Question

Mendel observed 7 pairs of contrasting characters in Pisum sativum. One of the following is not a part of that. Find out.
A. Tall and dwarf stem
B. Yellow and green seed color
C. Terminal and axial flower
D. Smooth and rough stem

Answer 1

Hint: A genetic study was made by the Mendel on the pea plant for seven years to study the characters which are passed on to the progeny and how they are transferred and which progeny receives more parental characters and which the least. He studied seven contrasting characters.

Complete answer:
The correct answer is (D).
Mendel is the one who is known as the father of genetics. He studied pea plants for the seven years from 1856- 1863 and used different contrasting characters and proposed the laws of inheritance.

The characters studied were:
- Stem height – tall/ dwarf
- Seed color – yellow/ green
- Seed shape – round/ wrinkled
- Pod color- green/ yellow
- Pod shape – inflated/ constricted
- Flower position – axial/ terminal
- Flower color- violet/ white

Mendel chose the pea plant because
- It has a short life cycle.
- It is a self-pollinated plant.
- It does not require much care.
- It clearly expressed the characters.

Mendel first crossed the tall pea plant (TT) with a short pea plant (tt) and in the first progeny observed that all the plants obtained are tall (Tt) and none of the plants are short. Then he self-pollinated the plant and in the second progeny observed that out of 4 plants, 3 plants are tall and only one plant is short.
On the basis of this, he gave the law of dominance and recessive. The dominant character is the one which is expressed either when both the alleles (TT) of the gene for the trait are present or only one allele (Tt) is also enough to express the trait whereas recessive traits are those which can only express themselves when both the alleles of the recessive trait (tt) are present.

Note: Mendel conducted the study on pea plants by studying seven contrasting features. These contrasting features were either the color of the seed or flower or the height of the plant or location of flower or shape of the seed. No feature related to the appearance of the surface of the stem was studied by Mendel.