Prepare for NEET Biology Anatomy of Flowering Plants with MCQs & PYQs on NEET.GUIDE. Enjoy free practice, previous year questions, and expert insights on plant tissues and structures.
A scientist is studying a newly discovered plant species. Microscopic analysis of the stem reveals living cells with unevenly thickened cell walls, primarily composed of pectin and hemicellulose, providing flexible support. These cells lack lignin and are found in patches beneath the epidermis. Which tissue type is being observed?
Collenchyma
Sclerenchyma
Parenchyma
Xylem
In which specific plant structures would you LEAST expect to find collenchyma tissue?
Beneath the epidermis of young stems
In the petioles of leaves
Supporting the veins of leaves
Mature vascular bundles of woody stems
Which statement BEST describes the relationship between collenchyma and sclerenchyma?
Both are composed of living cells at maturity.
Both have evenly thickened cell walls.
Both contain lignin in their cell walls.
Both provide structural support, but collenchyma provides flexible support in growing regions while sclerenchyma provides rigid support in mature regions.
Which feature distinguishes the conjunctive tissue in a dicot root from the typical parenchyma found in the cortex?
Presence of intercellular spaces
Thin-walled cells with large vacuoles
Sclerenchymatous nature in mature roots providing mechanical support
Abundant chloroplasts for photosynthesis
Which specific characteristic of sclerenchyma cells primarily contributes to their exceptional strength and rigidity, making them suitable for providing structural support in plants?
Presence of lignin in the secondary cell wall
High concentration of pectin in the middle lamella
Presence of living protoplasts at maturity
Thin and flexible primary cell wall
Considering the structural adaptations of sclerenchyma, which of these statements best explains why these cells are typically dead at maturity?
The heavily lignified cell wall restricts the entry of essential substances for cellular metabolism.
Sclerenchyma cells actively undergo programmed cell death during development to enhance structural integrity.
The lack of a nucleus and other organelles reduces the metabolic burden, optimizing the cell for support.
Sclerenchyma cells are produced in excess and are shed as the plant grows, similar to epidermal cells.
Sclereids are a type of sclerenchyma cell. Which of these is NOT a typical characteristic of sclereids?
Forming continuous, elongated fibers in plant stems
Occurring singly or in small groups within other tissues
Having highly thickened and lignified cell walls
Varying greatly in shape, from isodiametric to branched
The gritty texture of pear fruit is due to the presence of:
Stone cells (sclereids)
Collenchyma cells
Parenchyma cells
Xylem vessels
In a plant adapted to arid conditions, you would expect to find a higher proportion of sclerenchyma tissue in which region, and for what primary purpose?
Stem, to provide structural support against strong winds and reduce water loss
Leaves, to increase photosynthetic efficiency in harsh sunlight
Roots, to enhance water absorption from deep soil layers
Flowers, to attract pollinators in a resource-scarce environment
Which statement correctly describes the relationship between the pit canals and the function of sclerenchyma fibers?
Pit canals allow for limited intercellular communication and nutrient transport, even though the cells are typically dead at maturity.
Pit canals are sites of active lignin synthesis, contributing to the thickening of the secondary cell wall.
Pit canals weaken the cell wall, providing flexibility to the sclerenchyma fibers.
Pit canals store water, allowing sclerenchyma cells to survive in arid conditions.
