CBSE Class 12 Biology Viva Questions with Answers 2025

Preparing for the CBSE Class 12 Biology Viva can feel challenging, but with the right approach, it becomes a chance to demonstrate your understanding and confidence. The Biology practical examination, a key part of the curriculum, evaluates students on both theoretical knowledge and practical application. 

Viva questions are a crucial component, where students are assessed on their experiments, class records, and related concepts. For the 2025 session, students must prepare thoroughly for the viva, which carries 4 out of the total 30 marks, with additional marks allotted for the investigatory project and viva on the same. 

Understanding experiments and mastering core concepts is essential. This article provides important CBSE Class 12 Biology Viva Questions with Answers, including downloadable PDFs, to help students ace their practical exams and confidently impress their examiners.

CBSE Class 12 Biology Viva Introduction

The CBSE Class 12 Biology Viva is a vital component of the practical examination, designed to test a student’s understanding of biological concepts and their ability to apply theoretical knowledge in real-world scenarios. It plays a crucial role in evaluating a student’s grasp of experiments, practical skills, and critical thinking.

 This segment not only challenges students to think on their feet but also reinforces their learning through hands-on experience. The viva carries significant weight in the overall marks distribution, offering an excellent opportunity for students to boost their scores. With thorough preparation and a clear understanding of the concepts, students can confidently excel in this examination, demonstrating their proficiency and enhancing their academic performance.

Also Check

• NCERT Solutions for Class 12 Biology
• CBSE Class12 Biology Syllabus

CBSE Class 12 Biology Viva Questions with Answers 2025

If you're preparing for the upcoming CBSE Class 12 Biology exams, practicing these viva questions is essential before attending your practical exams.

1. What is the significance of preparing a temporary slide in a biology practical?
   Answer: Preparing a temporary slide helps students learn the process of slide preparation, handling of microscopic samples, and observing cell structures under the microscope. It is essential for understanding biological concepts like cell structure, tissues, and microorganisms.
2. What is the difference between mitosis and meiosis?
   Answer: Mitosis results in two identical daughter cells, while meiosis produces four genetically diverse gametes.
3. Define plasmolysis.
   Answer: Plasmolysis is the process where the cell membrane detaches from the cell wall due to the loss of water through osmosis.
4. What are monoclonal antibodies?
   Answer: Monoclonal antibodies are identical antibodies produced from a single type of immune cell, used in diagnostics and treatment.
5. Why is DNA replication called semi-conservative?
   Answer: DNA replication is semi-conservative because each new DNA molecule consists of one original strand and one newly synthesized strand.
6. What is the role of the stomata in plants?
   Answer: Stomata facilitate gas exchange and control water loss through transpiration in plants.
7. What role does xylem play in a plant's growth and survival?
   Answer: Xylem is responsible for the upward movement of water and essential minerals from the roots to the leaves and other parts of the plant. It also provides structural support, helping the plant maintain its shape and resist external pressures.
8. Define biodiversity hotspots.
   Answer: Biodiversity hotspots are regions with a high level of endemic species that are under significant threat from human activities.
9. What is genetic drift?
   Answer: Genetic drift refers to the unpredictable fluctuations in allele frequencies within a population, which occur by chance rather than natural selection. This phenomenon is more pronounced in smaller populations, where random events can significantly affect the genetic makeup over time.
10. Why is Rh incompatibility a concern during pregnancy?
    Answer: Rh incompatibility occurs when the mother's Rh-negative blood reacts against the Rh-positive blood of the fetus, leading to complications.
11. What are the components of an ecosystem?
    Answer: An ecosystem consists of biotic (living) and abiotic (non-living) components interacting with each other.
12. What is the function of ribosomes?
    Answer: Ribosomes play a crucial role in translating genetic information into proteins by assembling amino acids into polypeptide chains.
13. What are restriction enzymes?
    Answer: Restriction enzymes are molecular scissors that cut DNA at specific sequences, used in genetic engineering.
14. What is the significance of the Punnett square in genetics?
    Answer: The Punnett square helps predict the genotype and phenotype of offspring based on parental alleles.
15. What is ecological succession?
    Answer: Ecological succession is the gradual process where ecosystems evolve over time, with species replacing each other, leading to a more stable and complex community.
16. Why is hemoglobin important in the human body?
    Answer: Hemoglobin transports oxygen from the lungs to tissues and carries carbon dioxide back to the lungs for exhalation.
17. What is the significance of the greenhouse effect?
    Answer: The greenhouse effect traps heat in the atmosphere, maintaining Earth's temperature but can lead to global warming if excessive.
18. What is the difference between C3 and C4 plants?
    Answer: C3 plants use the Calvin cycle for carbon fixation, while C4 plants have a modified pathway to efficiently fix CO2 in hot, dry conditions.
19. What is a test cross?
    Answer: A test cross determines the genotype of an individual by crossing it with a homozygous recessive organism.
20. What is the importance of the Hardy-Weinberg principle?
    Answer: It provides a mathematical model to study genetic variation in a population under equilibrium conditions.
21. What are the symptoms of protein deficiency in humans?
    Answer: Symptoms include stunted growth, muscle wasting, fatigue, and a weakened immune system.
22. What is the difference between active and passive immunity?
    Answer: Active immunity is developed after exposure to an antigen, while passive immunity is acquired through antibodies from another source.
23. What is eutrophication?
    Answer: Eutrophication occurs when water bodies receive an overabundance of nutrients, primarily nitrogen and phosphorus. This nutrient overload promotes the rapid growth of algae, which, in turn, depletes oxygen levels in the water, harming aquatic life and disrupting the ecosystem.
24. What is the principle of gel electrophoresis?
    Answer: Gel electrophoresis is a laboratory technique used to separate DNA fragments according to their size by applying an electric field. Smaller fragments move faster through the gel matrix, while larger fragments move more slowly, allowing them to be sorted based on length.
25. Why is the human heart called a double pump?
    Answer: The heart pumps oxygenated blood to the body and deoxygenated blood to the lungs simultaneously.
26. What is the importance of the nitrogen cycle?
    Answer: The nitrogen cycle ensures the availability of nitrogen in forms usable by plants and animals.
27. What is polyploidy?
    Answer: Polyploidy refers to a genetic condition where an organism has multiple sets of chromosomes, exceeding the normal two sets found in diploid organisms. This can lead to variations in size, shape, and other characteristics in plants and animals.
28. What is a phylogenetic tree?
    Answer: A phylogenetic tree is a branching diagram that represents the evolutionary relationships among various species or organisms. It shows how species are related to one another through common ancestors, helping to understand the history of life on Earth.
29. What is the role of a control in an experiment?
    Answer: A control provides a baseline for comparison, ensuring the experiment's results are valid.
30. What are transgenic organisms?
    Answer: Transgenic organisms have genes from other species inserted into their genome through genetic engineering.

 CBSE Class 12 Biology Viva Questions: Marks Distribution

The CBSE Class 12 Biology Viva plays a crucial role in the practical examination, contributing significantly to the total score. 

• The marks distribution for the viva includes 5 marks for the major experiment,
• 4 marks for the minor experiment,
• 5 marks for slide preparation,
• 7 marks for spotting.
• Additionally, 4 marks are allotted for the practical record and viva voce, while the investigatory project, project record, and related viva carry 5 marks, making a total of 30 marks.

 Familiarity with this distribution enables students to allocate their preparation time effectively to each component.

Recommended Resources for CBSE Class 12 Biology 

To strengthen their preparation, students can refer to trusted resources like 

• Practical Skills in Biology Class 12 and Biology Lab Manual Class 12 by Arihant.
• Other valuable references include the Laboratory Manual Biology Class 12th [Experiments, Viva-Voce] and CBSE Class 12 Biology Lab Manual with Viva Voice Questions and Answers by Sahitya Bhawan. 

These resources provide detailed insights into experiments, projects, and viva questions, equipping students with the knowledge and confidence needed to excel in their practical exams.

CBSE Class 12 Biology Viva Questions Preparation Tips

1. Understand Experiment Concepts Thoroughly: Focus on the theoretical principles behind each experiment, as examiners often ask viva questions related to the purpose, methodology, and outcomes of practicals.
2. Prepare Your Practical Record: Keep your practical notebook neat and up to date. Review it thoroughly to ensure you can explain the experiments confidently during the viva.
3. Practice Common Viva Questions: Go through frequently asked questions related to biological terms, processes, and diagrams to enhance your readiness for spontaneous queries.
4. Revise Spotting and Slide Preparation: Spend time mastering spotting exercises and slide preparation techniques, as these are key sections of the viva where students often lose marks.
5. Stay Calm and Confident: Approach the viva with a positive attitude. Take a brief pause to gather your thoughts and respond thoughtfully, ensuring clarity and impact in your answers.