So, we have entered the last trimester of Class 12. It is not only the board exams which are approaching. It is the beginning of a new journey which is going to take you to your bright and brilliant future. Now is the time to consolidate all the knowledge which you have been gathering day after day sitting in your classrooms. Right planning and proper execution is very crucial to score well.
There are 16 chapters, arranged in five units, in the Class 12 biology syllabus. Marks allocation to different units is as:
* Unit I - reproduction, 14 marks
* Unit II - genetics and evolution, 18 marks,
* Unit III - biology in human welfare, 14 marks
* Unit IV - biotechnology, 10 marks
* Unit V - ecology, 14 marks
From this year, there will be value-based questions worth three or five marks.
While preparing for your boards, go unit-wise. Prepare all the chapters of each unit together as they are related. As unit II carries the maximum marks, my suggestion is that you start your preparation from this one. All the three chapters of this unit are very important. In the first chapter, principles and processes of inheritance, study very thoroughly both the laws of inheritance and how to explain them with the help of monohybrid and dihybrid cross. Sex-linked inheritance as well as autosomal and sex-linked diseases are other important topics of this chapter. In molecular basis of inheritance, various experiments like Griffith’s experiment, Harshey and Chase, Meselson and Stahl’s experiment and their diagrams are important. This entire chapter is very important, so prepare thoroughly. From evolution, in addition to origin of life (including Miller and Urey’s experiment) lay special emphasis on natural selection, Hardy-Weinberg principle and adaptive radiation.
Unit IV is related to unit II so after unit II pick unit IV. There are just two chapters in this unit but both are very important. In unit I, chapter two and three are more important than chapter one and four. Spermatogenesis, oogenesis, hormonal control of MRS and FRS, menstrual cycle, microsporogenesis, megasporogenesis, double fertilisation, triple fusion and apomixes, methods of birth control are some of the very important topics of this unit. In unit III, innate and acquired immunity active and passive immunity, T and B lymphocytes, humoral and cell mediated immunity, cancer, and AIDS are important topics. You should also be well versed in hybrid varieties of plants and animals and diseases they are resistant to. In Ecology, S and J-shaped population growth, interactions among organisms, productivity, succession, ecological pyramids, sewage treatment, biomagnifications, eutrophication and pollution are some important topics.
The entire paper will be from the NCERT book. So, read every word of it.
Learn experiments from the textbook
I concentrated entirely on my NCERT book as it is your key to getting a high score. Biology requires a thorough command of diagrams. Supplementing your answers with diagrams not only makes your answer presentable but it also makes your response complete. Questions that ask for definitions are the most scoring, provided you write a standard definition that summarises the concept. Genetics and evolution is a very important chapter and has more weightage as compared to other units. Emphasise more on ‘molecular basis of inheritance’ in this unit. Don’t forget to learn the various experiments performed by eminent scientists that are described in the text.
Biotechnology comprises 10 marks and is very scoring. Read thoroughly about how to facilitate cloning into a vector, polymerase chain reaction. All applications of biotechnology are equally important. One can expect five-mark questions from topics such as gametogenesis, megasporogenesis and pollination apart from other short questions from the chapter on ‘reproduction.’ Human health and disease is also an important chapter.
Ecology is important, especially its graphical interpretations, population interactions, ecological pyramids and the chapter on environmental issues. There is a five-mark question from this unit. Revise the various acts discussed in environmental issues.
All you need to do now is to focus on what is more important, time your study hours smartly and spend more time on topics that are most expected and scoring. You should consult the sample papers to get a review of the kind of questions one can get in the exam.
Savita Sharma taught life sciences in a college and biology in many schools. She is HOD of biology at HT Studymate