Test: Sex Determination - UPSC MCQ

In humans, the chromosome that determines the sex of an individual is:

 Y chromosome

In the human genetic system:

• XX indicates a biologically female individual.
• XY indicates a biologically male individual.

The Y chromosome carries the SRY gene, which is responsible for initiating male development. The presence of a Y chromosome results in male characteristics, while the absence of it (XX) leads to female characteristics.

The presence of the XY sex chromosome combination typically results in a male individual. The Y chromosome carries the genes responsible for male development.

Sex determination in humans is influenced by the presence or absence of the Y chromosome. If the Y chromosome is present, the individual develops as male, while its absence leads to female development.

The primary sex-determining gene in mammals is the SRY (sex-determining region Y) gene. This gene is located on the Y chromosome and plays a crucial role in initiating male development.

In birds, the sex chromosome combination ZZ determines maleness, while ZW combination determines femaleness. Unlike mammals, birds have a different sex chromosome system.

In honeybees, the determination of sex is influenced by genetic factors, hormonal factors, and environmental factors. The combined effect of these factors determines whether an individual develops as a queen or a worker bee.

Turtles exhibit temperature-dependent sex determination (TSD), where the incubation temperature of the eggs during a critical period determines the sex of the offspring.

Genetic sex determination, also known as chromosomal sex determination, relies on the presence of specific sex chromosomes (e.g., XX and XY in humans) that determine the development of male or female traits.

The SRY gene, responsible for initiating male development, is located on the Y chromosome in humans. Its presence triggers the differentiation of the gonads into testes.

Turner syndrome is characterized by the absence or incomplete structure of one of the X chromosomes in females. It results in various developmental and reproductive abnormalities.

Klinefelter syndrome is characterized by the presence of an extra X chromosome in males, resulting in the karyotype XXY. This condition can cause infertility and other physical and cognitive effects.

In Drosophila, the sex determination mechanism relies on the ratio of X chromosomes to autosomes. The balance between X chromosomes and autosomal sets determines whether an individual develops as male or female.

In mammals, the SOX9 gene is responsible for testis development. It plays a crucial role in the differentiation of the gonads into testes and the subsequent development of male reproductive structures.

In reptiles, the temperature at which eggs are incubated can influence the sex of the offspring. Certain temperature ranges promote the development of males, while others promote females.

Various environmental factors, including hormone levels, temperature, and nutrition, can influence sex determination in different organisms. These factors can affect gene expression and developmental pathways.

Humans exhibit genetic sex determination, where the presence or absence of specific sex chromosomes (X and Y) determines the development of male or female traits.

The presence of an additional X chromosome in males (XXY) results in Klinefelter syndrome. This condition can lead to infertility, hormonal imbalances, and other physical and cognitive effects.

X chromosomes are larger than Y chromosomes in humans. The Y chromosome is smaller and carries fewer genes compared to the X chromosome.

XYY syndrome is a genetic disorder caused by the presence of an extra Y chromosome in males. This condition can lead to tall stature, learning difficulties, and behavioral challenges.

Intersex refers to individuals who possess both male and female reproductive structures, or who have chromosomal, gonadal, or anatomical variations that do not fit typical definitions of male or female. It is a term used to describe a range of variations in sex characteristics.