Question

In a monocot root, vascular bundles are

• A. Conjoint, collateral, open
• B. Conjoint, collateral, closed
• C. Radial, polyarch
• D. Radial, diarch

Hint:

Remember that roots have radial vascular bundles. For monocot roots, the characteristic feature is a large number of xylem bundles (polyarch), whereas dicot roots have fewer xylem bundles (diarch to hexarch).

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks to characterize the arrangement of vascular bundles specifically in a monocot root.

Step 3: Detailed Explanation:
1. Root characteristics: In roots (both monocot and dicot), the vascular bundles are typically radial, meaning the xylem and phloem are arranged alternately on different radii. This distinguishes them from stems, where bundles are conjoint.
2. Monocot vs. Dicot roots:
* Dicot roots: Usually have fewer xylem bundles (diarch, triarch, tetrarch, or pentarch), typically 2 to 6.
* Monocot roots: Generally have more than six (often 8 or more) xylem bundles. This condition is described as polyarch. They also lack a vascular cambium, so they are 'closed' in that sense, but 'radial' and 'polyarch' are the defining characteristics of their arrangement.
3. Open/Closed: While monocot roots are 'closed' as they lack cambium and don't show secondary growth, this term is primarily used for stems. For roots, the arrangement (radial) and number of xylem bundles (polyarch) are more specific descriptors. Diarch refers to two xylem bundles.
Therefore, in a monocot root, vascular bundles are radial and polyarch.

Step 4: Final Answer:
The correct option is (C) Radial, polyarch.