GENETICS AND EVOLUTION
MOLECULAR BASIS OF INHERITANCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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A mutation happened during the production of the egg cell.
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More than one sperm fused with the egg at fertilisation.
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Radiation caused a change in structure of a gene in the father’s sperm.
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The mother was exposed to harmful chemicals while she was pregnant.
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Detailed explanation-1: -This means they have 47 chromosomes instead of 46. Down syndrome, Edward syndrome and Patau syndrome are the most common forms of trisomy. Children affected by trisomy usually have a range of birth anomalies, including delayed development and intellectual disabilities.
Detailed explanation-2: -In most cases of Down syndrome, a child gets an extra chromosome 21-for a total of 47 chromosomes instead of 46. Rarely, the extra chromosome 21 attaches to another chromosome. This extra genetic material causes the physical features and developmental delays in people with Down syndrome.
Detailed explanation-3: -Typically, a baby is born with 46 chromosomes. Babies with Down syndrome have an extra copy of one of these chromosomes, chromosome 21. A medical term for having an extra copy of a chromosome is ‘trisomy.’ Down syndrome is also referred to as Trisomy 21.
Detailed explanation-4: -Down syndrome is a genetic disorder caused when abnormal cell division results in an extra full or partial copy of chromosome 21. This extra genetic material causes the developmental changes and physical features of Down syndrome.