Question

Read the following statements about the menstrual cycle and select two correct statements.
(i)Lack of menstruation may be indicative of pregnancy.
(ii)The changes in the ovary and the uterus are induced by changes in the levels of ovarian hormones only.
(iii)LH surge induces ovulation.
(iv)If fertilization occurs, corpus luteum degenerates immediately.
(a)(i) and (ii)
(b)(ii) and (iii)
(c)(i) and (iii)
(d)(ii) and (iv)

Answer 1

Hint: Menstruation is a cyclic process that occurs in the females of primates with an average interval of 28-30 days. It is a very complicated process and is controlled by many hormones. Ovulation happens in the middle of the menstrual cycle.

Complete answer:
The menstrual cycle begins at the age of puberty and continues up to menopause and stopping temporarily in case of pregnancy. In the case of pregnancy, the corpus luteum develops and keeps releasing progesterone which does not let the lining of the endometrium to shed. This is done so that implantation can occur in the uterus lining.
In the absence of pregnancy, the corpus luteum degenerates, and the lining of the uterus is shed as menstrual flow. This marks the beginning of a new menstrual cycle. During the 14th day of the menstrual cycle, there is a sudden surge of Luteinizing hormone LH which induces ovulation.
During the menstrual cycle, changes occur in the ovary and uterus under the influence of the pituitary (LH and FSH) and ovarian hormones (estrogen and progesterone).
So, the correct answer is ‘(i) and (iii)’.

Note: -Corpus luteum is formed by the remains of the Graafian follicle after ovulation.
-The absence of menstruation can happen due to many reasons such as stress, PCOS, etc other than pregnancy.
-In human beings, the menstrual cycle ceases at the age of 50 years and is known as menopause. After this, the female can no longer produce offsprings i.e. not fertile anymore.