In a practical examination, the below given pedigree chart was given as spotter for identification. The students identified the pedigree chart as ________
Autosomal dominant
Pedigree analysis traces a trait through generations; filled symbols are affected, squares are males and circles are females. NCERT illustrates an autosomal dominant trait (for example myotonic dystrophy) with a chart of exactly this pattern.
Step 1 — Generation I: an affected mother and an unaffected father have both an affected son and an affected daughter, so the trait passes from mother to children of both sexes.
Step 2 — Generation II: the unaffected son marries an unaffected woman and none of their three children is affected; an unaffected parent pair does not pass the trait, as expected for a dominant allele.
Step 3 — Generation III: the affected daughter and her unaffected husband again have an affected daughter, so the trait appears in every generation without skipping and affects males and females alike.
Autosomal recessive traits typically skip generations and arise from unaffected carrier parents. A Y-linked trait passes only from father to son and never appears in females, yet three of the affected individuals here are female. Sex-linked recessive traits mostly affect males through carrier mothers, and the daughter affected here has an unaffected father, which a sex-linked recessive trait would not give. The vertical, both-sex transmission matches the autosomal dominant pattern shown in NCERT.
Autosomal dominant option is correct.
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Important Questions from Genetics and Evolution
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Assertion A : Forelimbs of human and bats are homologous.
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Statement II : *Homo sapiens* arose around 75000 to 10000 years ago.
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(b) genetic drift
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(d) disruption
Choose the correct answer from the options given below :
