If there are 4 microspore mother cells in an anther, what will be the number of pollen grains?
After double fertilisation, a mature ovule has
I diploid and I haploid cell
1 diploid and I triploid cell
2 haploid and I triploid cell
1 haploid and I triploid cell
1 diploid and I triploid cell
Double fertilisation is found only in angiosperms. In this group of plants, the pollen tube on entering the embryo sac bursts open in one of the two synergids to release the two male gametes.
One male gamete fuses with the egg or oosphere to form a diploid zygote or oospore. It is called generative fertilisation.
The second male gamete descends down and fuses with the diploid secondary nucleus of the central cell to form a triploid primary endosperm cell. It is known as vegetative fertilisation.
Thus, after double fertilisation, a mature angiospermous ovule contains one diploid cell (zygote) and one triploid cell (primary endosperm cell). The haploid cells of the ovule such as antipodals and synergids degenerate after fertilisation
Identify the parts labelled A, B, C and D in the given figure and select the correct option.
A- Scutellum, B- Epiblast, C- Coleoptile, D- Coleorhiza
A- Scutellum, B- Coleorhiza, C- Coleoptile, D- Epiblast
A- Scutellum, B- Coleoptile, C- Coleorhiza, D- Epiblast
A- Epiblast, B- Coleoptile, C- Coleorhiza, D- Scutellum
Match column I with column II and select the correct option from the given codes.
|Column I||Column II|
|A. Parthenocarpy||(i) Seed formation without fertilisation|
|B. Polyembryony||(ii) More than one embryo in same seed|
|C. Apomixis||(iii) Seedless fruits without fertilisation|
|D. Somatic embryogenesis||(iv) Embryo develops from a somatic cell|
A- (iv), B- (ii), C- (iii), D- (i)
A- (iii), B- (ii), C- (i), D- (iv)
A- (i), B- (iv), C- (iii), D- (ii)
A- (ii), B- (iii), C- (i), D- (iv)
What is the correct sequence of the formation of female gametophyte in angiosperms
Nucellus, megapore tetrad, megaspore mother cell, megaspore, female gametophyte
Megaspore tetrad, nucellus, megaspore mother cell, megaspore, female gametophyte
Nucellus, megaspore mother cell, megaspore tetrad, megaspore, female gametophyte
Megaspore mother cell, megaspore tetrad, megaspore, nucellus, female gametophyte
Primary endosperm nucleus (PEN) is formed by the fusion of
2 polar nuclei + I synergid cell nucleus
I polar nucleus + I antipodal cell nucleus + I synergid cell nucleus
2 polar nuclei+ I male gamete nucleus
2 antipodal cell nuclei + I male gamete nucleus
Tetradynamous condition is found in
formation of seeds by fusion of gametes
formation of seeds without syngamy and meiosis
formation of seeds with syngamy but no meiosis
none of the above
The following is the diagram of T.S. of anther. Identify the parts labelled A, B and C.
A- Connective tissue, B- Pollen grain, C- Endothecium
A- Endothecium, B- Connective tissue, C- Pollen grains
A- Pollen grains, B- Connective tissue, C- Endothecium
A- Endothecium, B- Pollen grains, C- Connective tissue
Assertion : Endothecium layer of anther wall plays an important role in dehiscence of anther.
Reason : The presence of fibrous bands and differential expansion of inner and outer tangential walls of endothecial cells cause dehiscence of anther.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false