Friday, 19 March 2021

Q. Which of the following phytohormone is responsible for regulating the opening and closing of stomata ?

... Answer is B). ABA

Abscisic acid (also called ABA), was discovered and researched under two different names before its chemical properties were fully known, it was called dormin and abscicin II. Once it was determined that the two compounds are the same, it was named abscisic acid. The name "abscisic acid" was given beceuse it was found in high concentrations in newly abscissed or freshly fallen leaves

In plants under water stress, ABA plays a role in closing the stomata. Soon after plants are water-stressed and the roots are deficient in water, a signal moves up to the leaves, causing the formation of ABA precursors there, which then move to the roots. The roots then release ABA, which is translocated to the foliage through the vascular system and modulates the potassium and sodium uptake within the guard cells, which then lose turgidity, closing the stomata.

Q. The amount of water to be added to 10 ml of 10 N HCL solution to make it decinormal solution is

... Answer is B). 990 ml

      N1V1 = N2V2

So 10x10 = 0.1 x V. 

or V = 1000 ml

So extra water addes will be 990 ml 

Thursday, 18 March 2021

Q. At which stage of mitosis do you find chromosomes being first visible under the microscope ?

... Answer is C). Prophase

Prophase is a stage of mitosis in which the chromatin condenses (it becomes shorter and fatter) into a highly ordered structure called a chromosome, which becomes visible under a light microscope.

Q. Which one of the following is not a water soluble vitamin ?

... Answer is C). Retinol

Retinol is one of the most usable forms of Vitamin A. a fat-soluble vitamin and diterpenoid. Retinoids include the compounds retinoic acid, retinal (aldehyde) and retinyl ester. These compounds are available from plant and animal sources. Vitamin, A is essential for proper epithelial function, and available retinoic acid is procured by hyaluronic acid in the keratogenous zone to increase dermal moisture.

While retinol is insoluble in water, its bioavailábility in the dermal layers is hydrolyzed to retinoic acid, which is subsequently sequestered by hyaluronic acid- in the extracellular matrix to increase water content in cells. These mechanisms effect normal, hydrated dermal development.

Thursday, 11 March 2021

Q. Histamine is released by which of these cells ?

... Answer is C). Mast cells

A mast cell is a resident cell of several types of tissues and contains many granules rich in histamine and heparin. Although best known for their role in allergy and anaphylaxis, mast cells play an important protective role as well, being intimately involved in wound healing and defense against pathogens.

Q. An allosteric inhibitor of an enzyme usually

... Answer is B). participates in feedback regulation

Allosteric enzymes are those that have more than one activation center and to which other substances, called allosteric regulators, bind. Allosteric regulators can be allosteric inhibitors or allosteric activators. The interaction between an allosteric enzyme and the allosteric inhibitor disallows the binding of the substrate to the enzyme. The interactión between the allosteric enzyme and the allosteric activator allows the binding of the substrate to the enzyme and sometimes increases the affinity of the enzyme for the substrate. This regulatory phenomenon of the enzyme activity is called allosterism.

Q. Which of the following group represents pro-inflammatory cytokines ?

... Answer is C). IL-1, IL-6, IL-12

Proinflammatory cytosines can be generally defined as small chemicals that are created by or help produce inflammation. These include IL-1, IL-6 and IL-12.