The Central Board of Secondary Education (CBSE) has developed the syllabus for Biology for Class 12 students preparing for the All India Senior Secondary School Examinations (AISSCE 2022). The syllabus includes the basic principles of biology, including those familiar to animals, plants, and microorganisms, and it also highlights the relationship between biology and other areas of knowledge.
This article provides information on the theory and practicals section of the CBSE Biology Class 12 syllabus 2021. And guidelines on how the theory and practical examinations get conducted are also discussed. The theory has five units: reproduction, genetics and evolution, biology and human welfare, biotechnology and its applications, and ecology and environment. Of the total 100 marks, the CBSE Biology Class 12 examination will have 70 marks for theory and 30 marks for practicals.
The academic year 2021-22
The total marks allocated for the theory paper in CBSE Biology Class 12 Syllabus 2021 is 70, and the total number of periods is 160. Compared to the previous year, there is a change in the allocation of marks for the unit “biotechnology and its applications” from 12 to 10 marks and the unit “ecology and environment” from 12 to 14 marks.
However, there has been no change in the pattern of the practical examination. The questions for CBSE Biology Class 12 examinations will be from five sections, namely, Sections A, B, C, D, and E. The questions test the competencies of knowledge and understanding (remembering and understanding), application of knowledge/concepts.
The following are the suggestive verbs for various competencies:
Demonstrate knowledge and understanding– State, name, list, identify, define, suggest, describe, outline, summarize, etc.
Application of knowledge/concepts -Calculate, illustrate, show, adapt, explain, distinguish, etc.
Formulate, analyze, evaluate, and create– Interpret, analyze, compare, contrast, examine, assess, discuss, construct, etc.
For the theory paper, the total marks (i.e., 70 marks) for various competencies get distributed as follows: Demonstrate knowledge and understanding [Remembering (14 marks) and understanding (21 marks)], Application of knowledge and concepts (21 marks), and formulate, analyze, evaluate, and create (14 marks).
All the questions are compulsory, and 33% of the questions have a choice. Section A has ten multiple-choice questions (including matching-type MCQs) and assertion-reasoning type questions of 1 mark each. Section B has a source-based/case-based/passage-based/integrated assessment that holds two questions of 5 marks each. Then there is 1 question of 4 marks with subparts value 1/2/3 marks each. Section C has six short answers (S.A.) type questions carrying two marks each. Section D has five long answer-I (LA-I) type questions carrying three marks each. Finally, section E has three long answer-II (LA-II) type questions carrying five marks each. So the internal choice would be provided in 3 questions of Section C, two questions of Section D, and all three questions of Section E.
Theory syllabus of CBSE Biology Class 12
| Unit | Title | No. of Periods | Marks |
| VI | Reproduction | 30 | 14 |
| VII | Genetics and Evolution | 40 | 18 |
| VIII | Biology and Human Welfare | 30 | 14 |
| IX | Biotechnology and its Applications | 30 | 10 |
| X | Ecology and Environment | 30 | 14 |
| Total | 160 | 70 |
The theory in NCERT Biology Class 12 Syllabus 2021 consists of five chapters focusing on contemporary topics of genetics combined with evolution. In addition, unit VI, i.e., “Reproduction,” has four chapters, namely, “Reproduction in organisms,” “Sexual reproduction in flowering plants,” “Human reproduction,” and “Reproductive health.”
With 14 marks, this unit has the second-highest weightage in the NCERT Biology Class 12 Syllabus theory paper. The unit “Genetics and Evolution” has three chapters, namely, “Principles of inheritance and variation,” “Molecular basis of inheritance,” and “Evolution.” With 18 marks, this unit has the highest weightage.
The unit “Biology and Human Welfare” has chapters, namely, “Human health and diseases,” “Strategies for enhancement in food production,” and “Microbes in human welfare.” This unit has a weightage of 14 marks.
The unit “Biotechnology and its applications” has chapters, namely, “Biotechnology-Principles and processes” and “Biotechnology and its application.” The unit “Ecology and Environment” has chapters, namely, “Organisms and populations,” “Ecosystem,” “Biodiversity and Conservation,” and “Environmental Issues.” The total weightage for these units is 14 marks.
Practical examination syllabus of CBSE Biology Class 12
The practicals examination in the CBSE Biology Class 12 Syllabus of 2021 aims at developing skills relevant to the study and practice of Biology. It encourages a systematic approach to problem-solving and promotes effective communication. The total allocation for practicals is 60 periods, and nine experiments have to be performed by students. The practical examination of the CBSE Biology Class 12 Syllabus carries 30 marks and gets allocated 3 hours.
| Evaluation scheme | Marks |
| One Major Experiment 5, 6, 8, 9 | 5 |
| Slide Preparation 1, 7 | 5 |
| One Minor Experiment 2, 3, 4 | 4 |
| Spotting | 7 |
| Practical Record + Viva Voce (Credit to the students’ work over the academic session may be given Investigatory Project and its Project and its Record + Viva Voce (Credit to the students work over the academic year may also be given | 4 5 |
| Total | 30 |
List of experiments of CBSE Biology Class 12
1. Preparation of a temporary mount for observation of pollen germination.
2. Study texture and moisture of the soil from at least two different sites to observe
content, pH, and water holding capacity. It has to correlate with the kinds of plants seen in those places.
3. Study of pH, clarity, and presence of any living organism from two different water bodies nearby.
4. Presence of suspended particulate matter in the air to be studied in two widely different sites.
5. Use of the quadrat method to study plant population density.
6. Use of the quadrat method to study plant population frequency.
7. Study of mitosis by preparing a temporary mount of the onion root tip.
8. Activity of salivary amylase on starch-based on the effect of different temperatures and three different pH levels.
9. Use plant materials such as spinach, green pea seeds, and papaya to isolate DNA
B. Learning through observation (spotting):
1. Different agents (wind, insects, birds) are involved in pollination and how flowers adapt.
2. Using a permanent slide or scanning electron micrograph for pollen germination on stigma.
3. Use permanent slides (from grasshoppers/mice) to identify stages of gamete development, i.e., T.S. of testis and T.S. of the ovary.
4. Use permanent slides for the study of meiosis in onion bud cells or grasshopper testis.
5. T.S. of blastula through permanent slides (Mammalian).
6. Study seeds of different colors/sizes of any plant to study Mendelian inheritance.
7. Prepare pedigree charts of any genetic traits such as rolling of tongue, blood groups, ear lobes, widow’s peak, and color blindness.
8. Controlled pollination – emasculation, tagging, and bagging.
9. Use permanent slides to study organisms that cause diseases such as Ascaris, Entamoeba, Plasmodium, or any fungi causing ringworm—use models or virtual images. Comment on the symptoms of diseases that they cause.
10. Comment on the morphological adaptations of two plants and two animals (models/virtual images) seen under xeric conditions.
11. Comment on the morphological adaptations of two plants and two animals (models/virtual images) seen under aquatic conditions.
FAQs of CBSE Biology Class 12
1) How many marks get allocated for the theory and practicals in Biology?
70 marks for theory and 30 marks for practicals
2) Are all questions compulsory?
Yes, all questions are compulsory, and some questions have choices.
3) Are there multiple-choice questions (MCQs)?
Yes, there will be 10 MCQs and four assertion-reasoning type questions, each of one mark. These will be in Section A of the question paper.
4) Which are the textbooks prescribed for Biology Class XII?
The textbook that should get referred to for your Biology studies is, Class-XII by NCERT. The other related books and manuals brought out by NCERT (including multimedia) and biology supplementary material (revised), available on CBSE Website.
5) What is the mark allocation for practical record and viva voce?
Total of 9 marks.