OUR ENVIRONMENT: Long Answer Type Question for Class 10th Chapter 10 JKBOSE/NCERT
LONG ANSWER TYPE
Questions: 1. What are biodegradable and non-biodegradable substances? How do they affect the environment?
Ans: Biodegradable substances are materials that can be broken down and decomposed by natural processes, such as the action of microorganisms, into simpler, non-toxic compounds. These substances include organic matter like food waste, plant material, paper, and some types of plastics. On the other hand, non-biodegradable substances are materials that do not easily break down or decompose in the environment. These include materials like certain plastics, metals, glass, and synthetic chemicals.
The impact of biodegradable and non-biodegradable substances on the environment differs significantly. Biodegradable substances can be broken down by microorganisms, which helps in the recycling of nutrients and the maintenance of a healthy ecosystem. They contribute to the natural nutrient cycles and do not accumulate in the environment to the same extent as non-biodegradable substances.
Non-biodegradable substances, however, pose significant environmental challenges. Since they do not readily decompose, they can persist in the environment for long periods. These substances can accumulate in ecosystems, leading to pollution and harmful effects on organisms. For example, plastic waste in the oceans can entangle marine animals, cause physical harm, and disrupt their natural behaviour. Additionally, some non-biodegradable substances can release toxic chemicals into the environment, posing risks to both wildlife and human health.
Questions 2. Define Ecosystem. What are its components?
Ans: An ecosystem refers to a dynamic and interconnected community of living organisms (biotic components) and their physical environment (abiotic components), functioning as a unit. It encompasses all the interactions and relationships among organisms and their environment within a given area.
The components of an ecosystem can be categorized into two main groups:
a) Biotic Components: These include all the living organisms within the ecosystem. This comprises plants, animals, microorganisms, and other forms of life.
b) Abiotic Components: These refer to the non-living or physical factors of the ecosystem. Abiotic components encompass elements like sunlight, water, air, soil, temperature, climate, and minerals.
Questions 3. Briefly mention the role of producers, consumers and decomposers in an ecosystem.
Ans: Producers, consumers, and decomposers play crucial roles in the functioning and balance of an ecosystem:
Producers: Producers, typically plants and some types of bacteria, are organisms capable of converting sunlight (or in some cases, chemical energy) into organic compounds through the process of photosynthesis. They are the primary source of energy in an ecosystem and form the base of the food chain. Producers capture energy from the sun, store it in their tissues, and provide sustenance for other organisms.
Consumers: Consumers, including animals, fungi, and some bacteria, obtain energy by consuming other organisms. They are categorized into different trophic levels based on their position in the food chain. Primary consumers (herbivores) feed directly on producers, while secondary consumers (carnivores) feed on primary consumers, and so on. Consumers obtain energy by breaking down the organic compounds present in their food.
Decomposers: Decomposers, mainly bacteria and fungi, break down dead organic matter, such as fallen leaves, dead animals, and waste products, into simpler inorganic substances. They play a vital role in the recycling of nutrients in the ecosystem. Decomposers break down complex organic compounds into simpler forms, which are then available to be taken up by producers for photosynthesis, thus closing the nutrient cycle.
Question 4. What are trophic levels? Give an example of a food chain and state the different trophic levels in it.
Ans: Trophic levels represent the hierarchical levels in a food chain or food web, indicating the energy transfer and nutritional relationships between different organisms. There are typically four main trophic levels:
Primary Producers (First Trophic Level): These are the autotrophic organisms, such as green plants and algae, that convert sunlight or chemical energy into organic matter through photosynthesis. They form the base of the food chain and are also known as primary producers.
Primary Consumers (Second Trophic Level): These are the herbivores that feed directly on the primary producers. They consume plant material or algae to obtain energy.
Secondary Consumers (Third Trophic Level): These are the carnivores or omnivores that feed on the primary consumers. They obtain energy by consuming herbivores or other primary consumers.
Tertiary Consumers (Fourth Trophic Level): These are the top-level predators in the ecosystem. They feed on secondary consumers or sometimes on other tertiary consumers.
An example of a food chain would be:
Grass → Grasshopper → Frog → Snake → Hawk
In this food chain, the grass is the primary producer (first trophic level), the grasshopper is the primary consumer (second trophic level), the frog is the secondary consumer (third trophic level), the snake is the tertiary consumer (fourth trophic level), and the hawk is the top predator.
Question 5. Track a path of energy flow in an ecosystem.
Ans: The path of energy flow in an ecosystem can be traced through the trophic levels:
The energy flow begins with the primary producers (plants) capturing sunlight and converting it into chemical energy through photosynthesis. This energy is stored in the form of organic compounds in the plant’s tissues. When herbivores (primary consumers) consume the plants, they obtain a portion of the energy stored in the plants. This energy is then transferred to the herbivores’ tissues.
Next, when carnivores or omnivores (secondary consumers) feed on the herbivores, they acquire the energy stored in the herbivores’ tissues. This energy transfer continues as predators consume other predators (tertiary consumers), with each level gaining energy from the previous level.
Throughout these energy transfers, some energy is lost at each trophic level as heat, metabolic processes, or undigested waste. As a result, the energy available to higher trophic levels decreases, leading to a pyramid-shaped distribution of energy in an ecosystem, known as an energy pyramid.
At each trophic level, some organisms die or produce waste, and this organic matter is broken down by decomposers (bacteria and fungi). Decomposers release energy through the process of decomposition, returning nutrients to the soil or water, and restarting the cycle.
Overall, energy flows through the ecosystem in a unidirectional manner, with energy decreasing as it moves up the trophic levels and being recycled through decomposers to sustain the system’s energy flow.
Question 6. Why do food chains generally consist of three or four steps?
Ans: Food chains generally consist of three or four steps due to energy loss and efficiency considerations. As energy flows through an ecosystem, it gets progressively diminished at each trophic level. Only a fraction of the energy from one trophic level is transferred to the next, with the rest being lost as heat or used for metabolic processes. This energy loss limits the length of food chains.
The efficiency of energy transfer from one trophic level to the next is typically around 10%. This means that if a primary producer captures 100 units of energy, only 10 units are transferred to the primary consumer, and so on. With each transfer, the energy available for the next level decreases. As a result, energy availability becomes insufficient to sustain additional trophic levels beyond three or four.
Moreover, as food chains become longer, it becomes increasingly challenging to find enough organisms at each level to support the energy needs of higher trophic levels. This scarcity of energy resources limits the length of food chains.
Question 7. Why is the Ozone layer in the atmosphere important to us? Which chemicals are responsible for its depletion?
Ans: The ozone layer in the atmosphere is crucial for several reasons:
Protection from UV Radiation: The ozone layer acts as a shield, absorbing a significant portion of the Sun’s ultraviolet (UV) radiation, particularly the harmful UV-B and UV-C rays. These rays can cause skin cancer, cataracts, and other harmful effects on both human and animal health.
Regulation of Climate: Ozone also contributes to the regulation of the Earth’s climate. It is a greenhouse gas that helps in trapping heat in the stratosphere, creating a balance between the warming and cooling effects of other greenhouse gases like carbon dioxide.
The depletion of the ozone layer is primarily attributed to human-made chemicals known as ozone-depleting substances (ODS). The most significant contributors to ozone depletion are chlorofluorocarbons (CFCs), halons, carbon tetrachloride, and methyl chloroform.
Question 8. How can you help in reducing the problem of waste disposal? Give any two methods.
Ans: To contribute to reducing the problem of waste disposal, here are two methods:
Recycling: Recycling involves collecting and processing waste materials to create new products. By participating in recycling programs, you can ensure that materials such as paper, plastic, glass, and metals are diverted from landfills and undergo processes to be transformed into new usable items. Separating recyclable waste from non-recyclable waste and supporting recycling initiatives helps conserve resources, reduce energy consumption, and decrease the amount of waste that ends up in landfills.
Composting: Composting is a natural process that decomposes organic waste, such as food scraps, yard trimmings, and other biodegradable materials, into nutrient-rich compost. By composting these materials instead of disposing of them as waste, you can produce a valuable soil amendment that enriches the soil and reduces the need for chemical fertilizers. Composting can be done at home or through community composting programs, contributing to waste reduction and promoting sustainable gardening practices.
Question 9. What are the problems caused by the non-biodegradable wastes that we generate?
Ans: Non-biodegradable wastes pose several problems:
Environmental Pollution: Non-biodegradable materials, such as plastics and certain chemicals, can persist in the environment for long periods without breaking down. They accumulate in landfills, water bodies, and other natural habitats, causing pollution.
Soil and Water Contamination: When non-biodegradable substances leach into the soil or water, they contaminate these valuable resources. Soil contamination can affect the fertility of agricultural lands, impairing plant growth and food production. Water contamination not only affects aquatic life but can also have detrimental effects on human health when polluted water sources are consumed.
Wildlife and Marine Life Impact: Non-biodegradable waste, particularly plastic, poses a severe threat to wildlife and marine life. Animals can get entangled in plastic debris, leading to injuries, suffocation, or starvation. Marine animals may also ingest plastic, which can cause digestive problems, blockages, and even death.
Long-Term Persistence: Non-biodegradable wastes can persist in the environment for hundreds of years, contributing to the long-term degradation of ecosystems. This accumulation of waste poses challenges for future generations in terms of managing and finding solutions for their safe disposal.
Question 10. What is biological magnification? Will the levels of this magnification be different at different levels of the ecosystem?
Ans: Biological magnification, also known as biomagnification or bioaccumulation, refers to the process by which certain substances, such as toxic chemicals or heavy metals, become increasingly concentrated as they move up the food chain.
When a pollutant or toxin is introduced into an ecosystem, it may be absorbed by primary producers from the environment. As herbivores consume the contaminated plants, they accumulate a higher concentration of the pollutant in their tissues than what was present in the plants. When secondary consumers feed on these herbivores, the pollutant concentration further increases. This pattern continues as the pollutant accumulates at each trophic level.
The levels of biological magnification can vary at different levels of the ecosystem. Typically, the highest levels of magnification occur at higher trophic levels. This is because predators consume a larger number of contaminated prey, resulting in the cumulative effect of the pollutant. Additionally, some substances can be stored in fatty tissues or have slow elimination rates, contributing to higher magnification in higher trophic levels.
However, it is important to note that not all substances undergo biomagnification. The potential for biomagnification depends on the chemical properties of the substance, its persistence in the environment, and its affinity for living tissues.