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Chapter 4 Practice Paper: Molecular Genetics — question paper

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QQ/S4CBI/CH4

Secondary 4 · Combined Science (Biology) (G2 / G3)

Chapter 4 Practice Paper

Molecular Genetics

Duration: 40 minutes
Total: 30 marks
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Class:
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Date:

READ THESE INSTRUCTIONS FIRST

  • Answer all questions.
  • Section A: choose the one correct answer for each multiple-choice question.
  • Section B: answer in the spaces provided; show all necessary working.
  • Give numerical answers to 3 significant figures where appropriate, with units.
  • Biological drawings are not required; describe or label structures in words where asked.
  • The use of a calculator is permitted.

Original practice material written for the MOE Combined Science (Biology) syllabus. It is not an official MOE or school examination paper. Chapter 4 (DNA–gene–chromosome relationships; nucleotide structure; complementary base pairing; one gene, one polypeptide; the genetic code).

For Examiner’s Use
Section A/ 10
Section B/ 20
Total/ 30

Section A: Multiple-choice questions[10 marks]

Choose the one correct answer for each question.

  1. 1

    DNA is described as a

    1. Asingle-stranded protein
    2. Bdouble helix of two nucleotide strands
    3. Ctype of chromosome
    4. Dstorage sugar
    ( )
  2. 2

    In DNA, cytosine pairs with

    1. Aadenine
    2. Bthymine
    3. Cguanine
    4. Duracil
    ( )
  3. 3

    A gene directly codes for

    1. Aone polypeptide
    2. Bone chromosome
    3. Cone cell
    4. Done base
    ( )
  4. 4

    The two strands of DNA are held together by

    1. Asugar–phosphate links between the strands
    2. Bcomplementary paired bases
    3. Camino-acid bonds
    4. Dmagnetic attraction
    ( )
  5. 5

    A human body cell contains

    1. A23 chromosomes
    2. B46 pairs of chromosomes
    3. C46 chromosomes in 23 pairs
    4. D64 chromosomes
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

  1. 1

    The genetic library of a cell is organised at several sizes.

    1. (a)

      Outline the relationships among DNA, genes and chromosomes.

      [3]
    2. (b)

      Name the three parts of a nucleotide.

      [3]
    3. (c)

      State where chromosomes are found in a cell.

      [1]
  2. 2

    A single strand of DNA reads T–A–C–G–G–A.

    1. (a)

      Write the complementary strand.

      [3]
    2. (b)

      State the rule used in (a).

      [1]
    3. (c)

      Explain why the two strands of a DNA molecule carry the same information.

      [3]
  3. 3

    A gene carries the code for a protein-digesting enzyme.

    1. (a)

      State what the gene's base sequence directly specifies.

      [2]
    2. (b)

      A different gene in the same cell codes for haemoglobin. Explain why the two proteins are different.

      [2]
    3. (c)

      Explain why genes are called units of inheritance.

      [2]

— End of paper —