(a) Kulhads (disposable cups made of clay) and disposable paper cups both are used as an alternative for disposable plastic cups. Which one of these two can be considered as a better alternative to plastic cups and why?
(a) Kulhads (disposable cups made of clay) and disposable paper cups both are used as an alternative for disposable plastic cups. Which one of these two can be considered as a better alternative to plastic cups and why?
- Reason for adverse effect on humans: Human beings occupy the top trophic level in any food chain. Since non-biodegradable chemicals (like pesticides) cannot be decomposed, they accumulate progressively at each trophic level. Consequently, the maximum concentration of these harmful chemicals gets accumulated in human bodies due to biological magnification.
- Why washing does not help: These chemicals are absorbed by the plants from the soil along with water and minerals (or from water bodies by aquatic plants and animals). Since they enter the internal tissues of the fruits, vegetables, and grains during growth, they cannot be removed by superficial washing or other external cleaning methods.
Marking Scheme
- 1Stating that humans occupy the top trophic level, leading to maximum accumulation: [1 Mark]
- 2Explaining that chemicals are absorbed internally by plants along with water and minerals: [1 Mark]
Hint
Recall the position of humans in a food chain and how plants absorb pesticides from the soil.
Quick Oral Answer
Humans are most affected because we are at the top of the food chain, where chemical concentration is highest. Washing doesn't work because the chemicals are absorbed internally by the plants through their roots.
Analysis & Explanation
Biological magnification is the progressive accumulation of non-biodegradable chemicals at each successive trophic level. Because energy transfer is low, biomass at higher levels must consume large amounts of biomass from lower levels, concentrating the toxins. Since humans are at the top of most food chains, we receive the highest concentration. Furthermore, because these chemicals are absorbed systemically through the roots along with water and minerals, they become part of the plant's internal structure, making surface washing ineffective.
Common Mistakes
- 1Stating that pesticides are only sprayed on the surface and can be washed off.
- 2Not mentioning that humans occupy the top level of the food chain.
Interesting Facts
DDT, a well-known pesticide, was found in high concentrations in the milk of nursing mothers and the eggs of predatory birds, causing eggshells to thin and break, which led to its ban in many countries.
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Frequently Asked Questions
How many marks does this question carry in CBSE Class 10 Science 2022?
This question carries 2 marks in the CBSE Class 10 Science 2022 examination.
Which chapter does this question come from in Science?
This question is from the chapter "Our Environment" in the CBSE Class 10 Science syllabus.
What topic does this question cover in Science?
This question covers the topic "Food Chains and Webs" from CBSE Class 10 Science.
What type of question is this in the CBSE Class 10 Science 2022 paper?
This is a Short Answer question from Section SECTION A in the CBSE Class 10 Science 2022 paper.