Question

The function of nodulated roots is
A. To store food
B. To provide extra strength
C. To perform photosynthesis
D. To give shelter to bacteria

Answer 1

Hint:
The irregular or the round mass or a lump of roots is called nodules within the cells are known as nodulated roots. They appear as bead-like structures on the roots. The bacteria are termed as nitrogen-fixing bacteria. The roots and bacteria are in a symbiont relationship. Root nodules are like swelling present on the roots.

Complete answer:
> A host-specific process with each rhizobium having a defined host-plant range of Rhizobia is called Nodulation. They are found in the soil, respond to the plant-root environment (rhizosphere) by increasing their population levels, and attaching to the root surface.
> The small nodule-like swelling present on the roots is root nodules. They give shelter to nitrogen-fixing bacteria. These bacteria fix atmospheric nitrogen into organic compounds of nitrogen.
> The roots having the irregular or the round mass or a lump called nodules within the cells.
> Primarily legumes, that form a symbiosis with nitrogen-fixing bacteria.
> Plants form a symbiotic relationship under nitrogen-limiting conditions with a host-specific strain of bacteria known as rhizobia.
> Nodulation is controlled by various factors both external (heat, acidic soil, drought) and internal (autoregulation of nodulation, ethylene)
> The bacteria that live on the roots of are termed nitrogen-fixing bacteria. These bacteria convert molecular nitrogen in the atmosphere into nitrites and nitrates, which are converted into amino acids. This is termed biological nitrogen fixation.
> These bacteria have proved to be beneficial to plants and in return, these obtain nourishment from the roots. These bacteria are termed symbiotic nitrogen-fixing bacteria as both bacteria and plants are mutually beneficial to each other.
> The bacteria multiply inside the roots of the plant to form nodules. Such roots are termed as nodulated roots and found in all leguminous plants like pea, gram, beans, etc.
> These nod factors initiate root hair curling. The curling starts at the tip of the root hair curling around the Rhizobium. Within the root tip, there is a small tube called the infection thread forms, which provides a pathway for the Rhizobium to travel into the root epidermal cells as the root hair continues to curl.
> Hence, the function of nodulated roots is to give shelter to bacteria.

Hence, option D is correct.

Note: Effective modulation takes around four weeks after crop planting, with the size, and shape of the nodules dependent on the crop.
Crops such as soybeans, or peanuts have larger nodules than forage legumes such as red clover, or alfalfa since their nitrogen needs are higher.
The number of nodules, and the internal color, will indicate the status of nitrogen fixation in the plant. They are found among the legume family- Fabaceae or Leguminosae.