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Chapter 7 Practice Paper: Inheritance — question paper

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QQ/S4BI/CH7

Secondary 4 · Biology (G2 / G3)

Chapter 7 Practice Paper

Inheritance

Duration: 40 minutes
Total: 30 marks
Name:
Class:
Register No.:
Date:

READ THESE INSTRUCTIONS FIRST

  • Write your name, class and register number in the spaces at the top of this page.
  • Answer all questions.
  • Give numerical answers correct to 3 significant figures unless stated otherwise.
  • The number of marks is given in brackets [ ] at the end of each question or part question.
  • The total number of marks for this paper is 30.

Original practice material written for the MOE Biology syllabus. It is not an official MOE or school examination paper. Genes and alleles; genotype and phenotype; dominant, recessive and co-dominant alleles; monohybrid crosses with 3:1 and 1:1 ratios; observed vs expected ratios; ABO blood groups; sex determination; mutation (sickle cell anaemia, Down syndrome) and mutagens; continuous and discontinuous variation; natural selection and evolution.

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

    The phenotype of an organism is

    1. Athe pair of alleles it carries
    2. Bthe observable characteristics it shows
    3. Cthe number of chromosomes in its cells
    4. Dthe sequence of one of its genes
    ( )
  2. 2

    A cross between two heterozygous tall pea plants gives 96 offspring. The EXPECTED number of short plants is

    1. A24
    2. B32
    3. C48
    4. D72
    ( )
  3. 3

    The genotype IAIB produces blood group AB because

    1. AIB is dominant over IA
    2. BIA and IB are co-dominant, so both are expressed
    3. CIO masks both alleles
    4. Dthe alleles blend into a new allele
    ( )
  4. 4

    Down syndrome is a mutation involving

    1. Aa change in the base sequence of one gene
    2. Bthe loss of all X chromosomes
    3. Ca change caused only by diet
    4. Dan extra chromosome, giving 47 in total
    ( )
  5. 5

    Height in humans shows continuous variation because it

    1. Afalls into distinct categories
    2. Bis controlled by a single gene only
    3. Cshows a full range of values, influenced by genes and environment
    4. Dcannot be measured
    ( )

Section B: Structured questions[20 marks]

Answer all questions in the spaces provided.

  1. 1

    In pea plants, the allele H for tall stems is dominant to the allele h for short stems. Two heterozygous plants are crossed.

    1. (a)

      State the genotypes of the two parent plants.

      [1]
    2. (b)

      Complete a Punnett square for the cross and state the genotype ratio of the offspring.

      [3]
    3. (c)

      State the phenotype ratio, and explain why a real brood of 40 offspring might not match it exactly.

      [2]
  2. 2

    The ABO blood groups are controlled by three alleles of one gene: IA, IB and IO.

    1. (a)

      State the relationship between IA and IB, and the relationship between IO and the other two alleles.

      [2]
    2. (b)

      Two parents have the genotypes IAIO and IBIO. Using a genetic diagram, work out which blood groups their children could have, with the expected ratio.

      [4]
    3. (c)

      Explain why this cross cannot produce a child of blood group O if the father were homozygous IAIA.

      [1]
  3. 3

    In a population of insects, wing length varies between individuals. After years of drought, only short-winged insects can shelter in the few remaining crevices during storms that kill long-winged insects.

    1. (a)

      Explain how natural selection would change the wing lengths of the population over many generations.

      [4]
    2. (b)

      Wing length in these insects shows a full range of values. State the type of variation and one factor that could influence it.

      [1]
    3. (c)

      During the drought, X-ray equipment used in a nearby laboratory leaked and exposed some insects to radiation. State and explain the risk this created for future generations.

      [2]

— End of paper —