Biology Questions and Answers – Inheritance and Variation Principles – Chromosomal Disorders

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This set of Biology Multiple Choice Questions & Answers (MCQs) focuses on “Inheritance and Variation Principles – Chromosomal Disorders”.

1. Which of the following is the carrier of genetic information?
a) Proteins
b) Amino acids
c) Carbohydrates
d) DNA
View Answer

Answer: d
Explanation: DNA is the carrier of genetic information. Genes located on the DNA present in the chromosome controls each and every feature of an organism.
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2. On which of the following chromosomal disorders are based on?
a) Mutant allele and their defective products
b) Imbalance in chromosome number and chromosome arrangement
c) Mutant allele and chromosome arrangement
d) Mutant allele and imbalance in chromosome number
View Answer

Answer: b
Explanation: The chromosomal disorders are the disorders that are based on the imbalance in chromosome number and chromosomal arrangement. The disorders which are due to the mutant allele and their defective products are known as Mendelian disorders.

3. In which year, Down’s syndrome was described?
a) 1866
b) 1986
c) 1898
d) 1968
View Answer

Answer: a
Explanation: In 1866, Down’s syndrome was first described by Langdon Down. This disorder is a result of the trisomy of chromosome number 21. Short stature, small round head, etc. are some of the effects of this disorder.
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4. Which of the following is not a characteristic feature of Down’s syndrome?
a) Very tall
b) Small round head
c) Furrowed tongue
d) Partially open mouth
View Answer

Answer: a
Explanation: Tallness is not a characteristic feature of Down’s syndrome. Some characteristic features include- Short stature, small round head, partially open mouth, furrowed tongue, etc.

5. Only mental development is retarded in the case of Down’s syndrome.
a) True
b) False
View Answer

Answer: b
Explanation: It is not true that only mental health is retarded in the case of Down’s syndrome. Physical and psychomotor skills are also not developed. They have underdeveloped gonads and genitals. Their joints are also loose.
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6. Which of the following is the characteristic feature of Down’s syndrome?
a) Congenital heart disease
b) Short stature
c) Broad palm with palm crease
d) Underdeveloped gonads
View Answer

Answer: c
Explanation: Congenital heart disease, short stature, and underdeveloped gonads are some features of Down’s syndrome which also occur in other people. But, broad palm with a palm crease is the characteristic feature of someone with Down’s syndrome.

7. Which of the following is not a feature of the tongue of the person suffering from Down’s syndrome?
a) Furrowed tongue
b) Big tongue
c) Wrinkled tongue
d) Straight tongue
View Answer

Answer: d
Explanation: The tongue of the person suffering from Down’s syndrome is not straight. It is wrinkled and is comparatively bigger than a normal human tongue. The tongue is also furrowed. These features help in the diagnosis of Down’s syndrome.
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8. What is the genotype of the person suffering from Klinefelter’s syndrome?
a) 44+ XXX
b) 42+ XXX
c) 44+ XXY
d) 42+ XXY
View Answer

Answer: c
Explanation: The genotype of the person suffering from Klinefelter’s syndrome is 44+ XXY. This deviation from a normal person’s genotype is due to the additional copy of the X-chromosome.

9. Which of the following is incorrect with respect to Klinefelter’s syndrome?
a) The fusion of an abnormal egg with normal sperm
b) The fusion of a normal egg with an abnormal sperm
c) The fusion of a normal egg with a normal sperm
d) An additional copy of X-chromosome
View Answer

Answer: c
Explanation: The fusion of a normal egg with a normal sperm leads to the formation of a healthy baby. Klinefelter’s syndrome appears due to the union of an abnormal egg (two X-chromosomes + autosomes) with a normal sperm (Y-chromosome+ autosomes) or a normal egg (X-chromosome + autosomes) with abnormal sperm (XY chromosomes+ autosomes).
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10. There are no loops on the finger-tips of the people suffering from Down’s syndrome.
a) True
b) False
View Answer

Answer: b
Explanation: It is not true that there are no loops on the finger-tips of the people suffering from Down’s syndrome. Instead, their finger-tips have many loops as compared to the finger-tips of normal human beings.

11. Which of the following is not the character of a person suffering from Klinefelter’s syndrome?
a) Short stature
b) Breast development
c) Small testes
d) Female type pubic hair pattern
View Answer

Answer: a
Explanation: Short stature is not a character of the person suffering from Klinefelter’s syndrome. The person’s height who is suffering from Klinefelter’s syndrome is taller than the average human height. Other characteristic features include breast development (gynecomastia), small testes (testicular atrophy), and female type pubic hair pattern.

12. Which of the following is not the character of the person suffering from Turner’s syndrome?
a) Short stature
b) Poor breast development
c) Well developed ovaries
d) No menstruation
View Answer

Answer: c
Explanation: Females suffering from Turner’s syndrome do not have well-developed ovaries. Instead, they have rudimentary ovaries. Other characteristic features of this disease are short stature, poor breast development, and no menstruation.

13. Which of the following is a representation of a recessive trait?
a) Achondroplasia
b) Blue eyes
c) Huntington disease
d) Brown eyes
View Answer

Answer: b
Explanation: Blue eyes are the representation of a recessive trait. Some other recessive traits include albinism, alkaptonuria, and cystic fibrosis. Some dominant traits are achondroplasia, brown eyes, brachydactyly, Huntington disease, etc.

14. Which of the following is the representation of a dominant trait?
a) Widow’s peak
b) Tongue non-roller’s
c) Fused ear lobes
d) Tay-Sachs disease
View Answer

Answer: a
Explanation: Widow’s peak is an example of a dominant trait. Other dominant traits include tongue rollers, morphan syndrome, free ear lobes, etc. Some recessive traits are tongue non-roller’s, Duchenne muscular dystrophy, Lesch-Nyhan syndrome, fused ear lobes, Tay- Sachs disease, etc.

15. What is the inheritance of characters by plasmagenes known as?
a) Extrafield inheritance
b) Maternal inheritance
c) Extrachromosomal inheritance
d) Maternal inheritance
View Answer

Answer: c
Explanation: The inheritance of characters by plasmagenes is known as extrachromosomal inheritance or extranuclear inheritance. Plasmagenes are some self-replicating genes which are present in the cytoplasm, mitochondrial DNA and chloroplast DNA.

16. Which of the following is an incorrect statement with respect to organelle inheritance?
a) Iojap inheritance in maize
b) Inheritance of poky
c) Plastid inheritance in Mirabilis jalapa
d) Coiling of shells
View Answer

Answer: d
Explanation: The coiling of shells is not an example of organelle inheritance. It is evidence of maternal inheritance. Examples of organelle inheritance include plastid inheritance in Mirabilis jalapa, iojap inheritance in maize, and inheritance of poky.

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