Chapter 8: Genetic Disorder — Online MCQ Test
BIOTECHNOLOGY · Grade 11 · CBSE(NCERT)
Practice Chapter 8: Genetic Disorder with a free chapter-wise online MCQ test.
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.
Chapter 8: Genetic Disorder — Important Questions & Answers
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.
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.
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.
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.
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.
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.