Question

The edible part of turnip is-
A) Modified adventitious roots
B) Modified tap root
C) Stem
D) Underground stem

Answer 1

Hint: In turnip, a swollen root stores food at the middle and tapers gradually at both the ends forming a spindle shaped structure. Small root-like projections can be seen coming out of it.

Complete answer:
Taproots usually have a large central which is a dominant root, many lateral roots arise from it. The central root is called primary root which is thick, straight, tapering in shape, and grows vertically downwards while several fibrous root-like extensions arise from the primary root and are called secondary and tertiary roots. In some plants, taproots perform modified function, it acts as a storage organ. The modification is developed in a manner that it is used as cultivating crops. Example- carrot, turnip, etc. In dicotyledonous plants, roots initiate with a main root forming from the enlarging radicle of the seed. When the radicle grows large and smaller lateral roots arise along the lateral sides of the taproot, it forms a persistent taproot system. The root is initially taproot which can be persistent, but most often it gets replaced by a fibrous root system during later development of plants. The taproots can be divided into following categories on the basis of their shape:
Conical root- the root tuber is conical in shape, it is wide at the top and steadily tapers towards the bottom. Example- Carrot.
Fusiform root- the root is broad in the middle and tapers towards the top and the bottom. Example- Radish.
Napiform root- It is very broad at the top and tapers suddenly like a tail at the bottom, such roots have a top like appearance. Example- Turnip.

Thus, the correct answer is B. modified taproot.

Note:A contrast can be observed between the taproot system and the adventitious root system as the main central taproot has many branched roots arising from it. The tap roots in several plant species are modified to store food.