Heredity and Sex Determination

In humans, the sex of an offspring is determined by the presence of either an X or a Y chromosome from the father. If the father contributes an X chromosome, the offspring will be female (XX). If the father contributes a Y chromosome, the offspring will be male (XY).

Environmental sex determination refers to the influence of environmental factors on an organism's sex. This means that the sex of an organism is not solely determined by genetics, but also by external factors like temperature or social conditions.

In temperature-dependent sex determination, the sex of the offspring is determined by the temperature experienced during a specific period of embryonic development. Some species are more likely to produce females at cooler temperatures and males at warmer temperatures.

The sex ratio of an organism (the proportion of males and females) is influenced by environmental temperature in some species. For example, in alligator snapping turtles, warmer temperatures during embryonic development lead to a higher proportion of males, while cooler temperatures tend to produce more females.

Parthenogenesis, also known as virgin birth, is a form of reproduction where an offspring develops from an unfertilized egg. This means that the offspring inherits all its genetic material from its mother, without any contribution from a male.

In the Komodo Dragon, females can reproduce through parthenogenesis, meaning they can lay fertile eggs without mating. The offspring are genetically identical to their mothers.

In the WZ sex determination system, the female is the heterogametic sex, possessing two different sex chromosomes (WZ). The male is the homogametic sex, possessing two identical sex chromosomes (ZZ). Individuals with WW chromosomes are typically not viable, meaning they do not survive.

Meiosis is a type of cell division that occurs in sexually reproducing organisms to produce gametes (sperm and egg cells). It is characterized by two rounds of division, resulting in four daughter cells with half the number of chromosomes as the parent cell. Meiosis is essential for genetic diversity and the formation of new combinations of genes.