Chapter Exam

Chapter 8: Genetic Disorder — Online MCQ Test

Q: Which of the following is a chromosomal disorder caused by trisomy 21?

Answer: B. Down syndrome — Down syndrome is caused by an extra copy of chromosome 21, hence it is called trisomy 21. It is a chromosomal abnormality, not a single-gene disorder.

Q: Haemophilia is inherited as a/an ______ disorder.

Answer: C. X-linked recessive — Haemophilia is an X-linked recessive disorder, which is why it is seen more commonly in males. Females are usually carriers unless they inherit the faulty gene from both parents.

Q: Which condition is caused by monosomy of the X chromosome?

Answer: B. Turner syndrome — Turner syndrome occurs when one X chromosome is missing, leading to monosomy X (45, XO). It affects females.

BIOTECHNOLOGY · Grade 11 · CBSE(NCERT)

Practice Chapter 8: Genetic Disorder with a free chapter-wise online MCQ test for CBSE(NCERT) Grade 11 BIOTECHNOLOGY. This chapter covers: Genetic disorders mutations chromosomal abnormalities inherited diseases gene defects chromosome analysis genetic counseling human genetics. AI-generated questions from basic to board-exam level, with instant results and explanations.

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Chapter 8: Genetic Disorder — Important Questions & Answers (FAQ)

Frequently asked questions from CBSE(NCERT) Grade 11 BIOTECHNOLOGY — Chapter 8: Genetic Disorder, with answers and explanations. These are sample questions; the exam has its own separate question set.

Which of the following is a chromosomal disorder caused by trisomy 21?

A. Turner syndrome
B. Down syndrome ✓
C. Haemophilia
D. Sickle-cell anaemia

Answer: B. Down syndrome
Down syndrome is caused by an extra copy of chromosome 21, hence it is called trisomy 21. It is a chromosomal abnormality, not a single-gene disorder.

Haemophilia is inherited as a/an ______ disorder.

A. autosomal dominant
B. autosomal recessive
C. X-linked recessive ✓
D. Y-linked dominant

Answer: C. X-linked recessive
Haemophilia is an X-linked recessive disorder, which is why it is seen more commonly in males. Females are usually carriers unless they inherit the faulty gene from both parents.

Which condition is caused by monosomy of the X chromosome?

A. Down syndrome
B. Turner syndrome ✓
C. Klinefelter syndrome
D. Sickle-cell anaemia

Answer: B. Turner syndrome
Turner syndrome occurs when one X chromosome is missing, leading to monosomy X (45, XO). It affects females.

A child shows features of an extra chromosome 21. Which of the following is the most appropriate conclusion?

A. The disorder is a point mutation in a single gene
B. The disorder is likely Down syndrome caused by nondisjunction ✓
C. The disorder is always inherited from the father
D. The disorder is caused by deletion of one X chromosome

Answer: B. The disorder is likely Down syndrome caused by nondisjunction
An extra chromosome 21 indicates trisomy 21, usually due to nondisjunction during meiosis. This is characteristic of Down syndrome.

Which of the following is the best reason genetic counselling is recommended before marriage in families with a history of inherited disorders?

A. To cure chromosomal disorders completely
B. To estimate the probability of the disorder appearing in offspring ✓
C. To change the chromosome number of parents
D. To prevent all mutations in future generations

Answer: B. To estimate the probability of the disorder appearing in offspring
Genetic counselling helps assess the likelihood of passing a disorder to the next generation. It does not cure genetic disease, but it supports informed reproductive decisions.