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Statement I: Developing dithecous anther is tetralocular.
                   Statement II: At maturity dithecous anther becomes bilocular.
A.Both statement I & II are correct
B.Both statement I & II are incorrect
C.Statement I is true but statement II is false.
D.Statement I is false but statement II is true.

Last updated date: 20th Jun 2024
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Hint: The male reproductive organ of a flower, anther is composed of individual units known as stamens. Stamens are comparable to microsporophylls of gymnosperms. Stamens may be arranged spirally, or concentrically in whorls. In some flowers they are arranged in many concentric whorls and in others they are arranged in one or two whorls.

Complete answer:
A stamen has three parts, namely filament, anther and connective. Filament is the slender stalk of the stamen and it terminally bears the anther. Those filaments which do not bear anthers at their tips are called staminodes.

Anther is the terminally bilobed structure. Proximal end of the filament is attached to the thalamus or the petal of the flower. The number and length of stamens are species specific. Normal angiosperm anther is bilobed with each lobe having two thecae, i.e. dithecous. The theca is separated by the longitudinal groove. The bilobed structure of anther is distinguishable in the transverse section of an anther.
The anther is tetragonal in structure consisting of four microsporangia situated at the corners, ie, two in each lobe. Developing dithecous anther is tetralocular. But at maturity, dithecous anther becomes bilocular. Mature pollen grain is two celled in state.
Further development of microsporangia produces pollen sacs. Pollen sacs extend longitudinally and are packed with pollen grains.

Microsporangium is generally surrounded by four layers. They are epidermis, endothecium, middle layers and tapetum. Outer three layers protection and dehiscence of anther. Innermost layer tapetum provides nourishment for pollen grains.

Additional information:
Pollen grains are the male gametophytes
They are spherical in shape.
Pollen grain has two layered walls, outer layer is exine and inner layer is intine.
Exine is formed of sporopollenin, which is a highly resistant material.
Pollen grain contains two cells, vegetative cell and generative cell.

Hence the correct answer is OPTION(A)

Note: Anthers are attached to the filaments in four distinct ways. Based on this, anthers are of four types, adnate, basifixed, dorsifixed and versatile. In adnate anthers, the filament is attached to the bulk of anther throughout its length. The extreme tip of filament is attached to the base of anther so that anthers seem to be sitting on the top of the filament in basifixed. In dorsifixed, filament is attached to the back of the anther. In versatile anthers, filament is attached to the middle of the anther.