CBSE Class 12 Biology Environmental Issues Diagrams

This Class 12 Biology page collects the four important diagrams of Chapter 16 Environmental Issues: the electrostatic precipitator and scrubber, the effect of sewage discharge on the characteristics of a river (dissolved oxygen and BOD), the relative contribution of greenhouse gases to global warming, and biomagnification of DDT in an aquatic food chain.

CHAPTER 16 - ENVIRONMENTAL ISSUES

1. ELECTROSTATIC PRECIPITATOR

[Figure: Two diagrams. Left, a scrubber: dirty air enters from the left side near the bottom of a tall vessel, a water/lime spray is applied near the top, particulate matter collects at the bottom outlet, and clean air leaves at the top. Right, an electrostatic precipitator: dirty air enters a chamber containing negatively charged wires with a discharge corona around each wire, dust particles are attracted to the grounded collection plates, and clean air leaves on the right]

2. EFFECT OF SEWAGE DISCHARGE ON THE CHARACTERITICS OF A RIVER

[Figure: A river drawn along the top with the sewage discharge entering at the left. Along the direction of flow the zone near the discharge is marked Fish kill and disappearance of clean water organisms, and further downstream is marked Reappearance of clean water organisms. Below it, a graph of Concentration against distance in the direction of flow: at the point of sewage discharge the curve of dissolved oxygen drops sharply to a minimum and then rises slowly back to its original level, while the BOD curve rises sharply to a maximum and then falls gradually to a low level]

3. RELATIVE CONTRIBUTION OF VARIOUS GREENHOUSE GASES TO GLOBAL WARMING

[Figure: Pie chart with Carbon dioxide 60%, Methane 20%, CFCs 14% and N₂O 6%]

4. BIOMAGNIFICATION IN AN AQUATIC FOOD CHAIN

[Figure: Vertical food chain with upward arrows from the bottom: Water (DDT 0.003 ppb) → Zooplankton (DDT 0.04 ppm) → Small fish (DDT 0.5 ppm) → Large fish (DDT 2 ppm) → Fish-eating birds (DDT 25 ppm)]