Explanation:

A cross between two types of PLANTS of same species considering only the transmission of ONE character is called monohybrid cross. For example, a cross between tall pea plants and dwarf pea plant that is considering only the height of the parents is a monohybrid cross. It will result in the formation of tall offsprings but they will be hybrid.

Representation of the monohybrid cross: character in focus is the height

Parents- TT X tt

(Tall) (dwarf)

F1. Tt

(Heterozygous tall)

On selfing:

Tt X tT

F2. TT Tt Tt tt

Phenotypic RATIO-

3 tall: 1 dwarf

Genotypic ratio-

1 homozygous tall: 2 heterozygous tall: 1 homozygous recessive

Example

F1-generation plants

Mendel crossed SS (spherical seeds) with ss (dented seeds.)

All of the gametes of the spherical seeded parent have the S (dominant) allele and all of the gametes of the dented seeded parent have the s (recessive) allele. All of the F1 generation plants will have the genotype of Ss (heterozygous), and all will be spherical seeded.

F1 generation

=

F2-generation plants

Mendel let the F1-generation plants self-pollinate to FORM a second generation and he analyzed the seeds of the resulting F2 generation.

F2 generation

=

All F1-hybrid plants have the genotype Ss and all are spherical (dominant characteristic). The recessive alleles segregate during gamete formation. As a result, one out of four possible combinations of F2-generation plants will have the homozygous recessive genotype (ss).