General Q&A for Class 12 · Page 249
5,215 free answers in General for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- GeneralClass 12All
Write any 10 symbols and what they stand for, used in a floral formula.
Solution: Symbol Meaning Br Bracteate (with bracts) K Calyx (sepals) C
- GeneralClass 12All
Write the floral characters of Fabaceae.
Solution: Family: Fabaceae (Leguminosae/Papilionaceae) Character Description Inflorescence Racemose Flower Bi
- GeneralClass 12All
Tabulate the essential differences in the structure of a dicotyledonous and monocotyledonous seed.
Solution: Character Dicotyledonous Seed Monocotyledonous Seed Cotyledons Two One (scutellum) <p
- GeneralClass 12All
Explain with diagram the placentation found in pea and mustard.
Solution: Marginal Placentation (Pea): Ovary unilocular (one-chambered) Placenta forms a ridge along ventral suture Ovules borne in two rows on the ridge Characteristic of monocarpellary ovaries Example: Pea, bean (Fabaceae) Parietal Placentation (Mustard):
- GeneralClass 12All
Write a short note on fourth whorl of a flower.
Solution: The gynoecium (pistil) is the female reproductive whorl composed of one or more carpels. Structure of a Carpel: Stigma: Receptive surface for pollen grains Often sticky or feathery Located at tip of style Style: <strong
- GeneralClass 12All
Explain the different types of floral symmetry.
Solution: Actinomorphic (Radial Symmetry): Flower can be divided into two equal halves by any vertical plane passing through center Also called regular or polysymmetric Symbol: ⊕ or ✱ Example: Mustard, datura, china rose Zygomorphic (Bilateral
- GeneralClass 12All
What is a compound leaf? Explain its two types with the help of example and diagram.
Solution: Compound Leaf: Leaf blade (lamina) is completely divided into separate leaflets. The incision reaches the midrib. Identification: Axillary bud present at base of petiole, but absent in axil of leaflets. Types: Pinnately Compound: Leaflets arranged along a central rachis
- GeneralClass 12All
What is a leaf? Where does it arise from? How is it borne on a stem? What is its function?
Definition: A leaf is a lateral, flattened, green outgrowth of the stem specialized for photosynthesis. Origin: Arises from the shoot apical meristem at nodes Arrangement: Borne on stem nodes in acropetal succession (youngest at top, oldest at base) Functions: Photosynthesis (primary function) Transpira
- GeneralClass 12All
Describe various stem modifications associated with food storage, climbing and protection.
Solution: Food Storage (Underground Stems): Rhizome (ginger, turmeric): Horizontal, underground stem Nodes, internodes, scale leaves, buds present Tuber (potato): Swollen tip of underground branch "Eyes" are axillary buds Corm (Colocasia, <em
- GeneralClass 12All
Describe briefly the various regions of root.
Solution: A typical root has four distinct zones: Root Cap (Calyptra): Protects the root apical meristem Secretes mucilage for lubrication Contains statoliths for gravity perception Region of Meristematic Activity: Located just above root cap Cells are
- GeneralClass 12All
Describe various root modifications associated with food storage, mechanical support and respiration.
Solution: Modification for Food Storage: Tap Roots: Conical (carrot): Broad at top, tapering at bottom Fusiform (radish): Swollen in middle, tapering at both ends Napiform (turnip): Spherical top, abruptly tapering Adventitious Roots: Tuberous roots (sweet potato
- GeneralClass 12All
Draw a well-labelled diagram of a typical leaf and label any five parts.
Solution: A typical angiosperm leaf consists of: Lamina (leaf blade) Petiole (leaf stalk) Leaf base (attachment to stem) Stipules (lateral appendages) Axillary bud (in leaf axil)
- GeneralClass 12All
Define root hair. From which region of the root do they arise? What is their function?
Solution: Root hairs are unicellular, tubular outgrowths of epidermal cells in the region of maturation (piliferous zone) of the root. Functions: Increase surface area for absorption Absorb water and minerals from soil Provide anchorage in soil
- GeneralClass 12All
Tendrils are found in the following plants. Identify whether they are stem tendrils or leaf tendrils.
Solution: Plant Type of Tendril (a) Cucumber Stem tendril (b) Peas Leaf tendril (c) Pumpkin <td width
- GeneralClass 12All
What are respiratory roots? How do they help the plant? Give an example.
Solution: Respiratory roots or pneumatophores are specialized aerial roots in plants growing in waterlogged, anaerobic soils (mangrove swamps). Characteristics: Grow vertically upward from underground roots Possess lenticels (pores) for gas exchange Facilitate oxygen uptake for aerobic respiration
- GeneralClass 12All
Write two differences and two similarities in the ovaries of Solanaceae and Liliaceae.
Solution: Similarities: Both have syncarpous ovaries (carpels fused) Both have superior ovaries Both show axile placentation Differences: Solanaceae Liliaceae <s
- GeneralClass 12All
Describe calyx, corolla and fruit of Solanaceae.
Solution: Family Solanaceae: Calyx: 5 sepals, gamosepalous (united), persistent, valvate aestivation Corolla: 5 petals, gamopetalous (united), valvate aestivation, often bell-shaped or tubular Fruit: Berry (tomato, brinjal) or capsule (datura)
- GeneralClass 12All
Describe the axile placentation with the help of an example.
Solution: Axile Placentation: Ovary is multilocular (2 or more chambers) Placenta develops along the central axis Ovules attached to the central column where septa meet Typical of syncarpous, superior ovaries Example: China rose (Hibiscus), tomato, lemon
- GeneralClass 12All
Explain the vexillary and imbricate aestivation.
Solution: Vexillary (Descending Imbricate) Aestivation: Specific type found in Fabaceae (pea family) 1 large standard (vexillum) petal overlaps 2 lateral wings (alae) Wings overlap 2 smallest keel (carina) petals Example: Pea, bean Imbricate Aestivation: Margins of petals/sepa
- GeneralClass 12All
Explain briefly the modification of stem found in Pistia and Eichhornia.
Solution: Both Pistia and Eichhornia (water hyacinth) exhibit offsets—a type of vegetative propagation. Offsets are lateral branches with: Short internodes Rosette of leaves at each node Adventitious roots hanging in water Used for rapid asexual reproduction in aquatic plants