Difficulty: Easy
Correct Answer: Criss-cross inheritance
Explanation:
Introduction / Context:Sex-linked traits often display characteristic transmission patterns across generations. Recognizing these patterns allows quick identification of X-linked recessive or dominant inheritance in pedigrees.
Given Data / Assumptions:
Concept / Approach:Criss-cross inheritance is typical for X-linked traits: a father passes his X chromosome to all daughters (never to sons). A daughter can then pass that X allele to her sons, producing the “male → daughter → grandson” path. Holandric inheritance is Y-linked (father to all sons), which does not match the pattern here.
Step-by-Step Solution:
Track the male’s X-linked allele → transmitted to the daughter (who is XX).Daughter passes that X to half of her sons (grandsons of the original male).This alternating sex transmission is termed criss-cross inheritance.Verification / Alternative check:Pedigree analysis examples of hemophilia or color blindness demonstrate this pattern repeatedly.
Why Other Options Are Wrong:
Common Pitfalls:Assuming all sex-linked traits are father-to-son; X-linked cannot go father-to-son because fathers pass Y to sons.
Final Answer:Criss-cross inheritance
Discussion & Comments