1. Morphology of flowering plants primarily deals with:
ⓐ. internal tissue arrangement and vascular differentiation
ⓑ. external form, organisation and visible structural features
ⓒ. biochemical pathways controlling growth and development
ⓓ. cellular mechanisms involved in mineral absorption
Correct Answer: external form, organisation and visible structural features
Explanation: Plant morphology concerns the externally observable form and organisation of a plant. It includes features such as the arrangement and structure of roots, stems, leaves, flowers, fruits and seeds. These characters can be recorded without examining the internal tissue organisation of the organs. Internal arrangement of tissues belongs mainly to anatomy, while biochemical pathways and cellular mechanisms are studied under physiology or related fields. Morphological study does more than name visible parts: it provides a systematic way to describe, compare and identify plants. Features such as the presence of nodes, the origin of roots, leaf arrangement and floral structure can reveal the identity of an organ or help distinguish one plant group from another.
2. Evaluate the statements about morphological study.
I. It uses visible structural features to describe plant organs.
II. Internal tissue distribution is primarily an anatomical concern.
III. Standard terms permit comparison between different specimens.
IV. Environmental variation makes morphological terminology unusable.
ⓐ. I and IV only
ⓑ. II and III only
ⓒ. I, III and IV only
ⓓ. I, II and III only
Correct Answer: I, II and III only
Explanation: Statement I is valid since morphology records externally observable structures such as roots, stems, leaves and floral parts. Statement II is also valid because the organisation of tissues inside an organ belongs mainly to plant anatomy rather than external morphology. Statement III identifies an important purpose of technical terminology: terms such as node, petiole, tap root and racemose inflorescence allow descriptions made by different observers to be compared consistently. Statement IV is not valid. Environmental conditions may alter the size, shape or development of an organ, but they do not make standard terminology useless. Instead, defined terms provide a framework within which such variation can be recognised and interpreted. The first three statements together describe the scope and value of morphological study accurately.
3. Assertion: Standard morphological terminology remains useful even when plants show environmentally influenced variation.
Reason: Defined terms allow observable structures to be described and compared using shared criteria.
ⓐ. Both Assertion and Reason are true, and Reason correctly explains Assertion
ⓑ. Both Assertion and Reason are true, but Reason does not explain Assertion
ⓒ. Assertion is true, but Reason is false and cannot explain Assertion
ⓓ. Assertion is false, but Reason is true and cannot explain Assertion
Correct Answer: Both Assertion and Reason are true, and Reason correctly explains Assertion
Explanation: The Assertion is true. Features such as organ size, shape or degree of development may vary with light, water availability and other environmental conditions, yet the organs can still be described using recognised morphological criteria. The Reason is also true. A shared vocabulary allows observers to compare structures according to their position, origin, component parts and arrangement instead of relying on vague visual impressions. The Reason directly explains why terminology remains valuable in the presence of variation. For example, leaves of different sizes may still be identified as opposite in phyllotaxy when a pair arises at each node. Standard terms do not deny natural variation; they organise it into comparable structural descriptions useful for identification and classification.
4. A diagram described in words shows Structure P as an axis below the soil with a primary member and lateral branches. Structure Q bears nodes, leaves, axillary buds, flowers and fruits. The most appropriate identification is:
ⓐ. P is a stem system, while Q is a root system
ⓑ. P is a leaf axis, while Q is an adventitious root
ⓒ. P is a root system, while Q is a shoot system
ⓓ. P is a floral axis, while Q is a primary root
Correct Answer: P is a root system, while Q is a shoot system
Explanation: Structure P contains a main root and lateral roots, which together form the root system. Structure Q bears the characteristic components of the shoot system: a stem with nodes, leaves, buds, flowers and fruits. Nodes and axillary buds are especially useful evidence of shoot identity. Position supports the interpretation, since roots are commonly underground and shoots commonly grow above the soil, but position alone is not an absolute criterion. Some roots arise above ground, while certain modified stems occur below ground. The complete combination of origin and structural features is more reliable than location by itself. In the described plant, the branched primary root identifies P as the root system, and the organ-bearing nodal axis identifies Q as the shoot system.
5. A storage organ is excavated from below the soil. It bears regularly spaced nodes, scale leaves and buds but lacks a root cap and root hairs. It should be classified as:
ⓐ. a storage root, since every underground organ belongs to the root system
ⓑ. a modified shoot organ, as its nodes and buds provide stem evidence
ⓒ. a primary root, as reserve food is commonly stored below the soil
ⓓ. a fibrous root, as several scale leaves occur along its surface
Correct Answer: a modified shoot organ, as its nodes and buds provide stem evidence
Explanation: Underground position does not by itself establish root identity. Nodes, scale leaves and buds are characteristic features of a stem or another shoot-derived structure. Buds can produce new shoots, and leaves arise from nodes; neither feature is normally present on a true root. A root would instead be recognised through evidence such as a root cap near its growing tip, root hairs in the maturation region and the absence of nodes and internodes. Storage is also not a decisive identity test, since both roots and stems may accumulate reserve food. The organ described here retains clear shoot features despite growing below the soil. Its classification must be based on its structural organisation rather than the simple observation that it was excavated from underground.
6. Arrange the following events in the developmental hierarchy of a typical tap-root system.
P. Tertiary roots arise from secondary roots.
Q. The radicle continues as the primary root.
R. Secondary roots arise laterally from the primary root.
ⓐ. \(\text{P}\rightarrow\text{Q}\rightarrow\text{R}\)
ⓑ. \(\text{R}\rightarrow\text{P}\rightarrow\text{Q}\)
ⓒ. \(\text{Q}\rightarrow\text{P}\rightarrow\text{R}\)
ⓓ. \(\text{Q}\rightarrow\text{R}\rightarrow\text{P}\)
Correct Answer: \(\text{Q}\rightarrow\text{R}\rightarrow\text{P}\)
Explanation: A tap-root system begins when the radicle of the embryo persists and develops into the primary root. The primary root forms the main central axis of the system. Secondary roots then arise as lateral branches from this primary root. Further branching produces tertiary roots from the secondary roots. The dependency between the stages fixes the sequence: a secondary root cannot arise before the primary root exists, and a tertiary root cannot arise before a secondary root is present. This branching hierarchy distinguishes a tap-root system from a fibrous system, in which the primary root is short-lived and is replaced by numerous roots near the stem base. Mustard provides a standard example of the persistent-radicle pattern represented by the stated order.
7. In a wheat seedling, the primary root remains short-lived and is replaced by numerous roots of nearly similar size arising near the stem base. This organisation represents:
ⓐ. a tap-root system
ⓑ. a prop-root system
ⓒ. a fibrous-root system
ⓓ. a storage-root system
Correct Answer: a fibrous-root system
Explanation: A fibrous-root system develops when the primary root formed from the radicle is short-lived and does not remain as the dominant central root. Numerous roots subsequently arise near the base of the stem, producing a tuft in which no single root forms a conspicuous main axis. Wheat is a standard example, and this organisation is generally associated with monocotyledonous plants. A tap-root system differs in retaining the primary root, from which secondary and tertiary roots branch. Prop roots are specialised adventitious roots that descend from branches to provide support, while storage describes a modified function rather than the overall branching pattern described for wheat. The loss of primary-root dominance and the cluster of stem-base roots together identify the fibrous system.
8. Review the following statements.
I. A fibrous-root system commonly develops after the primary root becomes short-lived.
II. Every group of adventitious roots necessarily forms a fibrous-root system.
III. Roots descending from banyan branches are adventitious in origin.
IV. Adventitious roots are defined by their origin rather than by their function.
ⓐ. I, III and IV only
ⓑ. I and II only
ⓒ. II, III and IV only
ⓓ. I, II, III and IV
Correct Answer: I, III and IV only
Explanation: Statement I is true: in a fibrous-root system, the short-lived primary root is replaced by numerous roots arising near the stem base. Statement II is an overgeneralisation. Adventitious roots are roots arising from a plant part other than the radicle, and they may occur individually or in specialised groups without forming the typical tufted organisation of a fibrous system. Statement III is true since banyan prop roots originate from branches rather than from the radicle. Statement IV is also true. A root may perform storage, support or another function, but it remains adventitious when its developmental origin is non-radicular. The valid set separates the organisation of an entire root system from the developmental origin used to classify an individual root.
9. Match each plant with the most characteristic root-system evidence. A Column II entry is used once.
| Column I | Column II |
|---|
| P. Mustard | 1. Persistent primary root with successive lateral branches |
| Q. Wheat | 2. Numerous roots arising near the stem base |
| R. Banyan | 3. Roots descending from branches toward the soil |
| S. Monstera | 4. Roots arising from the stem and assisting attachment |
ⓐ. P-2, Q-1, R-4, S-3
ⓑ. P-1, Q-2, R-3, S-4
ⓒ. P-3, Q-4, R-1, S-2
ⓓ. P-4, Q-3, R-2, S-1
Correct Answer: P-1, Q-2, R-3, S-4
Explanation: Mustard shows a typical tap-root system in which the radicle persists as the primary root and gives rise to secondary and tertiary branches, so P matches 1. Wheat develops a fibrous-root system composed of numerous roots arising near the stem base after the primary root becomes short-lived, linking Q with 2. Banyan produces prop roots that descend from branches and eventually enter the soil, making R-3 appropriate. Monstera develops adventitious roots from the stem that help the plant attach to or climb a support, so S matches 4. The final two plants both possess adventitious roots, but their particular growth positions and roles distinguish the corresponding descriptions. The mapping depends on origin and structural arrangement rather than underground or aerial position alone.
10. Four plant organs show the following observations.
| Specimen | Observed features |
|---|
| P | One dominant root continuous with the radicle and bearing lateral branches |
| Q | Many roots near the stem base after loss of primary-root dominance |
| R | Roots arising directly from stem nodes |
| S | Underground organ bearing nodes, scale leaves and buds |
The most accurate interpretation of the complete dataset is:
ⓐ. P-tap root; Q-tap root; R-fibrous root; S-fibrous root
ⓑ. P-adventitious root; Q-tap root; R-primary root; S-primary root
ⓒ. P-fibrous root; Q-adventitious root; R-tap root; S-root tuber
ⓓ. P-tap root; Q-fibrous root; R-adventitious root; S-modified shoot
Correct Answer: P-tap root; Q-fibrous root; R-adventitious root; S-modified shoot
Explanation: Specimen P has a dominant root continuous with the radicle, followed by lateral branching, which is the defining organisation of a tap-root system. Specimen Q lacks a persistent dominant primary root and instead has many roots arising near the stem base, identifying a fibrous-root system. Specimen R contains roots originating from stem nodes, so they are adventitious. Specimen S must not be called a root merely on account of its underground position. Nodes, scale leaves and buds are decisive shoot characters and indicate a modified stem or related shoot structure. The dataset illustrates three different root classifications and one non-root organ. Developmental origin and diagnostic structures provide a stronger basis for classification than position or storage appearance.
11. A young dicot has a persistent primary root with secondary and tertiary branches. Several portions of the system absorb water, anchor the plant and accumulate reserve food. The best description is:
ⓐ. a tap-root system performing several functions simultaneously
ⓑ. a fibrous-root system converted completely into storage tissue
ⓒ. an adventitious-root system that has lost its anchoring role
ⓓ. a shoot system performing absorption through underground buds
Correct Answer: a tap-root system performing several functions simultaneously
Explanation: Persistence of the primary root and the presence of secondary and tertiary branches establish a tap-root system. Root-system classification is based here on developmental origin and branching organisation, not on the number of functions performed. Roots commonly absorb water and minerals and anchor the plant in the soil. They may additionally accumulate reserve food, and the same system need not surrender its ordinary functions when storage becomes prominent. A fibrous system would lack one persistent dominant primary root, while adventitious roots would originate from parts other than the radicle. The description also contains no nodes, internodes or buds that would support shoot identity. This case demonstrates that organ identity, root-system type and specialised function are related but separate biological decisions.
12. The following functions are associated with root systems.
I. Absorption of water and mineral nutrients
II. Anchorage of the plant in the soil
III. Storage of reserve food in some plants
IV. Synthesis of certain plant growth regulators
ⓐ. I and II only
ⓑ. II, III and IV only
ⓒ. I, II, III and IV
ⓓ. I, III and IV only
Correct Answer: I, II, III and IV
Explanation: Statement I describes a major root function: young absorbing regions, especially those bearing root hairs, take up water and mineral nutrients from the soil. Statement II is also valid, as the branching root system fixes the plant to its substratum and resists displacement. Statement III applies to roots modified for reserve-food accumulation, but storage does not remove their root identity. Statement IV is included among the broader functions of roots; roots can synthesise certain plant growth regulators that influence development elsewhere in the plant. These functions are not mutually exclusive. A single root system may simultaneously provide anchorage and absorption while particular portions become specialised for storage or another task. The complete set recognises both the ordinary and specialised roles of roots.
13. Assertion: A root modified for storage can no longer participate in anchorage or absorption.
Reason: A root system may perform more than one function at the same time.
ⓐ. Both Assertion and Reason are true, and Reason correctly explains Assertion
ⓑ. Both Assertion and Reason are true, but Reason does not explain Assertion
ⓒ. Assertion is true, but Reason is false and cannot explain Assertion
ⓓ. Assertion is false, but Reason is true and cannot explain Assertion
Correct Answer: Assertion is false, but Reason is true and cannot explain Assertion
Explanation: The Assertion is false. Modification usually makes one function especially prominent, but it does not automatically eliminate every ordinary function of the organ. A thickened root may store reserve food while other parts of the same root system continue absorbing water and minerals and anchoring the plant. The Reason is true and states the principle that exposes the error in the Assertion: one root system may carry out several functions simultaneously. Root identity is retained through its developmental origin and structural continuity even when a specialised role becomes conspicuous. Treating storage, support or respiration as mutually exclusive categories would confuse dominant adaptation with total functional replacement. Morphological classification should separate what the organ is from the particular role that has become enhanced.
14. The thimble-like structure covering the extreme apex of a growing root is the:
ⓐ. root maturation zone
ⓑ. root cap
ⓒ. root elongation zone
ⓓ. root meristematic zone
Correct Answer: root cap
Explanation: The root cap forms a thimble-like covering over the extreme tip of the root. It protects the delicate underlying growing tissues as the root advances through soil particles. The meristematic region lies a short distance above the cap and contains actively dividing cells, so it is not the outer protective covering itself. Cells farther upward enter the elongation region, where they enlarge and contribute to an increase in root length. Still farther from the apex, cells differentiate in the maturation region, where some epidermal cells produce root hairs. The position of the root cap is central to its function: it receives much of the mechanical contact produced during movement through soil and shields the tender root apex from direct injury.
15. A root repeatedly grows through compact soil while its root cap is selectively removed. The remaining growth regions are initially undamaged. The earliest direct consequence is likely to be:
ⓐ. immediate loss of all water conduction through the mature root
ⓑ. conversion of the elongation region into a root-hair zone
ⓒ. reduced protection of the tender apex against mechanical injury
ⓓ. permanent transformation of dividing cells into lateral roots
Correct Answer: reduced protection of the tender apex against mechanical injury
Explanation: The root cap is positioned at the extreme apex and acts as a protective covering while the root pushes between soil particles. Selective removal of this cap exposes the tender tissues immediately behind it to abrasion and mechanical injury. The earliest direct effect would consequently concern protection rather than the specialised functions of more distant regions. Water and mineral absorption by existing root hairs may continue initially, and mature conducting portions of the root are not instantly destroyed by cap loss. The elongation region also does not become a maturation region simply through removal of the cap. Continued exposure may later impair growth if the underlying meristematic cells are damaged, but that would be a secondary consequence. The immediate prediction follows from the cap's location and protective role.
16. In a longitudinal view of a root tip, Region P covers the extreme apex, Region Q contains small actively dividing cells, Region R contains rapidly lengthening cells, and Region S bears numerous delicate root hairs. Region S is identified as:
ⓐ. the maturation region, where differentiated epidermal cells form root hairs
ⓑ. the meristematic region, where repeated divisions produce root hairs directly
ⓒ. the elongation region, where cell enlargement produces absorbing hairs
ⓓ. the root cap, where protective cells develop into epidermal hairs
Correct Answer: the maturation region, where differentiated epidermal cells form root hairs
Explanation: Root hairs occur in the region of maturation, where cells that have passed through division and elongation acquire specialised structures and functions. Some epidermal cells develop delicate tubular extensions that greatly increase contact with the soil and assist absorption of water and mineral nutrients. In the described sequence, P is the root cap, Q is the meristematic region and R is the elongation region. Region S lies farther from the apex and contains differentiated cells, fitting the maturation zone. Root hairs are not produced by the root cap, and they are not characteristic of cells that are still repeatedly dividing or rapidly elongating. Their presence is evidence that the epidermal cells have reached a mature, functionally specialised state.
17. Four treatments are applied separately to comparable root tips.
| Treatment | Immediate observation |
|---|
| P | Protective cells at the extreme apex are removed |
| Q | Mitosis declines sharply in small, thin-walled, densely protoplasmic cells |
| R | Rapid enlargement of recently produced cells is inhibited |
| S | Root hairs are lost while cell division continues normally |
The treatment acting most directly on the meristematic region is:
ⓐ. Treatment P
ⓑ. Treatment R
ⓒ. Treatment Q
ⓓ. Treatment S
Correct Answer: Treatment Q
Explanation: The decisive observation for Treatment Q is the sharp reduction in mitosis among small, thin-walled and densely protoplasmic cells. These are defining features of the meristematic region situated just above the root cap. Its cells divide repeatedly and supply new cells that later enter the elongation and maturation regions. Treatment P affects the protective cap at the extreme apex. Treatment R interferes mainly with the enlargement process characteristic of the elongation region. Treatment S removes root hairs, which are differentiated epidermal structures of the maturation region. The table must be interpreted by linking each observed cellular activity to its normal root-tip zone. A later reduction in root elongation could follow damage to the meristem, but the immediate fall in mitosis identifies the directly affected region. The contrast isolates loss of elongation rather than loss of cell production, protection or mature root-hair function.
18. Equal intervals are marked along a young root. After further growth, the intervals in a band just above the actively dividing region have increased greatly, whereas intervals in the root-hair-bearing region show little separation. The strongest inference is:
ⓐ. root hairs pull the mature region upward and account for most of the root's length increase
ⓑ. rapid cell enlargement in the elongation region contributes most directly to length increase
ⓒ. the root cap produces permanent tissues that later elongate and increase root length
ⓓ. cell division in the root-hair-bearing maturation region produces most root elongation
Correct Answer: rapid cell enlargement in the elongation region contributes most directly to length increase
Explanation: The marked intervals provide positional evidence about where an increase in root length occurs. Their greatest separation is found in the band immediately above the actively dividing meristematic region. This corresponds to the region of elongation, where newly produced cells rapidly enlarge along the root axis. The root-hair-bearing region contains differentiated cells that have largely completed elongation, so its marks remain relatively stable. The observation does not deny the importance of cell division: meristematic cells supply new cells, but substantial extension of the root follows when those cells enlarge. The root cap serves a protective role rather than producing most of the length increase. The experiment distinguishes cell production from cell enlargement by comparing changes in spacing along different root zones.
19. As a newly formed root cell moves away from the apex, the normal functional sequence is:
ⓐ. \(\text{differentiation}\rightarrow\text{elongation}\rightarrow\text{repeated division}\)
ⓑ. \(\text{elongation}\rightarrow\text{repeated division}\rightarrow\text{differentiation}\)
ⓒ. \(\text{repeated division}\rightarrow\text{differentiation}\rightarrow\text{elongation}\)
ⓓ. \(\text{repeated division}\rightarrow\text{elongation}\rightarrow\text{differentiation}\)
Correct Answer: \(\text{repeated division}\rightarrow\text{elongation}\rightarrow\text{differentiation}\)
Explanation: A new root cell originates in the meristematic region, where small, densely protoplasmic cells undergo repeated division. After leaving this zone, the cell enters the region of elongation and increases markedly in size, contributing to extension of the root. Farther from the apex, it reaches the maturation region and differentiates into a specialised cell type. Some epidermal cells in this region form root hairs, while other cells acquire functions appropriate to mature root tissues. The order is fixed by developmental dependency: a cell must first be produced, then enlarge, and finally specialise. Reversing elongation and division would place cell enlargement before the formation of the new cell population, while differentiation before elongation would not match the normal spatial organisation of a growing root tip.
20. A treatment selectively disables the elongation region of a root while leaving the meristematic region functional and existing root hairs temporarily intact. The most likely early result is:
ⓐ. new cells continue to form, but root-length increase falls sharply
ⓑ. cell division stops immediately, while root elongation remains unchanged
ⓒ. existing root hairs disappear at once, while length increase accelerates
ⓓ. the root cap begins producing elongated cells and restores normal growth
Correct Answer: new cells continue to form, but root-length increase falls sharply
Explanation: The meristematic region remains functional, so repeated cell division can continue to produce new cells. However, these cells normally pass into the elongation region, where rapid enlargement generates much of the increase in root length. Disabling that region interrupts the second step of the growth sequence. Cell production may persist for a time, but the cells cannot enlarge normally, and extension of the root declines sharply. Existing root hairs belong to the maturation region and may continue functioning temporarily since the treatment does not directly target them. The root cap cannot replace the elongation region; its main role is protection of the apex. This prediction separates the contribution of mitotic cell production from the contribution of subsequent cellular enlargement to overall root growth.
