Question
Biology Question on Environmental Issues
Which one of the following gases contributes maximum to the 'green house effect' on the earth?
A
carbon dioxide
B
chlorofluoro carbon
C
freon
D
methane.
Answer
carbon dioxide
Explanation
Solution
When sewage mixes with water body, micro- organisms present in it biodegrade organic matter of sewage using oxygen. This results into a sharp decline in dissolved oxygen which may cause mortality of aquatic creatures. Gradually, however, dissolved oxygen increases in concentration with the completion of biodegradation of sewage matter.