Genetics

The branch of biology which deals with the study of the transfer of parental characters to their offsprings is called genetics.

Scientist Gregor Johann Mendel studied the transmission of parental characters to their offspring for the first time. So, Scientist Mendel is known as the Father of Genetics.

Heredity

The process of transmission of parental characters to their offspring is called heredity.

Hereditary Characters

Those characters that transfer from parents to their offspring are called hereditary characters.

Example: height, the color of the skin, etc.

Acquired Characters

Those characters that are present in the offspring but not transferred from their parents are called acquired characters.

Example: skill, knowledge, etc.

Phenotype: The external appearance of an organism.

Genotype: The genetic composition of an organism.

Monohybrid Cross: The cross between two parents with one pair of pure contrasting characters is called a monohybrid cross.

Example: cross between pure tall pea plant and dwarf pea plant.

Dihybrid Cross: The cross between two parents with two pairs of pure contrasting characters is called a dihybrid cross.

Example: Cross between pure tall pea plant with pure red flower and dwarf pea plant with a white flower.

Hybrid: The organism produced by the cross between two genetically different parents.

Dominant Character: The character of the parent that is expressed by the hybrid phenotypically.

Recessive Character: The character of the parent that remains hidden in the hybrid.

Q. Why did Scientist Mendel select pea plants in his experiment?

- Scientist Mendel selected the pea plant in his experiment because of the following reasons:

• Pea plant has different contrasting characters such as tall and dwarf, red flower and white flower, round seed, and wrinkled seed.
• The life cycle of the pea plant completes in a short period of time. Due to this, a large number of experiments can be done in a short period of time.
• Self-pollination and cross-pollination can be easily carried out in pea plants.
• A large number of offspring can be reproduced at a time.

Q. What are the contrasting characters did Mendel selects in the pea plant?

- The following contrasting characters were selected by Mendel in pea plant:

1. Height of plant - Tall (T) and Dwarf (t)
2. Position of the flower - Axial (A) and Terminal (a)
3. Color of the pod - Green (G) and Yellow (g)
4. The shape of the pod - Inflated (I) and Constricted (i)
5. The shape of seed - Round (R) and Wrinkled (r)
6. Color of flower - Red (R) and White (r)
7. Color of cotyledon -Yellow (Y) and Green (y)