1 of 16

https://www.onlinesciencestudy.com

1

5/17/2022

1

1

1

1

11/05/2020 09:26PM

1

BIOLOGY in Marathi

Understanding is IMPORTANT.......

Prof. Deshmukh A. B.'s Biology Class

https://www.onlinesciencestudy.com

2 of 16

https://www.onlinesciencestudy.com

2

5/17/2022

1. REPRODUCTION IN LOWER & HIGHER PLANTS

-CREATED BY-

PROF. DESHMUKH A. B.

ASST. TEACHER

SEC. & HIGHER SEC. SCHOOL, SHENDI (BHANDARDARA DAM),

TAL. – AKOLE, DIST. - AHMEDNAGAR

3 of 16

1.11 Development of Embryo :

  • The process of development of zygote into an embryo is called embryogenesis.

https://www.onlinesciencestudy.com

3

5/17/2022

4 of 16

  • The embryo is developed at the micropylar end of embryo sac.
  • After fertilization the embryonic development begins.

​

https://www.onlinesciencestudy.com

4

5/17/2022

PEN

Zygote (Oospore)

5 of 16

https://www.onlinesciencestudy.com

5

5/17/2022

The growth of embryo triggers only after certain amount of endosperm is formed.

Endosperm

Oospore

Proembryo

6 of 16

  • The zygote divides to form two- celled proembryo.
  • The larger cell towards the micropyle is called basal or suspensor initial cell.
  • The smaller cell towards chalaza is called terminal or embryonal initial cell.
  • The suspensor cell divides transversely in one plane to produce filamentous suspensor of 6-10 cells.

https://www.onlinesciencestudy.com

6

5/17/2022

7 of 16

https://www.onlinesciencestudy.com

7

5/17/2022

Haustorium

8 of 16

  • The first cell of the suspensor towards the micropylar end becomes swollen and function as a haustorium.
  • The lowermost cell of suspensor is known as hypophysis.
  • The suspensor helps in pushing the embryo in the endosperm.

https://www.onlinesciencestudy.com

8

5/17/2022

9 of 16

https://www.onlinesciencestudy.com

9

5/17/2022

10 of 16

  • The embryonal initial undergoes three successive mitotic divisions to form octant.
  • The planes of divisions are at right angles to each other.
  • The lower tier of four cells of octant give rise to hypocotyl and radicle whereas
  • The four cells of upper tier form the plumule and the one or two cotyledons.

https://www.onlinesciencestudy.com

10

5/17/2022

Upper tier

Lower tier

11 of 16

https://www.onlinesciencestudy.com

11

5/17/2022

12 of 16

  • The hypophysis by further division gives rise to the part of radicle and root cap.
  • Subsequently, the cells in the upper tier of octant divide in several planes so as to become heart shaped which then forms two lateral cotyledons and a terminal plumule.
  • Further enlargement of hypocotyl and cotyledons result in a curvature of embryo and it appears horse-shoe shaped.

https://www.onlinesciencestudy.com

12

5/17/2022

13 of 16

  • The embryo development is similar in both dicots and monocots up to the octant stage.

https://www.onlinesciencestudy.com

13

5/17/2022

Initial Development of Monocot Embryo

14 of 16

  • The difference appears later.
  • In monocot embryo, single cotyledon occupies terminal position and plumule is lateral.

​

https://www.onlinesciencestudy.com

14

5/17/2022

15 of 16

  • The single shield shaped cotyledon is called as scutellum.
  • The protective sheath of plumule is called coleoptile and that of radicle is coleorhiza.

​

https://www.onlinesciencestudy.com

15

5/17/2022

16 of 16

  • Finally,

ovule is transformed into the seed and

ovary into the fruit.

​

https://www.onlinesciencestudy.com

16

5/17/2022