Class 12 Biology Notes Chapter 19 (Model Question Paper) – Examplar Problems Book

Detailed Notes with MCQs of Chapter 19 of your Biology Exemplar book, which is the Model Question Paper. Now, this isn't a typical chapter with concepts to learn, but rather a blueprint designed to give you a feel for the actual board examination pattern and the types of questions you can expect. Understanding its structure and the nature of questions is crucial, not just for your board exams, but also as a foundation for various government exams that test Class 12 level Biology.

Understanding the Model Question Paper (Chapter 19)

Think of this chapter as a crucial practice drill. It's designed based on the CBSE pattern (which often influences other competitive exams) and aims to test:

1. Knowledge & Understanding: Recalling facts, definitions, concepts (e.g., What is emasculation? Define point mutation).
2. Application: Using learned concepts in new situations (e.g., Applying principles of inheritance to solve a pedigree chart, explaining the application of rDNA technology).
3. Analysis & Synthesis: Breaking down information, identifying relationships, drawing conclusions (e.g., Analyzing population growth curves, comparing different types of immunity).
4. Evaluation: Making judgments based on criteria (e.g., Evaluating the impact of alien species invasion).
5. Skill: Drawing diagrams, interpreting graphs/charts (e.g., Drawing a neat labelled diagram of a sperm, interpreting an ECG).

Structure and Pattern Analysis (Based on Typical CBSE/Exemplar Model Papers):

• General Instructions: Always read these carefully. They specify the time limit, maximum marks, and section-wise instructions.
• Sections: The paper is usually divided into sections (e.g., A, B, C, D, E) with different question types and marks:
  • Very Short Answer (VSA - 1 Mark): Often require one-word or one-sentence answers. Tests recall and basic understanding. (e.g., Name the causative agent of typhoid. What is palindromic sequence?)
  • Short Answer Type I (SA-I - 2 Marks): Require slightly more explanation, maybe 2-3 points or a simple diagram. (e.g., Differentiate between benign and malignant tumors. Mention two applications of DNA fingerprinting).
  • Short Answer Type II (SA-II - 3 Marks): Need more detailed explanations, comparisons, or diagrams. Often tests application or analysis. (e.g., Explain the process of spermatogenesis with a diagram. Describe the salient features of the Human Genome Project).
  • Long Answer (LA - 5 Marks): Require comprehensive, well-structured answers with detailed explanations, diagrams where necessary, and often integrate concepts from different parts of the syllabus. Usually involves higher-order thinking skills. (e.g., Describe the structure of a transcription unit and explain the process of transcription in prokaryotes. Explain Darwin's theory of natural selection with suitable examples).
  • Case-Based/Source-Based Questions: May involve interpreting a paragraph, data, or diagram and answering related questions. Tests comprehension and analytical skills.

Key Takeaways for Government Exam Preparation:

• Conceptual Clarity: The model paper emphasizes understanding core concepts over rote memorization. Many government exams (like NEET, CUET, state-level exams) test deep conceptual understanding.
• Syllabus Coverage: The paper aims for broad coverage. Ensure you haven't skipped any chapters, especially high-weightage units like Genetics & Evolution, Biotechnology, Reproduction, and Ecology.
• Diagrams & Data Interpretation: Practice drawing neat, labelled diagrams and interpreting graphs/charts. These skills are often tested directly or indirectly.
• Application Questions: Pay special attention to questions that ask 'how' or 'why' or require you to apply a principle to a scenario. This is common in competitive exams.
• Time Management: Practicing with model papers helps you manage time effectively during the actual exam.

High-Weightage Areas Often Reflected in Model Papers:

1. Reproduction: Human Reproduction (Gametogenesis, Menstrual Cycle, Fertilization, Embryonic Development), Reproductive Health (STIs, Contraception, ARTs), Sexual Reproduction in Flowering Plants (Pollination, Fertilization, Post-fertilization events).
2. Genetics and Evolution: Principles of Inheritance (Mendelian genetics, deviations), Molecular Basis of Inheritance (DNA structure, Replication, Transcription, Translation, Gene Regulation - Lac Operon), Evolution (Hardy-Weinberg, Natural Selection, Human Evolution).
3. Biology and Human Welfare: Human Health and Disease (Common diseases, Immunity, AIDS, Cancer, Drugs), Strategies for Enhancement in Food Production (Plant breeding, Animal husbandry, Tissue culture), Microbes in Human Welfare (Household products, Industrial products, Sewage treatment, Biogas, Biocontrol agents).
4. Biotechnology: Principles and Processes (rDNA technology, tools, processes), Applications (Agriculture, Medicine - Insulin production, Gene therapy, Molecular diagnosis).
5. Ecology and Environment: Organisms and Populations (Population interactions, attributes, growth models), Ecosystem (Structure, Function, Productivity, Decomposition, Energy flow, Pyramids), Biodiversity and Conservation (Patterns, Importance, Loss, Conservation methods), Environmental Issues (Pollution, Climate change, Ozone depletion).

How to Use This Chapter Effectively:

1. Solve it Seriously: Treat it like a real exam. Time yourself.
2. Self-Assessment: Honestly evaluate your answers using the NCERT solutions or marking scheme principles.
3. Identify Weak Areas: Note down the topics/chapters where you struggled. Revisit those concepts thoroughly.
4. Analyze Question Types: Understand which types of questions you find difficult (e.g., application-based, diagram-based) and practice more of those.
5. Improve Presentation: Check if your answers are structured well, if diagrams are neat and labelled correctly.

Practice Multiple Choice Questions (MCQs)

Here are 10 MCQs reflecting the kind of objective questions you might encounter, based on the concepts tested in the Class 12 syllabus and often found in model papers:

1. During the process of DNA replication, the enzyme responsible for joining Okazaki fragments on the lagging strand is:
   (a) DNA Polymerase I
   (b) DNA Ligase
   (c) Helicase
   (d) Primase

2. Which of the following assisted reproductive technologies (ART) involves the transfer of an embryo with more than 8 blastomeres into the uterus?
   (a) ZIFT (Zygote Intrafallopian Transfer)
   (b) GIFT (Gamete Intrafallopian Transfer)
   (c) IUT (Intra Uterine Transfer)
   (d) ICSI (Intra Cytoplasmic Sperm Injection)

3. The phenomenon where a single gene exhibits multiple phenotypic expressions is known as:
   (a) Pleiotropy
   (b) Polygenic inheritance
   (c) Co-dominance
   (d) Incomplete dominance

4. Which of the following is NOT a characteristic feature of cancerous cells?
   (a) Loss of contact inhibition
   (b) Metastasis
   (c) Uncontrolled proliferation
   (d) Apoptosis (programmed cell death)

5. 'Bt' in Bt cotton refers to:
   (a) Biotechnology
   (b) Beta toxin
   (c) Bacillus thuringiensis
   (d) Biologically tested

6. According to the Hardy-Weinberg principle, which factor would NOT disrupt the genetic equilibrium of a population?
   (a) Gene flow
   (b) Genetic drift
   (c) Random mating
   (d) Mutation

7. Which trophic level accommodates the maximum energy in a typical grassland ecosystem?
   (a) Producers (Grasses)
   (b) Primary Consumers (Herbivores)
   (c) Secondary Consumers (Carnivores)
   (d) Decomposers

8. Emasculation, the removal of anthers from a bisexual flower before they dehisce, is performed in artificial hybridization to prevent:
   (a) Cross-pollination
   (b) Self-pollination
   (c) Cleistogamy
   (d) Xenogamy

9. The sequence of structural genes in the Lac operon of E. coli is:
   (a) lacA, lacY, lacZ
   (b) lacZ, lacY, lacA
   (c) lacZ, lacA, lacY
   (d) lacY, lacZ, lacA

10. Which type of immune response is primarily mediated by B-lymphocytes?
    (a) Cell-mediated immunity
    (b) Humoral immunity (Antibody-mediated immunity)
    (c) Innate immunity
    (d) Autoimmune response

Answer Key for MCQs:

1. (b) DNA Ligase
2. (c) IUT (Intra Uterine Transfer)
3. (a) Pleiotropy
4. (d) Apoptosis (programmed cell death) - Cancer cells evade apoptosis.
5. (c) Bacillus thuringiensis
6. (c) Random mating - This is a condition for maintaining equilibrium.
7. (a) Producers (Grasses) - Energy flows upwards and decreases at each level.
8. (b) Self-pollination
9. (b) lacZ, lacY, lacA
10. (b) Humoral immunity (Antibody-mediated immunity)

Remember, consistent practice with model papers and understanding the underlying concepts is your key to success. Good luck with your preparation!