• Mathematical Logic & Numerical Analysis: Mendel was among the earliest scientists to apply quantitative, mathematical logic and statistical analyses to solve complex biological problems.
• Large Sample Size: He analyzed a vast number of plant samples across successive generations, which minimized experimental error and provided high statistical credibility to his findings.
• Confirmation Across Generations: His experiments were performed systematically over several successive generations to confirm that the observed inheritance patterns were consistent and predictable.

I. Law of Dominance

States that in a heterozygote, one trait will conceal the presence of another trait for the same characteristic. The allele that is expressed is called dominant, while the masked allele is recessive.

II. Law of Segregation (Purity of Gametes)

States that during the formation of gametes (meiosis), the two alleles for a trait segregate from each other so that each gamete carries only one allele for each gene.

III. Law of Independent Assortment

States that alleles of two or more different genes assort independently of one another during gamete formation, provided the genes are on different chromosomes or far apart on the same chromosome.

Q1. For how many years did Gregor Mendel conduct experiments on garden pea plants?

• (a) 5 years (1850–1855)
• (b) 7 years (1856–1863)
• (c) 10 years (1860–1870)
• (d) 14 years (1856–1870)

Q2. How many pairs of contrasting traits did Mendel study in garden pea plants?

• (a) 5 pairs
• (b) 12 pairs
• (c) 7 pairs
• (d) 14 pairs

Q3. Which of the following is a recessive trait in pea plants according to Mendel’s experiments?

• (a) Tall stem height
• (b) Yellow seed color
• (c) Wrinkled seed shape
• (d) Green pod color

Q1. What is a true-breeding line in Mendelian genetics?

Answer: A true-breeding line is one that has undergone continuous self-pollination over several generations and shows stable, constant trait inheritance. Offspring produced by a true-breeding plant consistently express the same phenotype without unexpected variations.

Q2. Why was Mendel’s mathematical approach revolutionary for biological sciences?

Answer: Mendel was one of the first scientists to integrate mathematical logic, numerical analysis, and statistical probabilities into biological research. His use of large sample sizes provided high credibility and statistical validity to his laws of inheritance.

Q3. State Mendel’s Law of Segregation.

Answer: The Law of Segregation states that during gamete formation (meiosis), allele pairs segregate so that each gamete carries only one allele for each gene pair. This ensures that gametes are always pure for a given trait.

Q1. Explain why garden pea (Pisum sativum) was an ideal choice for Mendel’s hybridization experiments.

Answer: Mendel selected garden pea plants due to several distinct advantages:

• Clear Contrasting Traits: Pea plants possessed distinct, easily observable contrasting characters (e.g., tall vs. dwarf, round vs. wrinkled seeds).
• Short Life Cycle: Pea plants complete their life cycle quickly within a single season, allowing data collection across multiple generations in a short time.
• Controlled Breeding: Flowers are naturally self-pollinating, but artificial cross-pollination (hybridization) can be easily performed by emasculation and bagging.
• High Fertility: A single cross produces a large number of seeds, enabling reliable statistical analysis.

Q2. Differentiate between Dominant Traits and Recessive Traits with examples.