Morphology of Flowering Plants (Advanced Level / Expected MCQs)

Correct Answer: (b)
Primary growth (vertical elongation) occurs only at the apical meristems located at the tips of the shoots and roots. Once the tissues of the trunk have matured, they only grow in width through secondary growth; they no longer move vertically relative to the ground.

Correct Answer: (d)
Annual rings are composed of layers of secondary xylem produced during one growing season. These layers are generated by the vascular cambium, a lateral meristem.

Correct Answer: (d)
Peeling a potato (which is a modified underground stem called a tuber) removes the outer periderm (dermal tissue) and typically several layers of the underlying storage parenchyma (ground tissue).

Correct Answer: (b)
Shoot systems are characterized by the presence of nodes (where leaves attach) and internodes. Roots do not possess these structural segments.

Correct Answer: (c)
Root hairs are unicellular outgrowths of single epidermal cells, whereas lateral roots are complex, multicellular organs that originate internally from the pericycle.

Correct Answer: (a)
Removing the vascular cambium (a process known as girdling) is fatal to a tree because it destroys the tissue responsible for creating new xylem and phloem, thereby permanently severing the plant's transport systems.

Correct Answer: (a)
Unlike animal cells, plant cells are encased in rigid cell walls and cannot migrate. Therefore, plant organogenesis depends entirely on regulated patterns of cell division and cell expansion.

Correct Answer: (c)
The primary function of the root cap is to protect the delicate apical meristem as it pushes through abrasive soil particles. In a liquid hydroponic environment, there is no physical resistance, making the root cap unnecessary.

Correct Answer: (d)
In angiosperms like oak trees, sieve-tube members are the specialized cells within the phloem responsible for the long-distance transport of carbohydrates (photosynthate).

Correct Answer: (d)
Collenchyma cells are specialized for providing flexible structural support to growing plant organs. Photosynthesis is primarily performed by chlorenchyma, which is a specialized type of parenchyma tissue.

Correct Answer: (b)
Eudicot leaves generally show a clear differentiation of the mesophyll into an upper layer of tightly packed palisade parenchyma and a lower layer of loosely arranged spongy parenchyma.

Correct Answer: (a)
Guard cells regulate the opening and closing of stomata. When the stomata are open, they allow for the essential uptake of carbon dioxide required for photosynthesis.

Correct Answer: (c)
In monocot stems, the vascular bundles are scattered throughout the ground tissue. Consequently, there is no distinct central region of pith as found in the organized ring-like arrangement of eudicot stems.

Correct Answer: (b)
Primary growth is not restricted to the shoot apical meristem; it also occurs at axillary buds, which allow for the formation of lateral branches and flowers.

Correct Answer: (b)
Growth occurs outward from the central pith: first the primary xylem, then the secondary xylem (wood), then the vascular cambium, followed by the secondary and primary phloem, the cork cambium, and finally the cork.

Correct Answer: (d)
Sclerenchyma cells are specialized for structural support and possess thick secondary walls impregnated with lignin. They are typically dead at functional maturity, meaning they lack a living protoplast.

Correct Answer: (b)
While many roots (especially in eudicots) undergo secondary growth to increase in diameter, they do not develop the complex protective outer layer known as bark, which is characteristic of woody stems.

Correct Answer: (b)
Meristematic cells are characterized by thin, flexible primary cell walls that allow for continuous cell division. Secondary cell walls are only deposited after a cell has finished growing and begun to differentiate.

Correct Answer: (c)
Indeterminate growth is possible because meristem cells divide asymmetrically, producing one cell that differentiates and another cell that remains a meristematic 'initial,' effectively ensuring a permanent supply of stem cells.

Correct Answer: (d)
The pericycle is the internal tissue layer responsible for the initiation of lateral roots. If it were moved to the outside, lateral roots would emerge from the surface but would be physically disconnected from the internal vascular bundles (xylem and phloem).

Correct Answer: (c)
Root hairs are extensions of individual epidermal cells that appear in the zone of maturation (or differentiation), which is the region where cells reach their final functional form.