Biology Q3 S3 - Monohybrid Cross

Monohybrid Cross

A genetic cross that involves one pair of contrasting traits (e.g., tall plant vs. dwarf plant)

Gene

The unit of inheritance; a segment of DNA that codes for a specific trait

Allele (in monohybrid context)

An alternative form of a gene; different versions that produce different traits

Dominant Trait (In monohybrid)

The trait that appears in the F₁ generation when two pure parents with contrasting traits are crossed

Recessive trait (in monohybrid)

The trait that is masked or hidden in the F₁ generation and only appears when the dominant trait is absent

Genotype notation

The genetic makeup written using letters (e.g., TT, Tt, tt) where capital letters represent dominant alleles and lowercase letters represent recessive alleles

Phenotype Expression

The physical appearance of an organism based on its genotype (e.g., Tall or Dwarf appearance)

Homozygous Genotype

Having two identical alleles for a trait; can be homozygous dominant (TT) or homozygous recessive (tt)

Heterozygous genotype

Having two different alleles for a trait (Tt); also called hybrid

Genotype vs. phenotype principle

The genotype (genetic makeup) is not always equal to the phenotype (physical appearance); Tt and TT both appear tall but have different genotypes