Solve all MCQs on Our Environment Class 10
FAQs on Our Environment Class 10 MCQ to Practice
1. What are the key topics within 'Our Environment' from which 1-mark MCQs are frequently asked in the board exam?
For the CBSE Class 10 board exam 2025-26, 1-mark MCQs from 'Our Environment' typically focus on:
- Ecosystem Components: Identifying abiotic vs. biotic components.
- Trophic Levels: Identifying producers, primary/secondary consumers, and decomposers in a food chain.
- Energy Flow: The 10% law of energy transfer.
- Waste Types: Differentiating between biodegradable and non-biodegradable substances.
- Ozone Depletion: The chemical responsible (CFCs) and its primary function.
2. What is a good strategy to prepare for MCQs from Chapter 15 to score full marks?
To score full marks in MCQs from 'Our Environment', focus on a clear conceptual understanding rather than rote learning. First, thoroughly read the NCERT chapter. Then, create quick notes on key definitions like ecosystem, food web, and biomagnification. Practice assertion-reasoning and case-based questions, as these are common in the current exam pattern. Finally, solve a variety of MCQs to identify common traps and improve your speed and accuracy.
3. Why are decomposers like bacteria and fungi essential for an ecosystem, and what would happen if they disappeared?
Decomposers are essential because they break down complex organic matter from dead plants and animals into simpler inorganic substances. This process is crucial for replenishing nutrients in the soil, which are then used by producers (plants). If decomposers disappeared, dead organic matter would pile up, and the vital flow of nutrients back into the ecosystem would stop, eventually leading to the collapse of the entire food web.
4. How does the 10% law of energy transfer in a food chain lead to a limited number of trophic levels?
The 10% law states that only about 10% of the energy from one trophic level is transferred to the next. The remaining 90% is lost as heat during metabolic processes. Because of this significant energy loss at each step, there is very little usable energy left after three or four trophic levels. This is why food chains are typically limited to 3-4 trophic levels, as there isn't enough energy to sustain organisms at higher levels.
5. What is the main difference between biodegradable and non-biodegradable waste, with examples relevant to Chapter 15?
The main difference lies in their decomposition.
- Biodegradable waste can be broken down into harmless substances by microorganisms. Examples include food waste, paper, and cotton.
- Non-biodegradable waste cannot be broken down by natural biological processes and persists in the environment for a very long time. Examples include plastic bottles, glass, and pesticides like DDT.
6. A food chain consists of grass, a deer, and a tiger. If the grass has 10,000 J of energy, how much energy is available to the tiger? Explain the concept behind this calculation.
The energy transfer follows the 10% law.
- Energy available to the deer (primary consumer) from grass (producer) = 10% of 10,000 J = 1,000 J.
- Energy available to the tiger (secondary consumer) from the deer = 10% of 1,000 J = 100 J.
7. What are the primary causes and consequences of ozone layer depletion as per the CBSE Class 10 syllabus?
The primary cause of ozone layer depletion is the release of man-made chemicals called Chlorofluorocarbons (CFCs), which were used in refrigerants and aerosol sprays. The main consequence of a depleted ozone layer is that it allows harmful ultraviolet (UV) radiation from the sun to reach the Earth's surface, which can cause skin cancer, cataracts, and damage to plants and marine life.
8. Beyond just causing pollution, how does the accumulation of non-biodegradable waste like plastic disrupt local ecosystems and food webs?
The accumulation of non-biodegradable waste disrupts ecosystems in several ways. Plastic debris can physically harm animals through entanglement or ingestion, leading to injury or death. It can also break down into microplastics, which enter the food chain and can lead to biomagnification of associated toxins. Furthermore, large amounts of waste can alter habitats, for example, by blocking sunlight from reaching aquatic plants or changing the chemical composition of soil and water.
9. What types of MCQs, besides direct definition-based questions, can be expected from the 'Our Environment' chapter?
For the 2025-26 board exams, you should prepare for various MCQ formats from this chapter, including:
- Assertion-Reasoning (A/R) questions that test the link between a statement and its cause.
- Case-based/Source-based questions, where you answer MCQs based on a given paragraph or diagram of a food web.
- Diagram-based questions requiring you to identify trophic levels or energy flow in a given ecosystem diagram.
10. Why is it more environmentally beneficial to reduce consumption and reuse items rather than just relying on recycling?
While recycling is important, reducing and reusing are more beneficial because they address the problem at its source. Reducing consumption prevents the generation of waste in the first place, saving the energy and resources needed for manufacturing. Reusing items extends their life, also saving energy and resources. Recycling, on the other hand, is the last resort; it still requires significant energy and processes to convert waste into new products and isn't always 100% efficient.
