Down Syndrome Is a Common Disorder

question 22

Multiple Choice

Down syndrome is a common disorder.Which of the following circumstances results in Down syndrome?

• A)Defective,recessive alleles
• B)Defective,dominant alleles
• C)Insufficient number of chromosomes
• D)Extra chromosome

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Definitions:

Twin Study

A research design in behavioral genetics that compares the similarity of twins raised in different environments to understand the genetic and environmental influences on human traits.

Genetic Bases

The underlying genetic factors that contribute to the physical and behavioral characteristics of an organism.

Schizophrenia

A severe mental disorder characterized by disruptions in thought processes, perceptions, emotional responsiveness, and social interactions.

Concordance

A concept used in behavioural research into the genetic bases of psychiatric disorders. When the disorder that characterizes one person, called the index case or proband, also occurs in another person, the two are said to display concordance. The degree of concordance is thought to reveal the influence of genetics.