Class 12th Biology 2014 Set1 Delhi Board Paper Solution

Question 28

(a) Coconut palm is monoecious, while date palm is dioecious. Why are they so called?

(b) Draw a labelled diagram of sectional view of a mature embryo sac of an angiosperm.

OR

(a) How is 'oogenesis' markedly different from 'spermatogenesis' with respect to the growth till puberty in the humans?

(b) Draw a sectional view of human ovary and label the different follicular stages, ovum and Corpus luteum.

Answer

(a) Coconut palm is monoecious because both male and female flowers are borne on the same plant.

Date palm is dioecious because these plants bears exclusively either male flowers or female flowers.

(b) Diagram showing sectional view of a mature embryo sac of an angiosperm

(a)

Spermatogenesis	Oogenesis
It is the process by which sperms are formed from the sperm mother cell in males	It is the process by which ovum is formed from the oogonia in females
After the second meiotic divisions in a single spermatogonium, 4 spermatids are obtained, which undergo maturation to form 4 sperm cells, or spermatozoa	After the second meiotic divisions in the single oogonium, only one ovum and three polar bodies are obtained.
Spermatogenesis occurs in males from puberty almost until death.	In females, oogenesis starts before birth and occurs until menopause.

(b)