Q1. Source: CSIR NET NOV 20; Session I
Examples of antibiotic resistance highlight important features of natural selection. Which of the following statements is NOT true?
a. Evolution by natural selection is progressive; it makes individuals better
b. Natural selection acts on individuals but it is populations that change with time
c. Natural selection does not cause genetic changes in individuals
d. Natural selection acts on phenotype
Explanation
Natural selection does not have a predetermined goal or direction. Evolution is not progressive and does not always produce “better” organisms. Instead, it favors traits that improve an organism’s fitness in a particular environment.
Statement Analysis
B. True. Natural selection acts on individuals, but over generations, it is the population that evolves as allele frequencies change.
C. True. Natural selection does not create genetic changes in individuals. Mutations generate genetic variation, while natural selection simply acts on the existing variation.
D. True. Natural selection acts on an organism’s phenotype (observable traits). If those traits have a genetic basis, the underlying alleles become more or less common in future generations.
The right answer is a. Evolution by natural selection is progressive; it makes individuals better
Q2. Source: CSIR NET NOV 20; Session I
You wanted to conduct Miller-Urey experiment and used a simplified apparatus with Tungsten electrodes. You heated the glassware at 500°C for 3 hours to remove any organic contaminants. Gases NH₃, CH₄, CO and H₂ were introduced followed by generating electric spark. Which of the essential ingredients did you forget to add?
a. Oâ‚‚
b. Hâ‚‚O
c. HCN
d. CHO
Explanation
The classic Miller-Urey experiment simulated conditions believed to resemble the early Earth’s atmosphere. Along with gases such as methane (CHâ‚„), ammonia (NH₃), and hydrogen (Hâ‚‚), the apparatus also contained water (Hâ‚‚O), which was heated to produce water vapor that resembled moisture in the air.
Water played several essential roles:
- It simulated the primordial ocean.
- It supplied water vapor to the gas mixture.
- It participated in the chemical reactions that produced organic molecules.
Statement Analysis
Oâ‚‚ was intentionally excluded because the early Earth’s atmosphere was thought to be reducing rather than oxygen-rich.
HCN is not an initial component of the experiment; it is formed during the reactions.
CHO is not a chemical compound and is therefore not an essential ingredient.
Correct answer b. H2O
Your Score?
2/2 – Ecology & Evolution Expert!
1/2 – Great effort! Keep revising.
0/2 – Time to revisit the fundamentals.