Day-723 | Daily MCQs | UPSC Prelims | SCIENCE AND TECHNOLOGY

Answer: A
Explanation
• Gerozymes are age-associated enzymes which are factors behind progressive loss of muscle in old-age. Scientists at Stanford University have found a protein, known as 15-prostaglandin dehydrogenase (15-PGDH), that can stimulate growth of stronger and larger muscles. By inhibiting the 15-PGDH, also known as “gerozyme,” the researchers significantly improved the endurance and strength of the muscles grown in the lab.

Answer: A
Explanation
• Statement 1 is correct: Attosecond pulses (of the order of 10-18 m) allow scientists to capture ‘images’ of activities that happen in incredibly short time spans. As a result, scientists can use such pulses to explore electron dynamics properly.
• Statement 2 is correct and is the correct explanation of statement 1: The radius of an electron is 2.81 × 10-15 meters which is very small. Even an ultrafast microscope which generates light pulses at a femtometer scale will be unable to map the electron precisely as it is a scientific limitation that we cannot see anything smaller than the wavelength of the light used to produce the image. Thus, the development of attosecond pulses has far more implications in fields like materials science, electronics, and catalysis.

Note: The 2023 Nobel Prize for Physics was shared by three scientists—Pierre Agostini, Ferenc Krausz and Anne L’Huillier—for their “experimental methods that generate attosecond pulses for the study of electron dynamics in matter.

Answer: B
Explanation
• Statement 1 is correct: When one touches a frozen lake, the transfer of heat from the hand to the ice occurs faster than the transfer of heat from the surrounding air to the hand. Therefore, it feels colder.
• Statement 2 is correct: Ice has low thermal conductivity, meaning it does not conduct heat well. It acts as an insulator, slowing down the transfer of heat. While both statements are correct, Statement 2 is not a direct explanation for Statement 1 rather, it provides additional context about why the frozen lake feels colder.

Answer: D
Explanation
Colour Blindness is a sex-linked recessive disorder due to defects in either red or green cone of the eye resulting in failure to discriminate between red and green colour.
• Statement 1 is incorrect: Color Blindness occurs in about 8% of the males and only about 0.4% of females. Thus, it is more common in males than in females.
• Statement 2 is correct: Since it is a recessive disorder which occurs on genes found in X chromosomes. Men have only a single copy of the X chromosome. If the X chromosomes that men receive are mutated it results in color blindness whereas women contain two copies of the X chromosome. So even if one of the copies contains the mutation the other copy is normal, and the defect is compensated by the normal copy.

Answer: A
Explanation
• Statement 1 is incorrect: Cellular respiration involves the breakdown of glucose into simpler compounds, releasing energy. It does not convert glucose into more complex carbohydrates.
• Statement 2 is incorrect: Cellular respiration occurs in the mitochondria of both plant and animal cells, not in the chloroplasts. Chloroplasts are involved in photosynthesis.
• Statement 3 is correct: The end products of cellular respiration include carbon dioxide, water, and a significant amount of energy in the form of ATP (adenosine triphosphate).