Q. & A.s SCIENCE & TECH. – 7

Q. &  A.s  ‑‑‑  SCIENCE  & TECH. – 7

196Q. Why dogs always keep tongue out?

Through tongue the water gets evaporated and the body temperature is maintained. Why because dogs do not have seat pores or no sweating.

197Q. Why appendix is not developed in human beings?

In ruminating animals, carnivorous animals, appendix too participates in digestion process. The secretions are also helpful in digestion process.  Human beings eat cooked food. So the use of appendix is nonoperational.

198Q. Why do we get cold in winter?

Virus develops at 32^oC. Our body is at about 37^oC. As we remain in door because of poor ventillation the temperature inside nose comes to 32^oC. This temperature becomes host to virus. UV rays kill virus. But as the sun’s heat is less, less germs are killed.

199Q. How do birds fly?

Their muscles are strong and their bones are light. Their bones are light with spaces full of air.

Beating flight at the time of rising in sky or landing.

Gliding flight when they are carried away by current of air.

200Q. What happens when we are afraid?

The brain releases a hormone called adrenalin.

This increases the glucose content in the blood so that the muscles are given extra energy.

This adrenalin increases that heart beat and quickness of breath.

201Q. Why doesn’t earth cool itself?

The radio active rays released from the core of the earth release a lot of energy. Due to this the earth does not cool itself.

Secondly the amount of heat that it receives from the sun is more than what it loses.

202Q. Why sometimes heart beat is faster?

The movements of muscles create carbonic acid. It reaches the heart in 10 seconds. If more carbonic acid reaches the heart, the heart beats faster.

1.      The other reasons are

2.      When there is excitement,

3.      When we get fever

4.      When we are afraid,

The heart beats faster.

1.      The heart beats slow

2.      When we are depressed,

3.      When we sleep,.

203Q. Why there are 7 days in a week?

The number of days in a week differs from culture to culture.

West Africa     4 days.

China/Europe  5 days

Old calendars  6 days

Egypt              10 days

Secondly in those days only 7 planets were known.

The names of a week are given by Babylonians.

204Q. What imparts fragrance to flowers, fruits and spices?

It is due to  oils present in them.

Those oils are soluble in alcohol, ether, vegetable mineral oils.

These oils may be grouped as alcohols, esters, aldehydes, ketones, lactones oxides.

Oils are made in leaves but as plant grows they are transported to different parts of plant.

The main purpose is not known.

205Q. FPS to MKS.

1 pound           = 453 gms

1 stone            = 6.35 kgs

1 Newton        = 102 gms

1 ounce            = 28 gms

1 carat                         = .0002 kgs     = .2 gms

1 dram             = 1.77 gms

1 grain             = .065 gms

206Q. Positive Place values. Above zero.

Deca                            10¹

Hector                         10²

Kilo                 K         10³

Mega               M         10⁶

Giga                G         10⁹

Tera                 T          10¹²

Peta                 P          10¹⁵

Exa                  E          10¹⁸

Zetta                Z          10²¹

Yotta               Y         10²⁴

207Q. Negative place values. Below zero.

Deci                             10^-1

Centi                           10^-2

Milli                 m         10^-3

Micro                           10^-6

Nano               n          10^-9

Pico                 p          10^-12

Femto              f           10^-15

Atto                 a          10^-18

Zepto               z          10^-21

Yocto              y          10^-24

208Q. what are cosmic rays?

Cosmic rays are electromagnetic rays of very short wave length. These rays come from other stars.

209Q. what is anti matter?

For every particle of micro world there is anti particle.

Electron           x          anti-electron

Proton             x          anti-proton

Neutron           x          anti-neutron

And so on.

Matter consisting of anti-protons in the nucleus and anti-electrons going around it is called anti-matter.

210Q. How is the age of fossils measured?

Radioactive isotope of carbon is 146C. Its half life period is 5730 years. When  a fossil is found, the amount of carbon present in it indicates the life of the fossil.

If the life of the fossil is greater than thousands of years, other isotopes of radioactive radium or some other materials are used.

211Q. How is the height of a mountain measured?

Using triangulation method, using goniometer the height is measured.

Today we have lasers to accurately measure the heights.

212Q. How is the depth of the ocean measured?

Using SONAR [sound navigation and ranging]

This equipment is fitted at the bottom of the ship. It generates Ultrasonic waves. These waves travel to the depth, touch the bottom, reflect back and create a sound in the set. We know the speed of the Ultrasonic waves, the time can be recorded using stop clock and the distance can be calculated.

V = d/t

D = Vxt

If we half of it vxt/2 gives the depth of the ocean.

213Q. There is a peculiar smell after rain. Why?

Streptomycetes are the bacteria in the soil. It releases certain volatile chemical compounds. They release compounds such as geosmin and 2 methyl isoborneol  when wetted by rain water after a long dry spell. This odour is only after the first rain of the rainy season.

214Q. Why there is ice on the Himalayas?

In troposphere as we go up for every 1 km height 6.4^oC temperature is decreased. 6100 metres is called the ice line. Above this line we can see the formation of ice.

215Q. why do stars twinkle?

Light passes through layers of atmosphere having different temperatures. Light has a property called interference. That is why we see the stars twinkle. Actually they won’t.

215Q. water is colourless.  Then why water fall is white?

Water while falling from a height breaks into drops, gaps, etc. The light falling on those fragments reflects. That is why it seems white.

216Q. let water be poured in any container  or on land having pits has the surface straight. Why?

It is due to surface tension.

217Q. Why mercury drops are spherical?

Mercury has the highest surface tension. That is why each drop seems to be perfect sphere.

218Q. what are terminator seeds.

These are give crop only once. The seeds of these crops won’t give plants. That means after one generation they won’t work like seed.

They are good for only consumption.

219Q. why does sun flower always face the sun?

The sun flower has auxin hormone present in the stem. It exhibits phototropism. Due to this it always faces the sun.

220Q. Does the Sun rotate?

Yes. Unlike the earth, sun has differential rotations. That is all parts of the sun donot have the same period of rotation. The rotation time at its equator  is 26.9 days and at pole 31.1 days. The reason is a puzzle.