General Knowledge (Part-B: English) NDA/NA SOLVED PAPER 2021-II (101 to 150)

Total Questions: 50

11. Cornea in human eye

Correct Answer: (d) is composed of proteins and cells.
Solution:The cornea is composed of proteins and cells. It does not contain blood vessels, unlike most of the tissues in the human body. Blood vessels may cloud the cornea, which may prevent it from refracting light properly and may adversely affect vision.

12. Power of lens of focal length 25 cm is

Correct Answer: (c) +4 Dioptre
Solution:We define the power of a lens as the reciprocal of the focal length of the lens. So, the power of the lens is expressed as P = 1/f
Where f is the focal length and is expressed in meters.
So, the unit of power of the lens is expressed in m⁻¹. This is also expressed as diopter.
As we know that the focal length of a convex lens is taken as in positive sign and the focal length of a concave lens is taken negatively. So, the power of a convex lens is positive, and the power of a concave lens is negative.
In this question, it is given that the lens is convex, and its focal length is 25cm. First, we will convert the focal length into meters.
⇒ 25cm = 0.25m ⇒ 25cm = 0.25m
Now, substituting the value of focal length in the formula of power of lens we get
P = 1/0.25 m⁻¹
⇒ P = 4 m⁻¹
m⁻¹ is also expressed as diopters or D
As it is a convex lens so its power is positive.
Thus, the power of the lens is + 4D.

13. What is the total number of chambers in the stomach of domestic animals like cattle, buffalo, goat and sheep?

Correct Answer: (a) Four
Solution:Ruminant animals like cattle, sheep, goats, etc. have a four-compartment stomach that is: the rumen, reticulum, omasum, and abomasum.
Their stomach occupies three-fourth of the abdominal cavity. As these animals' food contain a lot of cellulose thus, they have cellulose enzymes that are absent in mammals.
Ruminants are herbivores in nature which make diets rich in cellulose thus, they produce cellulase enzymes within their stomach with the help of bacteria.

14. Intestinal bacteria are main source of which one of the following vitamins?

Correct Answer: (c) Vitamin B₁₂
Solution:Human faeces contain appreciable quantities of vitamin B12 or vitamin B12-like material presumably produced by bacteria in the colon, but this is unavailable to the non-coprophagic individual.
However, the human small intestine also often harbours a considerable microflora and this is even more extensive in apparently healthy southern Indian subjects.

15. Which one of the following hormones is responsible for the development of female sexual characters?

Correct Answer: (b) Estrogen
Solution:Estrogen is probably the most well-known sex hormone. Although the majority of estrogen production occurs in the ovaries, the adrenal glands and fat cells produce small amounts of estrogen, too. Estrogen plays a crucial role in reproductive and sexual development, which begins when a person reaches puberty.

16. Spherical mirror formula relating an object distance 'u' image distance 'v' and focal length of mirror 'f' may be applied to a plane mirror when

Correct Answer: (a) focal length goes to infinity.
Solution:By mirror formulae

17. Nuclear energy is generated by

Correct Answer: (a) nuclear fission and its expression was proposed by Einstein.
Solution:Nuclear energy originates from the splitting of uranium atoms - a process called fission. This generates heat to produce steam, which is used by a turbine generator to generate electricity.
Because nuclear power plants do not burn fuel, they do not produce greenhouse gas emissions.

18. Reverberation is a phenomenon associated with a

Correct Answer: (b) multiple reflection of sound.
Solution:Reverberation is a phenomenon associated with multiple reflections of sound waves. It occurs when sound waves bounce off surfaces and continue to collide and reflect before eventually dying out.

19. Which among the following is true for propagation of sound waves?

Correct Answer: (b) Sound cannot travel in vacuum and it is a longitudinal wave in air.
Solution:Sound waves are longitudinal in nature and longitudinal waves require a medium to travel through. Hence Sound waves cannot travel in a vacuum. However transverse waves can travel in a vacuum.

20. A tennis ball is thrown in the vertically upward direction and the ball attains a maximum height of 20 m. The ball was thrown approximately with an upward velocity of

Correct Answer: (d) 20 m/s
Solution: