BIOLOGY FLASHCARDS INVOLVING REMEMBERING DIAGRAMS

virus

lysosome

chromosomes

prophase I

prophase I

metaphase i

anaphase i

draw meiosis

draw non disjunction

draw non disjunction

The figure shows the inheritance of a

genetic disorder in a family.

Person 7 and person 8 plan to have

another child. Determine the

probability that the child will be a

male who has the disorder. Use the

symbol H for the dominant allele

and h for the recessive allele.

In this example, we first have to use the pedigree diagram to work out whether the disorder was caused by a

dominant or recessive allele. Since two parents without the disorder had a child with the disorder, it is caused by

a recessive allele.

We also need to use the diagram to work out the genotypes of 7 and 8 (parents). Since 7 has the disorder, he

must be homozygous recessive. 8 doesn’t have the disorder so must have at least one dominant allele. Since 7

and 8 have a child with the disorder, 8 must be heterozygous to have passed on the recessive allele.