Dicot and Monocot Roots Practice Questions
20 free Dicot and Monocot Roots practice questions for the NCERT Biology. Tap an option to answer — you get instant feedback, the correct answer, and a detailed explanation for every question.
The innermost layer of the cortex in a dicot root, which comprises a single layer of barrel-shaped cells without intercellular spaces, is the:
- A Pericycle
- B Endodermis
- C Epidermis layer
- D Stele region
Correct answer: Endodermis
The endodermis is the innermost boundary of the cortex. It is characterized by barrel-shaped cells packed tightly together to regulate the flow of water and minerals into the vascular cylinder.
Casparian strips, which are water-impermeable waxy material deposits, are found in the:
- A Radial and tangential walls of endodermis
- B Outer periclinal walls of epidermal cells
- C Lignified radial walls of the pericycle cells
- D Inner walls of sclerenchymatous hypodermis
Correct answer: Radial and tangential walls of endodermis
Casparian strips are made of suberin and are deposited on the radial and tangential walls of endodermal cells. This ensures that water must pass through the plasma membrane rather than around the cells.
In a dicot root, the initiation of lateral roots and vascular cambium during secondary growth takes place in the cells of:
- A Endodermis
- B Cortex
- C Pericycle
- D Pith
Correct answer: Pericycle
The pericycle is a layer of thick-walled parenchymatous cells located just next to the endodermis. It remains meristematic enough to initiate lateral roots and the vascular cambium.
Which of the following describes the pith in a dicot root?
- A Large and developed
- B Small or inconspicuous
- C Absent, replaced by xylem
- D Hollow and sclerenchymatous
Correct answer: Small or inconspicuous
In dicot roots, the central region or pith is usually very small or completely inconspicuous. This is due to the extensive development of primary xylem in the center.
The parenchymatous cells which lie between the xylem and the phloem in roots are called:
- A Complementary tissue
- B Conjunctive tissue
- C Intrafascicular cambium
- D Medullary rays
Correct answer: Conjunctive tissue
Conjunctive tissue consists of parenchyma cells situated between the xylem and phloem patches. In dicot roots, these cells eventually contribute to the formation of the cambium ring.
How many xylem bundles are typically found in a dicot root?
- A Two to four
- B Six or more
- C Ten to twelve
- D Only one
Correct answer: Two to four
Dicot roots usually exhibit diarch to tetrarch conditions, meaning there are two to four xylem and phloem patches. In contrast, monocot roots are usually polyarch.
Which of the following is a characteristic feature of monocot roots that distinguishes them from dicot roots?
- A Presence of radial vascular bundles
- B Presence of endodermis
- C Polyarch xylem bundles
- D Exarch arrangement of xylem
Correct answer: Polyarch xylem bundles
While both roots have radial and exarch xylem, monocot roots are typically polyarch, having more than six xylem bundles. Dicot roots have fewer bundles (2–4).
In terms of development, the pith in a monocot root is:
- A Inconspicuous
- B Large and well-developed
- C Replaced by a single metaxylem vessel
- D Made of dead sclerenchyma cells
Correct answer: Large and well-developed
Unlike the dicot root, the monocot root possesses a large and well-developed pith at its center. This is a key anatomical distinction between the two.
Secondary growth is observed in:
- A Dicot roots only
- B Monocot roots
- C Both dicot and monocot roots
- D Neither type of root
Correct answer: Dicot roots only
Monocot roots do not undergo any secondary growth throughout their lifespan. Dicot roots undergo secondary growth, resulting in an increase in girth.
The 'stele' in a root includes all of the following tissues EXCEPT:
- A Pericycle
- B Vascular bundles
- C Pith
- D Endodermis
Correct answer: Endodermis
The stele refers to all tissues on the inner side of the endodermis. Therefore, it includes the pericycle, vascular bundles (xylem and phloem), and the pith, but excludes the endodermis itself.
In roots, the protoxylem lies towards the periphery and metaxylem lies towards the center. This arrangement is called:
- A Endarch
- B Exarch
- C Centripetal
- D Diarch
Correct answer: Exarch
The exarch condition is a defining characteristic of roots. In this arrangement, the younger protoxylem is directed towards the outside (periphery) while the older metaxylem is towards the inside.
The layer of cells that gives rise to lateral roots is:
- A Epiblema
- B Cortex
- C Pericycle
- D Endodermis
Correct answer: Pericycle
Lateral roots are endogenous in origin, meaning they arise from the internal tissue known as the pericycle. These cells divide and push through the cortex and epidermis.
Which of the following is the correct sequence of layers in a dicot root from outside to inside?
- A Epidermis -> Endodermis -> Cortex -> Pericycle
- B Epidermis -> Cortex -> Endodermis -> Pericycle
- C Cortex -> Epidermis -> Pericycle -> Endodermis
- D Pericycle -> Endodermis -> Cortex -> Epidermis
Correct answer: Epidermis -> Cortex -> Endodermis -> Pericycle
The outermost layer is the epidermis (epiblema), followed by the multi-layered cortex. The innermost layer of the cortex is the endodermis, which leads to the pericycle within the stele.
The thin-walled cells of the endodermis located opposite the protoxylem, which lack Casparian strips, are called:
- A Bulliform cells
- B Subsidiary cells
- C Passage cells
- D Lenticels
Correct answer: Passage cells
Passage cells allow for the transfer of water and dissolved salts from the cortex directly into the xylem. They are strategically located opposite the protoxylem points.
In a monocot root, how many xylem bundles are typically present?
- A Two to four only
- B One to two only
- C More than 6
- D Exactly 5
Correct answer: More than 6
Monocot roots are described as polyarch because they contain many xylem bundles, usually more than six. Dicot roots are usually diarch, triarch, or tetrarch.
Suberin is a waxy substance associated with which tissue in the root?
- A Epidermis layer
- B Endodermis
- C Xylem vessels
- D Phloem
Correct answer: Endodermis
Suberin is found in the Casparian strips of the endodermis. Its waxy, hydrophobic nature makes the cell walls impermeable to water, forcing water into the symplastic pathway.
The vascular bundles in roots are always:
- A Conjoint and closed
- B Conjoint and open
- C Radial
- D Closed
Correct answer: Radial
In all roots (dicot and monocot), the xylem and phloem are arranged in a radial pattern. This means they are situated on different radii alternating with each other.
Epiblema is another name for the:
- A Innermost layer of cortex
- B Outermost layer of root
- C Layer below the pericycle
- D Vascular cambium
Correct answer: Outermost layer of root
The epidermis of the root is specifically called the epiblema or piliferous layer. It often bears unicellular root hairs for absorption.
Which tissue in the dicot root is responsible for the formation of the cork cambium?
- A Epidermis
- B Outer cortex
- C Pericycle
- D Endodermis
Correct answer: Pericycle
In dicot roots, the pericycle not only forms part of the vascular cambium but also gives rise to the cork cambium (phellogen) during secondary growth.
Which of the following statements about the monocot root is FALSE?
- A It has a large, well-developed pith.
- B Vascular bundles are arranged radially.
- C It shows significant secondary growth.
- D The cortex is generally wide.
Correct answer: It shows significant secondary growth.
Monocot roots do not undergo secondary growth. The absence of a cambium between the primary xylem and phloem makes them 'closed' to secondary development.