Q22 of 42 Page 1

Explain the events in a normal woman during her menstrual cycle on the following days.

(a) Ovarian event from 13-15 days


(b) Ovarian hormones level from 16 to 23 days
(c) Uterine events from 24 to 29 days


a. During the 13-15 days, the ovulatory phase occurs in the menstrual cycle. The Graafian follicle ruptures to release the ovum. Generally, on the 14th day of the cycle, one ovum is released from one ovary. This process is called ovulation.

b. During the 16-23 days, the oestrogen levels drop whereas the progesterone levels increase.


c. During 24-29 days, the inner lining of the uterus i.e., endometrium, disintegrates and the menstrual cycle begins again.


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(a) Dihybrid cross between two garden pea plant one homozygous tall with round seeds and the other dwarf with wrinkled seeds was carried.


(i) Write the genotype and phenotype of the F1 progeny obtained from this cross.


(ii) Give the different types of gametes of the F1 progeny.


(iii) Write the phenotypes and its ratios of the F2 generation obtained in this cross along with the explanation provided by Mendel.


(b) How were the observations of F2 progeny of dihybrid crosses in Drosophila by Morgan different from that of Mendel carried in pea plants ? Explain giving reasons.