Why Might the Incidence of Trisomy from Maternal Origin Be

question 4

Multiple Choice

Why might the incidence of trisomy from maternal origin be higher than that from paternal origin?
Source: Hassold,T.,Chiu,D.Human Genetics.1985;70(1) :11-7.)

• A)Eggs are arrested in meiosis in the mother from approximately birth until ovulation.
• B)Sperm travel to the site of fertilization,and an extra chromosome may slow them down.
• C)Eggs move little from their site of release to the site of fertilization.
• D)All of the above are possible explanations for the higher incidence of trisomy of maternal origin.

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