Tag: biology

Traditionally, all the organisms of the world used to be divided into two kingdoms, i.e, Plant kingdom and animal kingdom. This system was given by Linnaeus in the book Systema Naturae. As per this system of classification, photosynthetic organisms are included into the plant kingdom and non- photosynthetic in animal kingdom.

Lycopersicon is a genus in the flowering plant family Solanaceae. The tomato is the edible, often red fruit/berry.
The onion (Allium cepa), also known as the bulb onion or common onion, is used as a vegetable and is the most widely cultivated species of the genus Allium.
The potato is a starchy, tuberous crop from the perennial nightshade, Solanum tuberosum. The word "potato" may refer either to the plant itself or, more commonly, the edible tuber.
Saccharum officinarum is sugarcane. It is a large, strong-growing species of grass in the genus Saccharum. It originated in southeast Asia and is now cultivated in tropical and subtropical countries worldwide for the production of sugar and other products.

Aristotle was an ancient Greek philosopher and scientist, one of the greatest intellectual figures of Western history. He was the author of a philosophical and scientific system that became the framework and vehicle for both Christian Scholasticism and medieval Islamic philosophy. Even after the intellectual revolutions of the Renaissance, the Reformation, and the Enlightenment, Aristotelian concepts remained embedded in Western thinking.Aristotle’s intellectual range was vast, covering most of the sciences and many of the arts, including biology, botany, chemistry, ethics, history, logic, zoology, etc. He was the founder of formal logic, devising for it a finished system that for centuries was regarded as the sum of the discipline; and he pioneered the study of zoology, both observational and theoretical, in which some of his work remained unsurpassed until the 19th century. But he is, of course, most outstanding as a philosopher. His writings in ethics and political theory as well as in metaphysics and the philosophy of science continue to be studied, and his work remains a powerful current in contemporary philosophical debate. Aristotle was born on the Chalcidice peninsula of Macedonia, in northern Greece. After his father’s death in 367, Aristotle migrated to Athens, where he joined the Academy of Plato (c. 428–c. 348 BCE). He remained there for 20 years as Plato’s pupil and colleague.

Source and sink are important concepts in translocation in plants. In plants, organic solutes are translocated from regions of their synthesis like green leaves or storage organs like tubers in stem and roots to the region of their active utilisation like the regions of active growth at tips of stem and roots. Thus green leaves and storage organs act as source, whereas regions of active growth act as sink for organic solutes.

Plastoquinone (PQ) acts as a proton pump in the photosynthetic electron transport chain of the thylakoid membrane. It accepts electrons from Photosystem II along with protons from the stroma, and subsequently releases those protons into the thylakoid lumen.

The translocation of sugars in a plant occurs from source to sink by active loading at source or supply end and active unloading at the sink end. The source and sink are not fixed and keep on changing depending on the physiology of plant. In water transport water is always transported from roots to the aerial parts but not so in case of sugars. 

In plants sugars are translocated by phloem tissue. This can be experimentally demonstrated by girdling experiments. In girdling experiments all tissues from phloem to epidermis, including secondary phloem are removed. This stops flow of sugars to plant parts below the level of girdle. Thus, the roots are starved and consequently the plant is killed.

Plants photosynthesize to produce sugars. Sugars are produced as monosaccharides- glucose or fructose. They are transported in the disaccharide form of sucrose through phloem tissue. Sugars are stored as polysaccharides, starch in storage organs.