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Level 2 Worksheet: Our Environment

Class: 10 Science Topic: Logic & Analysis Max. Questions: 30
Name:
Date:
Section A: Ecological logic
  1. If we remove all decomposers from the ecosystem, what will be the immediate consequence? (Accumulation of dead matter).
  2. Why is it said that energy flow in an ecosystem is governed by Thermodynamics? (Energy neither created/destroyed, only converted and lost).
  3. In the following food chain: Plants $\rightarrow$ Mice $\rightarrow$ Snake $\rightarrow$ Hawk. If 1000 J of energy is available to plants, how much energy (a) Mice (b) Hawk will receive? (Plants=1000? No, 1% of Sun? Or if Plants have 1000J? Assuming Plants have 1000J: Mice 100J, Snake 10J, Hawk 1J).
  4. Why do farmers prefer to use manure instead of fertilizers? (Soil fertility, biological health).
  5. Which of the following will have the maximum concentration of harmful chemicals: Peacock, Snake, Grass, Frog? (Peacock - Top level).
Section B: Energy Numericals
  1. Consider the food chain: Sunlight $\rightarrow$ Plant $\rightarrow$ Deer $\rightarrow$ Lion. If the Plants capture 20 J of energy (1%), how much energy was supplied by the Sun? (2000 J). How much reaches the Lion? (Plant 20 -> Deer 2 -> Lion 0.2 J).
  2. A food chain has 3 trophic levels. If 10 kJ energy is available to the second trophic level (Herbivore), calculate the energy available to the producer (100 kJ) and the carnivore (1 kJ).
  3. Suppose 1000 J of solar energy falls on the leaves of green plants. Calculate the energy available to the primary consumer. (Plants harness 1% = 10J. Primary Consumer gets 10% of 10J = 1J). Note: Be careful if Q says 'energy available to plants' vs 'solar energy falling'.
Section C: Scientific Reasoning
  1. Why is an aquarium considered an artificial ecosystem? (Man-made, requires cleaning, pump).
  2. Why are some substances biodegradable and others non-biodegradable? (Presence of specific enzymes in bacteria).
  3. Damage to the ozone layer is a cause for concern. Why? (UV radiation, Cancer, Eye Cataract).
  4. Why does the number of organisms generally decrease as we move up the trophic levels? (Energy limitation).
  5. Cloth bags are better than plastic bags. Justify. (Reusable, Biodegradable).