If this is regarding NEET, Biology is the biggest section in NEET, comprising about half of the exam, and acing this subject can help you in scoring more in the exam. Human Physiology and Genetics have maximum weightage in NEET. Diversity of Living Organisms has 14% weightage. Structural Organisationi n Plants and Animals takes 5%. Plant Physiology has 6% and Cell Structure and Function has 9%. Human Physiology has 20% weightage. Reproduction chapter has 9% and Genetics and Evolution has 18% weightage. Biology and Human Welfare has 9% weightage. Biology and its application has 4% weightage and Ecology and Environment has 6% weightage. It is advisable to practise questions of Genetics from previous year question papers, which will give you a thorough understanding of how the questions are being asked. Topics of Plant and Animal kingdom have a lot of portion to memorize. You can prepare these topics by making a comparative table for the sub-topics and studying it together. Plant physiology is also equally important and easy to score. For more tips, please visit our page at: https://medicine.careers360.com/articles/how-prepare-for-neet-biology . There are no do or die Chapters per se. But there are chapters that carry more weightage than the rest. Biology section for NEET is for 360 marks and to be honest just preparing for few Chapters cannot get you 280. And if you are preparing for NEET, you may as well try our NEET Knockout package: https://learn.careers360.com/knockout-neet-may/ . And because you have 2 more months to prepare for NEET, you may as well use this opportunity. But if this is  not regarding NEET and any other exam, please do let us know and we shall help you with relevant information.