Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
The reproductive phase of life begins at puberty (around to years of age) and generally lasts until the age of approximately to years in females, whereas it lasts much longer in males.
In females, the cycle of producing an egg, its maturation, thickening of the uterine wall, and its breakdown (if fertilization does not occur) is called the Menstrual Cycle. This cycle occurs roughly every to days.
Menarche refers to the first menstrual flow that begins at puberty, while Menopause is the stage at which the menstrual cycle stops permanently.
Sex determination in humans depends on sex chromosomes. Humans have pairs of chromosomes; one pair consists of sex chromosomes, designated as and .
Females have two chromosomes (), while males have one and one chromosome ().
All female gametes (ova) contain one chromosome. Male gametes (sperms) are of two types: one type has an chromosome and the other has a chromosome.
The sex of the unborn child depends on whether the zygote has or chromosomes, which is determined by the type of sperm that fertilizes the egg.
📐Formulae
💡Examples
Problem 1:
A woman gives birth to a baby girl. Explain using chromosomal notation how the sex of this child was determined at the time of fertilization.
Solution:
The baby girl has the sex chromosome configuration of . This occurred because an egg (which always carries an chromosome) was fertilized by a sperm carrying an chromosome.
Explanation:
Since the mother only produces gametes with chromosomes (), the father's sperm determines the sex. In this case, the sperm must have been , resulting in a zygote with chromosomes.
Problem 2:
Calculate the approximate duration of the reproductive phase in a woman if she attains menarche at years and menopause at years.
Solution:
Duration = years.
Explanation:
The reproductive phase is the period between menarche and menopause during which the female is capable of conceiving.