General Q&A for Class 12 · Page 257
5,215 free answers in General for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- GeneralClass 12All
Name three main activities of crop improvement
The three main activities of crop improvement are introduction, selection, and hybridization. Introduction involves bringing new crop varieties or germplasm from other regions or countries where they have been successfully cultivated and testing their performance under local conditions, potentially providing immediate access to superior traits without lengthy breeding programs. Selection is the process of identifying and multiplying individual plants with des
- GeneralClass 12All
What are the different methods of plant breeding
Plant breeding employs several methods to develop improved crop varieties, each suited to different breeding objectives, crop types, and available resources. Selection is the foundational method involving identification and propagation of superior individual plants from genetically variable populations, including mass selection where seeds from multiple good plants are combined, and pure-line selection where a single superior plant's progeny is multiplied. Hybridizati
- GeneralClass 12All
How do good animal husbandry practices benefit farmers?
Good animal husbandry practices directly increase farm profitability by improving animal health, productivity, and product quality. Proper feeding regimens with balanced nutrition boost milk yields in dairy cattle by 20-30%, while scientific breeding programs reduce calving intervals and improve offspring quality. Disease prevention through timely vaccination and hygienic housing reduces veterinary costs and mortality rates, ensuring consistent income streams. Farmers implementing these pract
- GeneralClass 12All
What products are obtained from bee-keeping?
Beekeeping yields multiple valuable products: honey (the primary product, used as a natural sweetener and preservative), beeswax (used in cosmetics, candles, and pharmaceuticals), royal jelly (a protein-rich secretion fed to queen larvae, valued in health supplements), propolis (a resinous antimicrobial substance used in medicines), and bee pollen (collected as a nutritional supplement). Honey alone represents a significant economic return, with a single healthy colony producing 25-40 kilogra
- GeneralClass 12All
Write the name of one indigenous and one foreign breed of poultry bird.
An indigenous poultry breed is Aseel, a native Indian breed known for its hardiness, disease resistance, and excellent meat quality, while a foreign breed is Leghorn, an Italian-origin bird recognized worldwide for exceptional egg-laying capacity. Aseel chickens are raised primarily in rural India for their strong immunity to local diseases and ability to thrive on minimal inputs, though they produce fewer eggs (80-100 annually) compared to commercial layers. Their muscular build and flavorfu
- GeneralClass 12All
What is apiculture?
Apiculture is the scientific practice of maintaining and managing honeybee colonies in man-made hives for the production of honey, beeswax, royal jelly, propolis, and bee pollen. This branch of agriculture involves breeding bees, providing optimal hive conditions, managing diseases and pests, and harvesting bee products while ensuring colony health and sustainability. Commercial apiculture requires knowledge of bee biology, seasonal behaviors, and proper equipment like Langstroth hives, smoke
- GeneralClass 12All
Name the six species of fish cultivated in composite fish culture systems.
Composite fish culture systems in India typically cultivate six compatible species that occupy different feeding zones of a pond: Catla (surface feeder), Rohu (middle zone feeder), Mrigal (bottom feeder), Grass Carp (vegetation feeder), Silver Carp (plankton feeder in upper water layers), and Common Carp (bottom feeder consuming detritus and decaying matter). This combination maximizes productivity by utilizing all ecological niches within the pond ecosystem without competition for food resou
- GeneralClass 12All
What are genetically modified plants? How are they produced? What are their advantages
Genetically modified (GM) plants, also called genetically engineered or transgenic plants, are crops whose DNA has been altered through genetic engineering techniques to introduce specific traits that do not occur naturally in the species through conventional breeding. Unlike traditional breeding which shuffles existing genes within compatible species, genetic modification allows precise insertion of specific genes from any organism—bacteria, other plants, animals, or even synthetic gen
- GeneralClass 12All
Write an example, explain the advantages of crop rotation and intercropping
Consider a farmer practicing a two-year crop rotation combined with intercropping: Year 1 involves growing maize (a cereal and heavy nitrogen feeder) intercropped with cowpea (a legume) during the Kharif season, followed by wheat in the Rabi season. Year 2 shifts to cotton in Kharif season, followed by chickpea (gram) in Rabi. This integrated system demonstrates how rotation and intercropping work synergistically to maximize farm productivity and sustainabili
- GeneralClass 12All
Write about some preventive and control measures for storage of grains
Proper grain storage is critical for preventing post-harvest losses and maintaining food security, requiring preventive measures that begin even before harvest. Pre-storage preparations include cleaning storage structures thoroughly, repairing cracks and holes to prevent pest entry, sun-drying structures to eliminate moisture and existing pests, and fumigating empty stores with approved chemicals. Grains should be harvested at proper maturity, adequately dried to 12-14% moist
- GeneralClass 12All
What is mixed cropping and intercropping? Give examples
Mixed cropping and intercropping are both multiple cropping practices where two or more crops are grown simultaneously on the same field, but they differ in their planting patterns and management. Mixed cropping involves growing two or more crops together in the same field without any distinct row arrangement, with seeds of different crops mixed and sown randomly—for example, wheat and gram mixed together, or groundnut and sunflower scattered across the field. The crops
- GeneralClass 12All
Differentiate between Rabi and Kharif crops. Give example
Rabi and Kharif represent the two major cropping seasons in India and other South Asian countries, differentiated primarily by their sowing and harvesting times in relation to the monsoon cycle. Kharif crops are sown at the beginning of the monsoon season (June-July) and harvested after the rains end (September-October), relying heavily on monsoon rainfall for their water requirements and growing during warm, humid conditions with temperatures ranging from 25-35°C. <stron
- GeneralClass 12All
What are the different types of hybridization
Hybridization in plant breeding is classified based on the genetic relationship between the parents being crossed. Intravarietal hybridization involves crossing different plants within the same variety to maintain variety purity and vigor while eliminating off-types, mainly used for variety maintenance rather than creating new varieties. Intervarietal hybridization crosses two different varieties of the same species—such as crossing two wheat varieties
- GeneralClass 12All
What is green manure? Give example
Green manure refers to crops that are grown specifically to be plowed back into the soil while still green and before they mature, decomposing in place to add organic matter and nutrients to the soil. This practice enhances soil structure, increases nitrogen content (especially when legumes are used), improves water retention capacity, suppresses weeds, and stimulates beneficial soil microbial activity. Green manuring is an ancient, cost-effective, and environmentally friendly method of maint
- GeneralClass 12All
What are the different types of insect pests harming our crops
Insect pests that damage crops are categorized based on their feeding mechanisms and the type of damage they inflict on plants. Chewing or biting insects such as grasshoppers, locusts, caterpillars, and beetles physically consume leaves, stems, roots, or fruits, creating visible holes and defoliation that reduce photosynthetic capacity and overall plant vigor. Sucking insects including aphids, whiteflies, jassids, and mealy bugs pierce plant tissues and extract sap, causing wilting, yellowing
- GeneralClass 12All
What is crop rotation? How is it advantageous
Crop rotation is the systematic practice of growing different types of crops in a planned sequence on the same piece of land across different seasons or years, rather than continuously cultivating the same crop. This strategic approach typically involves alternating between crop families with different nutrient requirements, root depths, and pest profiles—for example, following nitrogen-depleting cereals with nitrogen-fixing legumes, or rotating deep-rooted crops with shallow-rooted one
- GeneralClass 12All
What is Plant breeding
Plant breeding is the scientific art and practice of deliberately selecting and crossing plants with desirable characteristics to develop new varieties that exhibit improved traits such as higher yield, disease resistance, drought tolerance, better nutritional quality, or enhanced adaptation to specific environmental conditions. This systematic process involves identifying plants with favorable genes, controlling their reproduction through various techniques, evaluating the offspring over mul
- GeneralClass 12All
What is 'Zaid'? Give examples
Zaid refers to a short cropping season in India that falls between the two main agricultural seasons—Rabi (winter) and Kharif (monsoon)—typically spanning from March to June during the hot summer months. Zaid crops are cultivated using irrigation since this period receives little to no rainfall and is characterized by high temperatures, making water availability the limiting factor for cultivation. These crops have short growing periods and are adapted to withstand warm weather co
- GeneralClass 12All
Name some fodder crops raised as food for the livestock
Common fodder crops cultivated specifically to feed livestock include berseem (Egyptian clover), lucerne (alfalfa), Sudan grass, napier grass (elephant grass), maize fodder, oats, and cowpea. These crops are selected for their high nutritional value, palatability, digestibility, and ability to provide either green fodder during growing seasons or dry fodder (hay) for storage. Leguminous fodder crops like berseem and lucerne are particularly valuable because they are protein-rich and also fix
- GeneralClass 12All
What are micronutrients
Micronutrients are essential mineral elements required by plants in very small quantities for their normal growth, development, and physiological functions, yet their absence causes severe deficiency symptoms and reduced crop yields. Unlike macronutrients such as nitrogen, phosphorus, and potassium needed in large amounts, micronutrients are needed in trace quantities—often measured in parts per million. The primary micronutrients include iron, manganese, zinc, copper, boron, molybdenum