Question

Number of cells and nuclei in embryo sac in flowering plants are

• A. 7, 8
• B. 6, 8
• C. 8, 7
• D. 8, 6

Hint:

Structure of a typical mature embryo sac (Polygonum type) in angiosperms: - 7-celled, 8-nucleate. - Components: - Egg apparatus (at micropylar end): 1 egg cell + 2 synergids (total 3 cells, 3 nuclei). - Central cell: Contains 2 polar nuclei (total 1 cell, 2 nuclei). - Antipodal cells (at chalazal end): 3 antipodal cells (total 3 cells, 3 nuclei). - Sum: 3+1+3 = 7 cells; 3+2+3 = 8 nuclei.

Answer 1

The Correct Option is A

Step 1: Recall the structure of a mature embryo sac (female gametophyte) in most flowering plants (Polygonum type).
A mature embryo sac is typically a 7-celled, 8-nucleate structure.

Step 2: Describe the components.
The components are: - Egg apparatus: Located at the micropylar end.
It consists of: - One egg cell (1 cell, 1 nucleus).
- Two synergid cells (2 cells, 2 nuclei).
- Central cell: A large cell located in the center.
It contains: - Two polar nuclei (which may fuse to form a diploid secondary nucleus before or after fertilization).
Initially, these are two distinct nuclei within the single central cell.
(1 cell, 2 nuclei).
- Antipodal cells: Located at the chalazal end.
Typically, there are: - Three antipodal cells (3 cells, 3 nuclei).

Step 3: Count the total number of cells and nuclei.
- Total cells = 1 (egg) + 2 (synergids) + 1 (central cell) + 3 (antipodals) = 7 cells.
- Total nuclei = 1 (in egg) + 2 (in synergids) + 2 (polar nuclei in central cell) + 3 (in antipodals) = 8 nuclei.
Thus, the embryo sac is 7-celled and 8-nucleate.

Step 4: Match with the options.
The number of cells is 7 and the number of nuclei is 8.
This matches option (1) "7, 8".