Question

Pith cavity occurs in the stem of?
A.Helianthus
B.Zea mays
C.Cucurbita
D.Dracaena

Answer 1

Hint: The large number of parenchymatous cells which occupy the central portion of the stem comprises the pith. These parenchymatous cells are rounded in shape and have large intercellular spaces.

Complete answer:
Some points about monocot and dicot stem:
The hypodermis is made-up of collenchymatous cells in dicot Stem whereas, in monocot stem, the hypodermis is made up of sclerenchymatous cells.
Pith and medullary rays are present in the Dicot stem whereas the (pith and medullary rays) are absent in the monocot stem.
Ground tissue is differentiated into the cortex, endodermis, pericycle, and pith in dicot stem whereas in monocot stem ground tissue is not differentiated, but it is a continuous mass of parenchyma.
Vascular bundles are open in the dicot stem whereas they (vascular bundles) are close in monocots.
Some points about monocot and dicot root
Pith is usually large at the center in monocot root whereas it (pith) is usually absent in dicot root.
> Option -A- Helianthus: In Helianthus( a dicot) pith cavity does not disintegrate to produce a cavity. So, this option can't be correct.
> Option -B- Zea mays: In the case of Zea mays too, no pith cavity is present. So, this option also stands incorrect.
> Option -C- Cucurbita: The central part of the pith in some dicots as in Cucurbita disintegrates to produce a cavity, called pith cavity. So, in Cucurbita pith cavity is present hence, this option holds good for the above statement.
> Option -D- Dracaena: Dracaena too lacks the pith cavity. So, this again is not the correct option to the above statement.

So, the correct answer to this question is an option C "Cucurbita".

Note:
Pith rays: These are also known as medullary rays. Medullary ray or pith ray is constituted by cells of the pith present in between the vascular bundles. The parenchymatous cells are radially arranged in between the bundles and give the appearance of rays. These rays (Pith rays) help in the radial conduction of food.