Question Discussion & Solution

The correct answer is Light Pen.

Key Points 

• Light Pen -
  • It is an input device of the computer which serves to give commands to the computer.
  • It is also called an electronic pen.
  • It looks like an ordinary pen.
  • It is used as a mouse.

Additional Information 

• A wave of light emerges from the tip of this pen.
• With this point, the icon made on the screen is touched and clicked.
• This work is done in the same way that we click by moving the mouse pointer on the screen.
• The tip of the light pen acts in a way like the Enter / Ok button.​

CONCEPT:

• The pressure cooker is based on the principle that the boiling of water increases with the increase in pressure.

EXPLANATION:

• When we give heat to the pressure cooker then due to an increase in temperature the steam generated in the vessel.
• Due to this generated steam, the pressure inside the vessel increases. So the food gets cooked soon.
• Thus by the application of pressure the boiling point of the water increases. Hence option 1 is correct.
• There is no relation between food-grains with the boiling point of water. So options 2, 3, and 4 are wrong.

Concept-

• DNA stands for Deoxyribonucleic acid.
• DNA as an acidic substance present in the nucleus was first identified by Friedrich Meischer in 1869.
• He named it ‘Nuclein’.
• DNA acts as the genetic material in most organisms.
• A DNA molecule consisting of all the genetic material of an organism is known as a chromosome.
• These are thread-like (helical) structures of protein and nucleic acids which​ carry all the genetic information in the form of genes.

Explanation-

• ​Deoxyribonucleic acid (DNA) is a nucleic acid and is therefore made up of nucleotide.
• Each nucleotide consists of a phosphate group, a nitrogenous base (A, T, G, C), and ribose sugar (deoxyribose in case of DNA).
• A nucleoside contains only pentose sugar and a nitrogenous base.
• Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are the two types of nucleic acids found in living systems.
• DNA is a long polymer of deoxyribonucleotides.
• The length of DNA is usually defined as the number of nucleotides (or a pair of nucleotides referred to as base pairs) present in it.

Thereby DNA is composed only of nucleic acid.

Additional Information

Lipids: 

• ​These organic compounds are nonpolar molecules, which are soluble only in nonpolar solvents and insoluble in water because water is a polar molecule.
• In the human body, these molecules can be synthesized in the liver and are found in oil, butter, whole milk, cheese, fried foods, and also in some red meats.

Proteins:

• Proteins are composed of amino acids, arranged into different groups.
• These fundamental amino acid sequences are specific and their arrangements are controlled by the DNA. 
• These are the fundamental building blocks of our bodies.
• They are large and complex macromolecules or bio-molecules which perform a major role in the functioning and regulating of our body cells, tissues, and other organs in the human body.​

Windows is NOT correct.

Key Points 

• Among the options, only Windows is NOT an open-source operating system.
• Windows is a closed source operating system marketed by Microsoft.
• Microsoft first introduced the Windows operating system on 20 November 1985.
• Closed Operating Systems are built with numerous codes and complex programming and that is called source code. 
• An Open-source Operating System is the Operating System in which source code is visible publically and editable.
• The operating system is a collection of programs that controls the overall operations of the computer.
• Operating system is a System software in computers.
• It works as an interface between user and computer hardware components.
• Examples of operating systems are:
  • Linux.
  • Unix.
  • DOS.
  • Windows.
  • Ubuntu.
  • Embedded operating system.
  • OpenBSD.
  • Mac OS.

After reading statement and conclusion we say that -

i) All people who are good at dance are pianists. → False (We cannot say that all good dancer are pianists)

ii) Some people who are good at dance are pianists. → True ( As all pianists are good dancer means some of the good dancers are pianists) 

Hence, "Only conclusion ii) follows" is the correct answer.