WHAT ROLE DO CELLS PLAY IN PLANT?
Most of the cells in a plant stem are very strong, sometimes 100 times longer than they are wide. A plant size is determine by the number of cells it has – a big plant has a large number of cells, small plants have relatively few. There is a limit to the smallness of a flowering plant.
Though cells are uniform in size, they come in many shapes, and an easy way to see a large variety of these is to look at the hairs of plants. They maybe long or short, spiny or club-shaped; they maybe gland cells which excrete oil or digestive enzymes, or they may absorptive such as root hairs. When the cells are joined into tissue, the cell shapes are harder to recognize; then one has to made thin section with a razor blade. From a large number of such section, cut in different direction, the shape of cells can be inferred.
In the plant body there is a strict division of labor between various kind of cells. Some filled with chloroplasts, have the job of carrying out the vital process of photosynthesis, transforming energy from light into the cehmical energy the plant needs- these occur in the leaves. Others perform various function in roots and stem. The vessel is the transport system of moving water from the roots throughout its system and the sieve tubes which carry sugar from the photosynthesizing leaves.
A cell is the smallest unit of the plant. It reproduces itself, but also designs and organize the tissue that will provide framework, water and food supply, storage and protective outer covering. In plants, the cytoplasm carries some bodies that are quite different from an animal cells.
The growth of plants is accounted for by the simple swelling up and elongation of the cells as they absorbed water piped up from the roots. The tips of developing stems and roots grow through an increase of cells brought about by cell division.
Cell division may be trigerred by an increase in the amount of cytoplasm coupled with the synthesis of certain chemicals or by chemical action without previous growth. During this stage, the nucleus is large and the chromosomal materials is reproduced, molecule for molecule with all its genes. Coming together as threads, the chromosomes then condensed to compact bodies and mitosis begin.
