Amazing Notes 10th Biology Ch 16: Man and His Environment

Amazing Notes 10th Biology Ch 16: Man and His Environment

Man and His


Ecosystems are dynamic systems characterized by intricate interactions between living organisms and their physical environment. To comprehend these complex relationships, exploring various ecological concepts, such as the pyramids of number and biomass, the carbon and nitrogen cycles, and the interactions between species like competition, predation, and symbiosis is crucial. Furthermore, understanding how human activities disrupt ecological balance and contribute to air and water pollution is essential for fostering sustainable environmental practices.


  1. Explain what you mean by the Nitrogen cycle. Pyramids of Number: This pyramid represents the number of individual organisms at each trophic level in an ecosystem. Typically, it shows a decrease in the number of organisms as you move up the trophic levels, starting with a large number of producers at the base and fewer top predators at the apex. However, this can vary in certain ecosystems, such as forests, where a single tree (producer) supports numerous herbivores. Pyramids of Biomass: This pyramid represents the total biomass of organisms at each trophic level. Biomass is the total mass of living matter, usually measured in grams per square meter (g/m²). In a typical pyramid of biomass, the biomass decreases from the base to the top, as the energy transfer between trophic levels is inefficient, leading to a loss of energy as heat and metabolic processes.
  2. Write a note on the Carbon cycle. The Carbon Cycle is the biogeochemical process through which carbon is exchanged among the atmosphere, land, oceans, and organisms. It involves several key processes:
    • Photosynthesis: Plants and other autotrophs capture atmospheric carbon dioxide (CO₂) and convert it into organic compounds like glucose.
    • Respiration: Organisms break down organic compounds to release energy, producing CO₂ as a byproduct.
    • Decomposition: Decomposers break down dead organisms, releasing carbon back into the soil and atmosphere.
    • Combustion: Burning of fossil fuels and biomass releases stored carbon into the atmosphere as CO₂.
    • Ocean Absorption: Oceans absorb CO₂ from the atmosphere, which can be used by marine organisms for photosynthesis or stored in ocean sediments.
  3. What are the different stages of the Nitrogen cycle? The Nitrogen Cycle consists of several stages that transform nitrogen into various chemical forms essential for life:
    • Nitrogen Fixation: Conversion of atmospheric nitrogen (N₂) into ammonia (NH₃) or related compounds by bacteria (e.g., Rhizobium) or through industrial processes.
    • Nitrification: Conversion of ammonia into nitrites (NO₂⁻) and then nitrates (NO₃⁻) by nitrifying bacteria (e.g., Nitrosomonas and Nitrobacter).
    • Assimilation: Uptake of nitrates by plants to synthesize proteins and nucleic acids.
    • Ammonification: Decomposition of organic matter by decomposers, converting organic nitrogen back into ammonia.
    • Denitrification: Conversion of nitrates back into N₂ gas by denitrifying bacteria (e.g., Pseudomonas), releasing it into the atmosphere.
  4. Write notes on competition, predation, and symbiosis.
    • Competition: This occurs when organisms vie for the same resource (e.g., food, space, mates) in an ecosystem. It can be interspecific (between different species) or intraspecific (within the same species). Competition can limit population sizes and influence the distribution of species.
    • Predation: This interaction involves a predator feeding on its prey. Predation helps control prey populations and can drive evolutionary adaptations in both predators and prey, such as camouflage, speed, and defensive mechanisms.
    • Symbiosis: This is a close, long-term interaction between different species. Types of symbiosis include:
      • Mutualism: Both species benefit (e.g., bees pollinating flowers).
      • Commensalism: One species benefits while the other is neither harmed nor helped (e.g., barnacles on whales).
      • Parasitism: One species benefits at the expense of the other (e.g., tapeworms in intestines).
  5. Explain how human activities have contributed to the loss of balance in nature. Human activities have significantly disrupted natural ecosystems, leading to a loss of balance through:
    • Deforestation: Clearing forests for agriculture or urban development reduces biodiversity, disrupts carbon and water cycles, and leads to soil erosion.
    • Pollution: Release of pollutants into air, water, and soil harms wildlife, disrupts ecosystems, and contributes to climate change.
    • Overfishing and Hunting: Excessive hunting and fishing deplete species populations, disrupt food chains, and cause ecosystem imbalances.
    • Urbanization: Expansion of cities and infrastructure fragments habitats, leading to loss of biodiversity and natural resources.
    • Climate Change: Emission of greenhouse gases from fossil fuel burning leads to global warming, affecting weather patterns, sea levels, and ecosystems.
  6. Write a note on the causes and effects of air and water pollution.
    • Air Pollution:
      • Causes: Emissions from vehicles, industrial processes, burning of fossil fuels, and deforestation.
      • Effects: Respiratory diseases in humans, acid rain, global warming, and damage to the ozone layer, affecting ecosystems and biodiversity.
    • Water Pollution:
      • Causes: Discharge of industrial effluents, agricultural runoff containing pesticides and fertilizers, sewage, and oil spills.
      • Effects: Contamination of drinking water, death of aquatic life, disruption of the aquatic ecosystems, and bioaccumulation of toxic substances in the food chain.


  1. What are the different levels of ecological organization? The levels of the environmental organization are:
    • Organism: An individual living being.
    • Population: A group of organisms of the same species living in a specific area.
    • Community: Different populations of various species living and interacting in a particular area.
    • Ecosystem: A community of living organisms interacting with their physical environment.
    • Biome: A large geographic area with similar climate, flora, and fauna.
    • Biosphere: The global sum of all ecosystems, encompassing all life on Earth and their environmental interactions.
  2. Define ecosystem and its components. An ecosystem is a biological community of interacting organisms and their physical environment. Its components include:
    • Biotic factors: All living organisms (plants, animals, bacteria, fungi).
    • Abiotic factors: Non-living elements (water, air, soil, sunlight, temperature).
  3. How the flow of energy is different from that of materials? Flow of Energy:
    • Energy flows in one direction through an ecosystem, from producers to various consumers and finally to decomposers.Energy is not recycled; it is dissipated as heat at each trophic level according to the second law of thermodynamics.
    Flow of Materials:
    • Materials (nutrients) are recycled within an ecosystem through biogeochemical cycles (e.g., carbon, nitrogen, water cycles).
    • Nutrients move from the abiotic environment to living organisms and back to the abiotic environment.
  4. Define food chain and food web.
    • Food Chain: A linear sequence of organisms where each is eaten by the next member in the chain. It represents the flow of energy from producers to top consumers.
    • Food Web: A complex network of interconnected food chains in an ecosystem. It shows the multiple feeding relationships among different organisms, illustrating how energy and nutrients circulate within the ecosystem.
  5. What do you mean by the concept of 3Rs with reference to the conservation of natural resources? The concept of 3Rs refers to:
    • Reduce: Minimizing waste and resource use by opting for products with less packaging, using energy-efficient appliances, and conserving water.
    • Reuse: Extending the life of products by finding new uses for them instead of discarding them, such as repurposing containers or donating items.
    • Recycle: Processing used materials into new products to prevent waste, conserve natural resources, and reduce pollution, like recycling paper, glass, and plastics.


Ecosystems are complex networks where living organisms interact with their environment. Key concepts include the pyramids of number and biomass, which illustrate the distribution of organisms and their mass at different trophic levels. The carbon and nitrogen cycles describe how these essential elements circulate within ecosystems. Species interactions like competition, predation, and symbiosis shape community dynamics. Human activities, such as deforestation, pollution, and urbanization, disrupt ecological balance, leading to significant environmental issues like air and water pollution. Understanding these concepts is crucial for promoting sustainable practices and conserving natural resources.


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