(a) When a seed of an orange is squeezed, many embryos, instead of one are observed. Explain how it is possible.
(b) Are these embryos genetically similar or different ? Comment.
                                                OR
(a) Explain the following phases in the menstrual cycle of a human female : (i) Menstrual phase (ii) Follicular phase (iii) Luteal phase
(b) A proper understanding of menstrual cycle can help immensely in family planning. Do you agree with the statement? Provide reasons for your answer.

a) This phenomenon is called polyembryony. The nucellar cells which surround the embryo sac divides and protrudes into the embryo sac. This gives rise to multiple embryos.

b) Since this embryo is formed mitotically no genetic variation is seen. Hence they are genetically similar.

                                                   OR

a.
 

Menstrual phase: It occurs from day 1-5 . In this event the endometrium wall breaks down.
Follicular phase : It occurs from 1-13 days. Follicle maturation occurs and FSH secretion begins. Estrogen secretion increases. Ovulation occurs at 14 th day. LH spikes.
Luteal phase: It occurs from 15-28 days. LH secretion continues. Progesterone secretion increases. Corpus luteum is formed.
b) A proper understanding of menstrual cycle will help in family planning. At the 14th day of menstrual cycle ovulation occurs. So on this day coitus should be avoided as the chance of fertilization is maximum during this time.