Details about reproduction in plants

1. SEXUAL REPRODUCTION
IN FLOWERING PLANTS
CHAPTER 2
Prepared by,
Bhanupriya R

2. A
B
C
D
F
G
H

3. • Anther is bilobed
• Dithecus
• Four sided structure -
microsporangia

4. Structure of microsporangium
• Microporangia Pollensacs

5. MICROSPOROGENESIS
Anther develops, the cells of the sporogenous tissue
undergo meiotic divisions to form microspore tetrad.
The process of formation of microspores from a
pollen mother cell through meiosis is called
microsporogenesis.

6. Microspores arranged Microspore tetrad
Mature
Pollen grains

7. PREVIOUS YEAR QUESTIONS
 A microsporangiumis surrounded by 4layers. Namethe first 3 layersand write theirfunction.
 Innermostwall layerof microsporangium whichnourishesthe developing pollen grainis called ....................
 Thedevelopment of pollengrains inangiosperms is called_________
 Observe the relationship between the first two terms and fill in the blank.
Endothecium: Protection; Tapetum : ___________
 Theinnermostwall layerof Microsporangium is Tapetum.
 (a) What is its function ?
 (b) Write two features of tapetal cells.

8. Two features of tapetum
Cells of the tapetum possess dense cytoplasm.
Have more than one nucleus.
They assistwith pollen grain growth and development.

9. Can you think of how tapetal cells could
become bi-nucleate?
Tapetal cells undergo endomitosis where
the nucleus in the nuclear membrane
splits, but cytokinesis does not happen.

11. Exine-
SPOROPOLLENIN
Intine – Cellulose and
pectin
Germ pore
sporopollenin is absent
Vegetative cell

12. Myosotis Mirabilis

13. In 60 % plants, Pollen grains shed at the 2-celled
stage.
In 40% plants, Generative cell mitotically to give rise
to the two male gamates before the pollen grains are
shed ( 3 Celled Stage)

14. Parthenium or carrot
grass – Pollen allergy

15. PISTIL,
MEGASPORANGIUM
AND EMBRYO SAC

16. APOCARPOUS SYNCARPOUS

17. Syncarpous apocarpous

18.  Placenta is located inside the ovary
 Arising from placenta are the megasporangia commonly
called ovules.

20. MEGASPOROGENESIS
 The process of formation of megaspores from the megaspore
mother cell is called megasporogenesis.
 Ovule generally differentiate a single megaspore mother cell(MMC)
in the micropylar region.
 MMC undergo meiosis and produce four megaspores.
1 -functional
3- degenerate

22. FEMALE GAMETOPHYTE
Only the functional megaspore develops into
the female gametophyte (embryo sac).
This method of embryo sac formation from a
single megaspore is termed monosporic
development.

23. FEMALE GAMETOPHYTE- 8 NUCLEATED 7 CELLED

24. PREVIOUS YEAR QUESTIONS
 Observe the relationship between the first two terms and fill in the blank.
Funicle : Stalk of the ovule
________ : Protective Envelopes of the ovule
 _______ is the female gametophyte of angiosperms
 Synergids have special cellular thickening at micropylar end. Write the name and function of this structure.
 A typical angiosperm embryo sac is 8-nucleate and 7-celled.
(a) Name the cells that constitute egg apparatus.
(b) Explain monosporic type of embryo sac development
 Reeja a science student observed the structure of a mature embryosac comprising antipodals, central cells and
egg apparatus. Explain each one of them.

27. Example of cleistogamous
Clitoria ternatea

28. AGENTS OF POLLINATION

31. MERITS OF CROSSPOLINATION
1.Genetic recombination and variability
2.Improved offsprings
3.Undesired characters are also removed
4.Increases adaptability
5.High yield and vigour

32. DEMERITS OF CROSS POLLINATION
• Dependent upon external agencies
• Pollen grains areto be produced in enormousquantities

33. POST – FERTILISATION EVENTS

35. ENDOSPERM
 Cells of endosperm are filled with reserve food materials and are used for the
nutrition of developing embryo.
 PEN Mitotic division Endosperm

41. EMBRYO
Zygote Pro embryo Globular
HEART SHAPED
Embryo

44. 2 cotyledons

46. SEED
ALBUMINOUS AND NON- ALBUMINOUS SEED
Remnants of nucellus are persistent in some seeds. This is called
perisperm
Eg. : Black pepper

47. SEED
Ovule Seed
INTEGUMENTS SEED COAT
MICROPYLE remain as small pore which
facilitate oxygen and water supply

48. FRUIT
 OVARY FRUIT
FRUITS ARE OF TWO TYPES
FALSE FRUIT
TRUE FRUIT

49. FALSE FRUIT

50. TRUE FRUITS

51. Fruit develop without fertilisation is called
Parthenocarpic fruits.

54. APOMIXIS – SEEDS WITHOUT
FERTILISATION

56. POLYEMBRYONY