Family Trees

• What is a family tree used for in genetics?

  To show inheritance of traits through generations
• In a family tree, what does a circle usually represent?

  A female
• In a family tree, what does a square usually represent?

  A male
• What does it mean if a shape is shaded in a family tree?

  The person shows the inherited condition
• What is a carrier?

  Someone who does not have a condition but can pass it on
• How many copies of a recessive allele are needed for the person to show the condition?

  Two
• How many copies of a dominant allele are needed for the person to show the condition?

  One
• If both parents are carriers of a recessive disorder, what is the chance their child will have the disorder?

  25%
• If a child has a genetic condition but neither parent does, what does this suggest?

  The condition is recessive and both parents are carriers
• Which inheritance pattern does not skip generations?

  Dominant
• What can be learned by analysing a family tree?

  How a trait is inherited
• If a condition affects males more than females in a family tree, what might this suggest?

  It’s sex-linked
• What does a horizontal line connecting a circle and a square show?

  Marriage or partnership
• What does a vertical line from a couple to a shape below represent?

  A child
• What type of inheritance is shown if two unaffected parents have an affected child?

  Recessive