KPSC KAS PRELIMS 2024 PAPER 2 PART 4

Question

31. The molecule acting as a second messenger in the biological system is:

cDNA

cAMP

tRNA

hnRNA

Answer: (2) cAMP

Explanation:

Cyclic adenosine monophosphate (cAMP) is a well-known second messenger in biological systems. It relays signals from extracellular stimuli (like hormones) to intracellular pathways, thus amplifying the signal and triggering specific cellular responses.

cDNA is complementary DNA, synthesized from an mRNA template.

tRNA (transfer RNA) is involved in protein synthesis by transferring specific amino acids to the ribosome.

hnRNA (heterogeneous nuclear RNA) is the precursor to mRNA before splicing.

Thus, the correct answer is (2) cAMP.

32. The important function of the ionosphere is:

To create rainbow

Radio wave propagation to distant places on the earth

Blocking of sunlight

Blocking of sound

Answer: (2) Radio wave propagation to distant places on the earth

Explanation:

The ionosphere is a layer of Earth's atmosphere that is ionized by solar and cosmic radiation. It is crucial for long-distance radio wave propagation as it reflects radio waves back to Earth, allowing them to travel beyond the horizon.

Rainbow formation is a result of the refraction and reflection of light in water droplets.

Blocking of sunlight is not a function of the ionosphere; rather, it absorbs certain high-energy solar radiation.

Blocking of sound is not relevant to the ionosphere.

Thus, the correct answer is (2) Radio wave propagation to distant places on the earth.

33. Fuse in an electric circuit is used to prevent excessive flow of current. A fuse is made up of using:

Tungsten

Duralumin

Sterling silver

Alloy of tin and lead

Answer: (4) Alloy of tin and lead

Explanation:

A fuse in an electric circuit is designed to protect the circuit from excessive current flow, which can cause overheating and potentially start a fire. The fuse is a safety device that melts and breaks the circuit if the current exceeds a certain level.

Material Composition: The fuse is made from a material that has a low melting point so that it can quickly melt and disconnect the circuit when there is an overload. The material must also have good electrical conductivity to allow normal current to flow without significant resistance.

Alloy of Tin and Lead: Fuses are commonly made from an alloy of tin and lead. This specific alloy is chosen because it has a low melting point (typically between 183°C to 190°C depending on the composition), which allows the fuse to melt quickly under excessive current conditions. The alloy provides the right balance of conductivity and the ability to melt at the correct temperature to protect the circuit effectively.

Other Materials: Tungsten, Duralumin, and Sterling silver are not suitable for fuses because they either have high melting points (like Tungsten and Sterling silver) or are not designed for use as a fusible link (like Duralumin).

Therefore, the correct answer is:

(4) Alloy of tin and lead

34. Which of the following are true about nanomaterials?

(a) The properties strongly depend on the surface atoms.

(b) They have a large surface area.

(c) Nanoparticles have typical sizes > 100 nm.

(d) We cannot see particles of nanomaterials from the naked eye.

Select the correct answer using the code given below:

(a), (b), and (c)

(a), (c), and (d)

(b), (c), and (d)

None of the above

Answer:3. None of the above

Based on this, the correct answer is:

(a), (b), and (d)

Explanation:

Let's assess each statement about nanomaterials:

(a) The properties strongly depend on the surface atoms.

Correct. For nanomaterials, surface-to-volume ratio is significant, and many of their unique properties arise from the surface atoms.

(b) They have a large surface area.

Correct. Nanomaterials have a large surface area relative to their volume due to their small size.

(c) Nanoparticles have typical sizes > 100 nm.

Incorrect. Nanoparticles typically have sizes ranging from 1 nm to 100 nm. Particles larger than 100 nm are generally not classified as nanomaterials.

(d) We cannot see particles of nanomaterials from the naked eye.

Correct. Nanoparticles are so small that they cannot be seen with the naked eye.

Based on this, the correct answer is:

(a), (b), and (d)

Given that option (c) is incorrect

35. Consider the following:

(a) Mica

(b) Graphite

(c) Sulphur

(d) Human body

Which among the above is/are electrical conductors?

Only (a), (b), and (d)

Only (b), (c), and (d)

Only  (b), and (c)

Only (b) 

Answer: 3. Only (b) 

Thus, the correct answer is:

Only (b) and (d)

Explanation:

Let's analyze each material for its electrical conductivity:

(a) Mica

Mica is an insulating material and does not conduct electricity.

(b) Graphite

Graphite is a good conductor of electricity due to the presence of delocalized electrons in its structure.

(c) Sulphur

Sulphur is a non-metal and does not conduct electricity.

(d) Human body

The human body contains water and electrolytes, making it a conductor of electricity.

Thus, the correct answer is:

Only (b) and (d)

Answer 1

36. During a hot sunny day people feel cool in the shadow under a big tree 

(a) because the tree blocks direct sunlight.

(b) because heat from the air is used in the evaporation of water by tree leaves reducing the temperature.

(c) because photosynthesis by tree leaves absorbs energy from sunlight.

(d) because tree leaves absorb water vapour from the air, which is an endothermic process.

The correct answer is:

Only (a)

Only (a) and (b)

Only (a), (b), and (c)

All (a), (b), (c), and (d)

Answer: (3) Only (a), (b), and (c)

Explanation:

During a hot sunny day, the cooling effect experienced in the shadow under a big tree can be attributed to several factors:

(a) because the tree blocks direct sunlight.

This is true. The primary reason people feel cooler in the shade is that the tree blocks direct sunlight, reducing the heat from solar radiation reaching them.

(b) because heat from the air is used in the evaporation of water by tree leaves reducing the temperature.

This is also true. Trees lose water through transpiration, which absorbs heat from the surrounding air, thereby cooling the environment.

(c) because photosynthesis by tree leaves absorbs energy from sunlight.

This is partially true. Photosynthesis does absorb sunlight, but its direct role in cooling the surrounding area is less significant compared to the effects of shading and transpiration. While the primary cooling effect of being in the shade is due to blocking sunlight and the evaporative cooling from transpiration, the photosynthesis process does contribute by absorbing some solar energy.

(d) because tree leaves absorb water vapour from the air, which is an endothermic process.

This is not accurate. While transpiration is an endothermic process, tree leaves primarily release water vapor rather than absorbing it from the air.

Therefore, the correct answer is:

Only (a), (b), and (c)

37. Match the following and choose the correct answer in view of polymer products:

Polymer Name | Uses

A) Polyethylene | (i) Nonstick surfaces

B) Polyvinyl chloride | (ii) Adhesives

C) Polytetrafluoroethylene | (iii) Water bottles

D) Polyvinyl acetate | (iv) Pipes

The correct answer is:

A-(iii), B-(iv), C-(i), D-(ii)

A-(ii), B-(iv), C-(iii), D-(i)

A-(iii), B-(ii), C-(i), D-(iv)

A-(iv), B-(i), C-(iii), D-(ii)

Answer:1.  A-(iii), B-(iv), C-(i), D-(ii)

Explanation:

A) Polyethylene | (iii) Water bottles

Polyethylene is widely used in the production of various plastic products, including water bottles, plastic bags, and containers, due to its durability, flexibility, and safety.

B) Polyvinyl chloride | (iv) Pipes

Polyvinyl chloride (PVC) is a common plastic used in the manufacturing of pipes, plumbing, and electrical cable insulation. It is valued for its strength, durability, and resistance to corrosion.

C) Polytetrafluoroethylene | (i) Nonstick surfaces

Polytetrafluoroethylene (PTFE), commonly known as Teflon, is used for nonstick coatings on cookware due to its high heat resistance and low friction properties.

D) Polyvinyl acetate | (ii) Adhesives

Polyvinyl acetate (PVA) is a synthetic polymer used in adhesives like glue due to its strong bonding properties and flexibility.

Therefore, the correct match is A-(iii), B-(iv), C-(i), D-(ii).

38. A secondary rainbow is always seen with a rainbow, because:

(a) A secondary rainbow appears above or outside a primary rainbow.

(b) The secondary rainbow is always fainter than the corresponding primary rainbow.

(c) The orders of colours of the primary rainbow and the secondary rainbow are opposite.

(d) A secondary rainbow is only a refraction of a primary rainbow.

The correct statement(s) among the above is/are:

Only (a)

Only (a) and (b)

Only (a), (b), and (c)

All (a), (b), (c), and (d)

Answer: (3) Only (a), (b), and (c)

Explanation:

(a) A secondary rainbow appears above or outside a primary rainbow: Correct. The secondary rainbow is seen outside the primary rainbow.

(b) The secondary rainbow is always fainter than the corresponding primary rainbow: Correct. The secondary rainbow is fainter due to the additional reflection within the water droplets, which causes more light to be absorbed or dispersed.

(c) The orders of colors of the primary rainbow and the secondary rainbow are opposite: Correct. The colors in a secondary rainbow are reversed compared to those in the primary rainbow.

(d) A secondary rainbow is only a refraction of a primary rainbow: Incorrect. A secondary rainbow involves two reflections inside the water droplet, not just refraction.

Thus, the correct answer is (3) Only (a), (b), and (c).

39. Iodex is:

Methyl salicylate

Ethyl salicylate

Acetylsalicylic acid

Ortho-hydroxy benzoic acid

Answer: (1) Methyl salicylate

Explanation:

Iodex is a pain-relieving ointment that primarily contains methyl salicylate. It is known for its analgesic and anti-inflammatory properties, making it effective in relieving muscle and joint pains.

Methyl salicylate is also known as wintergreen oil, which is commonly used in topical pain relievers.

Ethyl salicylate, acetylsalicylic acid (aspirin), and ortho-hydroxy benzoic acid are related compounds but are not the main ingredients in Iodex.

Thus, the correct answer is (1) Methyl salicylate.

40. Aditya-L1 is the first Indian space-based observatory to study the Sun

From a geostationary orbit

From the first Lyapunov orbit around the Sun

From a halo orbit around Sun-Earth Lagrangian point

From the first orbit around the Sun-Earth Lavoisier point

Answer: (3) From a halo orbit around Sun-Earth Lagrangian point

Explanation:

Aditya-L1 is an Indian mission designed to study the Sun. The spacecraft will be placed in a halo orbit around the Sun-Earth Lagrangian point (L1). This position allows continuous observation of the Sun without any interruptions caused by eclipses or occultation.

Answer 2

41. The scientific objectives of Aditya-L1 mission include:

(a) Study of coronal heating and solar wind acceleration.

(b) Study of solar neutrino oscillation and conversion of solar hydrogen through fusion.

(c) Study of Coronal Mass Ejections (CME) and dynamics of solar atmosphere.

Choose the correct answer from the options given below:

Only (a) and (b) are correct

Only (b) and (c) are correct

Only (a) and (c) are correct

All (a), (b), and (c) are correct

Answer: (3) Only (a) and (c) are correct

Explanation:

(a) Study of coronal heating and solar wind acceleration: Correct. One of the key objectives of the Aditya-L1 mission is to understand the processes responsible for coronal heating and the acceleration of the solar wind.

(b) Study of solar neutrino oscillation and conversion of solar hydrogen through fusion: Incorrect. While solar neutrinos are an important area of study, this is not a primary objective of the Aditya-L1 mission.

(c) Study of Coronal Mass Ejections (CME) and dynamics of solar atmosphere: Correct. Understanding the origin and impact of CMEs and studying the dynamics of the solar atmosphere are key scientific goals of the mission.

Thus, the correct answer is (3) Only (a) and (c) are correct.

42. In connection with Chandrayaan-2, CLASS refers to:

An X-ray spectrometer

A solar X-ray monitor

An atmospheric compositional explorer

A dual frequency radar

Answer: (1) An X-ray spectrometer

Explanation:

CLASS (Chandrayaan-2 Large Area Soft X-ray Spectrometer) is an X-ray spectrometer onboard the Chandrayaan-2 orbiter. It is designed to map the major elements present on the lunar surface through X-ray fluorescence generated by solar X-rays and its emissions from the Moon's surface.

43. Consider the following computer memories:

(a) Main memory

(b) Cache memory

(c) Register memory

(d) Auxiliary memory

Arrange the above computer memories in decreasing order of their accessing speed:

(d), (a), (b), (c)

(b), (c), (a), (d)

(c), (b), (a), (d)

(a), (b), (c), (d)

Answer: (3) (c), (b), (a), (d)

Explanation:

The correct order of the memories in terms of accessing speed from fastest to slowest is:

(c) Register memory: The fastest memory, used directly by the CPU to process data.

(b) Cache memory: Slightly slower than registers, used to store frequently accessed data for quick retrieval.

(a) Main memory (RAM): Slower than cache memory, used to store data currently in use by the computer.

(d) Auxiliary memory: The slowest among these, used for long-term storage, like hard drives and SSDs.

Thus, the correct order is (c), (b), (a), (d).

44. Which of the following statements is/are true about blockchain?

(a) A blockchain is a centralized digital ledger consisting of records called blocks.

(b) A blockchain database is managed autonomously using a peer-to-peer network and a distributed timestamping server.

(c) A blockchain has been described as a value-exchange protocol.

Select the correct answer using the code given below:

(a) and (b) only

(b) and (c) only

(a) only

(a), (b), and (c)

Answer: (b) and (c) only

Explanation:

(a) A blockchain is a centralized digital ledger consisting of records called blocks: Incorrect. Blockchain is decentralized, not centralized. It is a distributed ledger where records are stored across multiple nodes.

A blockchain is “a distributed database that maintains a continuously growing list of ordered records, called blocks.” These blocks “are linked using cryptography. Each block contains a cryptographic hash of the previous block, a timestamp, and transaction data.

(b) A blockchain database is managed autonomously using a peer-to-peer network and a distributed timestamping server: Correct. Blockchain operates on a decentralized peer-to-peer network and uses distributed timestamping.

(c) A blockchain has been described as a value-exchange protocol: Correct. Blockchain can be considered a protocol that allows for the exchange of value in a secure and transparent way.

Thus, the correct answer is (2) (b) and (c) only.

45. Consider the following statements regarding LASER:

(a) Laser beam is monochromatic.

(b) Laser beam is coherent.

(c) Laser beam is highly divergent.

(d) In the emission of laser beam stimulated emission is absent.

Select the correct answer using the code given below:

(a) and (b) only

(a), (b), and (c) only

(a) and (d) only

(c) and (d) only

Answer: (1) (a) and (b) only

Explanation:

(a) Laser beam is monochromatic: Correct. A laser emits light of a single wavelength, which makes it monochromatic.

(b) Laser beam is coherent: Correct. Laser light waves are coherent, meaning the light waves maintain a constant phase relationship.

(c) Laser beam is highly divergent: Incorrect. A laser beam is actually highly collimated, meaning it has very little divergence and remains narrow over long distances.

(d) In the emission of laser beam stimulated emission is absent: Incorrect. Stimulated emission is the fundamental process that produces laser light.

Thus, the correct answer is (1) (a) and (b) only.