Gregor Mendel and Pea Plant Selection
📌 Gregor Mendel, an Austrian biologist, conducted his inheritance studies using the **pea plant (*Pisum sativum*).
🌱 Mendel chose pea plants because they have a short life cycle, are easy to cross-pollinate, produce many varied offspring, and show distinct observable traits**.
🧬 The pea plant variations observed included flower color (purple/white), seed color (yellow/green), pod shape (smooth/wrinkled), and flower position.

Key Genetic Terminology
🧬 Genes are represented by letters on chromosomes, with capital letters denoting dominant (strong) alleles and small letters denoting recessive (weak) alleles.
🐩 Genotype is the complete genetic information (e.g., AA, Aa, aa), while Phenotype is the observable physical trait (e.g., purple flower).
⚖️ Genotypes where alleles are the same (e.g., AA or aa) are called homozygous (dominant or recessive, respectively); genotypes with different alleles (e.g., Aa) are heterozygous.
➡️ Gametes are sex cells carrying half the parent's genes, formed through the segregation (independent separation) of alleles during meiosis, which forms the basis of Mendel's First Law (Law of Segregation).

Monohybrid Cross: Dominant Inheritance
🔬 A monohybrid cross involves tracking only one trait (e.g., flower color).
🌷 Crossing homozygous dominant (e.g., $\text{P}\text{P}$ - Purple) with homozygous recessive (e.g., $\text{pp}$ - White) results in $\text{F}\text{1}$ offspring that are all heterozygous ($\text{Pp}$) and show the dominant phenotype (Purple).
📊 The $\text{F}\text{2}$ generation, resulting from crossing $\text{F}\text{1}$ individuals ($\text{Pp} \times \text{Pp}$), yields a genotypic ratio of 1:2:1 ($\text{PP}:\text{Pp}:\text{pp}$) and a phenotypic ratio of 3:1 (3 Purple : 1 White).

Monohybrid Cross: Intermediate Inheritance
🧬 Intermediate inheritance occurs when the dominant and recessive alleles meet, resulting in a new, intermediate phenotype (blending).
🌸 For example, crossing red flowers ($\text{M}\text{M}$) with white flowers ($\text{mm}$) results in $\text{F}\text{1}$ offspring that are pink ($\text{Mm}$), as pink is the blend of red and white.
📊 In the $\text{F}\text{2}$ generation for intermediate inheritance, the phenotypic ratio is 1:2:1 (Red : Pink : White), which is the same as the genotypic ratio, unlike in dominant crosses.

Key Points & Insights
➡️ Mendel's research is fundamental to understanding heredity, relying on controlled crosses of _Pisum sativum_ for clarity.
➡️ In dominant inheritance, the dominant allele always masks the recessive trait in heterozygotes ($\text{Aa}$).
➡️ Intermediate inheritance demonstrates a blending effect, where heterozygotes ($\text{Aa}$) exhibit a third, intermediate trait, leading to a $\text{1:2:1}$ phenotypic ratio in the $\text{F}\text{2}$ generation.
➡️ The next topic of study will cover Dihybrid crosses (Mendel's Second Law), involving the tracking of two traits simultaneously.

📸 Video summarized with SummaryTube.com on Jan 15, 2026, 04:22 UTC