This set of Class 12 Biology Chapter 3 Multiple Choice Questions & Answers (MCQs) focuses on “Human Reproduction – Menstrual Cycle – 2”.
1. The regeneration of uterine wall begins during what phase?
a) Menstrual phase
b) Follicular phase
c) Luteal phase
d) Secretory phase
Explanation: The menstrual phase involves shredding of the uterine endometrium. Right after menses, the follicular phase onsets. During this phase, the endometrium starts to regenerate.
2. What pituitary hormones peak during the proliferative phase?
a) LH only
b) FSH only
c) Neither LH or FSH
d) LH and FSH
Explanation: The anterior pituitary releases Luteinizing Hormone and Follicle Stimulating Hormone as the proliferative phase or follicular phase progresses. Both of these hormones along with the ovarian hormone estrogen is responsible for the regeneration of uterine wall and maturation of follicles.
3. Which of the following does not occur during the follicular phase?
a) Maturation of primary follicles to Graafian follicles
b) Peaking of estrogen
c) Peaking of progesterone
d) Regeneration of uterine endometrium
Explanation: Follicular phase is an important phase to ensure the development of egg and maturation of the follicle it is contained in. It is also characterized by the thickening of uterine wall. These changes are brought about the pituitary hormones LH and FSH and the ovarian hormone estrogen. Progesterone is required for egg release and it peaks during the luteal phase.
4. The luteal phase is also called as ______
a) secretory phase
b) proliferative phase
c) menstrual phase
d) follicular phase
Explanation: Luteal phase involves the rupture of the Graafian follicle and the release of egg from the ovary. Hence it is also called the secretory phase.
5. A student was studying primate uterine thickness. She had 3 samples of uterine tissues. The thickness in mm for the samples are as follows:
Sample A – 4 mm, Sample B – 10 mm, Sample C – 1 mm
Given the knowledge of menstrual cycle in humans, what phases do you think each sample belongs to?
a) Sample A: Menstrual phase, Sample B: Follicular phase, Sample C: Luteal phase
b) Sample A: Proliferative phase, Sample B: Luteal phase, Sample C: Menstrual phase
c) Sample A: Secretory phase, Sample B: Menstrual phase, Sample C: Proliferative phase
d) Sample A: Menstrual phase, Sample B: Secretory phase, Sample C: Follicular phase
Explanation: The uterine endometrium is shed off during menstrual phase. Thus this wall has the least thickness. During the follicular or proliferative phase, the endometrium starts building up and the wall is completely thick during the luteal or secretory phase to house the expected fertilized egg.
6. Which hormone surge triggers ovulation?
Explanation: LH is released by the anterior pituitary. It reaches a peak level during the middle of menstrual cycle. This is called LH surge. It acts on Graafian follicles causing their rupture and release of egg in the process of ovulation.
7. Luteal phase is characterized by the conversion of a ruptured Graafian follicle into _______
a) corpus luteum
b) corpus albicans
c) corpora quadrigemina
d) primary follicle
Explanation: During the luteal or secretory phase, the Graafian follicle is ruptured and the egg is released from the ovum into the fallopian tube to encounter the sperm. The empty Graafian follicle gets filled with the external theca and granulosa cells. This is the onset of degeneration of Graafian follicle and is called the corpus luteum.
8. What hormone is responsible for the maintenance of endometrium?
Explanation: Progesterone is secreted by the corpus luteum. It is responsible for proper maintenance of the embryo so that if an egg is fertilized, the developing embryo can get a proper attachment and doesn’t exit through vagina.
9. What part of ovary secretes progesterone?
b) Epithelial covering
c) Graafian follicle
d) Corpeus luteum
Explanation: Corpeus luteum is formed by the degeneration of Graafian follicle after it releases an egg. This degenerating tissue releases progesterone to maintain the proper function and structure of endometrium.
10. What is the fate of corpus luteum in case of unfertilized egg?
a) Rapid proliferation
c) Secretion of progesterone
d) Onset of next menstrual cycle
Explanation: Corpus luteum releases progesterone to support endometrium required for homing the embryo. But if the egg is not fertilized, the endometrium is useless and should be released off to save energy. Thus corpus luteum is degraded.
11. The end of menstrual cycle is called _______
Explanation: Menopause in humans occurs at an age of approximately 55 years. This is the last menstrual cycle. Thus the normal reproductive phase lasts between menarche and menopause.
12. Which hormone elevates twice during a menstrual cycle?
Explanation: LH and FSH peak during the middle of the menstrual cycle. Progesterone peaks after release of egg due to formation of corpus luteum. Estrogen peaks twice. First during the ovulation and second prior to menstruation.
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