Q. 25

(a) Draw a labell

Answer :

(a)


Figure:Sectional view of microsporangium of an angiosperm


(b) The development of male gametophyte in the microsporangium as follow:


• The each cell of the sporogenous tissue is capable of gives rise to microspore tetrad.


• Each one is potential pollen or microspore mother cell.


• The microsporogenesis is the process of formation of microspores from a pollen mother cell (PMC) through meiosis.


• As microspores are formed, they are arranged in a cluster of four cells that is the microspore Tetrad.


• As the anthers mature and dehydrate after that the microspores dissociate from each other and develop into pollen grains.


• 4-pollen grains represent the male gametophytes and are shed at 2-celled stage.


Explanation:



OR


(a)


• At the age of puberty, spermatogenesis starts due to the secretion of gonadotropin releasing hormone (GnRH). In testis spermatogonia (the immature male germ cells) produce sperms by the process of spermatogenesis.


• On the inside wall of seminiferous tubules, the spermatogonia present and they are multiply by mitotic division and eachspermatogonium is diploid (2N).


• Primary spermatocytes periodically undergo meiosis and complete the first meiotic division (reduction division).


• The first mitotic division leading to the formation of two equal haploid cells (2N) called secondary spermatocytes.


• For the production of 4 equal haploids (N) spermatids, the secondary spermatocytes undergo for the second mitotic division.


• Spermiogenesis is the process by which the spermatids are transformed into spermatozoa (sperms).


• Flow chart of spermatogenesis



(b)



Fig. Mature human sperm


i. Tail


ii. Middle piece/ mitochoridria


iii. Acrosome


Explanation:(a)



(b)



Rate this question :

How useful is this solution?
We strive to provide quality solutions. Please rate us to serve you better.
Try our Mini CourseMaster Important Topics in 7 DaysLearn from IITians, NITians, Doctors & Academic Experts
Dedicated counsellor for each student
24X7 Doubt Resolution
Daily Report Card
Detailed Performance Evaluation
caricature
view all courses
RELATED QUESTIONS :

Write the sex of Biology - Board Papers

Why do gametes prBiology - Exemplar