Biology Class 12 Regular Assessment
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Questions and Answers

What is a mutation?

  • A type of genetic drift
  • A process of cell division
  • A change in the structure of DNA (correct)
  • A form of natural selection

    • Which best describes the central dogma?

  • The process of protein synthesis only
  • The replication of DNA in a cell
  • The flow of genetic information from DNA to RNA to Protein (correct)
  • The structure of a double helix

    • What is the defect caused by the substitution of glutamic acid by valine at the sixth position of the beta globin chain of the haemoglobin molecule?

  • Haemophilia
  • Sickle cell anaemia (correct)
  • Phenylketonuria
  • Thalassemia

    • In genetics, what is the meaning of co-dominance?

    <p>Both alleles are fully expressed in the phenotype</p> Signup and view all the answers

    What is the difference between homozygous and heterozygous?

    <p>Homozygous carries two identical alleles; heterozygous carries two different alleles.</p> Signup and view all the answers

    Thalassemia is classified as what type of disease?

    <p>An autosome linked recessive blood disease</p> Signup and view all the answers

    Who first discovered Down syndrome?

    <p>Langdon Down</p> Signup and view all the answers

    Which law describes the inheritance of traits in a monohybrid cross?

    <p>Law of Segregation</p> Signup and view all the answers

    What disorder is caused by the absence of one of the X chromosomes, specifically 45 with XO?

    <p>Turner’s Syndrome</p> Signup and view all the answers

    Who first identified DNA as an acidic substance present in the nucleus?

    <p>Friedrich Meischer</p> Signup and view all the answers

    What is the haploid content of human DNA?

    <p>3.3×10^9 base pairs</p> Signup and view all the answers

    What type of sugar is present in DNA?

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

    Which of the following statements is correct regarding DNA?

    <p>Adenine pairs with Thymine</p> Signup and view all the answers

    What is the total number of chromosomes in a normal human cell?

    <p>46</p> Signup and view all the answers

    What is the term for the loss or gain of chromosomes during cell division due to failure of segregation?

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

    Which option indicates the correct format of the objective questions in the examination?

    <p>Choose the correct option's (a, b, c, d)</p> Signup and view all the answers

    What type of questions will carry 5 marks in the assessment?

    <p>Long answer questions</p> Signup and view all the answers

    What is the duration of the exam as stated in the instructions?

    <p>90 minutes</p> Signup and view all the answers

    What is the marking scheme for very short answer questions?

    <p>2 marks each</p> Signup and view all the answers

    When are students permitted to leave the examination hall?

    <p>After the exam duration is complete</p> Signup and view all the answers

    What is indicated by the mark 'x' next to the objective questions?

    <p>The number of questions to be answered</p> Signup and view all the answers

    Study Notes

    Examination Structure

    • Subject: Biology for Class 12, administered by Jharkhand Council of Educational Research and Training.
    • Duration: 90 minutes.
    • Total Marks: 40.

    Instructions

    • All questions are mandatory and the total number is 16.
    • Marks allocation:
      • 2 marks for each objective question,
      • 2 marks for very short answer questions,
      • 3 marks for short answer questions,
      • 5 marks for long answer questions.
    • No negative marking for incorrect answers.
    • Objective questions (1-10) have four answer choices (a, b, c, d).
    • Very short answer questions (11-12), short answer questions (13-14), and long answer questions (15-16) must be written in the answer sheet.
    • Students must remain in the examination hall until the end of the exam.

    Section A: Objective Questions

    • Total of 10 questions worth 2 marks each.

    • Chromosome count in a normal human cell is 46.

    • The term describing the gain or loss of chromosomes due to failed chromatid segregation is Aneuploidy.

    • A defect from the substitution of glutamic acid by valine in hemoglobin is Sickle cell anaemia.

    • Thalassemia is classified as an autosome linked recessive blood disease.

    • Down Syndrome was first discovered by Langdon Down.

    • Turner’s Syndrome is characterized by the absence of one X chromosome, resulting in 45, XO.

    • DNA was first identified as acidic by Friedrich Meischer.

    • The haploid content of human DNA is approximately 3.3×10^9 base pairs.

    • The sugar present in DNA is Deoxyribose.

    • Correct pairings in DNA are Adenine with Thymine and Guanine with Cytosine.

    Section B: Very Short Answer Questions

    • Define Mutation as a change in the DNA sequence that may lead to changes in gene functions.
    • Define Central dogma as the process of transferring genetic information from DNA to RNA to protein.

    Section C: Short Answer Questions

    • Differentiate between:

      • Dominance: A trait that masks another trait in heterozygous conditions.
      • Recessive: A trait that is masked by a dominant trait.
      • Homozygous: Organisms with identical alleles for a trait.
      • Heterozygous: Organisms with different alleles for a trait.
      • Monohybrid cross: A genetic cross between individuals that involves one pair of contrasting traits.
      • Dihybrid cross: A genetic cross involving two different traits.

    • Explain the following with examples:

      • Co-dominance: Both alleles in a heterozygote contribute to the phenotype. Example: AB blood type.
      • Incomplete dominance: A situation where the phenotype is an intermediate blend of the two homozygous phenotypes. Example: Red and white flowers producing pink offspring.

    Section D: Long Answer Questions

    • Explain the Law of Dominance using a Monohybrid Cross, showcasing how one trait can dominate another in the progeny.
    • Highlight salient features of the Double-helix structure of DNA, including its antiparallel strands, base pairing rules (A with T, C with G), and overall helical shape which supports its function in genetic information storage.

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    Description

    This quiz is designed for Class 12 students focusing on Biology. It includes various compulsory questions aimed at improving learning outcomes. Students have 90 minutes to complete the assessment, which is worth 40 marks.

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