GK: Class 12 General Q&A · Page 170
3,658 free answers on GK (General) for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- GeneralClass 12All
Explain the modified stem – stolon, in brief.
Solution: Stolon (runner): A lateral branch that arises from the base of the stem, grows aerially for some distance, then arches downward to touch the ground. Characteristics: Develops adventitious roots at nodes upon contact with soil New plants arise at rooting points Vegetative propagation
- GeneralClass 12All
Which symbols are used to represent the following in a floral formula?
Solution: | (a) Inferior ovary | G̅ | | (b) Calyx | K | | (c) Male | ♂ | | (d) Zygomorphic flower | % | | (e) Perianth | P | | (f) Gynoecium | G |
- GeneralClass 12All
Describe the function of a stem.
Functions of Stem: Mechanical support: Bears leaves, flowers, and fruits Conduction: Xylem: Water and minerals from roots to leaves Phloem: Food from leaves to storage organs Storage: Food (potato, ginger), water (cactus) Vegetative reproduction: Runners, suckers, bulbils Photosynthesis: Flattened stems
- GeneralClass 12All
Draw the floral diagram for the family Solanaceae.
The floral diagram shows: Actinomorphic flower (⊕) 5 sepals (gamosepalous, persistent) 5 petals (gamopetalous, valvate) 5 stamens (epipetalous—attached to petals) Bicarpellary, syncarpous, superior ovary (oblique septum)
- GeneralClass 12All
What is stigma? Why is it important?
Stigma is the terminal receptive part of the carpel (pistil). Importance: Receives pollen grains during pollination Often sticky or feathery to trap pollen Initiates pollen germination Recognition mechanism for compatible pollen (self-incompatibility)
- GeneralClass 12All
What do you understand by asymmetric symmetry?
Asymmetric symmetry: A flower that cannot be divided into two equal halves by any vertical plane passing through the center. Example: Canna (Cannaceae)
- GeneralClass 12All
Diagrammatically explain the difference between parallel and reticulate venation.
Solution: Reticulate Venation (Dicots): Veins form a network Midrib prominent with lateral veins branching Parallel Venation (Monocots): Veins run parallel from base to apex No network formation
- GeneralClass 12All
Describe the type of leaf present in neem.
Neem (Azadirachta indica) has a pinnately compound leaf. Characteristics: Midrib forms a rachis Multiple leaflets arranged along the rachis Reticulate venation Leaflets have serrated margins
- GeneralClass 12All
Explain alternate phyllotaxy with the help of an example.
Solution: Alternate phyllotaxy: A single leaf arises at each node in an alternate pattern along the stem. Example: China rose, mustard, sunflower
- GeneralClass 12All
. Explain valvate aestivation.
Valvate aestivation: The margins of sepals or petals in a whorl just touch each other at the edges without any overlapping. Example: Calotropis (Apocynaceae), Annona (Annonaceae)
- GeneralClass 12All
What is the family of Aloe? Why is it important?
Solution: Family: Liliaceae (sometimes placed in Asphodelaceae in APG classification) Importance: Aloe vera is a source of: Medicinal gel (skin care, wound healing) Laxative (aloin from latex) Cosmetic products
- GeneralClass 12All
Which drupe has a fibrous mesocarp?
Solution: Coconut (Cocos nucifera)—the mesocarp is fibrous (coir), the endocarp is hard and stony.
- GeneralClass 12All
What is the fate of ovule and ovary after fertilisation?
Solution: Ovule → Develops into seed Ovary → Develops into fruit Additional changes: Ovary wall → Pericarp Integuments → Seed coat (testa and tegmen)
- GeneralClass 12All
What is mesocarp?
Solution: Mesocarp is the middle layer of the fruit wall (pericarp), located between the epicarp (outer layer) and endocarp (inner layer). In mango, the mesocarp is fleshy and edible.
- GeneralClass 12All
Name the inflorescence in which the flowers are arranged in a basipetal manner.
Cymose inflorescence—the main axis terminates in a flower, and subsequent flowers develop in basipetal succession (oldest at top, youngest at base).
- GeneralClass 12All
What is the ploidy level of aleurone layer?
The aleurone layer is triploid (3n)—formed from the primary endosperm nucleus during double fertilization.
- GeneralClass 12All
Name the fumigatory plant belonging to the family Solanaceae.
Solution: Tobacco (Nicotiana tabacum)—contains addictive alkaloid nicotine.
- GeneralClass 12All
Write the floral formula for family Liliaceae.
Solution: ⊕ ⚥ P₃₊₃ A₃₊₃ G₍₃₎ Interpretation: Actinomorphic, bisexual Perianth: 3+3 (two whorls of tepals) Androecium: 3+3 (two whorls of stamens) Gynoecium: Tricarpellary, syncarpous, superior ovary
- GeneralClass 12All
here may be a variation in the length of filaments of stamens within a flower. Give two examples.
Solution: Salvia (sage): Two stamens of unequal length (didynamous in modified form) Mustard (Brassica): Six stamens—four long (inner whorl) and two short (outer whorl) = Tetradynamous condition
- GeneralClass 12All
Write a short note on endosperm, embryo and seed coat found in seed of maize plant.
Solution: Structure of Maize Grain (Caryopsis): Endosperm: Triploid (3n) nutritive tissue Bulky, occupies major seed volume Surrounded by aleurone layer (protein-rich, single cell layer) Stores starch and proteins Provides nutrition during germination <stron