Tag: cell division in embryo development

RBC (red blood cell) of the human is the best material for the study of structure of cell membrane. Chemical studies on the RBC cell membrane enabled the scientists to infer the possible structure of plasma membrane.

A typical cell is composed of the plasma membrane (boundary), the cytosol (fluid matrix), and various organelles (functional structures).

The cell membrane acts as a selective barrier that regulates the transport of materials, provides structural integrity, and maintains the internal environment of the cell. All listed functions are primary roles of the plasma membrane.

The movement of pollen tube towards embryosac though style is chemotactic as it secrets pectinases and other hydrolytic enzymes to create a passage for its entry into style .

12, 36, 24; because pollen grains are haploid while endosperm has triploid chromosome number and integument is diploid in nature.

In porogamy, filiform apparatus of synergids secretes, some chemotropically active sunstances, which direct the pollen tube towards micropyle of ovule.

The pollen grain wall consists of an outer exine (sporopollenin) and an inner intine. The intine is composed of pecto-cellulose.

This type of tapetum can be seen easily in Alisma, Butomus, Tradescantia, and Typha, etc. The tapetal cells fuse among themselves for forming a tapetal plasmodium. The protoplast of the fused tapetal cells then moves into the locule, where they surround the pollen mother cells or pollen grains. This protoplast movement into the locule is taking place during meiotic prophase. 

Thus the correct answer is option D.

The pollen wall actually is the multi-layered structure that includes an intine, which is composed mainly of polysaccharide, and an exine, which consists mainly of sporopollenin. The exine can be further divided into the sexine and nexine. Sexine is the single layer of bacula which is covered by a layer of the tectum.

So the correct answer is C.