Day-571 | Daily MCQs | UPSC Prelims | SCIENCE AND TECHNOLOGY

Answer: A
Explanation
Asymmetric and symmetric encryption are two primary techniques used to secure data. Symmetric encryption uses the same key for both encryption and decryption, while asymmetric encryption uses a pair of keys: a public key for encryption and a private key for decryption.
• Statement 1 is correct: Asymmetric encryption is considered more secure due to the use of two separate keys, making it harder for attackers to compromise the system.
• Statement 2 is incorrect: Symmetric encryption is generally faster than asymmetric encryption, as it requires less computational power, making it suitable for encrypting large amounts of data. Symmetric encryption is ideal for bulk data encryption and secure communication within closed systems, whereas asymmetric encryption is often used for secure key exchanges, digital signatures, and authentication in open systems.

Answer: B
Explanation
There are three common ways to analyse any internal organ malfunction in the body using radiology. These are: CT scan, MRI scan and PET scan.
• Statement 1 is correct: CT (or Computer Tomography) scan uses a thin X-ray beam to produce detailed images inside the body. It takes multiple cross-sectional images to show the “shape” of internal organs and other structures, such as bones and blood vessels.
• Statement 2 is incorrect: Unlike a CT scan which uses radiation, an MRI uses a powerful magnet and radio waves to create detailed images of organs and other structures inside the body. An MRI takes longer to perform than a CT and is more expensive, but it doesn’t expose the person to radiation.
• Statement 3 is correct: A PET scan is used to see metabolism (chemical activity) within the body. While a CT and MRI scan looks at the “form” of structures inside the body, a PET scan looks at their function and shows unusual cellular activity.

Answer: A
Explanation
CRISPR-Cas9 is a genome editing tool that is popular in the science world. It is faster, cheaper and more accurate than previous techniques of editing DNA and has a wide range of potential applications. It is a unique technology that enables geneticists and medical researchers to edit parts of the genome by removing, adding or altering sections of the DNA sequence.
The CRISPR-Cas9 system consists of two key molecules that introduce a change (mutation) into the DNA. These are:
1. An enzyme called Cas9 which acts as a pair of ‘molecular scissors’ that can cut the two strands of DNA at a specific location in the genome so that bits of DNA can then be added or removed.
2. a piece of RNA called guide RNA (gRNA) which is designed to find and bind to a specific sequence in the DNA.
• Statement 1 is correct: Cas9 is an enzyme which acts as a pair of ‘molecular scissors’ that can cut the two strands of DNA at a specific location in the genome so that bits of DNA can then be added or removed.
• Statement 2 is incorrect: The Cas9 follows the guide RNA to the same location in the DNA sequence and makes a cut across both strands of the DNA. Moreover, it is clear in the name that guide RNA is the one which guides the enzymes to act at the specific location not the other way around.
More Information on CRISPR-Cas9
• The use of CRISPR-Cas9 and other gene editing technologies in somatic cells (non-reproductive cells) is uncontroversial. Indeed, they have already been used to treat human disease on a small number of exceptional and/or life-threatening cases. but there has been a lot of interest in and debate about the potential to edit germline (reproductive) cells. This is because any changes made in germline cells will be passed on from generation to generation which has important ethical implications.

Answer: A
Explanation
• Statement 1 is incorrect: FASTags use radio waves to identify vehicles by scanning the FASTags sticker pasted on the front portion of the vehicle. It works on the same principle as RFID cards.
• Statement 2 is correct: Tap and Go card use the Near Field Communication (NFC) technology. Tap and go works using tokens and radio frequencies. For example, metro cards.
• Statement 3 is incorrect: A bar code consists of white and black bars. Data retrieval is achieved when bar code scanners shine a light at a bar code, capture the reflected light and replace the black and white bars with binary digital signals.

Answer: A
Explanation
Quantum dot LED (or QLED) and Organic LED (or OLED) are two of the most popular display technologies in the premium display segment. But there is a difference in technology between the two.
• Statement 1 is incorrect: OLED produces better contrasts and can achieve true black. Because each pixel produces its own light, black is possible by just turning off the pixel — something that’s not possible with any backlit panel. Those deep blacks improve contrast and produce a more film-like viewing experience. Those individual pixels also can produce amazingly accurate colors.
• Statement 2 is incorrect: QLED displays use quantum dots which produce brighter colours when excited by a backlight. However, the display lacks the colour accuracy produced by OLED.
• Statement 3 is correct: AMOLEDs remove the limitation of display sizes. One can fit it into any display size. This is because AMOLED uses active matrix which is more flexible in operation as compared to organic material used in OLED.