Biology · Class 12 · Chapter 13
Biodiversity and Conservation
12 lessons 90 min 2 simulations
This chapter measures the variety of life and asks why it is worth keeping. It defines biodiversity at the genetic, species and ecological levels, counts the species recorded worldwide and in India, explains why the tropics are richer and why species rise with area (log S = log C + Z log A), links diversity to ecosystem stability through Tilman's plots and the rivet popper analogy, lists the extinctions and the four human causes behind them, and closes with the reasons for conservation and its in situ and ex situ methods.
What the exam asks
NEET asks for the three levels of biodiversity with their examples, the global and Indian species figures (about 1.5 million described, Robert May's 7 million, India's 2.4 per cent of land and 8.1 per cent of species), the bird counts along the latitudinal gradient, the Z ranges 0.1-0.2 and 0.6-1.2, the evil quartet with its examples, the 34 hotspots and the three in India, the counts of protected areas, and which methods are in situ and which ex situ. Marks are lost by swapping the Z ranges, by naming over-exploitation as the chief cause of extinction, and by putting sacred groves or seed banks on the wrong side of in situ and ex situ.
Lessons
12 lessons · 90 min
1What biodiversity isNCERT §13.17 min2How many species on EarthNCERT §13.1.17 min3Biodiversity of IndiaNCERT §13.1.15 min4Latitudinal gradientsNCERT §13.1.27 min5Species-area relationshipNCERT §13.1.210 min 1 sim6Diversity and ecosystem stabilityNCERT §13.1.39 min 1 sim7Loss of biodiversityNCERT §13.1.47 min8The evil quartetNCERT §13.1.47 min9Why conserve biodiversityNCERT §13.2.16 min10In situ conservationNCERT §13.2.27 min11Ex situ conservationNCERT §13.2.26 min12Chapter reviewMust-know facts, traps and formulas12 min