Skip to main content

Development of Female Gametophyte Short Note class 12


Describe the development of female gametophyte of  angiosperms?(5 mark)


Ans-The process of development of female gametophyte or embryo sac from megaspore is called megagametogenesis.

      The megaspore is the first cell of the female gametophyte.The process of formation of megaspore from the megaspore mother cell is called megasporogenesis.
Development of female gametophyte:-
i) The functional megaspore is the first cell of female gametophyte.

ii) The nucleus of the megaspore divide mitotically to form eight nuclei.

iii) Generally four nuclei are seen at the micropylar end and other four,seen at chalazal end of the enlarged megaspore.

iv) One nucleus from each end migrate to the centre of embryo sac and form polar nuclei.

v) The three cell at the micropylar end form egg apparatus and those at chalazal end form antipodal cells.



Structure of female gametophyte:-


  • The female gametophyte is a 7 celled and 8 nucleotide structure.

  • The middle cell of egg apparatus called egg cell  and two laterally placed cells are called synergies

  • Polar nuclei situated in the centre of the embryo sac.
The antipodal cells at chalazal end are degenerate soon after fertilization.

Conclusion:-

  • After formation of female gametophyte,fertilization may take place in favourable condition in angiospermic plant it is double fertilization and triple fusion.
  • After fertilization the egg cell develop into embryo and polar nuclei develop into endosperm.

Comments

Post a Comment

Popular posts from this blog

CLASS 12 PHYSICS - ELECTROSTATICS ( Long and Short Questions Most probable)

ELECTROSTATICS (Long And Short Questions) Short Q: State Gauss's law in Electrostatics? State the properties of equipotential lines? What is electric dipole and dipole moment? Quantization of charge means? What is Coulomb's law? What is Electric field? Potential Difference? Electric flux? Equipotential Surface? Gauss Law? Capacitor? Capacitance? Use of capacitor? Long Q: Derive an expression for the Electric field intensity at a point on the equipotential line or, on broadside-on-position or, on TAN-B position of the Electric dipole? Derive an expression for Electric field intensity at a point on the axial line or, on end on position or,TAN-A position of the electric dipole? State Gauss's law of Electrostatics. Then give its application to derive for Electric field intensity due to uniformly Charged infinite planed sheet. Drive an expression for the Electric field intensity due to an infinitely long, straight wire of linear charge density \cm-. Drive Coulomb's law using...
Post a Comment
Read more

What is Electrostatics?Class12

Electrostatics : Definition: It is branch of science which deals with the study of charges at rest. It is also known as static electricity or frictional electricity. Electric Charge: Electric charge is an Intrinsic property of the elementary particles like electrons, protons etc.of which all the objects are made up of. Quantization of charge: The quantization of charge means that charge can exist only as integral multiple of electronic charge i.e. q=+-ne,where n is an integer. • It was first suggested by by faraday. Charge conservation: In an isolated system,the total net charge of the system always remains constant. Charge is always associated with mass : Charge can not exist without mass though mass can be exist without charge. Additivity of charge:  Total charge of a system is the algebraic sum of all individual charges in the system. Charge is invariant:  Charge is independent of the frame of reference. Coulomb's Law:  Coulomb's law states that the magnitude of ...
Post a Comment
Read more