Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Sex determination is the genetic or environmental mechanism by which the sex of an individual is decided during development.
In humans, sex is determined genetically. There are pairs of chromosomes in the nucleus of human cells.
pairs are called autosomes, which do not determine the sex of the individual.
The pair is known as the sex chromosomes. Females have a perfect pair of sex chromosomes, both called chromosomes ().
Males have a mismatched pair of sex chromosomes, one normal-sized and one shorter chromosome ().
All children inherit an chromosome from their mother regardless of whether they are boys or girls.
The sex of the child is determined by what they inherit from their father. An chromosome from the father results in a girl (), while a chromosome from the father results in a boy ().
In some animals like snails, individuals can change sex, indicating that sex is not always genetically determined. In some reptiles, the temperature at which fertilized eggs are kept determines the sex.
📐Formulae
💡Examples
Problem 1:
Show the inheritance of sex in humans using a flow chart (Punnett Square).
Solution:
Explanation:
The Punnett square shows that there is a ratio or chance for the offspring to be either male or female. Since the mother only produces gametes with chromosomes, the chromosome from the father is the deciding factor for a male child.
Problem 2:
A woman has only daughters. Does it mean that the woman's body is responsible for producing only female children? Explain.
Solution:
No, the woman is not responsible. Mathematically: . .
Explanation:
In human beings, the sex of the child depends on the type of sperm that fertilizes the egg. If a sperm carrying the chromosome fertilizes the egg, the child will be a girl (). If a sperm carrying the chromosome fertilizes the egg, the child will be a boy (). Since the woman produces only -type eggs, she cannot be the determining factor for the sex of the child.