Fraternal Twins (Produced from two eggs) Some times two eggs are released from ovaries at a time and both may get fertilized to produce two individuals. Such twins produced from two eggs are called fraternal twins. Fraternal twins may be either both boys, or both girl, or one boy and one girl. Also known as Diovular or Dizygotic twins. About . . .
Gas Test 1.Hydrogen (H2) Burns with pale blue flame producing a 'pop' sound Extinguishes burning splinter. Neutral to Litmus Colourless, Odourless 2.Oxygen (O2) Colourless alkaline pyrogallol solution turns brown. R . . .
Blood Clotting - Coagulation of blood at wound to prevent excess loss of blood. Clotting occurs in a series of steps as follows - 1. At the site of wound, platelets release an enzyme thrombokinase or thromboplastin (also called Factor 'X' or Stuart factor) 2. Thrombokinase along with calcium ion present in blood plasma, conver . . .
Different metals show different reactivity towards different chemical compounds. Following chart shows the chemical properties of metals. . . .
RBCs (Erythrocytes) Structure Biconcave, disk shaped, colourless (red due to haemoglobin), spongy, flat at center & thick & round at periphery. 2 micron in size. Count About 4.5 to 5 million / mm3 but in infants 6 – 7 million / mm3 Its count lowers by 5% during sleep & increases during pregnancy & emotion . . .
White Blood Cells (Leukocytes) Structure Count 4000 – 8000 per mm3 Have nucleus, amoeboid in shape. Increase in the number of WBCs at the cost of RBCs is called Leukemia. Abnormal decrease in the number of WBCs is called Leukopenia. Production & death Produced in red bone marrow, lymph nodes & some time in li . . .
Tests to detect cations present in a metallic salts with sodium & ammonium hydroxide . . .
Useful role of Bacteria In Medicine (i) Production of antibiotics 1. Antibiotic – An antibiotic is a chemical substance produced by a living organism which can stop the growth of some disease producing bacteria and fungi e.g. streptomycin, chloromycetin, tetracycline, penicillin etc. 2. Penicillin is the first produced antibiotic discovered by . . .
How does soaps clean dirt from cloth Soaps are molecules in which the two ends have differing properties, one is hydrophilic, that is, it dissolves in water, while the other end is hydrophobic, that is, it dissolves in hydrocarbons. When soap is at the surface of water, the hydrophobic ‘tail’ of soap will not be soluble in water and the s . . .
Alkanes - saturated hydrocarbons The names of the straight chain saturated hydrocarbons for up to a 12 carbon chain are shown below. The names of the substituents formed by the removal of one hydrogen from the end of the chain is obtained by changing the suffix -ane to -yl. Number of Carbons . . .
Types of WBCs . . .
Accommodation of Eye for near & distant objects This is the process of focusing of eye at different distances. • Mainly brought about by a change in the curvature of the elastic lens making it thinner& fatter. • For distant objects the lens become more flattened or thinner. • For near vision (nearer than 6 meter) the lens be . . .
There are so many chemical compounds which are widely used in chemistry and play an important role in our domestic life, Industries and in analytical chemiatry. Following is the list of such compounds with their chemical formula, chemical name & common name. . . .
To prevent spoilage of food the food is preserved & made germ free by some techniques under food preservation. (a) Boiling or heating – Boiling water kills bacteria & at increased pressure it kills even spores so the canning industry employes heating to kill bacteria before packing & sealing food. (b) Salting – Used to . . .
Light & dark adaptation Dark adaptation • When a person come in a dark room from a bright lighted area it is difficult to see objects for some time after that the vision is improved & the person can see objects clearly. • This is done by (i) The regeneration of visual purple (rhodopsin), the pigment of rods, which was earlier broke . . .