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
32oC. Our body is at about 37oC. As we remain in door
because of poor ventillation the temperature inside nose comes to 32oC.
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 6.4oC 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.
No comments:
Post a Comment