Experiments simulating Earth’s early conditions provide insights into abiogenesis.
Stanley Miller's experiment produced Amino acids.
(A) Pigments - Incorrect: No photosynthetic pigments were formed in the experiment.
(B) Fats - Incorrect: Complex lipids weren't detected in Miller-Urey's results.
(C) Nitrogen bases - Incorrect: While possible in similar experiments, these weren't Miller's primary finding.
(D) Amino acids - Correct: Glycine, alanine, and other amino acids were identified (1953 experiment).
The correct answer is (D) Amino acids, providing evidence for chemical evolution's first steps toward life.
Stanley Miller conducted a famous experiment in 1953 that simulated the conditions of the early Earth. He used a spark-discharge apparatus to create a mixture of gases believed to be present in the early atmosphere, including methane (CH4), ammonia (NH3), and hydrogen (H2).
After applying electric sparks (to simulate lightning), Miller found that several organic compounds, including amino acids (the building blocks of proteins), were formed.
Option (D) is correct because the experiment demonstrated that amino acids could be synthesized under prebiotic conditions.
List I | List II | ||
---|---|---|---|
A | Mesozoic Era | I | Lower invertebrates |
B | Proterozoic Era | II | Fish & Amphibia |
C | Cenozoic Era | III | Birds & Reptiles |
D | Paleozoic Era | IV | Mammals |
A block of certain mass is placed on a rough floor. The coefficients of static and kinetic friction between the block and the floor are 0.4 and 0.25 respectively. A constant horizontal force \( F = 20 \, \text{N} \) acts on it so that the velocity of the block varies with time according to the following graph. The mass of the block is nearly (Take \( g = 10 \, \text{m/s}^2 \)):
A wooden block of mass M lies on a rough floor. Another wooden block of the same mass is hanging from the point O through strings as shown in the figure. To achieve equilibrium, the coefficient of static friction between the block on the floor and the floor itself is