Igcse Model Questions Vol1 2020 Biology Question 5

Practice objective / multiple choice question 5 from the 2020 Igcse Model Questions Vol1 Biology examination.

Igcse Model Questions Vol1 2020 Biology Objective / Multiple Choice Medium Difficulty
Question 5 IGCSE_MODEL_QUESTIONS_VOL1 • 2020 • BIOLOGY • objective

In a certain autosomal recessive disorder both parents are carriers (genotype Aa). They have three children: one is affected (aa), one is a carrier (Aa) and one is unaffected and not a carrier (AA). (a) What is the probability that their next child will be affected? (b) The affected child later marries a person who is known to be a non‑carrier (AA). What is the probability that their first child will be a carrier for the disorder?

Answer Options

A. (a) 0 % chance of an affected child. (b) 100 % chance that the first child will be a carrier for the disorder.
B. (a) 25 % chance of an affected child. (b) 0 % chance that the first child will be a carrier for the disorder.
Correct Answer C. (a) 25 % chance of an affected child. (b) 100 % chance that the first child will be a carrier (Aa).
D. (a) 50 % chance of an affected child. (b) 50 % chance that the first child will be a carrier for the disorder.
Correct Answer
C
Correct Option:
(a) 25 % chance of an affected child. (b) 100 % chance that the first child will be a carrier (Aa).

About This Question

This is Igcse Model Questions Vol1 2020 Biology Question 5. It is one of the objective questions from the 2020 Igcse Model Questions Vol1 Biology examination.

Difficulty level: Medium .

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