60. What is the term for different forms of the same gene?
[DSSSB Assistant Superintendent, 6 July 2026 (Shift 2)]
(a) Chromosomes
(b) Traits
(c) Genotypes
(d) Alleles
Answer: (d) Alleles
Explanation: Alleles are alternative versions of a particular gene at the same chromosomal locus. A diploid organism generally receives one allele from each parent. Different allelic combinations help explain inherited variation, such as contrasting seed colours in pea plants.
59. Assertion (A): In polygenic inheritance, each gene has a major and easily identifiable phenotypic effect.
Reason (R): Polygenes usually exert only slight effects individually.
Select the correct answer.
[UPHESC Assistant Professor (Botany), 18 April 2026 (Shift 2)]
(a) Both A and R are true, and R explains A.
(b) A is false, but R is true.
(c) A is true, but R is false.
(d) Both A and R are true, but R does not explain A.
Answer: (b) A is false, but R is true.
Explanation: Polygenic traits arise from the combined action of many genes, each usually contributing a small effect. Human height and skin pigmentation illustrate such inheritance. The assertion wrongly attributes a large individual effect to every contributing gene, while the reason is correct.
58. Which scientist is honoured with the title “Father of Genetics”?
[DSSSB MTS, 5 March 2026 (Shift 3)]
(a) Mendel
(b) Lamarck
(c) Franklin
(d) Darwin
Answer: (a) Mendel
Explanation: Gregor Johann Mendel uncovered fundamental inheritance patterns by crossing garden pea plants and counting offspring with contrasting traits. His evidence established segregation and independent assortment. Darwin studied evolution, Lamarck proposed acquired-character inheritance, and Rosalind Franklin contributed to elucidating DNA structure.
57. What was Mendel’s contribution to genetics?
[RRB Group D, 30 December 2025 (Shift 2)]
(a) Theory of Evolution
(b) Discovery of DNA
(c) Inheritance of Acquired Traits
(d) Laws of Inheritance
Answer: (d) Laws of Inheritance
Explanation: Mendel experimentally showed that hereditary factors are transmitted in predictable patterns, developing laws of dominance, segregation and independent assortment. His approach relied on controlled crosses and counting pea-plant offspring. He did not discover the molecular structure of DNA.
56. What is the main purpose of creating DNA copies during reproduction?
[RRB Group D, 30 December 2025 (Shift 1)]
(a) To change the structure of cells
(b) To make organisms immune to diseases
(c) To produce identical twins
(d) To pass genetic information to offspring
Answer: (d) To pass genetic information to offspring
Explanation: DNA replication provides offspring or daughter cells with genetic instructions inherited from the parent. The copying mechanism is usually accurate but can introduce small variations. Those variations, when heritable, help create diversity on which evolutionary processes can act.
55. How many contrasting characters were used by Mendel to formulate the laws of inheritance?
[RRB Group D, 21 December 2025 (Shift 1)]
(a) 5
(b) 7
(c) 8
(d) 4
Answer: (b) 7
Explanation: Mendel examined seven pairs of contrasting traits in garden pea plants, including tall versus dwarf stems and round versus wrinkled seeds. Carefully following these discrete differences across generations enabled him to discover consistent numerical patterns of inheritance.
54. Why did Mendel use true-breeding plants as parents in his crosses?
[RRB Group D, 14 December 2025 (Shift 1)]
(a) To get a large number of plants quickly
(b) To grow them in similar soil conditions
(c) To study environmental effects on plant growth
(d) To study inheritance patterns
Answer: (d) To study inheritance patterns
Explanation: True-breeding lines consistently reproduce the same observable trait when self-pollinated, making their inherited characteristics predictable. Crossing contrasting pure lines let Mendel determine how parental factors combine in hybrids and how recessive traits reappear in subsequent generations.
53. Which of the following is NOT a trait Mendel studied in pea plants?
[RRB Group D, 9 December 2025 (Shift 1)]
(a) Plant height
(b) Flower position
(c) Seed shape
(d) Leaf size
Answer: (d) Leaf size
Explanation: Mendel chose seven readily distinguishable features, including plant height, seed shape, seed colour, pod shape, pod colour, flower colour and flower position. Leaf size was not among his selected contrasting characters, making it the exception in these options.
52. Which of the following can be considered a reason for Mendel’s success in formulating laws of inheritance?
[RRB Group D, 8 December 2025 (Shift 1)]
(a) He had supernatural power.
(b) He was a monk.
(c) He had knowledge of mathematics.
(d) He was a well-trained scientist.
Answer: (c) He had knowledge of mathematics.
Explanation: Mendel used systematic counting and mathematical ratios to interpret large numbers of pea-plant offspring. Quantitative treatment revealed regular segregation patterns instead of relying only on visual impressions. His mathematical analysis was especially important for identifying Mendelian inheritance laws.
51. Assertion (A): Mendel chose pea plants because they were easy to grow and showed distinct contrasting traits.
Reason (R): Pea plants reproduce asexually, allowing Mendel to control crosses easily.
[RRB Group D, 5 December 2025 (Shift 3)]
(a) A is false, but R is true.
(b) A is true, but R is false.
(c) Both A and R are true, and R explains A.
(d) Both A and R are true, but R does not explain A.
Answer: (b) A is true, but R is false.
Explanation: Garden peas are sexually reproducing flowering plants capable of self-pollination and controlled cross-pollination, not asexual reproduction. Their short generation time and clear alternative traits were useful. Therefore, the assertion correctly explains their experimental suitability, but the reason is false.