Section A: High Order Thinking Skills (HOTS)
- Biomagnification Limit: Why is biological magnification highest in top carnivores?
(Accumulation at each step). Can it be reversed naturally? (Very slow process/No).
- Energy Paradox: If energy decreases at each level, how do top predators (like
tigers) get enough energy to be so powerful/strong? (They consume larger quantities of biomass;
requires large territory).
- Waste Analysis: Disposable plastic cups were replaced by clay cups (kulhads) on
trains, but then replaced by disposable paper cups. Why were kulhads discontinued? (Top soil
depletion). Why are paper cups better than plastic? (Biodegradable).
- Pesticide Trace: A sample of wheat was found to contain trace amounts of pesticide.
Suggest path of entry. (Soil/Water $\rightarrow$ Plants).
Section B: Case Study Based Questions
Case I: The Ozone Shield. Ozone is a molecule formed by three atoms of oxygen. While O2
is essential, O3 is deadly poison. At higher levels, it shields the surface of earth from UV radiation.
- Write the reaction involved in formation of Ozone. ($O_2 \rightarrow O+O; O+O_2 \rightarrow O_3$).
- In year 1980s, the amount of ozone dropped sharply. Identify the synthetic chemical responsible.
(CFCs).
- How does UV radiation affect humans? (Skin cancer, cataract, immune system damage).
Case II: Waste Disposal. Improvements in lifestyle have resulted in greater amounts of
waste material generation. Changes in packaging have resulted in much of our waste becoming
non-biodegradable.
- Differentiate between composting and incineration. (Composting: Biological degradation.
Incineration: Burning at high temp).
- Suggest one method to reduce non-biodegradable waste at home. (Reduce use of single-use plastics).
- Why are bacteria and fungi called decomposers? (They break down complex organic matter).
Section C: Assertion & Reasoning
Directions: Read Assertion (A) and Reason (R) and select the correct option.
- Assertion (A): Human beings occupy the top level in any food
chain.
Reason (R): Maximum concentration of chemicals get accumulated in human
bodies.
(True/True - Correct Explanation).
- Assertion (A): Flow of energy in a food chain is unidirectional.
Reason
(R): Energy captured by autotrophs does not revert back to the solar input.
(True/True - Correct Explanation).
- Assertion (A): Aquariums and crop-fields are natural ecosystems.
Reason
(R): They are self-sustaining units.
(False/False - Artificial).
- Assertion (A): Ozone layer protects earth from UV radiation.
Reason
(R): CFCs are used as fire extinguishers.
(A is True, R is True but not
explanation. Also Halons are used in extinguishers, CFCs in refrigerants).
