Plant Morphology — Set 1

Correct Answer: A. Root

• **Root** = The root system anchors the plant in soil and directly absorbs water and dissolved minerals from the surroundings. • **Root hairs** — microscopic extensions that dramatically increase the surface area available for absorption, making uptake far more efficient. • Roots also store food in many plants and anchor the body against wind and water. • 💡 Option B (Stem) is wrong because the stem conducts water upward but does not absorb it from soil; Option C (Flower) is wrong because flowers function only in reproduction; Option D (Leaf) is wrong because leaves perform photosynthesis, not mineral absorption.

Correct Answer: B. Photosynthesis

• **Photosynthesis** = Leaves are the primary food-making organs; their chlorophyll-rich cells trap sunlight to synthesise glucose from CO₂ and water. • **Chloroplasts** — organelles packed with green pigments that capture light energy and drive the photosynthetic reactions inside every leaf cell. • Leaves are thin and flat to maximise light interception while stomata allow gas exchange essential for the process. • 💡 Option A (Support) is wrong because mechanical support is provided by the stem and lignified tissues; Option C (Anchorage) is wrong because that function belongs to the root system; Option D (Reproduction) is wrong because reproduction is carried out by flowers.

Correct Answer: D. Parallel venation

• **Parallel venation** = Veins run side by side from leaf base to tip without forming a branching network, a hallmark of monocot plants. • **Monocot connection** — grasses, wheat, maize, banana, and lilies all display this pattern in their long, strap-like leaves. • Vein arrangement is one of the key features used to distinguish monocots (parallel) from dicots (reticulate). • 💡 Option A (Whorled venation) is wrong because no such venation type exists in standard plant classification; Option B (Reticulate venation) is wrong because it describes a net-like branching pattern found in dicots like mango and rose; Option C (Alternate venation) is wrong because alternate is a term used for leaf arrangement on stems, not vein patterns.

Correct Answer: A. Stamen

• **Stamen** = The complete male reproductive unit of a flower, consisting of a pollen-bearing anther mounted on a slender filament. • **Anther** — contains four pollen sacs (microsporangia) that produce and store pollen grains, each carrying the male genetic material. • The number and arrangement of stamens is an important taxonomic character used to identify plant families. • 💡 Option B (Sepal) is wrong because sepals form the calyx that protects the flower bud, not a reproductive structure; Option C (Petal) is wrong because petals attract pollinators but play no direct role in pollen production; Option D (Pistil) is wrong because the pistil is the female reproductive organ comprising stigma, style, and ovary.

Correct Answer: C. Ovary

• **Ovary** = After fertilisation the ovary wall (pericarp) develops and enlarges to become the fruit, enclosing and protecting the seeds. • **Dispersal role** — the fruit's flesh, hooks, or wings are adaptations that help scatter seeds far from the parent plant. • A single ovary can contain one or many ovules, each becoming a seed after fertilisation. • 💡 Option A (Ovule) is wrong because the ovule itself develops into the seed, not the fruit; Option B (Stigma) is wrong because the stigma only receives pollen and does not develop further; Option D (Style) is wrong because the style is a temporary pollen-tube pathway and withers after fertilisation.

Correct Answer: B. Nodes

• **Nodes** = Precisely defined points on the stem from which leaves, axillary buds, and sometimes adventitious roots arise, making them the most active growth regions. • **Meristematic tissue** — concentrated at nodes allows rapid cell division, supporting new branch and leaf formation throughout the growing season. • The region of bare stem between two successive nodes is called the internode, which functions mainly in elongation. • 💡 Option A (Buds) is wrong because buds are undeveloped shoot tips or axillary structures, not the point of leaf attachment itself; Option C (Thorns) is wrong because thorns are modified leaves or stems used for protection; Option D (Internodes) is wrong because internodes are the stretches of stem between two nodes, not the attachment points.

Correct Answer: A. Potato

• **Potato** = A stem tuber — an enlarged, fleshy underground stem bearing nodes called 'eyes', each of which is an axillary bud capable of sprouting a new plant. • **Starch reservoir** — the tuber accumulates starch during the growing season to fuel next year's growth before new leaves can start photosynthesising. • The presence of nodes, internodes, and scale leaves confirms potato is a modified stem, not a root. • 💡 Option B (Carrot) is wrong because carrot is a swollen taproot that stores food but lacks nodes or buds; Option C (Sweet potato) is wrong because it is a modified adventitious root, not a stem; Option D (Radish) is wrong because radish is also a modified taproot, identifiable by the absence of axillary buds.

Correct Answer: C. Calyx

• **Calyx** = The collective term for all sepals in a flower; these green, leaf-like structures form the outermost whorl and guard the delicate inner organs during bud stage. • **Protective role** — sepals enclose the bud tightly before the flower opens, shielding petals, stamens, and carpels from mechanical damage and drying out. • In some flowers the calyx persists after petal fall and aids fruit development or dispersal. • 💡 Option A (Androecium) is wrong because androecium refers to all the stamens collectively, forming the male reproductive whorl; Option B (Corolla) is wrong because corolla is the collective term for petals, which form the second whorl inward from the sepals; Option D (Gynoecium) is wrong because gynoecium comprises the female carpels at the flower's centre.

Correct Answer: A. Leaves

• **Leaves** = In pea plants the terminal leaflets of compound leaves are modified into slender, coiling tendrils that grip any nearby support to help the plant climb. • **Thigmotropism** — tendrils respond to touch by curling tightly around supports, allowing a weak-stemmed plant to reach higher light levels without investing energy in thick woody stems. • This is a classic example of a vegetative organ being repurposed for a mechanical function while reducing the photosynthetic area of that leaf. • 💡 Option B (Flowers) is wrong because flowers serve only reproductive purposes and cannot be modified for climbing; Option C (Roots) is wrong because roots are positively geotropic and grow into the soil, not upward; Option D (Stem) is wrong because the stem in pea is the weak structure that needs support, not the one providing it.

Correct Answer: D. Carpel

• **Carpel** = The basic unit of the female reproductive system, comprising the sticky stigma at the top, a hollow style in the middle, and the ovary at the base that contains the ovules. • **Pollen pathway** — pollen lands on the stigma, germinates, and the pollen tube grows down through the style to deliver the male nucleus to the ovule inside the ovary. • A flower may have one or many carpels fused or free; collectively they are called the gynoecium or pistil. • 💡 Option A (Anther) is wrong because the anther is the male organ that produces and releases pollen, not a female structure; Option B (Filament) is wrong because the filament is the stalk supporting the anther in the stamen; Option C (Stamen) is wrong because the stamen is the entire male unit (anther + filament), not the female part.