Morphology of Flowering Plants
Short Questions
1. What is the primary function of roots in angiosperms?
Answer: Anchorage, absorption of water and minerals, and conduction to the stem.
2. What is a tap root system?
Answer: A root system developing from the radicle, with primary, secondary, and tertiary roots.
3. Name a plant with pneumatophores.
Answer: Rhosszophora.
4. What is the difference between simple and compound leaves?
Answer: Simple leaves have an entire lamina, while compound leaves have divided leaflets.
5. What is phyllotaxy?
Answer: The arrangement of leaves on the stem to optimize light exposure.
6. Define inflorescence.
Answer: A specialized axis bearing flowers in a definite manner.
7. What is a hypogynous flower?
Answer: A flower with a superior ovary and other whorls below it.
8. What is the role of the calyx in a flower?
Answer: It protects inner floral parts in the bud stage.
9. What is placentation?
Answer: The arrangement of ovules on the placenta within the ovary.
10. Name a parthenocarpic fruit.
Answer: Banana.
11. What is a false fruit?
Answer: A fruit developing from floral parts other than the ovary, like an apple.
12. What is the seed coat composed of?
Answer: Outer testa and inner tegmen.
13. Which family does the pea plant belong to?
Answer: Fabaceae.
14. What type of inflorescence is seen in Datura?
Answer: Cymose-solitary.
15. What is the function of velamen tissue in epiphytic roots?
Answer: It absorbs moisture from the air.
Long Questions
1. Explain the structure of a typical root and its regions.
Answer: A typical root consists of the root cap, meristematic region, region of elongation, region of root hairs, and region of maturation. The root cap protects the apex and aids soil penetration, while the meristematic region drives growth through cell division. The elongation region increases length, the root hair region enhances water absorption, and the maturation region forms tissues for fixation and conduction.
2. Differentiate between tap roots and adventitious roots with examples.
Answer: Tap roots develop from the radicle, forming a primary root with branches, as seen in dicots like pea. Adventitious roots arise from non-radicle parts, such as stems or leaves, forming fibrous systems in monocots like maize. They are used for support or propagation in plants like Euphorbia.
3. Describe the modifications of tap roots for food storage.
Answer: Tap roots modified for food storage become swollen and fleshy, classified as fusiform (swollen middle, tapering ends, e.g., radish), conical (broad base, narrow apex, e.g., carrot), or napiform (highly swollen base, narrow apex, e.g., beet). The primary root stores food, while secondary roots remain thin. These adaptations support perennation during unfavorable conditions.
4. What are pneumatophores, and why are they important for halophytes?
Answer: Pneumatophores are negatively geotropic roots growing vertically upwards in halophytes like Rhizophora, found in waterlogged saline soils. They have lenticels for gaseous exchange, compensating for poor soil aeration. These roots ensure respiration and mineral absorption, crucial for survival in marshy habitats.
5. Discuss the role of underground stem modifications in plants.
Answer: Underground stems like rhizomes (e.g., ginger), tubers (e.g., potato), bulbs (e.g., onion), and corms (e.g., Colocasia) store food, enabling perennation during adverse conditions. They produce aerial shoots under favorable conditions, aiding vegetative propagation. These modifications ensure plant survival and reproduction in challenging environments.
6. Explain the types of leaf venation and their significance.
Answer: Leaf venation, the arrangement of veins, is reticulate (net-like, common in dicots) or parallel (veins run parallel, common in monocots). Veins conduct water, minerals, and food while providing structural support to the lamina. The venation pattern influences leaf strength and efficiency in nutrient transport.
7. What is the difference between racemose and cymose inflorescence?
Answer: Racemose inflorescence has unlimited peduncle growth, with older flowers at the base and acropetal succession (e.g., mustard). Cymose inflorescence has limited growth, with the oldest flower at the apex and basipetal succession (e.g., Hibiscus). These arrangements affect pollination efficiency and flower maturation order.
8. Describe the structure and function of the androecium in a flower.
Answer: The androecium, the male reproductive whorl, consists of stamens, each with an anther, filament, and connective. The anther produces pollen grains, the filament elevates the anther for pollen dispersal, and the connective links anther lobes. It may show cohesion (e.g., syngenesious in sunflower) or adhesion (e.g., epipetalous in Datura).
9. What are the types of placentation in angiosperms?
Answer: Placentation types include marginal (ovules on fused margins, e.g., pea), axile (ovules on central axis, e.g., China rose), parietal (ovules on inner wall, e.g., papaya), basal (single ovule at base, e.g., sunflower), and free central (ovules on unattached axis, e.g., Dianthus). These arrangements determine ovule positioning and seed development. The type of placentation influences the fruit’s structure and seed dispersal.
10. Compare the floral characteristics of Fabaceae and Solanaceae families.
Answer: Fabaceae (e.g., pea) has zygomorphic, bisexual flowers with gamosepalous calyx, polypetalous corolla (vexillary), diadelphous androecium, and monocarpellary gynoecium, producing legumes. Solanaceae (e.g., Datura) has actinomorphic, bisexual flowers with gamosepalous calyx, gamopetalous corolla, epipetalous androecium, and bicarpellary syncarpous gynoecium, forming berries or capsules. These traits reflect adaptations for pollination and fruit development.
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