Tag: basis of the classification of animals

A staple food, sometimes simply referred to as a staple, is a food that is eaten routinely, and in such quantities that it constitutes a dominant portion of a standard diet in a given population, supplying a large fraction of the needs for energy-rich materials and generally a significant proportion of the intake of other nutrients as well. Most people live on a diet based on just a small number of staples.
Staple foods vary from place to place, but typically they are inexpensive or readily available foods that supply one or more of the three organic macronutrients needed for survival and health: carbohydrates, proteins, and fats.
Wheat (Triticum spp.) is a cereal grain, originally from the levant region of the Near East but now cultivated worldwide. In 2013, world production of wheat was 713 million tons, making it the third most-produced cereal after maize (1,016 million tons) and rice (745 million tons). 

Genetic diversity refers to the total number of genetic characteristics in the genetic makeup of the species. Genetic diversity serves as a way for populations to adapt to changing environments.
In order to capture the maximum genetic diversity of a species, recent, old, wild - all kind of varieties will be considered and taken into account and searched.
Thus, the correct answer is option (D),  'All of the above'.

Extinction of a particular animal or plant species occurs when there are no more individuals of that species alive anywhere in the world - the species has died out. When it does not exist at all , preserving it also not possible.

Genetic erosion is a process whereby an already limited gene pool of an endangered species of plant or animal diminishes even more when individuals from the surviving population die off without getting a chance to meet and breed with others in their endangered low population. Low genetic diversity in a population of wild animals and plants leads to a further diminishing gene pool, inbreeding and a weakening immune system and fast tracks that species towards eventual extinction. 

Wild varieties of plants must be conserved because they are of utmost value to plant breeders for producing improved and favourable varieties of plants by selecting useful genes from a wide range of their wild relatives. In other words, new and improved varieties of crops are derived from their wild relatives by genetic modification. Useful traits are like high yielding, disease resistant, stress resistant etc.

Germplasm is a living tissue from which new plants can be grown. It can be a seed or another plant part like a leaf, a piece of stem, pollen or even just a few cells that can be turned into a whole plant. Germplasm contains the information for a species genetic makeup, a valuable natural resource of plant diversity. 

Shoot tip culture is the culture of terminal part of shoot to a plant in in-vitro condition or in lab called as shoot tip culture. Mostly the shoot tip culture used for obtain disease free plant without genetically changes. The plant which affected by any contaminant mostly by viruses have saved by shoot tip culture, because shoot tip of any affected plant is less or free from contamination (viruses, bacteria, fungus). 

Norman Borlaug developed a special breed of dwarf wheat that resisted a wide spectrum of plant pests and diseases and produced two to three times more grain than the traditional varieties. During the period from 1949-55, M S Swaminathan undertook research on potato, wheat, rice and jute genetics, after which he worked on Mexican dwarf wheat varieties.

Vavilov worked on global genetic diversity of cultivated plants throughout his life, from which he developed several major theories that have played an important role in the development of botany, genetics and plant breeding. One such theory among several is "Theory of centres of origin of cultivated plants" (1920).