Igcse Model Questions Vol1 2019 Biology Question 27

Practice objective / multiple choice question 27 from the 2019 Igcse Model Questions Vol1 Biology examination.

Igcse Model Questions Vol1 2019 Biology Objective / Multiple Choice Medium Difficulty
Question 27 IGCSE_MODEL_QUESTIONS_VOL1 • 2019 • BIOLOGY • objective

Both parents are carriers (genotype \(Aa\)) for an autosomal recessive disorder. (i) What is the probability that a child born to them will be affected? (ii) If a child is known to be phenotypically normal, what is the probability that this child is a carrier? (iii) Assuming the first child is phenotypically normal, what is the probability that their second child will be affected?

Answer Options

A. Affected probability: 1\/2; carrier probability given normal phenotype: 1\/2; probability second child affected: 1\/2
Correct Answer B. Affected probability: 1/4; carrier probability given normal phenotype: 2/3; probability second child affected: 1/4
C. Affected probability: 1\/4; carrier probability given normal phenotype: 1\/3; probability second child affected: 1\/8
D. Affected probability: 1\/3; carrier probability given normal phenotype: 2\/3; probability second child affected: 1\/3
Correct Answer
B
Correct Option:
Affected probability: 1/4; carrier probability given normal phenotype: 2/3; probability second child affected: 1/4

About This Question

This is Igcse Model Questions Vol1 2019 Biology Question 27. It is one of the objective questions from the 2019 Igcse Model Questions Vol1 Biology examination.

Difficulty level: Medium .

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