Biology practical exams play a significant role in a student’s overall performance in CBSE Class 12th. To excel, thorough preparation of viva questions is essential. Below is a curated list of 50 viva questions, along with concise answers, to help you ace your practical examination.
Section A: Experiments
- Q: What is the principle of plasmolysis?
A: Plasmolysis occurs when a plant cell loses water in a hypertonic solution, causing the cytoplasm to shrink away from the cell wall. - Q: What is the function of a compound microscope?
A: It magnifies small objects using multiple lenses for detailed study. - Q: How do you test for the presence of starch in a leaf?
A: Boil the leaf, decolorize it with alcohol, and add iodine. A blue-black color indicates starch. - Q: What is osmosis?
A: The movement of water molecules through a semi-permeable membrane from a region of low solute concentration to high solute concentration. - Q: What is mitosis?
A: A type of cell division that results in two identical daughter cells.
Section B: Specimens and Slides
- Q: What is the shape of RBCs?
A: Biconcave. - Q: How can you differentiate between a dicot and a monocot stem?
A: A dicot stem has vascular bundles arranged in a ring, while monocots have scattered vascular bundles. - Q: What is the function of stomata?
A: Stomata regulate gas exchange and water loss through transpiration. - Q: Identify the given slide showing binary fission in Amoeba.
A: Binary fission in Amoeba shows one parent cell dividing into two identical daughter cells. - Q: What is a permanent slide?
A: A slide prepared for long-term use with specimens mounted permanently.
Section C: Biochemical Tests
- Q: How do you test for proteins?
A: Use the Biuret test; a violet color indicates proteins. - Q: What reagent is used to test for glucose?
A: Benedict’s solution. - Q: What is the positive test for lipids?
A: A translucent spot on paper confirms lipids. - Q: What does a positive iodine test indicate?
A: The presence of starch. - Q: What is the role of enzymes in digestion?
A: Enzymes break down complex food molecules into simpler forms.
Section D: Ecology and Environment
- Q: Define ecosystem.
A: An ecosystem is a community of living organisms interacting with their physical environment. - Q: What is biomagnification?
A: The increase in concentration of toxins in organisms at higher trophic levels. - Q: What is the greenhouse effect?
A: Trapping of heat in the atmosphere due to gases like CO2 and methane. - Q: Name a biodegradable and a non-biodegradable material.
A: Biodegradable: Paper; Non-biodegradable: Plastic. - Q: What is eutrophication?
A: Excessive nutrient accumulation in water bodies leading to algal bloom and oxygen depletion.
Section E: Genetics
- Q: Who is the father of genetics?
A: Gregor Mendel. - Q: Define mutation.
A: A sudden change in the genetic sequence. - Q: What are alleles?
A: Variants of a gene. - Q: What is the significance of the 9:3:3:1 ratio?
A: It represents the phenotypic ratio in a dihybrid cross. - Q: Name two sex-linked disorders.
A: Hemophilia and color blindness.
Section F: Human Physiology
- Q: What is the normal blood pressure range?
A: 120/80 mmHg. - Q: What is the function of hemoglobin?
A: Transport oxygen in the blood. - Q: Define reflex action.
A: An automatic response to a stimulus. - Q: What is the role of insulin?
A: It regulates blood sugar levels. - Q: What is the pH of gastric juice?
A: Around 1.5 to 3.5.
Section G: Miscellaneous
- Q: What is the role of antibiotics?
A: To kill or inhibit the growth of bacteria. - Q: Name a unicellular organism.
A: Amoeba. - Q: What is phototropism?
A: Growth of a plant towards light. - Q: Define fermentation.
A: Anaerobic conversion of sugar to alcohol or acid by microbes. - Q: What is biodiversity?
A: The variety of life forms in an ecosystem.
Advanced Questions
- Q: Explain electrophoresis.
A: A technique to separate DNA or proteins based on size and charge. - Q: What is the significance of Rh factor in blood?
A: It determines if blood type is positive or negative. - Q: Define tissue culture.
A: Growing plant or animal cells in a nutrient medium. - Q: What is the role of mycorrhiza?
A: A symbiotic association between fungi and plant roots for nutrient exchange. - Q: Name two endangered species in India.
A: Bengal Tiger and Indian Rhinoceros.
Practical Application Questions
- Q: Why is staining important in microscopy?
A: To enhance visibility of cell structures. - Q: Define transpiration.
A: Loss of water vapor from aerial parts of plants. - Q: What is the purpose of a quadrant in ecology?
A: To measure the population density of species. - Q: What is DNA fingerprinting?
A: Identifying individuals based on their unique DNA patterns. - Q: What does a pH indicator do?
A: Determines the acidity or alkalinity of a solution.
Final Rapid-Fire Questions
- Q: What is the chromosome number in humans?
A: 46 (23 pairs). - Q: Name the functional unit of the kidney.
A: Nephron. - Q: What is the full form of HIV?
A: Human Immunodeficiency Virus. - Q: What is pollination?
A: Transfer of pollen from anther to stigma. - Q: Define anaerobic respiration.
A: Respiration that occurs without oxygen, producing less energy.
Tips for Answering Viva Questions
- Be Concise: Provide direct and to-the-point answers.
- Understand the Concepts: Memorizing answers is less effective than understanding them.
- Ask for Clarification: If a question is unclear, politely ask for clarification.
- Stay Calm and Confident: Your demeanor matters as much as your knowledge.
Prepare thoroughly and give your best! Good luck! 😊
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