We understand plant physiology as the way to describe, through physics and chemistry (and therefore mathematics), how plants produce their own organic matter by absorbing water and nutrients from the soil, capturing CO2 from the atmosphere around it and transforming solar energy into chemical energy.
This science tries to explain the functioning of the plant world by responding to the following points:
- Water balance in the plant; how water enters the plant, how it moves and how it leaves it.
- Mineral nutrition; what nutrients and what importance they have in the normal development and growth of plants, how they are absorbed and displaced to the different organs of the plant and how they are processed.
- Gaseous balance; inputs and outputs of CO2 and O2 depending on metabolic needs.
- Metabolic reactions that occur in illuminated plants and that lead them to synthesize their own organic matter.
- Vegetative growth; as through metabolism, vegetables obtain a gain of organic matter and energy.
- Formation of new plant structures.
- How environmental conditions influence the growth and development of the plant.
THE PLANT CELL
All living organisms are made up of fundamental anatomical unit cells of all living organisms, usually microscopic, consisting of cytoplasm, one or more nuclei and a membrane that surrounds it. Prokaryotic cells are characterized by not having a well-defined nucleus. The rest of the cells, both from the animal and plant worlds, contain a nucleus surrounded by a double membrane and are known as eukaryotes.
In eukaryotic cells, the genetic material, DNA, is included in a distinct nucleus, surrounded by a nuclear membrane. These cells also have several organelles delimited by membranes that divide the cellular cytoplasm into several compartments, such as chloroplasts, mitochondria, endoplasmic reticulum, the Golgi apparatus, vacuoles (a vacuole is a cellular organelle present in all plant eukaryotic cells.
It also appears in some animal prokaryotic and eukaryotic cells. Vacuoles are closed compartments or limited by the plasma membrane as they contain different fluids, such as water or enzymes, although in some cases they may contain solids, for example sugars, salts, proteins and other nutrients). Plant cells fall within the eukaryotic world.
There is a noticeable difference between animal cells and plant cells and this is the presence of a cell wall; this cell wall performs the functions of skin and skeleton of plants (it is responsible for the lignification or hardening of the stem) without preventing the diffusion of water and ions from the environment to the plasma membrane, which is the true permeability barrier of the cell. This wall can be of two types:
· Primary cell wall, which is the one that develops into an actively growing young cell.
· Secondary cell wall, which is the one that develops when the cell ceases to grow. This wall is formed on the inner face of the primary wall, having a different composition from that of the primary.
The most abundant compounds in plant cell walls are polysaccharides (carbohydrates formed by the binding of various sugar molecules). The three types of polysaccharides found in plant cell walls are cellulose, hemicellulose, and peptic substances. In addition we find proteins, lipids, lignin, waxes, cutin and minerals.