Which of the following is an example of a biodegradable pollutant?
A. Mercury
B. DDT
C. Plastic
D. Sewage
Answer: Option D
Solution (By JKExamLibrary)
Sewage contains organic matter that can be broken down by microorganisms, hence biodegradable. DDT, plastics, and mercury are non-biodegradable, persisting in the environment and accumulating in food chains (biomagnification). Biodegradable pollutants can be decomposed naturally, reducing long-term harm, but excessive loads can cause eutrophication. Non-biodegradable pollutants require special disposal and cause lasting ecological damage.
Consider statements about plant biology: 1. Transpiration occurs through stomata. 2. Guttaion occurs through hydathodes. 3. Phloem transports water upwards. Which are correct?
Explanation:
Transpiration is the loss of water vapor primarily through the stomata on the leaf surface. Guttation is the exudation of liquid water from the margins of leaves through specialized structures called hydathodes, usually at night when root pressure is high. Phloem is responsible for the translocation of organic food (bidirectional), while xylem transports water and minerals upwards. Thus, statements 1 and 2 are correct.
Explanation:
The cohesion-tension theory states that transpiration from leaves creates tension, pulling water up the xylem; water molecules cohere, forming a continuous column. Root pressure is minor.
Explanation:
Fossils are the preserved remains or impressions of past organisms, showing transitional forms and evolutionary change over geological time.
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