Read the following passage and answer the next five questions:
The reproductive cycle of female primates is called menstrual cycle. Menstrual cycle starts only after attaining sexual maturation (puberty). Generally, during ovulation only one ovum is released per menstrual cycle. The cyclical changes in the ovary and the uterus during menstrual cycle are induced by changes in the levels of pituitary and ovarian hormones. After coitus, sperms are transported to the junction of the isthmus and ampulla, where the sperm fertilises the ovum leading to formation of a diploid zygote.
Which of the following does not take place before ovulation in human female?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → The corpus luteum secretes large amounts of progesterone.
The menstrual cycle has a follicular phase before ovulation (about day 14) and a luteal phase after it.
Option (1) The secretion of LH and FSH increases during follicular phase. — Takes place before ovulation. The follicular phase comes before ovulation. The rising LH (luteinising hormone) and FSH (follicle stimulating hormone), the gonadotropins of the pituitary, make the follicles grow and secrete estrogens.
Option (2) The corpus luteum secretes large amounts of progesterone. — Does not take place before ovulation. The corpus luteum is formed from the remains of the Graafian follicle after it has released the ovum. So it cannot exist, or secrete progesterone, before ovulation. This happens in the luteal phase.
Option (3) LH and FSH attains a peak level in the middle of the cycle. — Takes place before ovulation. The peak of LH (luteinising hormone) and FSH (follicle stimulating hormone) comes in mid-cycle, just before and leading to ovulation.
Option (4) Maximum secretion of LH induces rupture of Graafian follicle. — Takes place before ovulation. The LH surge, the rapid rise of luteinising hormone to its maximum, breaks open the Graafian follicle. This rupture is the event that releases the ovum, so it comes first.
Note: This passage is taken from NCERT as it is. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.
NCERT Extract:
Menstrual Cycle – “… The secretion of gonadotropins (LH and FSH) increases gradually during the follicular phase, and stimulates follicular development as well as secretion of estrogens by the growing follicles. Both LH and FSH attain a peak level in the middle of cycle (about 14th day). Rapid secretion of LH leading to its maximum level during the mid-cycle called LH surge induces rupture of Graafian follicle and thereby the release of ovum (ovulation). The ovulation (ovulatory phase) is followed by the luteal phase during which the remaining parts of the Graafian follicle transform as the corpus luteum (Figure 2.9). The corpus luteum secretes large amounts of progesterone which is essential for maintenance of the endometrium.”
