Quiz 160 – Previous UPSC Paper – Science – Explained Answers

Which among the following has the highest energy?

(a) Blue light

(b) Green light

(c) Red light

(d) Yellow light

Explanation

According to VIBGYOR, blue has minimum wavelength in the given radiation. Hence it will be associated with maximum energy.

Ans- (a)

 


In a dry cell (battery), which of the following are used as Electrolytes?

(a) Ammonium chloride and Zinc chloride

(b) Sodium Chloride and Calcium chloride

(c) Magnesium chloride and Zinc chloride

(d) Ammonium chloride and Calcium chloride

Explanation

Zinc-Carbon cell also called the Leclanche cell or dry cell. Dry cell has a Zinc negative electrode and a maganese dioxide positive electrode, and the electrolyte is a solution of ammonium chloride. The carbon rod is in contact with the positive electrode (but takes no part in the chemical reaction) and is called the current collector. The emf is 15V and the internal resistance about 0.5 ohm. This is more popular cell, where low current is required or for occasional use, as in torches. The high power version uses specially prepared manganese dioxide rather than natural ore.

Ans- (a)

 


Which of the following types of waves are used in Night Vision apparatus?

(a) Radio Waves

(b) Micro Waves

(c) Infra-red waves

(d) None of these

Explanation

Night Vision is the ability to see in a dark environment whether by biological or combination of two approaches: Night Vision Device (NVD) is a device comprising an infra-red image intensifier tube in a rigid casing, commonly used by military force. Lately Night Vision technology has become more widely available for civilian use for example Night Vision filming and photography, night life observation, marine navigation and security. Some car manufacturers install portable Night Vision cameras in their vehicles.

Ans- (c)

 


Which one of the following used as an explosive?

(a) Phosphorus tricloride

(b) Mercuric oxide

(c) Graphite

(d) Nitroglycerine

Explanation

Nitroglycerine, Trinitroglycerine, 1, 2, 3-trinitroxypropane and glyceryl trinitrate is a heavy colourless, oily, explosive liquid obtained by nitrating glycerol. Since the 1860s it has been used as an active ingredient in the manufacture of explosives, specially dynamite and as such is employed in the construction and demolition of industries. Similarly, since the 1880, it has been used by the military as an active ingredient and a gellatinizer for nitrocellulose, in some solid propellant such as cordite and Ballistde. Nitroglycerine is also used medically as a vasodilator to treat heart conditions. Such as angina and chloride heart failure.

Ans- (d)


The marine animal called dugong which is vulnerable to extinction is a/an:

(a) amphibian

(b) Bony fish

(c) Shark

(d) Mammal

Explanation

The Dugong (Dugong dugon) is the only strictly herbivorous marine mammal which is vulnerable to extinction.

Ans- (d)

 


Consider the following statements:

  1. Sweet orange plant is propagated by grafting technique.
  2. Jasmine plant is propagated by layering technique.

Which statement(s) given above is/are correct?

  • 1 only
  • 2 only
  • Both 1 and 2
  • Neither 1 nor 2

Explanation

Sweet orange plant is propagated by grafting technique. Jasmine plant is propagated by layering technique. Hence, both statements are true. Hence, the answer is the choice (C)

Ans- (c)

 


In the context of genetic disorders, consider the following:

A woman suffers from colour blindness while her husband does not suffer from it. They have son and a daughter. In this context, which one of the following statements is most probably correct?

  • Both children suffer from colour blindness
  • Daughter suffers from colour blindness while son does not suffer from it
  • Both children do not suffer from colour blindness
  • Son suffers from colour blindness while daughter does not suffer from it

Explanation

Colour blindness, a colour vision deficiency, is the inability to perceive differences between some of the colours that others can distinguish. It is most often of genetic nature, but may also occur because of eye, nerve, or brain damage or due to exposure to certain chemicals. About 5-8 per cent of males, but less than one per cent of females are colour blind in some way or another, whether it be one colour, a colour combination or another mutation. The reason males are at a greater risk of inheriting an X-linked mutation is because males only have one X chromosome. If the woman inherits a normal X chromosome in addition to the one which carries the mutation, they will not display the mutation, while men have no spare normal chromosome to override the chromosome which carries the mutation. If 5 per cent of variants of a given gene are defective, the probability of a single copy being defective is 5 per cent, but the probability that the copies are both defective is 0.5 x 0.5 = 0.0025 or just 0.25 per cent.

Ans- (d)


Consider the following:

  1. Camphor
  2. Chicory
  3. Vanilla

Which of the above is/are Plant product(s)?

  • 1 and 2
  • 3 only
  • 1 and 3
  • 1, 2 and 3

Explanation

Camphor is a waxy, white or transparent solid with a strong aromatic odour. It is a terpenoid with the chemical formula C10 H160. It is found in wood of the camphor laurel, large evergreen tree found in Asia, particularly in Borneo and Taiwan. It also occurs in some other related trees in the laurel family. Notably ocotea usambarensis. It can also be synthetically produced from oil of turpentine.

Common Chicory is a bushy perennial herb with blue lavender or occasionally white flowers. It grows as a wild plant on roadsides in its native Europe and in North America and Australia, where it has become naturalized. Common chicory is also known as blue sailors, succory and coffeeweed. It is also called cornflower, although that name forms are grown for their leaves or for the roots, which are baked ground and used as a coffee substitute and additive.

Vanilla is a flavouring agent derived from orchids of the genus Vanilla native to Mexico.

Ans- (d)

 


In the context of Indian wild life, the flying fox is a:

(a) Bat

(b) Kite

(c) Stork

(d) Vulture

Explanation

Bats of the genus pteropus belonging to the Megachiroptera sub- order are the largest bats in the world. They are commonly known as the Fruit Bats or Flying Foxes among other numerous colloquial names. They live in the tropics and subtropics of Asia, Australia, Indonesia, Island of East Africa (but not the mainland Africa), and a number of remote oceanic islands in both the Indian and Pacific Oceans.

 

Ans- (a)


In making the saffron spic, which one of the following parts of the plant is used?

(a) Leaf

(b) Petal

(c) Sepal

(d) Stigma

Explanation

In making the saffron spice stigma of the plant is used. Saffron, the most expensive spice in the world is derived from the dry stigmata of the Plant Crocus Sativus. The plant is a bulbous, perennial with globular corms, 15-20 cm high. It has 6 to 10 leaves present at anthesis, one to two flowers with a lilac-purple colour with perianth segments of 3.5-5 cm and style branches of 2.5-3.2 cm.

The yellow style is deeply divided into three branches and the stigmata are bright red. Flowers are arising directly from the corms. Flowers have tri-lobed stima, which along with the style tops yield the saffron of commerce.

Ans- (d)

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