101. Assertion: Xylem and phloem are both classified as complex permanent tissues.
Reason: Each contains several specialised cell types that cooperate in conduction and associated functions such as storage or support.
ⓐ. Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
ⓑ. Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
ⓒ. Assertion is true and Reason is false; the false Reason cannot explain the Assertion
ⓓ. Assertion is false and Reason is true; the true Reason cannot explain a false Assertion
Correct Answer: Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
Explanation: The Assertion is true since neither xylem nor phloem consists of only one principal cell type. Xylem combines tracheids, vessels, fibres and parenchyma. Phloem combines sieve-tube elements, companion cells, fibres and parenchyma. In each tissue, the components contribute differently: some conduct, some provide metabolic support, some store substances and some strengthen the vascular region. The Reason accurately states this cooperative organisation and directly explains the classification as complex permanent tissue. Complexity refers to the participation of several specialised cell types, not to the difficulty of the function or to the presence of both living and dead cells alone. The tissues are permanent since their components are differentiated for established roles, even though the vascular system may occur in organs that continue growing elsewhere.
102. Xylem and phloem are best related as:
ⓐ. two simple tissues containing one identical conducting cell type
ⓑ. two complex permanent tissues forming the vascular system
ⓒ. one meristematic tissue and one permanent tissue
ⓓ. two epidermal derivatives protecting opposite organ surfaces
Correct Answer: two complex permanent tissues forming the vascular system
Explanation: Xylem and phloem are distinct complex permanent tissues. Xylem conducts water and minerals through tracheids and vessel elements and also contains fibres and parenchyma. Phloem transports organic food mainly through sieve-tube elements supported by companion cells and may also contain fibres and parenchyma. When arranged within an organ, the two tissues together form vascular bundles and constitute the vascular or conducting tissue system. Their different transported materials and conducting cells do not place them in separate organisational levels. Neither is meristematic, as their cells are differentiated, and neither belongs to the epidermal system. Recognising their relationship requires moving from tissue composition to tissue-system organisation: xylem and phloem retain separate identities while operating as complementary conducting tissues within the same vascular system.
103. Let \(C\) represent principal conducting cells, \(L\) cells living at functional maturity and \(D\) cells dead at functional maturity. Which relation correctly compares the principal conducting elements of xylem and phloem?
ⓐ. Xylem: \(C\subset L\); Phloem: \(C\subset D\)
ⓑ. Xylem: \(C\subset D\); Phloem: \(C\subset L\)
ⓒ. Xylem: \(C\subset L\); Phloem: \(C\subset L\)
ⓓ. Xylem: \(C\subset D\); Phloem: \(C\subset D\)
Correct Answer: Xylem: \(C\subset D\); Phloem: \(C\subset L\)
Explanation: The principal conducting cells of xylem are tracheids and vessel elements. Both lose their protoplasts during maturation and function as dead, hollow, lignified pathways, so the xylem relation is \(C\subset D\). The principal conducting cells of phloem are sieve-tube elements. They lose their nuclei but retain living cytoplasm and remain metabolically linked with companion cells, placing the phloem conducting set within \(L\). Loss of a nucleus must not be mistaken for death in this comparison. The symbolic relation concerns principal conducting elements rather than every component of each tissue. Xylem also contains living parenchyma, while phloem contains dead fibres, so it would be inaccurate to classify the entire tissues as wholly dead or wholly living. The relations capture the contrasting viability of the conducting pathways specifically. This distinction also explains why damage to the living companion-cell association affects phloem conduction, whereas water can pass through the hollow walls and lumens of mature xylem conducting cells.
104. Consider the following statements about plant tissue systems.
I. The epidermal system forms the outer interface of the primary plant body.
II. The ground system includes tissues outside the epidermal and vascular systems.
III. The vascular system is formed principally by xylem and phloem.
IV. Each organ contains only one of the three tissue systems.
ⓐ. Only statements I and IV are correct
ⓑ. Only statements II and III are correct
ⓒ. Only statements I, III and IV are correct
ⓓ. Only statements I, II and III are correct
Correct Answer: Only statements I, II and III are correct
Explanation: The three major tissue systems are epidermal, ground and vascular. The epidermal system occupies the surface and includes the epidermis, stomata and organ-specific appendages. The ground or fundamental system comprises tissues that are neither epidermal nor part of the vascular bundles; its exact organisation differs among roots, stems and leaves. The vascular system consists of xylem and phloem arranged for transport. Statement IV is incompatible with organ organisation. A root, stem or leaf normally integrates all three systems rather than selecting only one. Their relative positions and specialised structures vary, yet they cooperate within the same organ. The valid statements distinguish the systems by location and composition while preserving their integration into roots, stems and leaves.
105. Match each tissue system with the description that identifies it most accurately. A Column II entry is used once.
| Column I | Column II |
|---|
| P. Epidermal system | 1. Xylem and phloem organised for transport |
| Q. Ground system | 2. Several tissue systems arranged into a root, stem or leaf |
| R. Vascular system | 3. Surface covering, stomata and epidermal appendages |
| S. Organ level | 4. Tissues outside the epidermal covering and vascular bundles |
ⓐ. P-3, Q-4, R-1, S-2
ⓑ. P-4, Q-3, R-2, S-1
ⓒ. P-1, Q-2, R-4, S-3
ⓓ. P-3, Q-1, R-2, S-4
Correct Answer: P-3, Q-4, R-1, S-2
Explanation: The epidermal system forms the plant's surface interface and includes epidermal cells, stomata and appendages such as root hairs or trichomes, fixing P-3. The ground system is defined broadly by exclusion: it includes tissues outside the epidermal layer and vascular bundles, so Q-4. Xylem and phloem together form the conducting vascular system, making R-1. A root, stem or leaf represents the organ level, at which several tissue systems are spatially integrated; S matches entry 2. The mapping separates a tissue system from an organ. A system groups tissues by structural position and coordinated function, while an organ combines multiple systems into one plant part. This hierarchy also explains why the same three system categories can occur in different organs even though their detailed anatomical arrangements differ.
106. An aerial organ retains normal internal ground tissue and vascular bundles, but its outer layer, stomata and surface hairs are removed together. The damaged structures collectively belonged to the:
ⓐ. vascular system, which supplies all outer appendages
ⓑ. ground system, which includes every non-conducting tissue
ⓒ. epidermal system forming the organ-environment interface
ⓓ. meristematic system, which remains permanently exposed
Correct Answer: epidermal system forming the organ-environment interface
Explanation: The removed structures form a coherent surface system. Epidermal cells create the outer covering, stomata provide regulated pores for gaseous exchange and transpiration, and surface hairs are epidermal appendages. Their shared position at the organ-environment boundary places them in the epidermal tissue system. Ground tissue occupies internal regions outside vascular bundles, but it does not include the epidermal covering merely because epidermal cells are non-conducting. The vascular system remains represented by xylem and phloem, which are stated to be intact. Meristematic tissue is classified by active division and is not the permanent exposed covering of an aerial organ. The combined removal would impair several surface functions simultaneously, including protection and regulation of exchange, reinforcing the identification of one integrated epidermal system rather than three unrelated structures.
107. Use the surface arrangement described below. Region P is a continuous outer layer. At Site Q, two specialised cells surround a pore. Structure R is a hair arising from the shoot surface. All three belong to the same tissue system. That system is:
ⓐ. ground, as every structure is non-vascular
ⓑ. epidermal, since all three structures arise at the surface
ⓒ. vascular, as the pore regulates movement of materials
ⓓ. meristematic, as hairs and guard cells divide continuously
Correct Answer: epidermal, since all three structures arise at the surface
Explanation: Region P is the epidermal covering itself. Site Q describes a stoma, where guard cells surround a pore, while structure R is a shoot trichome. These structures differ in shape and immediate function, but they occupy the plant surface and are components or derivatives of the epidermal system. Classification by system depends on anatomical position and organisational relationship rather than on whether the structures conduct materials. The ground system includes internal tissues not assigned to the epidermal or vascular systems, and the vascular system is built from xylem and phloem. Guard cells and many trichomes are differentiated cells rather than continuously dividing meristematic populations. The described arrangement illustrates how one tissue system contains an ordinary covering, specialised exchange structures and protective appendages.
108. A unicellular extension from a root surface and a usually multicellular hair from a shoot surface are related as:
ⓐ. conducting elements of xylem and phloem, respectively
ⓑ. ground-tissue cells performing identical storage roles
ⓒ. meristematic cells responsible for primary and secondary growth
ⓓ. epidermal appendages specialised for different functions
Correct Answer: epidermal appendages specialised for different functions
Explanation: The unicellular root-surface extension is a root hair, formed as an elongation of an epidermal cell. It increases the contact area with the soil and supports absorption of water and minerals. The usually multicellular shoot-surface hair is a trichome, which may be branched or unbranched, soft or stiff and sometimes secretory. Many trichomes help reduce transpiration or provide surface protection. Both structures belong to the epidermal system, yet their organ locations and major functions differ. Their common classification should not erase the distinction between absorption in roots and water-loss reduction or protection on shoots. They are neither vascular conducting cells nor meristems, and their shapes do not make them one identical tissue type. Their relationship is best expressed as specialised epidermal appendages adapted to different surface demands.
109. Consider the following features of the epidermis in the primary plant body.
I. It is usually a continuous single layer.
II. Its cells are generally compactly arranged.
III. Epidermal cells are commonly parenchymatous with a large vacuole.
IV. Wide permanent gaps between ordinary epidermal cells improve protection.
ⓐ. Only statements I and IV are correct
ⓑ. Only statements I, II and III are correct
ⓒ. Only statements II and III are correct
ⓓ. Statements I, II, III and IV are correct
Correct Answer: Only statements I, II and III are correct
Explanation: The epidermis normally forms a continuous surface layer in the primary plant body. Compact arrangement reduces uncontrolled openings and helps establish an effective protective boundary. Ordinary epidermal cells are living and parenchymatous, often elongated, with peripheral cytoplasm and a large central vacuole. These properties permit a thin living covering while leaving most of the cell volume occupied by vacuolar contents. Wide permanent gaps among ordinary epidermal cells would interrupt the protective surface rather than improve it. Regulated apertures such as stomata are specialised structures with guard cells, not random breaks in epidermal continuity. The valid statements describe the general organisation of the epidermal layer while allowing specialised cells and appendages to occur within it. Continuity and compactness are especially important when relating epidermal anatomy to protection and controlled exchange.
110. Equal patches of a young leaf are examined after treatment. In patch P, the compact epidermal layer remains intact. In patch Q, ordinary epidermal cells are separated, creating irregular gaps without damaging the underlying mesophyll. Q loses water more rapidly and is more easily injured. The strongest inference is:
ⓐ. epidermal gaps improve gas exchange without affecting protection
ⓑ. mesophyll alone forms the protective surface of a leaf
ⓒ. a compact, continuous epidermis contributes to surface protection
ⓓ. separation converts ordinary epidermal cells into guard cells
Correct Answer: a compact, continuous epidermis contributes to surface protection
Explanation: The treatment alters one decisive feature: the ordinary epidermal cells in patch Q no longer form a compact continuous covering. The underlying mesophyll is stated to remain undamaged, so the increased water loss and susceptibility to injury can be linked to disruption of the epidermal barrier rather than to direct destruction of photosynthetic tissue. An intact epidermis limits uncontrolled exposure of internal cells and creates an organised surface in which exchange occurs through specialised structures. Irregular gaps are not equivalent to stomata, since they lack guard cells and cannot be regulated. The comparison between P and Q supports a structural conclusion about continuity and compactness. It does not prove that the epidermis prevents all water loss or all injury, but it shows that its organised arrangement makes an important contribution to protection and water conservation.
111. A mutation prevents ordinary epidermal cells from fitting closely together, although stomatal guard cells remain functional. The most likely direct effect is:
ⓐ. improved control of exchange through formation of extra stomatal apparatuses
ⓑ. loss of xylem and phloem differentiation inside the organ
ⓒ. conversion of ground tissue into a continuous protective covering
ⓓ. uncontrolled exposure and water loss through irregular surface gaps
Correct Answer: uncontrolled exposure and water loss through irregular surface gaps
Explanation: Ordinary epidermal cells normally form a compact continuous layer. Their close contact restricts unregulated pathways between the organ interior and the environment, while stomata provide specialised apertures whose opening can be controlled. If ordinary epidermal cells fail to fit together, irregular gaps develop independently of guard-cell action. Even normally functioning stomata cannot close those uncontrolled openings, so internal tissues become more exposed and water loss is likely to rise. The mutation does not directly determine differentiation of xylem, phloem or ground tissue, as those systems have separate developmental identities. It also does not create additional stomatal apparatuses, since a stoma requires a specific pair of guard cells and associated organisation. The predicted defect follows from loss of epidermal continuity rather than from failure of the existing stomatal mechanism.
112. Assertion: Aerial epidermal surfaces commonly possess a cuticle that helps limit water loss.
Reason: The cuticle is a waxy layer deposited external to the epidermis and resists uncontrolled evaporation from the surface.
ⓐ. Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
ⓑ. Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion
ⓒ. Assertion is true and Reason is false; the false Reason cannot explain the Assertion
ⓓ. Assertion is false and Reason is true; the true Reason cannot explain a false Assertion
Correct Answer: Both Assertion and Reason are true, and Reason is the correct explanation of Assertion
Explanation: Both statements are true, and the second statement gives the structural basis for the first. The cuticle is a waxy layer deposited on the outer surface of the epidermis in aerial parts. Because wax resists the movement of water, this layer slows uncontrolled evaporation directly across the epidermal surface. Stomata still provide regulated pores for gaseous exchange and transpiration, so the cuticle does not make the surface completely impermeable. Its contribution is especially important in limiting non-stomatal water loss. Root epidermis usually lacks a comparable cuticle because its surface must remain suitable for absorption of water and minerals. The external position, waxy composition and resistance to evaporation stated in the Reason directly account for the water-conserving role described in the Assertion.
113. A young root is experimentally coated with a continuous waxy layer while its internal vascular tissues remain undamaged. Compared with an untreated root, the coated root is expected to show:
ⓐ. reduced absorption across the wax-coated root epidermis
ⓑ. increased formation of root hairs through wax deposition
ⓒ. enhanced water entry through a more impermeable covering
ⓓ. immediate conversion of epidermis into vascular tissue
Correct Answer: reduced absorption across the wax-coated root epidermis
Explanation: Roots characteristically lack a waxy cuticle over their absorptive epidermis. This absence leaves the surface, including root hairs, suitable for contact with soil water and dissolved minerals. Applying a continuous waxy coating introduces a hydrophobic barrier at the point where absorption normally occurs. Even with intact vascular tissues, less water can cross the coated epidermal interface, so delivery to the internal conducting system declines. The coating does not generate new root hairs or transform epidermal cells into vascular tissue. Its impermeable character is also incompatible with enhanced entry. The changed condition demonstrates that the same structure can be beneficial or harmful depending on organ function: a cuticle conserves water on aerial organs, whereas an equivalent barrier on an actively absorbing root would obstruct the exchange needed at that surface.
114. Two similar aerial shoots are maintained under identical conditions. The cuticle is removed from treatment P without damaging stomata or internal tissues; treatment Q remains intact. P loses mass more rapidly over time. The best conclusion is:
ⓐ. stomata are the only route through which an aerial organ can lose water
ⓑ. cuticle removal increases water uptake from the surrounding air
ⓒ. internal vascular tissues normally produce the external waxy layer
ⓓ. the cuticle restricts non-stomatal water loss from the epidermal surface
Correct Answer: the cuticle restricts non-stomatal water loss from the epidermal surface
Explanation: The treatment specifically removes the cuticle while leaving stomata and internal tissues undamaged. Both shoots experience the same environment, so the more rapid mass loss in P is most reasonably attributed to increased escape of water across the exposed epidermal surface. Stomata remain present in both treatments and cannot account for the difference by themselves. The result supports a role for the cuticle in restricting non-stomatal water loss, not in absorbing atmospheric water. The cuticle is deposited at the outer epidermal surface rather than being an internal vascular layer. The inference should remain proportional to the experiment: it demonstrates resistance to surface water loss under the stated conditions, while not claiming that the cuticle makes an aerial organ completely impermeable or eliminates the regulated transpiration occurring through stomata.
115. Surfaces P and Q are tested under identical conditions.
| Surface | Untreated condition | After applying a waxy coating |
|---|
| P | Absorbs water readily | Water entry decreases sharply |
| Q | Loses water slowly | Water loss changes only slightly |
Which interpretation best fits the observations?
ⓐ. P is a cutinised aerial epidermis, while Q is an untreated root surface.
ⓑ. Both P and Q are root surfaces with identical absorptive functions.
ⓒ. P is an absorptive root surface; Q bears a water-limiting cuticle.
ⓓ. P is vascular tissue, while Q is photosynthetic ground tissue.
Correct Answer: P is an absorptive root surface; Q bears a water-limiting cuticle.
Explanation: Surface P absorbs water readily before treatment, indicating an epidermal region adapted for uptake rather than conservation. The sharp decline after addition of a waxy coating shows that the new barrier interferes with entry, a pattern expected for a root surface that normally lacks cuticle. Surface Q already loses water slowly, and applying more wax produces only a small additional effect. This suggests that Q possessed an existing water-limiting cuticle typical of an aerial epidermis. The comparison uses changes after treatment, not merely the initial rates. It also illustrates the organ-dependent value of a waxy barrier: absence favours absorption in roots, while presence limits loss from aerial parts. Neither record supports identification as internal vascular or ground tissue, since the measured processes occur across external surfaces.
116. A stomatal preparation shows each pore surrounded by two dumb-bell-shaped guard cells. The preparation most likely came from:
ⓐ. a typical root-hair zone
ⓑ. the epidermis of a grass leaf
ⓒ. the pith of a young dicot stem
ⓓ. the cortex of a dicot root
Correct Answer: the epidermis of a grass leaf
Explanation: Guard-cell shape provides a useful epidermal clue when the structure has already been identified as a stoma. In grasses, the two guard cells are characteristically dumb-bell shaped. In many dicot leaves, guard cells are more commonly bean shaped. A root-hair zone is specialised mainly for absorption and does not ordinarily provide the stated leaf-stomatal pattern. Pith and cortex are internal ground-tissue regions rather than epidermal surfaces bearing stomata. The shape should not be used to identify an entire plant group without other evidence, but it can support classification of the stomatal preparation under the supplied alternatives. Both dumb-bell-shaped and bean-shaped guard cells perform the same basic regulatory role: they surround an aperture and alter its opening, even though their visible geometry differs.
117. Two epidermal peels contain functional stomata. Peel P has bean-shaped guard cells, while peel Q has dumb-bell-shaped guard cells. Their most appropriate relationship is:
ⓐ. P is consistent with many dicots, whereas Q is consistent with grasses.
ⓑ. P is necessarily from a root, whereas Q is necessarily from a stem pith.
ⓒ. P lacks stomata, whereas Q contains a complete vascular bundle.
ⓓ. P is phloem tissue, whereas Q is xylem tissue.
Correct Answer: P is consistent with many dicots, whereas Q is consistent with grasses.
Explanation: The two preparations are explicitly epidermal peels with functional stomata, so the comparison concerns guard-cell form rather than tissue-system identity. Bean-shaped guard cells are commonly associated with many dicot leaves, while dumb-bell-shaped guard cells are characteristic of grasses. The wording consistent with is important: guard-cell shape is a useful typical diagnostic feature but should not be expanded into an absolute claim about every species or every organ. Both preparations remain parts of the epidermal system and both regulate a stomatal pore. Neither represents internal xylem, phloem, cortex or pith. The relationship combines shared function with structural variation: the same aperture-regulating role is carried out by differently shaped guard-cell pairs in two common flowering-plant patterns.
118. A stomatal complex is rotated in a microscopic field. Label P points to the wall of a guard cell directly bordering the pore, while label Q points to the wall facing away from the pore. The correct interpretation is:
ⓐ. P is thinner than Q, and neither wall affects aperture regulation.
ⓑ. P and Q are equally thick, while subsidiary cells alone open the pore.
ⓒ. P is relatively thick, whereas Q is thinner and more extensible.
ⓓ. P is a sieve plate, whereas Q is a perforated xylem end wall.
Correct Answer: P is relatively thick, whereas Q is thinner and more extensible.
Explanation: Rotation of the microscopic image does not change the biological orientation of the walls. Label P is defined by its position next to the pore, so it marks the inner guard-cell wall. This wall is relatively thick and less extensible. Label Q faces away from the pore and marks the thinner outer wall, which can expand more readily as guard-cell water status changes. The unequal wall properties help convert changes in guard-cell shape into changes in pore width. Subsidiary cells may surround guard cells, but they do not replace this wall asymmetry or act as the sole aperture-control mechanism. Sieve plates and perforated vessel end walls belong to vascular tissues and are unrelated to the epidermal arrangement described. Position relative to the pore, not left-right orientation on the page, determines wall identity.
119. A mutation makes the pore-facing and outer walls of each guard cell equally thin and equally extensible, while the cells remain alive and contain chloroplasts. The most likely consequence is:
ⓐ. conversion of the stomatal pore into a vascular bundle
ⓑ. improved directional bending of guard cells during every water-status change
ⓒ. permanent formation of root hairs from the guard-cell pair
ⓓ. impaired conversion of guard-cell swelling into controlled aperture movement
Correct Answer: impaired conversion of guard-cell swelling into controlled aperture movement
Explanation: Normal guard cells possess an important mechanical asymmetry. Their inner walls bordering the pore are relatively thick, while their outer walls are thinner and more extensible. When guard-cell volume changes, the two sides respond differently, producing a change in cell curvature or shape that alters pore width. If both walls become equally thin and equally extensible, swelling is more likely to produce similar expansion on both sides rather than the directional deformation needed for effective aperture control. Chloroplasts and living cytoplasm remain present, so the defect is not simple cell death or loss of all metabolism. The mutation also cannot transform epidermal cells into vascular tissue or root hairs. The expected result is a weakened link between guard-cell water status and pore movement, showing how unequal wall construction contributes to regulated exchange.
120. Consider the following statements about guard cells.
I. Guard cells contain chloroplasts.
II. Ordinary epidermal cells generally lack the chloroplast feature characteristic of guard cells.
III. Chloroplasts alone keep every stomatal pore permanently open.
IV. Living guard cells regulate aperture movement with the aid of their specialised wall organisation.
ⓐ. Only statements I and III are correct
ⓑ. Only statements II and IV are correct
ⓒ. Only statements I, II and IV are correct
ⓓ. Statements I, II, III and IV are correct
Correct Answer: Only statements I, II and IV are correct
Explanation: Guard cells are specialised epidermal cells that contain chloroplasts, unlike ordinary epidermal cells in the usual primary surface. They occur as a pair around a stomatal pore and regulate its opening and closing. Their regulatory ability cannot be attributed to chloroplasts alone. The unequal construction of their walls is also important: the wall facing the pore is relatively thick, while the outer wall is thinner and more extensible. Changes in the living guard cells are converted by this wall asymmetry into movement of the pore. A chloroplast-bearing guard cell is not a permanently open structure. The valid statements combine cellular contents, specialised wall organisation and regulatory function without reducing stomatal movement to one isolated feature.
