Question

Ripe fruits soften due to
A. Degeneration of cell walls
B. Partial solubilization of pectic compounds
C. Metabolism of tannins
D. Exosmosis

Answer 1

Hint: Fruit ripening is one of the developmental phases through which fruit goes. Ripening occurs when fruit growth is completed. Various changes in color, flavor, and aroma are seen during ripening. The fruit cell walls contain a naturally occurring heteropolysaccharide that solubilizes to cause aging and ripening of fruits.

Complete answer:Fruit ripening is a natural phenomenon that occurs when the fruit passes the aging stage of development. Fruits are harvested in their mature phases and when they are stored they undergo the process of aging. Aging eventually leads to the ripening of fruit marked by wrinkles on the skin of the fruit, change in aroma, and flavor of the fruit. The ripening process starts with partial solubilization of the naturally occurring heteropolysaccharide that is present in the cell walls of the fruit wall. It is called pectin and it forms the primary component of fruit cell walls. Pectin is a natural fiber and is found majorly in the fruit skin. Depolymerization and loss of neutral side chains of pectic compounds lead to wrinkling of cell walls.
Climacteric is one of the phenomena that lead to the ripening of fruits like apples, bananas, papaya, etc. It refers to rapid increases in respiration rate of fruit wall cells of fleshy fruits. Increased RNA synthesis is also an indication of the ripening stage. Plant hormone called Indole Acetic Acid which is one of the Auxins hormones decreases due to which another plant hormone called ethylene becomes active. Ethylene causes the degradation of fruit tissue. All of these activities result in partial solubilization of pectic compounds which causes fruit ripening.

Thus, option B is the right answer.

Note: Fruits can be stored for many weeks and months without degradation. This is achieved by the application of various physiological and chemical agents. Refrigeration also increases the shelf life of fruits as it slows down respiration. Ethylene levels can be controlled by varying temperatures which ensures stored fruits stay fresh.