▶️ Answer/Explanation
The menstrual cycle begins with Day $1$, which marks the first day of menstruation. During this phase, if fertilization has not occurred, the levels of progesterone and estrogen drop significantly. This hormonal shift causes the thickened functional layer of the uterus lining (endometrium) to lose its blood supply and shed. This shedding process is what we recognize as a period, where the lining literally breaks down and exits the body. Following this, the cycle moves into the follicular phase where the lining begins to repair and thicken again under the influence of rising estrogen levels. Therefore, the very start of the cycle is defined by the breakdown of the lining.
✅ Answer: (A)
✅ Answer: (A)
▶️ Answer/Explanation
Testosterone is the primary male sex hormone produced in the testes. During puberty, increased levels of testosterone trigger the development of secondary sexual characteristics in males. These include the deepening of the voice, increased muscle mass, and the stimulation of hair follicles leading to facial hair growth. In contrast, options (A), (C), and (D) are characteristics primarily driven by female sex hormones like estrogen and progesterone. Therefore, facial hair growth is the only characteristic listed that is directly associated with testosterone.
✅ Answer: (B)
▶️ Answer/Explanation
In a standard $28$-day menstrual cycle, ovulation—the release of a mature egg from the ovary—typically occurs at the midpoint, which is day $14$. The cycle begins with menstruation (days $1$–$5$), where the uterine lining breaks down and is shed, making option D incorrect. Following this, the lining repairs and thickens. After ovulation on day $14$, the lining continues to thicken and becomes highly vascularized to prepare for potential pregnancy, meaning it does not break down during days $14$–$21$ as suggested in option C. Therefore, the release of the egg on day $14$ is the only accurate description provided.
✅ Answer: (A)
✅ Answer: (A)