GENETICS AND EVOLUTION
GENETIC BASIS OF INHERITANCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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A person with an extra X chromosome would have more severe conditions than a person with an extra 21st chromosome
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Chromosomal abnormalities involving nondisjunction are fairly common.
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People with Turner’s Syndrome (X0) don’t tend to survive to adulthood.
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The chances of nondisjunction during meiosis increases with age.
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Detailed explanation-1: -During meiosis in human oocytes, chromosome nondisjunction increases with maternal age, leading to disorders such as Down’s syndrome.
Detailed explanation-2: -If nondisjunction occurs in meiosis I, all four products of meiosis will be chromosomally abnormal. Two of the four products of meiosis will have two copies of the chromosome involved in the nondisjunction event, and two of the four products of meiosis will have no copies of that particular chromosome.
Detailed explanation-3: -The most common reason for aneuploidy is non-disjunction of chromosomes during either mitosis or meiosis. Non-disjunction of chromosomes during mitosis occurs during anaphase. If a somatic cell undergoes mitosis and experiences non-disjunction, the two daughter cells formed will be aneuploid.
Detailed explanation-4: -Nondisjunction is the most common mechanism resulting in aneuploidy. Nondisjunction is an error in which there is unequal distribution of the members of a single chromosome pair in cell division.