1
Which of the following is absent in polluted water?
- Larva of stone fly
- Hydrilla
- Blue-green algae
- Water hyacinth
Answer
(1) Larva of stone fly
Solution
Organisms that need clean, well-oxygenated water act as indicators of unpolluted water.
∵ Stone fly larvae are very sensitive to pollution and low dissolved oxygen, they are found only in clean water and disappear from polluted water.
As per NCERT, sewage and other organic wastes add nutrients to water bodies, which favours the growth of algae (including blue-green algae) and aquatic plants such as water hyacinth and Hydrilla (eutrophication).
∴ The larva of stone fly is absent in polluted water.
Answer: (1)
Out of syllabusAIPMT 2002