Question

What would be expected to happen if
A. $G{A_3}$ is applied to rice seedlings.
B. Dividing cells stop differentiating.
C. A rotten fruit gets mixed with unripe fruits.
D. You forget to add cytokinin to the culture medium

Answer 1

Plants have various kinds of hormones in them to promote different physiological functions. Some hormones promote the growth and maturation of the plant like auxins and some inhibit it. Some hormones also help the fruits to ripen like ethylene.

Complete answer:
In the first statement, we are given that if $G{A_3}$ is applied to rice seedlings, then –
Statement A: $G{A_3}$ is a type of gibberellic acid. Gibberellic acids show the bolting phenomenon. Bolting is the sudden elongation in the length of the stem during the flowering or reproductive growth of plants. It promotes germination in cereals and starchy seeds. It inhibits the formation of the abscission layer. It promotes maleness in plants. So, when $G{A_3}$ is applied to rice seedlings, it will cause a sudden elongation in the rice plant. it will promote the germination of rice as it is a cereal. It will inhibit the formation of the abscission layer and it will promote maleness in the plants.
In the second statement, we are given that if dividing cells stop differentiating, then –
Statement B: Differentiation is the process of the change in the structure and the function of the cells according to their specific role. Differentiation causes the formation of the roots, shoot, stem, leaves, etc. from the callus. If the dividing cells will stop differentiating then the formation of the tumor of the callus will occur. No plant organs like roots, stems, or leaves, etc. will be formed.
In the third statement, we are given that if a rotten fruit gets mixed with unripe fruits, then –
Statement C: The rotten fruit emits ethylene. The ethylene is known as the fruit ripening hormone. It shows the climacteric phenomenon. It is used maximum in agriculture for ripening the fruits. It promotes seed germination by breaking dormancy and femaleness. It promotes the formation of the abscission layer. It promotes horizontal growth. Hence, when a rotten fruit gets mixed with the unripened fruits, then the rotten fruit starts releasing ethylene which ripens the unripened fruits. If the rotten fruit is kept with the unripened fruits for a prolonged-term, then it will rot all the unripened fruits too.
In the fourth statement, we are given that if you forget to add cytokinin to the culture medium, then –
Statement D: Cytokinin is used in tissue culture. Cytokinin promotes cell division. It helps in organ differentiation, especially in the shoot. It decreases senescence. It promotes femaleness. Hence, if we forget to add cytokinin to the culture medium then the callus will not differentiate into the shoot system.

Note: The cytokinin is added along with auxin in the culture medium. This is because of both of these help in organ differentiation. The auxin helps in the development of the roots from the callus whereas the cytokinin helps in the development of the shoot from the callus. The auxin and cytokinin are used in an equal ratio to promote adequate growth.