NEET Genetics and Evolution 2 — Questions and Answers
Question 1: The chromosomal theory of inheritance, which linked Mendel's factors to physical chromosomes, was proposed by:
- Gregor Mendel and Charles Darwin
- Walter Sutton and Theodor Boveri (Correct answer)
- Watson and Crick
- Hugo de Vries and Carl Correns
Correct answer: Walter Sutton and Theodor Boveri
Walter Sutton and Theodor Boveri independently proposed the chromosomal theory of inheritance around 1902, connecting Mendel's hereditary factors to the behavior of chromosomes during meiosis.
Question 2: A point mutation that changes a single nucleotide and results in a codon that codes for a different amino acid is called a:
- Silent mutation
- Nonsense mutation
- Missense mutation (Correct answer)
- Frameshift mutation
Correct answer: Missense mutation
A missense mutation substitutes one nucleotide, altering a codon so it specifies a different amino acid, potentially disrupting protein structure and function.
Question 3: According to Darwin's theory of natural selection, which individuals are most likely to survive and leave more offspring?
- The largest and physically strongest individuals
- Those best adapted to their current environment (Correct answer)
- Those that produce the most offspring regardless of survival
- The longest-lived individuals in the population
Correct answer: Those best adapted to their current environment
Natural selection favors individuals whose heritable traits make them better adapted to their environment, giving them a reproductive advantage over less adapted individuals.
Question 4: Which of the following provides the strongest molecular evidence for evolution from a common ancestor?
- Similar body plans among vertebrates
- Presence of vestigial structures in many species
- Highly conserved DNA sequences (e.g., ribosomal RNA genes) across diverse species (Correct answer)
- Similar ecological niches occupied by unrelated species
Correct answer: Highly conserved DNA sequences (e.g., ribosomal RNA genes) across diverse species
Highly conserved DNA sequences shared across vastly different species indicate descent from a common ancestor, as random mutation would have altered these sequences if species evolved independently.
Question 5: Genetic drift is best described as:
- The movement of alleles between different populations via migration
- Random changes in allele frequencies in a population due to chance events (Correct answer)
- Directed changes in allele frequencies driven by natural selection
- The tendency for all populations to evolve toward the same genotype
Correct answer: Random changes in allele frequencies in a population due to chance events
Genetic drift refers to random fluctuations in allele frequencies that arise by chance, particularly pronounced in small populations where chance events have a disproportionate impact.
Question 6: Which type of natural selection favors individuals with intermediate phenotypes and acts against both extremes of the population?
- Directional selection
- Disruptive selection
- Stabilizing selection (Correct answer)
- Sexual selection
Correct answer: Stabilizing selection
Stabilizing selection reduces phenotypic variation by favoring intermediate trait values and selecting against extreme variants, maintaining the population near the current average.
Question 7: The Hardy-Weinberg principle states that allele and genotype frequencies in a population will remain constant generation after generation if:
- The population is very large and no evolutionary forces (mutation, selection, drift, gene flow) are acting (Correct answer)
- All individuals have equal survival rates regardless of genotype
- Random mating occurs but the population size is small
- No mutation and no migration occur but natural selection is present
Correct answer: The population is very large and no evolutionary forces (mutation, selection, drift, gene flow) are acting
Hardy-Weinberg equilibrium requires a large population with random mating, no mutation, no migration, no genetic drift, and no natural selection — essentially describing a non-evolving population.
NEET Genetics and Evolution 2
The chromosomal theory of inheritance, which linked Mendel's factors to physical chromosomes, was proposed by: