Question

In Ipomoea batatas (Sweet potato), the food is stored in
A. Root tuber
B. Stem tube
C. Bud
D. Leaves

Answer 1

Stem tube, an underground stem modification, is an oval or spherical underground swollen stem structure which does not bear adventitious roots. For example: Potato. A bud may be defined as a condensed immature or embryonic shoot having a growing point surrounded by closely immature leaves. Leaves are green, dissimilar exogenous lateral flattened outgrowths which is borne on the node of a stem or its branch and is specialized for photosynthesis.

Complete answer:
In Ipomoea batatas (Sweet potato), the food is stored in A) Root tuber.

Roots that grow from any part of a plant other than the radicle or its branches are called adventitious roots.
They branch like the tap roots.
Adventitious root systems may be underground or aerial.
They generally develop from stem nodes, internodes, leaves etc.
Adventitious roots modify for storage of food. One such modification is Root tuber or tuberous roots.
The swollen roots occur singly.
The tuberous roots do not have a specific shape.
Very fine secondary roots occur all over the tuber.

Additional information: -
The largest bud is that of cabbage. According to their nature, buds can be vegetative, floral and mixed.
Sucker, rhizome and corm are other underground stem modifications.
Stem tubers are covered by a corky skin having lenticels for aeration.

Note: Besides storage of food, adventitious roots are also modified for mechanical support like prop roots, stilt roots.
Fleshy adventitious roots, Fasciculated fleshy roots and palmate roots are the other modifications for storage of food.