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Combined science (Foundation)
Inheritance, genotype and phenotype

Starter quiz

  • Which is the best definition of genotype?
    • An individual’s genetic make-up.
    • All of an individual’s genes.
    • An individual’s physical characteristics.
    • An individual’s combination of alleles.  ✓
    • An individual’s combination of genes.
  • Horses can breed with donkeys to produce offspring called mules. Horse body cells have 64 chromosomes and those of a donkey have 62. How many chromosomes will the zygote that grows into a mule have?
    • 126
    • 64
    • 63  ✓
    • 62
    • 2
  • Tay-Sachs is a single gene disorder caused by a recessive allele. Here is a family tree. It shows three generations. The shaded male has Tay-Sachs. Which statement is true?
    Tay-Sachs is a single gene disorder caused by a recessive allele. Here is a family tree. It shows three generations. The shaded male has Tay-Sachs. Which statement is true?
    • All the grandparents must be carriers of Tay-Sachs.
    • One grandparent is a carrier of Tay-Sachs.
    • One parent is a carrier of Tay-Sachs
    • Both parents are carriers of Tay-Sachs.  ✓
    • All the females are carriers of Tay-Sachs.
  • Albinism is caused by a recessive allele. The Punnett square shows the possible genotypes resulting from two carriers having a child. What is the probability that a child will be a carrier?
    Albinism is caused by a recessive allele. The Punnett square shows the possible genotypes resulting from two carriers having a child. What is the probability that a child will be a carrier?
    • 0.00
    • 0.25
    • 0.50  ✓
    • 0.75
    • 1.00
  • A student thinks you can tell the genotype of an individual by looking at its phenotype. When is this statement true?
    • Always.
    • Only if the individual is heterozygous.
    • Only if the individual is homozygous dominant.
    • Only if the individual is homozygous recessive.  ✓
    • Never.
  • Although it wasn’t recognised at the time, Mendel made a significant contribution to our modern understanding of inheritance. What was this contribution?
    • He worked out that proteins are made from amino acids.
    • He isolated DNA from a nucleus.
    • He worked out that three DNA bases code for each amino acid.
    • He discovered the double helix structure of DNA.
    • He worked out rules of inheritance of some traits.  ✓
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