Razzaq Archive
During seed maturation , the embryo enters a quiescent phase in response to desiccation. Seed germination can be defined as the resumption of growth of the embryo of the mature seed; it depends on the same environmental conditions as vegetative …
Unlike auxins, gibberellins, and cytokinins, the hormone abscisic acid(ABA) is represented by a single 15-carbon sesquiterpene. ABA also appears to have a more limited range of specific effects than auxins, gibberellins, and cytokinins. THE DISCOVERY OF ABSCISIC ACID As more …
During the 19th century, when coal gas was used for street illumination, it was observed that trees in the vicinity of streetlamps defoliated more extensively than other trees. Eventually it became apparent that coal gas and air pollutants affect plant …
The cytokinins were discovered in the search for factors that stimulate plant cells to divide (i.e., undergo cytokinesis). Since their discovery, cytokinins have been shown to have effects on many other physiological and developmental processes, including leaf senescence, nutrient mobilization, …
Gibberellins are members of a large and varied family of plant constituents known as the terpenoids. Terpenes are normally recognized on the basis of their chemical structure, which may be dissected into one or more 5-carbon isoprene units. Gibberellins are …
The first plant hormone we will consider is auxin. Auxin deserves pride of place in any discussion of plant hormones because it was the first growth hormone to be discovered in plants, and much of the early physiological work on …
The electron transport chain described above is shared in essentially the same form by virtually all organisms plants, animals and microorganisms. Plant mitochondria contain, in addition, several other redox enzymes, atleast two of which are unique to plants. These enzymes …
We noted earlier that one of the principal functions of the respiration is to retrieve, in useful form, some of the energy initially stored in assimilates. Our traditional measure of useful energy in most processes is the number of ATP …
The second stage of respiration is the complete oxidation of pyruvate to CO2 and water through a series of reactions known as the citric acid cycle (CAC). The citric acid cycle is also known as the tricarboxylic acid (TCA) cycle …
The first stage of respiratory carbon metabolism is a group of reactions by which hexose sugars undergo a partial oxidation to the three-carbon acid pyruvic acid or pyruvate. Occurrence: These reactions, collectively known as glycolysis, are catalyzed by enzymes located …