Life Sciences Questions and Answers – Sex Determination


This set of Life Sciences Multiple Choice Questions & Answers (MCQs) focuses on “Sex Determination”.

1. Genes of sex linked characters are located on the ___________
a) Chromosome 18
b) Chromosome 13
c) Chromosome 14
d) Sex chromosome
View Answer

Answer: d
Explanation: The characters are said to be sex linked if their genes are located on the sex chromosome. According to modern genetics, the x-chromosome linked character is called sex-linked character while y-linked characters are called male limited characters.

2. In sex linkage, reciprocal cross yield identical results.
a) True
b) False
View Answer

Answer: b
Explanation: In the case of sex linkage reciprocal cross do not yield identical results, but it shows a criss-cross inheritance pattern, i.e. male transmits its sex linked genes to all daughters who in turn transmit them to half of their male progeny.

3. Which of the following is X-linked recessive disorder?
a) Color blindness
b) Sickle cell anemia
c) PTC tasting
d) Albinism
View Answer

Answer: a
Explanation: In humans, three proteins in the cons cells act as color sensors, the two color sensors are encoded by X-linked genes while one is encoded by a gene located on the seventh autosome.

4. Which of the following statement is NOT true regarding Partial sex linkage?
a) The X-Y chromosome pair during meiosis
b) Pairing occurs in the terminal region
c) The inheritance pattern in the PAR region show sex-linkage
d) PAR stands for the pseudo autosomal region
View Answer

Answer: c
Explanation: The inheritance pattern of the genes present in such terminal regions (PAR) of the sex chromosome is not like that of sex-linked genes but it resembles that of autosomal genes.

5. Identify the disease which causes excessive production of uric acid.
a) Duncan muscular dystrophy
b) Lesch-Nyhan syndrome
c) Hunter syndrome
d) Hemophilia
View Answer

Answer: b
Explanation: Lesch-Nyhan syndrome is an X-linked disorder which is the example of congenital hyperuriemic (excessive production of uric acid). It causes HGPRT (Hypoxanthine Guanine Phosphoribosyl Transferase) gene defective.

6. Which of the following characteristics does not belong to the Hunter syndrome?
a) Muscular deterioration
b) Abnormal hairiness
c) Mental retardation
d) Long protruding tongue
View Answer

Answer: a
Explanation: Hunter syndrome is an X-linked recessive disorder where the affected person have long protruding tongue and mental retardation while muscular deterioration occurs in another disorder called Duncan muscular dystrophy.

7. Which of the following is NOT a sex-limited role?
a) Pitch of voice
b) Musculature
c) Baldness
d) Milk production
View Answer

Answer: c
Explanation: Baldness is a sex-influenced character, not a sex-limited character. Sex-limited characters are those whose development is limited to only one of the two sexes.

8. Which of the following disease is characterized by excessive trinucleotide repeats (CAG)?
a) Cystic fibrosis
b) PTC tasting
c) Dwarfism
d) Huntington’s disease
View Answer

Answer: d
Explanation: Huntington’s disease is an autosomal disorder which is caused by excessive trinucleotide repeats, approx 50 to 100 times more than normal condition.

9. What is pedigree analysis?
a) Record of inheritance pattern
b) Linkage map
c) Quantitative genetic
d) Polygene analysis
View Answer

Answer: a
Explanation: Pedigree is a record of inheritance of certain genetic traits for two or more than two generations presenting in the form of a diagram.

10. Name the principle on which pedigree analysis work?
a) Regression
b) Probability
c) Random mating
View Answer

Answer: b
Explanation: Pedigree analysis is used to study the transmission genetics where controlled process is not possible and it works on the principle of probability.

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