GK: Class 12 General Q&A · Page 173
3,658 free answers on GK (General) for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- GeneralClass 12All
Name the phyllotaxy in Alstonia.
Alstonia exhibits whorled phyllotaxy, where three or more leaves arise from a single node in a circular pattern around the stem.
- GeneralClass 12All
What type of aestivation is found in Calotropis?
Calotropis displays valvate aestivation, where the margins of sepals or petals just touch each other without overlapping. This is typical of the family Apocynaceae (formerly Asclepiadaceae).
- GeneralClass 12All
What type of venation occurs in banana?
Solution: Banana exhibits parallel venation, where veins run parallel to each other from the base to the apex without forming a network. This is characteristic of monocotyledonous plants (Class Liliopsida).
- GeneralClass 12All
Which parts in ginger and potato are edible?
Ginger: The edible part is the rhizome, a modified underground stem that grows horizontally and stores food. Potato: The edible portion is a tuber, another modified underground stem characterized by swollen nodes called "eyes" (axillary buds). Key Point: Both are stems, not roots, as evidenced by the presence of nodes, internodes, and axillary buds.
- GeneralClass 12All
Describe the type of fertilization that is unique to plants in which seeds are enclosed by fruits.
Double fertilization (unique to angiosperms): Syngamy: Male gamete + Egg → Zygote (2n) → Embryo Triple fusion: Male gamete + Secondary nucleus (2n) → PEN (3n) → Endosperm
- GeneralClass 12All
Represent schematically the haplo-diplontic life cycle.
Sporophyte (2n) → Meiosis → Spores (n) → Gametophyte (n) → Gametes (n) → Syngamy → Zygote (2n) → Sporophyte (2n) Both phases are multicellular and often free-living
- GeneralClass 12All
What are the two classes of angiosperms? Give an example for each.
Class Cotyledon Number Example Dicotyledons Two Pisum sativum (Pea) Monocotyledons One
- GeneralClass 12All
Mention three economic importance of the first terrestrial plants having vascular tissues.
Soil binding: Prevents erosion on slopes Medicinal value: Dryopteris provides anthelmintic drugs Ornamental use: Ferns cultivated for decorative foliage
- GeneralClass 12All
Write the names of any three classes of pteridophytes. Give one example for each.
Class Example Psilopsida Psilotum Lycopsida Lycopodium Sphenopsida Equ
- GeneralClass 12All
Name the three classes of algae and mention the pigments present in them.
Class Common Name Pigments Chlorophyceae Green algae Chlorophyll a, b Phaeophyceae Brown algae <
- GeneralClass 12All
What is the ploidy of endosperm in flowering plants and how is it formed? Ploidy: Triploid (3n)
Formation: Triple fusion—one haploid male gamete fuses with diploid secondary nucleus (formed from two polar nuclei)
- GeneralClass 12All
Write two examples of green algae that are filamentous. What is the common mode of vegetative reproduction in green algae?
Examples: Ulothrix, Spirogyra Vegetative reproduction: Fragmentation and spore formation (zoospores, aplanospores)
- GeneralClass 12All
Name three algae that show haplodiplontic life cycle. Name one alga that shows diplontic life cycle.
Haplodiplontic: Ectocarpus, Polysiphonia, Kelps Diplontic: Fucus
- GeneralClass 12All
How does asexual reproduction occur in liverworts?
Fragmentation: Thallus fragments regenerate into complete plants Gemma formation: Multicellular propagules in gemma cups detach and grow into new individuals
- GeneralClass 12All
How do the gametophytes of bryophytes differ from those of gymnosperms?
Feature Bryophytes Gymnosperms Independence Free-living, dominant phase Dependent on sporophyte Size Macroscopic <td width=
- GeneralClass 12All
How does isogamous reproduction differ from anisogamous reproduction?
Isogamous: Fusion of morphologically identical gametes (same size, structure) Anisogamous: Fusion of morphologically different gametes (differing sizes) Name the characteristic pigments of brown algae. Chlorophyll a & c, carotenoids, and xanthophylls (especially fucoxanthin)
- GeneralClass 12All
Name the two main parts of a stamen.
Filament (stalk) Anther (pollen-producing structure)
- GeneralClass 12All
Name the structure formed by the germination of a spore of a fern.
Prothallus (heart-shaped gametophyte)
- GeneralClass 12All
What type of sexual reproduction is shown by Volvox?
Oogamous reproduction (fusion of large non-motile egg with small motile sperm)
- GeneralClass 12All
What are gymnosperms?
Gymnosperms are vascular seed plants characterized by naked seeds—ovules and seeds not enclosed within ovary or fruit tissue.