosystem.

Plastic is synthetic and resistant to microbial degradation. It does not decompose naturally and hence accumulates in the environment causing long-term pollution problems.

Chlorofluorocarbons released from refrigerators and aerosol sprays reach the stratosphere where they break down ozone molecules leading to thinning of the ozone layer.

Producers form the base of the food chain by converting solar energy into chemical energy which is then transferred to herbivores and higher trophic levels.

Biological magnification is the process by which toxic substances like pesticides increase in concentration at each successive trophic level in a food chain.

A deer is a herbivore that feeds on producers like grass. It occupies the second trophic level and is classified as a primary consumer in food chains.

Glass is a man-made material that does not break down through natural processes. It remains in the environment indefinitely unless recycled mechanically.

Only about 10% of energy is passed from one trophic level to the next. The rest is lost as heat limiting the length of food chains to 4 or 5 levels.

In a typical forest food chain grass is the producer eaten by deer (primary consumer) which in turn is preyed upon by lion (secondary consumer or carnivore).

Fungi feed on dead and decaying matter breaking down complex organic substances into simpler nutrients which enrich the soil and support producers.

Recycling plastic transforms used materials into new products reducing environmental pollution conserving resources and minimizing waste in landfills and water bodies.

UV radiation from the Sun damages skin cells and DNA. Excessive exposure increases the risk of skin cancer making the ozone layer’s protection vital.

Using public transport reduces individual carbon footprint saves fuel and minimizes air pollution. It is a sustainable and eco-friendly travel option.

Chlorofluorocarbons have been widely used as refrigerants and propellants. However they damage the ozone layer leading to increased ultraviolet radiation reaching Earth.

The ozone layer in the stratosphere absorbs most harmful ultraviolet radiation from the Sun thereby preventing skin cancer cataracts and damage to crops and aquatic life.