Category Career Queries

How is Artificial insemination done?

Artificial insemination is a method used in animal husbandry to genetically upgrade stock by producing good quality off springs. In humans, the process is used to induce pregnancy in case of reproductive blocks.

Sperm from a donor of high genetic quality is collected, tested and counted under the microscope. The samples are stored in fine glass tubes and frozen in liquid nitrogen. This makes it possible for samples to be sent all over the world without the donor having to leave the area. During the actual process of artificial insemination, sperm samples are introduced into the opening of the wombs by means of a syringe to which a long tube is attached. Entire herds may be impregnated at a time using samples from a donor of high quality. In humans, the process is used if there is a blockage in the mouth of the womb. In this case the sperm is directly introduced into the womb itself. 

How does Sunlight produce vitamin D?

Vitamin D is a group of about 10 fat soluble compounds. The form of vitamin D produced in humans is called vitamin and that in plants is called vitamin . Both vitamin  and can be formed from their respective precursors in the presence of sunlight. In humans, exposure to sunlight leads to secretion of a compound called 7-dehydrocholesterol at the surface of the skin. The ultraviolet rays in sunlight convert 7-dehydrocholesterol into vitamin D by means of a series of chemical reactions. The vitamin D formed at the surface of the skin is reabsorbed into the blood stream.

How is Water purified?

Water supplied to cities and towns is usually taken from rivers or lakes and contain various kinds of pollutants, and so has to be purified. First, the raw water is passed through screens to separate coarse solids and it is then fed into settling tanks where the suspended solids settle out. Some times, substances such as alum are added to aid the settling process.

From the settling tanks the water is sent to sand filter beds -large concrete tanks with thick layers of coarse and fine sand at the bottom. The sand filters remove the remaining suspended matter from the water. Finally, the clear water is treated with chlorine gas in a closed tank to kill bacteria. The purified water is then pumped into tanks for distribution. For industrial use, water is sometimes passed through ion exchangers to remove ions like magnesium and calcium present in hard water.

 

How do Fireworks display colours?

The brilliant white, sparkling yellow, glowing red and the shimmering blue colours in the fireworks that brighten up a Diwali evening are produced by metals or metal salts present in the fireworks. Metals have the property of emitting light of a particular colour while they burn. For instance, when sodium or its salts burn, yellow light is given out. Similarly, on burning, finely divided aluminium gives out bright white light. Strontium salts give out red colour while copper and barium salts produce intense blue and green colours respectively. Fireworks manufacturers make use of this property of metals and their salts and use them in various combinations in crackers to produce spectacular fireworks display. 

How does Shampoo Produce lather?

Lather or foam is nothing but a collection of tiny soap bubbles. There is always a large quantity of air trapped between the hair strands on our head.

Shampoo is made of mild soap-like material with high solubility in water. When shampoo is rubbed on the hair with water, thin soap films are formed which during rubbing traps the air present between the hair strands to form small bubbles. As there are thousands of hair strands on the scalp, copious lather is produced.

 

How do Metals corrode?

The corrosion of metals is caused by chemical reaction. Water, salts, acids and gases — all can react with metals and over time corrode it. Iron, for example, combines readily with the oxygen in air in the presence of moisture to form red iron oxide, we call rust. Copper as bronze corrodes in presence of acids or sulphur dioxide in air forming a greenish coating of copper salts called patina, Metals can also corrode due to electrochemical reaction if two dissimilar metals such as steel and copper are Joined together and exposed to water. Here one of the metals gives up electrons and gets corroded in the process.