Class XII Biology Sample Question Paper 2024-25
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Questions and Answers

What is the maximum number of marks for the Biology exam?

  • 70 (correct)
  • 80
  • 75
  • 60

    • How many sections are included in the Biology question paper?

  • 4
  • 6
  • 7
  • 5 (correct)

    • What type of questions does Section-D include?

  • Fill in the blanks questions
  • Short answer questions
  • True or false questions
  • Case-based questions (correct)

    • What is the total number of questions in the Biology paper?

    <p>33</p> Signup and view all the answers

    What is the marking scheme for the questions in Section-C?

    <p>3 marks each</p> Signup and view all the answers

    What must students draw whenever necessary?

    <p>Diagrams with correct labels</p> Signup and view all the answers

    How many options are provided for selection in questions with internal choices?

    <p>Two options only</p> Signup and view all the answers

    In which section does a question carry the highest mark value?

    <p>Section-E</p> Signup and view all the answers

    What is the correct mRNA sequence produced after transcribing the given DNA template strand?

    <p>5´ AUUGCC 3´</p> Signup and view all the answers

    Which gas is primarily produced during the fermentation of idli-dosa dough?

    <p>CO2</p> Signup and view all the answers

    What is the result of adaptive radiation typically characterized by?

    <p>Rapid divergence of traits among populations inhabiting a given geographical area</p> Signup and view all the answers

    What is the number of nucleotides present in the sticky ends formed after Eco R1 cuts DNA between G and A?

    <p>2 &amp; 4 for Vector and Foreign DNA</p> Signup and view all the answers

    How does the secondary treatment of sewage alter the effluent due to the action of flocs?

    <p>Reduction in BOD</p> Signup and view all the answers

    In the context of cells of tapetum, what is the reason for their multiple nuclei?

    <p>They undergo meiosis without cytokinesis</p> Signup and view all the answers

    Which forest has the maximum energy loss by respiration?

    <p>Forest C</p> Signup and view all the answers

    What is a key function of deoxyribonucleoside triphosphates?

    <p>Proofreading during DNA synthesis</p> Signup and view all the answers

    How many embryos are produced in the ovary of seed X, which is produced by apomixis?

    <p>3 Embryos</p> Signup and view all the answers

    What is the main advantage of plants developed from seed Y over seed X?

    <p>Higher genetic variation</p> Signup and view all the answers

    What happens to the floating cover placed over the slurry in a biogas plant?

    <p>It keeps on rising due to gas production</p> Signup and view all the answers

    Where in the human ovary is the first meiotic division completed during oogenesis?

    <p>Mature Graafian follicle</p> Signup and view all the answers

    What is a key difference in the pairing of nitrogenous bases during DNA replication and transcription?

    <p>A pairs with T in replication, U in transcription</p> Signup and view all the answers

    In which process is the DNA segment copied into RNA?

    <p>Template transcription</p> Signup and view all the answers

    How are multiple embryos formed in citrus fruits?

    <p>Via polyembryony</p> Signup and view all the answers

    What is the chromosome number of the first polar body produced during oogenesis?

    <p>23</p> Signup and view all the answers

    What does a negative hCG blood test imply?

    <p>Pregnancy is highly unlikely.</p> Signup and view all the answers

    Which hormone is primarily secreted by the tissue that produces hCG?

    <p>Progesterone</p> Signup and view all the answers

    In gel electrophoresis, how do DNA fragments behave based on their size?

    <p>Larger fragments move slower.</p> Signup and view all the answers

    What type of mutation is typically more harmful to DNA?

    <p>Nonsense mutation</p> Signup and view all the answers

    What is the significance of UTRs in mRNA?

    <p>They help stabilize mRNA.</p> Signup and view all the answers

    What phenomenon occurs when a sperm fertilizes an ovum?

    <p>The ovum creates a barrier to prevent additional sperm entry.</p> Signup and view all the answers

    What is the primary relationship observed between HIV levels and helper T cell counts shortly after infection?

    <p>Initial HIV levels peak while T cell counts drop.</p> Signup and view all the answers

    In a culture plate of Lactobacillus, what causes the variance in colony color?

    <p>pH changes in the medium.</p> Signup and view all the answers

    What is the primary reason only a segment of DNA is copied into RNA during transcription?

    <p>Specific genes are activated based on cell type.</p> Signup and view all the answers

    Which of the following correctly describes a step involved in Southern blot hybridization?

    <p>Blotted DNA is hybridized with a radiolabeled VNTR probe.</p> Signup and view all the answers

    How do bio-fertilizers primarily enrich soil nutrient quality?

    <p>By improving nitrogen fixation through microbial activity.</p> Signup and view all the answers

    In the context of PCR, what is the role of temperature cycling?

    <p>To allow for denaturation, annealing, and extension.</p> Signup and view all the answers

    What does Gause's exclusion principle state regarding species co-existing?

    <p>Two species competing for the same resources cannot coexist.</p> Signup and view all the answers

    What is one factor responsible for the temperature pattern observed in a person with a non-viral disease transmitted by mosquitoes?

    <p>Host immune responses triggering temperature variation.</p> Signup and view all the answers

    Study Notes

    General Instructions

    • All questions are compulsory in the exam.
    • The question paper includes five sections with a total of 33 questions.
    • Section A: 16 questions worth 1 mark each (multiple choice).
    • Section B: 5 questions worth 2 marks each.
    • Section C: 7 questions worth 3 marks each.
    • Section D: 2 case-based questions worth 4 marks each.
    • Section E: 3 questions worth 5 marks each.
    • No overall choice; internal choices provided in some questions.
    • Diagrams must be neat and properly labeled where necessary.

    Section A Highlights (1 Mark Questions)

    • Signals for parturition in humans originate from both the placenta and a fully developed fetus.
    • To produce 1600 seeds, 2000 meiotic divisions are required.
    • If a DNA sample has a thymine content of 27%, then the expected guanine content is 23%.
    • For transcription, the mRNA generated from a given DNA template strand is 5' AUUGCC 3'.
    • Idli-dosa dough rises due to CO2 production.
    • Adaptive radiation leads to rapid divergence of traits among populations in geographical areas.
    • Eco R1 restriction enzyme cuts DNA between bases G and A, forming sticky ends.
    • The secondary treatment of sewage reduces the BOD due to flocs.

    Section B Highlights (2 Marks Questions)

    • Negative hCG levels imply no pregnancy; hCG is produced by the placenta.
    • The ovum blocks additional sperm entry by alterations in its membrane after the first sperm fertilization.
    • Not all copulations lead to fertilization due to various factors including timing and sperm viability.
    • Mutations can vary in type; specific examples are required for identification.
    • The Human Immunodeficiency Virus (HIV) can be tracked through T-cell counts and immune response dynamics.

    Section C Highlights (3 Marks Questions)

    • Apomictic seeds can produce multiple embryos; sexual reproduction seeds have one embryo.
    • First meiotic division during oogenesis occurs in the ovarian follicle, resulting in a secondary oocyte and a polar body.
    • Central Dogma involves the processes of DNA replication, transcription into RNA, and translation into proteins.
    • Southern blotting utilizes radiolabeled probes to identify specific DNA sequences.

    Section D Highlights (4 Marks Questions)

    • Hardy-Weinberg principle calculations include frequencies of alleles; example given with black and red beetles.
    • Patterns of temperature in diseases transmitted by mosquitoes can indicate the presence of specific pathogens, which multiply in the human body.
    • Transmission of diseases can occur through various forms, including vectors like mosquitoes.

    Additional Information

    • Visual impairments adaptations provided, including simplified explanations without diagrams.
    • Critical understanding of ecological principles like Gause's exclusion principle noted for cooperative species.

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    Description

    Prepare for your Class XII Biology exam with this sample question paper designed for the 2024-25 session. This paper includes a variety of questions across multiple sections, testing your knowledge on key biological concepts. Ensure you cover all topics to achieve maximum marks in your upcoming assessment.

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