CBSE Biology Class 12: Important Topics You Should Not Miss

By Sashikanth Sai

The CBSE Class 12 Biology exam has been scheduled on Mar 27, 2018. This is one of the theoretical subjects in the Class 12, loved by many students because of its concepts. As the exam is approaching, it's time for students to focus on the revision because it has a huge syllabus.

After careful consideration of previous years' question papers, we take pleasure to provide you with some of the important topics from the Biology syllabus. The topics we are going to discuss below have a huge chance of appearing in this year's question paper. Students are advised to consider them in their last leg of preparation.



This unit is very familiar to students because many topics are covered in Class 10. There could be questions related to the double fertilization. The topics of birth control and sexually transmitted diseases are also not to be ignored. Here are the important topics.

  • Modes of asexual reproduction
  • Pre-fertilisation events
  • Inbreeding depression
  • Double fertilisation
  • Gametogenesis, fertilisation and events of pregnancy
  • Birth control methods
  • Sexually transmitted diseases
  • Techniques to treat infertility
Genetics And Evolution

Genetics And Evolution

Students should give utmost importance to this unit. One should know complete details about the Mendel and its crosses and post Mendelian genetics besides the chromosomal disorders. This year we are expecting a question on genetic code on Operon theory. The Hardy-Weinberg principle and adaptive radiation are expected from evolution. Other important topics are:

Chromosomal disorders and pedigree analysis

  • Structure of DNA
  • Experiments of F. Griffith, Hershey & Chase and Meselson & Stahl
  • Mechanism- replication, transcription and translation
  • Salient features of genetic code
  • Lac operon
  • Homologous and analogous organs
  • Adaptive radiation
Biology In Human Welfare

Biology In Human Welfare

Try to understand the motive behind the concepts because it will provide other information too. One should know the differences between innate and adaptive immunity. Students should give importance to topics such as sewage treatment, biogas production plant. Other important areas:

  • Life cycle of Plasmodium
  • Causative agents of different diseases and their mode of transmission
  • AIDS and drug abuse
  • Inbreeding and outbreeding
  • Single cell protein
  • Microbes and their products


The questions from this unit can be either short or long answer type. This unit plays a key role in the entrance examination also. So go for a detail study but focus on the board exam point of view.

  • Restriction enzymes
  • Cloning vectors
  • Transformation processes
  • Bt cotton
  • RNA interference
  • Gene therapy
  • Genetically engineered insulin
Ecology And Environment

Ecology And Environment

This is an easy area to score in the examination. One should give importance to ecological succession, nutrient cycling and air pollution because they are usually ask for long answer questions. Focus on eutrophication also. Other important topics are:

  • Population interactions
  • Pyramids of number, energy and biomass
  • Causes of biodiversity losses
  • Biomagnification

7 Common Mistakes You Should Avoid In The CBSE Class 12 Biology

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