Anatomy of the Monocotyledonous Root
The monocot root is a variation on a familiar theme. It keeps the same concentric sequence of tissues you already met in the dicot root — epidermis, cortex, endodermis, pericycle, vascular bundles and pith — but changes the proportions and the permanence of the organ.
In this quiz you will test your understanding of three key shifts:
- Polyarch condition — usually more than six xylem bundles, compared with the fewer bundles of the dicot root.
- Large, well-developed pith — a conspicuous central zone that gives the section its distinctive visual signature.
- No secondary growth — monocot roots show no cambial activity at all.
Work carefully through each question and justify every difference you see between a monocot and a dicot root section. Precision with terms such as casparian strips, pericycle, conjunctive tissue and stele is what allows a transverse section to be read confidently rather than guessed at.
Q1. Which set of tissues is found in the monocot root, showing its similarity to the dicot root?
The anatomy of the monocot root is similar to the dicot root in many respects: it has epidermis, cortex, endodermis, pericycle, vascular bundles and pith.
Q2. In the monocot root, the number of xylem bundles is usually:
Compared with the dicot root, which has fewer xylem bundles, the monocot root usually has more than six (polyarch) xylem bundles.
Q3. The term "polyarch" as applied to the monocot root means that the root has:
The lesson states that there are usually more than six (polyarch) xylem bundles in the monocot root, so polyarch refers to this many-bundled condition.
Q4. Compared with the monocot root, the dicot root typically has:
The lesson states that the dicot root has fewer xylem bundles, whereas the monocot root usually has more than six (polyarch) bundles.
Q5. Which statement correctly describes the pith of a monocot root?
The lesson states that in the monocot root the pith is large and well developed, in contrast with the small or inconspicuous pith of the dicot root.
Q6. Monocotyledonous roots do not undergo any secondary growth because they lack:
The lesson states plainly that monocotyledonous roots do not undergo any secondary growth, which reflects the absence of cambial activity in these roots.
Q7. The outermost protective layer of the monocot root, which bears root hairs, is the:
The epidermis is the outermost layer of the root, the protective boundary bearing root hairs that extend its absorptive surface into the surrounding soil.
Q8. Which description best fits the cortex of the monocot root?
Beneath the epidermis lies the cortex, a broad zone of parenchymatous tissue whose cells are separated by intercellular spaces, giving it a loose, aerated character suited to storage and transport.
Q9. The innermost layer of the cortex in the monocot root is the:
The innermost layer of the cortex is called the endodermis; it comprises a single layer of barrel-shaped cells without any intercellular spaces.
Q10. The water-impermeable, waxy material deposited in the casparian strips of the endodermal cells is:
The tangential as well as radial walls of the endodermal cells have a deposition of water-impermeable, waxy material suberin in the form of casparian strips.
Q11. In the monocot root, the pericycle lies immediately next to the endodermis and consists of:
Next to the endodermis lies a few layers of thick-walled parenchymatous cells referred to as the pericycle.
Q12. All tissues on the inner side of the endodermis — pericycle, vascular bundles and pith — together constitute the:
All tissues on the inner side of the endodermis, such as pericycle, vascular bundles and pith, constitute the stele.
Q13. The parenchymatous cells which lie between the xylem and the phloem are called:
The parenchymatous cells which lie between the xylem and the phloem are called conjunctive tissue.
Q14. Which combination of features best identifies a monocot root section under the microscope?
The monocot root shows the polyarch condition (usually more than six xylem bundles) together with a large and well-developed pith, giving the section its distinctive visual signature.
Q15. A student compares a monocot root with a dicot root and notes that the monocot root has no cambium ring and no secondary growth. This observation is:
The lesson states that monocotyledonous roots do not undergo any secondary growth, unlike the dicot root where a cambium ring develops between the xylem and phloem.