LIVE Course for free

Rated by 1 million+ students
Get app now
JEE MAIN 2023
JEE MAIN 2023 TEST SERIES
NEET 2023 TEST SERIES
NEET 2023
CLASS 12 FOUNDATION COURSE
CLASS 10 FOUNDATION COURSE
CLASS 9 FOUNDATION COURSE
CLASS 8 FOUNDATION COURSE
0 votes
12.5k views
in Biology by (49.8k points)

With a neat labelled diagram, explain the 7 celled, 8 nucleate nature of the female gametophyte.

1 Answer

+1 vote
by (61.0k points)
selected by
 
Best answer

The female gametophyte (embryo sac) develops from a single functional megaspore. Thus, megaspore undergoes three successive mitotic divisions to form 8 nucleate embryo sac. The first mitotic division in the megaspore forms 2 nuclei. One nucleus moves towards the micropylar end while the other nucleus moves towards the chalazal end. Then these nuclei divide at their respective ends and redivide to form 8 nucleate stages.

As a result there are 4 nuclei each at both the ends i.e., at the micropylar and the chalazal end in the embryo sac. At the micropylar end, out of 4 nuclei only 3 differentiate into 2 synergids and one egg cell. Together they are known as egg apparatus. Similarly, at the chalazal end 3 out of 4 nuclei differentiates as antipodal cells. The remaining 2 cells (of the micropylar and chalazal end) move towards the centre and are known as the polar nuclei, which are situated in the centre of embryo sac. Hence, at maturity, the female gametophyte appears as a 7 celled structure, though is has 8 nucleate.

Welcome to Sarthaks eConnect: A unique platform where students can interact with teachers/experts/students to get solutions to their queries. Students (upto class 10+2) preparing for All Government Exams, CBSE Board Exam, ICSE Board Exam, State Board Exam, JEE (Mains+Advance) and NEET can ask questions from any subject and get quick answers by subject teachers/ experts/mentors/students.

Categories

...