MIDDYA'S NEET BIOLOGY

Bt-Toxin is an insectisidal protein produced by Bacillus thuringiensis  genome which is used in genetical engineering for making  Transgenic  Pest-resistant crop variety . The toxin  protein encoded by cry- gene exists as inactive protoxins in the bacterial cells ,which only gets activated when it is taken by insects in their Gut , The alkaline PH of the gut activates it ......This is the reason For that the bacteria do not harmed by  Bt-toxins .

                                  BIOTECHNOLOGY J Biotechnology deals with techniques of using live   Organisms, cells or their components   or enzymes from organisms to produce products   and processes(Services)   useful to humans. J In this sense, making curd ( By Lactobacillus & Lacticacid bacteria), bread or wine( By Yeast) , which are all microbe-mediated processes, could also be thought as a form of biotechnology. J However, it is used in a restricted sense today, to refer to such of those processes which use genetically modified organisms( GMO) to achieve the same on a larger scale. Further, many other processes/techniques are also included under biotechnology. For example, in vitro fertilisation leading to a ‘test-tube’ baby, synthesising a gene and using it, developing a DNA vaccine or correcting a defective gene, are all part of biotechnology. T...

Types of respiration 1 ) Pulmonary respiration : vascularised bags called lungsb –e.g. terrestrial molluscs ,amphibians, reptiles, birds and mammals respire through lungs. 2) Branchial respiration : By Special vascularized structures called gills. E.g-most of the aquatic arthropods and molluscs, Among vertebrates fishes. 3) Tracheal respiration : By a network of tubes . e.g. Insects 4) Cutaneous respiration : through moist skin also. E.g.- Amphibians like-frogs, earthworms, RESPIRATORY ORGANS OF ANIMALS  Mechanisms of breathing vary among different groups of animals depending mainly on their 1) habitats and 2) levels of organisation

Human respiratory disorders RESPIRATORY DISORDER Asphyxia :    is a condition of severely deficient supply of  oxygen  to the  body . characterized by an inability of an individual to acquire sufficient oxygen through breathing for an extended period of time. Asphyxia can cause coma or death. So increase in CO2 concentration, It paralyses the respiratory centre . Hypoxia: Hypoxia [1]  is a condition in which the body or a region of the body is deprived of adequate  oxygen  supply at the  tissue  level.   Causes –         1)    Hypoxic hypoxia:Arterial Po2 is low   2) Anemic hypoxia:   Low amount of 02 carrying haemoglobin 3)   Stagnant hypoxia :   Lower cardiac output or Intence local vasoconstriction   Though Arterial blood has lower P02. 4) Artificial hypoxia : Shortage of oxygen in the air such as high altitude 5) Ischemia , meaning insufficient...

Q.   How many times a cell could divide A.            It is fully genetically controlled information  programmed in the cell.  The average cell will divide between  50-70 times( The Hayflick limit ( Leonard Hayflick  in 1961),  before programmed   cell death( apoptosis) . As the cell divides the telomeres on the end of the  chromosome get smaller.  due to the telomeres shortening through each division, the   telomeres will eventually no longer be    present on the   chromosome   .Cancer cells can divide indefinitely since they   use an enzyme called telomerase to maintain the telomere length       e.g.     Meristematic cell go on dividing     but permanent cell     normally don’t divide