General Q&A for Class 12 · Page 61
5,215 free answers in General for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- GeneralClass 12All
Write three characteristics of division Thallophyta.
Three key characteristics of Division Thallophyta: Simple, undifferentiated body structure: The plant body is a thallus without differentiation into true roots, stems, or leaves. This simple organization ranges from unicellular to multicellular forms but lacks specialized tissue systems found in higher plants. Absence of vascular tissue: Thallophytes lack xylem and phloem, the condu
- GeneralClass 12All
Write a short note on Kingdom Protista.
Kingdom Protista encompasses unicellular or simple multicellular eukaryotic organisms that don't fit into plant, animal, or fungi kingdoms. Proposed by Ernst Haeckel and refined in Whittaker's five-kingdom system. Key characteristics: Cell structure: Eukaryotic cells with membrane-bound nucleus and organelles Organization: Primarily unicellular; some colonial or simple multicellular fo
- GeneralClass 12All
Which categories are listed in hierarchy in the classification of organisms?
The hierarchical categories (taxonomic ranks) in biological classification, from broadest to most specific, are: Kingdom - Largest, most inclusive group (e.g., Animalia, Plantae) Phylum/Division - Division is used for plants; Phylum for animals (e.g., Chordata, Angiospermae) Class - Subdivision of phylum (e.g., Mammalia, Dicotyledonae) Order - Grou
- GeneralClass 12All
Give two basic differences between bryophytes and pteridophytes.
Two fundamental differences between bryophytes and pteridophytes: Vascular Tissue: Bryophytes: Lack vascular tissue (xylem and phloem), making them non-vascular plants. Water and nutrients move through simple diffusion and osmosis, limiting their size. Pteridophytes: Possess well-developed vascular tissue (xylem and phloem) for efficient transp
- GeneralClass 12All
Briefly explain sub-kingdom Cryptogamae.
Sub-kingdom Cryptogamae (meaning "hidden reproduction") includes plants with inconspicuous or hidden reproductive organs that don't produce flowers or seeds. The term comes from Greek "kryptos" (hidden) and "gamos" (marriage/reproduction). Characteristics: Non-flowering plants Reproduce through spores rather than seeds Include both vascular and non-vascular plants Lack true fruits <li
- GeneralClass 12All
What is air pollution?
Air pollution is the contamination of the atmosphere by substances at concentrations harmful to human health, other living organisms, or the environment. These pollutants can be solid particles, liquid droplets, or gases and originate from both natural sources (volcanic eruptions, wildfires, dust storms) and human activities (vehicle emissions, industrial processes, power generation, agriculture). Primary pollutants are emitted directly into the atmosphere, such as carbon mon
- GeneralClass 12All
Who wrote "The Origin of Species"?
Charles Darwin authored the groundbreaking scientific work "On the Origin of Species by Means of Natural Selection" (commonly shortened to "The Origin of Species"), published on November 24, 1859. This revolutionary book introduced the scientific theory of evolution through natural selection, fundamentally transforming biological sciences and our understanding of life's diversity. Darwin's observations during his voyage on HMS Beagle, particu
- GeneralClass 12All
1. Which organisms have bilateral and radial symmetry?
Bilateral symmetry is found in organisms where the body can be divided into two identical halves along only one plane. Examples include humans, butterflies, earthworms, and most vertebrates. Radial symmetry occurs in organisms whose body parts are arranged around a central axis, allowing division into similar halves through multiple planes. Common examples are jellyfish (Aurelia), sea anemones, starfish, and hydra. These symmetry patterns reflect evolutionary
- GeneralClass 12All
Does silverfish belong to class Pisces?
No, silverfish does not belong to class Pisces. Despite its misleading common name, the silverfish (Lepisma saccharina) is an insect belonging to the order Thysanura within class Insecta and phylum Arthropoda. It's called "silverfish" due to its silvery, metallic appearance and fish-like movement, but it's a small, wingless insect commonly found in homes, feeding on carbohydrates like paper, glue, and starch.
- GeneralClass 12All
What does the word 'Arthropoda' mean?
The term Arthropoda derives from Greek words: "arthron" meaning jointed and "podos" meaning feet or legs. Thus, Arthropoda literally translates to "jointed legs" or "jointed feet." This name perfectly describes the phylum's defining characteristic—segmented bodies with paired, jointed appendages. Arthropods represent the largest and most diverse animal phylum, including insects, spiders, crustaceans, and centipedes. The
- GeneralClass 12All
Which organisms have naked embryos?
Gymnosperms are the group of seed-bearing plants characterized by naked embryos or naked seeds. The term "gymnosperm" comes from Greek words "gymnos" (naked) and "sperma" (seed), indicating that their seeds are not enclosed within fruits or ovaries. Instead, seeds develop exposed on the surface of cone scales or similar structures. Common examples include conifers (pine, fir, spruce), cycads, ginkgo, and gnetophytes. This distinguishes them from angiosperms (
- GeneralClass 12All
Name two egg-laying mammals.
The two primary examples of egg-laying mammals (monotremes) are: Platypus (Ornithorhynchus anatinus) - A semi-aquatic mammal native to eastern Australia with a duck-like bill, beaver tail, and venomous spurs Echidna (Tachyglossus aculeatus) - Also called spiny anteaters, found in Australia and New Guinea These remarkable mammals represent the most primitive living mammalian group, combining reptilian c
- GeneralClass 12All
Name two groups of warm-blooded animals with four-chambered hearts.
The two groups of warm-blooded (endothermic) animals with four-chambered hearts are: Birds (Class Aves): Including eagles, sparrows, penguins, ostriches, and all other avian species Mammals (Class Mammalia): Including humans, whales, bats, elephants, and all other mammalian species The four-chambered heart (two atria and two ventricles) allows complete separation of ox
- GeneralClass 12All
Which organisms have bilateral and radial symmetry?
Bilateral symmetry is found in organisms where the body can be divided into two identical halves along only one plane. Examples include humans, butterflies, earthworms, and most vertebrates. Radial symmetry occurs in organisms whose body parts are arranged around a central axis, allowing division into similar halves through multiple planes. Common examples are jellyfish (Aurelia), sea anemones, starfish, and hydra. These symmetry patterns reflect evolutionary
- GeneralClass 12All
What does the word 'thallose' mean from the word 'Thallophyta'?
The term "thallose" or "thallus" (from Greek "thallos" meaning young shoot or twig) refers to a simple, undifferentiated plant body lacking true roots, stems, and leaves. In Thallophyta, the plant body is a thallus a relatively simple structure without distinct tissue differentiation. This contrasts with higher plants that have specialized organs and vascular tissue. Thallophytes include algae, fungi, and lichens, where the entire body absorbs nutrients and water, rather than having specializ
- GeneralClass 12All
Who proposed binomial nomenclature?
Carolus Linnaeus (Carl von Linné), a Swedish botanist and physician, developed and formalized the system of binomial nomenclature in the 18th century, particularly in his work "Systema Naturae" (10th edition, 1758) and "Species Plantarum" (1753). This naming system forms the foundation of modern biological taxonomy. Binomial nomenclature assigns each organism a two-part scientific name: <o
- GeneralClass 12All
What is the other name of Planaria?
<p>Planaria is commonly known as <strong>flatworm</strong> or belongs to the group <strong>Turbellaria</strong> within phylum <strong>Platyhelminthes</strong>. The scientific name often refers to the genus <em>Dugesia</em> or <em>Planaria</em>. These free-living flatworms are famous in biological research for their extraordinary <strong>regenerative abilities</strong>—a planarian cut into pieces can regene
- GeneralClass 12All
Give examples of plants that bear naked seeds.
Plants bearing naked seeds are called gymnosperms. Notable examples include: Conifers: Pines (Pinus), firs (Abies), spruces (Picea), cedars (Cedrus), redwoods Cycads: Cycas revoluta (sago palm), Zamia Ginkgo: Ginkgo biloba (maidenhair tree) Gnetophytes: Ephedra, Gnetum, Welwitschia These plants produce seeds exposed on cone scales o
- GeneralClass 12All
In which kind of plants does reticulate venation occur?
Reticulate venation (also called net venation) occurs predominantly in dicotyledonous plants (dicots). In this venation pattern, leaf veins form a complex network or web-like structure with smaller veins branching from larger midribs in various directions. Common examples include rose, mango, peepal, hibiscus, and most broadleaf trees. This contrasts with parallel venation found in monocots (like grasses, lilies, and palms), where veins run p
- GeneralClass 12All
What is the cell wall of Thallophyta made up of?
The cell wall composition in Thallophyta varies between groups: Algae (photosynthetic thallophytes): Cell walls are primarily made of cellulose, similar to higher plants, with some species incorporating additional polysaccharides like pectin, algin (in brown algae), or agar (in red algae) Fungi (non-photosynthetic thallophytes): Cell walls are composed primarily of chitin, a nitrogen-containing polysa