Question

The stem is modified to store food in
A) Potato
B) Carrot
C) Turnip
D) Dahlia

Answer 1

Hint: Food is stored in different parts of the plants in the form of starch and that is the source of energy which is being transferred to those who consume it. Starch is a polymeric carbohydrate molecule which has a large number of glucose subunits attached together with the help of glycosidic bonds.

Complete answer:
Modifications in stem help them to perform several functions like providing support, storing food, vegetative propagation and protection. The modification of stems for the purpose of food storage involves aerial, sub-aerial and underground modifications.
Stem is modified to store food in several plants like potatoes, ginger, sweet potato, colocasia and many more. In this question we have four plants being given in which potato stores food in modified stem called tubers and the other three carrots, turnip and dahlia have root modifications for food storage.

So the answer for this question is A - The stem is modified to store food in Potato.

Additional Information: Stems undergo different modifications-
Aerial modifications: These modifications involve
Stem tendrils – Stem modifies into threadlike structures called tendrils which are meant for climbing as in Grapevine.
Thorns – Terminal buds of plants get modified into hard pointed structures which are meant for the protection of plants as in Bougainvillea.
Phylloclades – Leaf modification that reduce transpiration, they also take part in photosynthesis. Such modifications are seen in desert plants like cactus.
Bulbils – Axillary/ floral buds are modified for storing food. They also have the potential to form a new plant by vegetative propagation. Example – Agave.
Sub-Aerial modifications: The modifications that take place when the stem is partly above the ground and partly below the ground. These include
Runner – They are creepers running horizontally on the surface of the soil. Example - Mint
Sucker – They develop from the basal part of the main stem and move horizontally under the soil and obliquely move upwards. Example - Mentha
Stolon – They grow aerially first and then bend and touch the ground. New stem arises from terminal buds as in Jasmine.
Offset – They are mostly found in aquatic plants and are shorter and thicker and grow horizontally after being originated from the axis of the leaf. Example – Pistia.
Underground modification: these modifications are focussed for food storage majorly. They include:
Tubers – They are fleshy parts of the plant stem which store food as in potato.
Bulb – They constitute fleshy scale leaves forming a bulb as in Onion and garlic.
Rhizome – They are mostly brown in colour having nodes and internodes. They store food and that is why they are fleshy as in ginger.

Note: Plants from food by the process of photosynthesis in the form of glucose and this food is stored in different parts of the plants as in leaves, stem and roots. Plants adapt themselves accordingly by modifying the structures for storing food. These structures are being consumed by other organisms as the source of energy.