Class 10 Science Chapter 13 Question Answers - Our Environment

Q1: Suggest any four activities in daily life which are eco-friendly.
Ans: The eco-friendly activities in life are:

• Planting of trees.
• Segregating biodegradable and non-biodegradable wastes.
• Using cloth bags, jute bags or paper bags instead of plastic bags.
• Creating awareness on environment protection through initiatives and campaigns.
• Using of manures and organic agricultural methods.
• Using less of chemical fertilizers and pesticides.
• Controlling pollution by using fuels like CNG.

Q2: Make food chains in (i) forest (ii) grassland (iii) pond. How does food chain differ from a food web?
Ans: Food chains in:
(i) Forest: Plants → Deer → Lion
(ii) Grassland: Plants → Grasshopper → Frog → Snake → Eagle
(iii) Pond: Aquatic plants → Scorpion Fish → Flamingo
Food Chain: It is a series of organisms feeding on one another.
Food Web: It is a network of food chains consisting of a number of interlinked food chains.

Q3: Indicate the flow of energy in an ecosystem. Why is it unidirectional?
Ans: The flow of energy generally is:
Sun → Producer → Herbivore → Carnivore
The flow of energy is unidirectional because it goes progressively from one trophic level (lower) to another trophic level (higher) and does not revert back.
It is impossible for energy to flow in the reverse direction as the available energy decreases in the higher trophic levels.

Q4: Name the wastes which are generated in your house daily. What measures would you take for their disposal?
Ans: The wastes generated in our house daily are:

• Kitchen wastes
• Paper wastes like newspapers, bags, envelopes
• Plastic bags
• Vegetable/fruit peels/rinds

The measures which can be taken for their disposal are:

• Segregate the wastes as biodegradable, non-biodegradable and hazardous ones.
• Dispose of the plastic bags and bottles in a proper way.
• Vegetable/fruit peels can be used to make compost.
• Paper wastes can be used for recycling.
• Prepare a vermicompost pit for the organic wastes from the kitchen.

Q5: What are the by-products of fertiliser industries? How do they affect the environment?
Ans: The harmful by-products of fertiliser industries are the harmful gases like SO₂ and NO. They cause air pollution and combine with the water vapour in the atmosphere to cause harmful acid rain.

Q6: Explain some harmful effects of agricultural practices on the environment.
Ans:

• Change in the chemistry of soil and killing of useful microbes due to excessive use of fertilisers.
• Biological magnification occurs due to excessive use of chemical pesticides.
• Water table gets lowered due to the excess use of ground water.
• Soil fertility is lost due to extensive cropping.
• The natural ecosystems is harmed due to ploughing during agriculture.

Q7: Explain the term "ecosystem" and its components. Describe the interrelationship between biotic and abiotic factors within an ecosystem.
Ans: An ecosystem refers to a dynamic and interconnected system where living organisms (biotic components) interact with each other and their non-living surroundings (abiotic components). Ecosystems can vary in size, from small ponds to vast forests. The interrelationship between biotic and abiotic factors is crucial for the functioning of an ecosystem.
Components of an Ecosystem:

• Biotic Components: These include living organisms such as plants, animals, microorganisms, and decomposers. They interact with each other, forming intricate food chains and webs, and contribute to the flow of energy and nutrients in the ecosystem.
• Abiotic Components: These comprise non-living factors such as temperature, sunlight, water, soil, air, minerals, and physical features of the environment. Abiotic factors influence the distribution, behavior, and survival of biotic components.

Interrelationship between Biotic and Abiotic Factors:

• Biotic and abiotic factors are interconnected and interdependent in an ecosystem.
• Biotic factors rely on abiotic factors for their survival. For example, plants require sunlight for photosynthesis, and animals need water for drinking.
• Abiotic factors influence the availability of resources. For instance, temperature affects the metabolic processes of organisms, and soil composition affects plant growth.
• Biotic factors, in turn, influence abiotic factors. For instance, plants can alter soil properties through their root systems.

The interactions between biotic and abiotic components shape the structure and functioning of ecosystems, and any disturbance to this delicate balance can have far-reaching consequences.

Q8: Define "environmental pollution" and discuss the harmful effects of air pollution on human health. Explain how pollutants like particulate matter (PM) and sulfur dioxide (SO₂) are released into the air.
Ans: Environmental pollution refers to the introduction of harmful substances or pollutants into the environment, causing undesirable changes that adversely affect the well-being of living organisms. Air pollution, a significant form of environmental pollution, has detrimental effects on human health.
Harmful Effects of Air Pollution on Human Health:

• Respiratory Issues: Air pollutants such as particulate matter (PM), sulfur dioxide (SO₂), nitrogen oxides (NOx), and volatile organic compounds (VOCs) can irritate the respiratory system, leading to conditions like bronchitis, asthma, and reduced lung function.
• Cardiovascular Problems: Air pollution is associated with an increased risk of heart diseases, including heart attacks and strokes. Pollutants can enter the bloodstream and affect the cardiovascular system.
• Impaired Lung Development: Children exposed to air pollutants may experience impaired lung development, leading to long-term respiratory problems.
• Aggravation of Existing Conditions: Air pollution can exacerbate existing health conditions, making them more severe.

Release of Pollutants into the Air:

• Particulate Matter (PM): PM is a mixture of tiny solid particles and liquid droplets suspended in the air. It is released from various sources, including vehicle emissions, industrial processes, construction activities, and burning of fossil fuels.
• Sulfur Dioxide (SO₂): SO₂ is produced primarily from burning fossil fuels like coal and oil. It is released during combustion processes in power plants, industrial facilities, and vehicles.
• Nitrogen Oxides (NOx): NOx is emitted from combustion engines of vehicles and industrial processes. It forms when nitrogen in the air reacts with oxygen at high temperatures.

Air pollution prevention and control measures are essential to mitigate its adverse effects on human health and the environment.

Q9: Describe the process of eutrophication and its consequences on aquatic ecosystems. Explain how excessive nutrient enrichment leads to eutrophication and the steps to prevent it.
Ans: Eutrophication is a process characterized by excessive nutrient enrichment, particularly nitrogen and phosphorus compounds, in aquatic ecosystems. It leads to the rapid growth of algae and other aquatic plants, disrupting the balance of the ecosystem and causing several negative consequences.
Process of Eutrophication:

• Nutrient Enrichment: Excess nutrients, often from agricultural runoff, sewage, and industrial discharges, enter water bodies.
• Algal Bloom: Nutrient-rich water stimulates the rapid growth of algae, leading to an algal bloom on the water surface.
• Reduced Sunlight: The dense algal growth blocks sunlight from penetrating the water, affecting submerged plants' ability to photosynthesize.
• Oxygen Depletion: Algae die and decompose, consuming oxygen during the decomposition process. Oxygen levels in the water decrease, leading to hypoxia (low oxygen levels) or anoxia (absence of oxygen).
• Fish Kills: The depletion of oxygen can lead to fish kills and the death of other aquatic organisms.

Consequences of Eutrophication:

• Oxygen Depletion: Reduced oxygen levels harm aquatic life, leading to fish kills and other organism deaths.
• Altered Food Chains: Algal blooms disrupt aquatic food chains, impacting predator-prey relationships.
• Water Quality: Eutrophication degrades water quality, affecting recreational activities and water supply.

Prevention of Eutrophication:

• Proper Waste Management: Proper treatment and disposal of sewage and industrial effluents reduce nutrient inputs into water bodies.
• Nutrient Management: Responsible use of fertilizers and agricultural practices reduces nutrient runoff.
• Wetland Conservation: Wetlands act as natural filters, trapping nutrients and preventing their entry into water bodies.
• Reforestation: Planting trees along riverbanks and watersheds reduces soil erosion and nutrient runoff.

Preventing eutrophication is crucial to maintaining the health and balance of aquatic ecosystems.

Q10: Define "biodegradable" and "non-biodegradable" substances. Explain the environmental impact of non-biodegradable waste. Provide examples of each type of waste and their effects on ecosystems.
Ans: Biodegradable substances are materials that can be broken down naturally by biological processes into simpler, non-harmful substances. Non-biodegradable substances are materials that persist in the environment for long periods and do not degrade easily. The environmental impact of non-biodegradable waste is significant and has far-reaching consequences.
Environmental Impact of Non-Biodegradable Waste:

• Accumulation: Non-biodegradable waste, such as plastics and synthetic materials, accumulates in the environment, leading to pollution and aesthetic degradation.
• Soil and Water Contamination: Non-biodegradable waste can leach harmful chemicals into soil and water, affecting the quality of these resources.
• Wildlife Harm: Animals may ingest or become entangled in non-biodegradable waste, causing injury or death. Marine animals are particularly vulnerable to plastic pollution.
• Microplastic Formation: Non-biodegradable plastics break down into microplastics, which can enter the food chain and have adverse effects on ecosystems and human health.

Examples of Biodegradable and Non-Biodegradable Waste:

• Biodegradable: Food waste, paper, wood, organic matter. These materials break down naturally, contributing to nutrient cycles.
• Non-Biodegradable: Plastics, synthetic fibers, glass, metal, certain chemicals. These materials persist in the environment, causing pollution and harm.

Addressing non-biodegradable waste requires proper waste management practices, recycling, and reducing the use of single-use plastics.