Find Out Why | Sunday Observer

Find Out Why

Question 1: How can forensic scientists determine the time of death from one or two drops of blood?


Answer 1: The blood coming out from a damaged blood vessel, is bright red as it contains the red pigment haemoglobin. Over time, spilled blood turns darker and darker, and as it dries, its haemoglobin breaks down into a compound called methaemoglobin. As more time passes, dried blood continues to change, growing even darker due to formation of another compound called haemochrome. Forensic experts know how long it takes for each colour change to appear in that drop of blood. So they can determine the time of death fairly accurately.


Question 2: Why do pimples appear on the face?


Answer 2: When you touched your face, specially the nose, you must have felt that the fingers got oily. Our skin has oil producing glands called sebaceous glands. This oil comes out of the pores in the skin, and protects the skin, specially from dehydration. But if excess oil emerges through these pores and stays there, it will get mixed with dirt and may clog the oil-pores. Eventually this dried up oil causes the skin in that place to swell into a pimple.

Question 3: Why do satellites glow and flicker like stars?


Answer 3: A satellite is an object in space that circles around a bigger object. Natural satellites are the earth orbiting the sun and moon orbiting around the earth. Artificial satellites are machines launched into space, to gather information about planets etc. by orbiting around those planets. Satellites do not produce light. But the light produced by the stars falling on the satellites, get reflected, to make them shine and flicker, just like stars.

Question 4: Why do we have to chew our food?


Answer 4: Chewing food in the mouth helps to break down larger particles, so that there is more surface area of starch in the food, to get digested. Chewing food properly, releases more saliva, which contains amylase enzyme, that digests starch. Tiny pieces of food helps the food to move through the digestive tract. Also, it sends messages to the rest of the digestive tract to indicate that food is on the way, and this triggers HCl production by the stomach wall, to speed up digestion.

Question 5: Why should margarine not be preferred to butter?


Answer 5: According to various publications, this is how margarine is made. Various chosen plant oils are extracted, and hydrogenated using high temperature and high pressure and a meatal catalyst like nickel or nickel oxide. Next it is mixed with starch to get a better consistency, and steam cleaned to remove its unpleasant odour. Then it’s unappetizing grey colour is removed using bleach. Dyes and strong flavours are added to make pleasant and resemble butter. Finally the mixture is compressed and packaged and sold.

Question 6: Dolphin looks like a fish but is not a fish. Why?


Answer 6: Dolphins are mammals, not fish. Fish respire through gills, but dolphin has no gills. It respires by lungs. Dolphin comes to the surface of water to send out spent air through the hole at the top of it’s head, and draws air through the same. Body temperature of fish varies with that of the environment. That is, they are cold blooded. Dolphins are warm blooded and they have a constant body temperature, which is a little above that of their environment. Fish reproduce by eggs while dolphins give birth to young ones. Dolphins have mammary glands that the fish lack.

Question 7: How is the chromosome number in a species, maintained a constant?


Answer 7: Within the parental reproductive cells, meiosis occurs. Here the gametes formed have only half the chromosome number as that of the parent. Human body has 46 chromosomes in each cell. But gametes formed by meiosis contain 23 chromosomes each. When the female gamete with 23 chromosomes fuse with the male gamete, also with 23 chromosomes, the zygote formed will have 46 chromosomes. So, the embryo formed by cell division of this zygote, will also have 46 chromosomes in each cell.