Q.Plant breeding is best defined as:

Showing the 12 most recent of 17 on this concept.

1. CBSE 2025Set F1 markMCQ
   Q.Which of the following is used to induce mutation in crop plants?

   (a) Gamma rays

   (b) Alpha rays

   (c) X-rays

   (d) Sunrays

   ›Reveal solutionSolution

   Gamma rays are used as the physical mutagen in mutation breeding of crops.

   Mutation breeding deliberately induces heritable variation so that useful new traits (disease resistance, dwarfness, higher yield) can be selected. Gamma rays are a highly penetrating, high-energy ionising radiation and are the mutagen most widely used to treat seeds/plant material for this purpose. Although X-rays and alpha rays are also ionising, gamma rays are the standard choice in crop mutation breeding; ordinary sunrays are not effective mutagens for this. (A famous example is the gamma-ray-induced high-yielding groundnut.)

   ✓Final answer

   (A) Gamma rays.

2. CBSE 2023Set ANNUAL1 mark
   Q.How is the use of 'Sonalika' variety of wheat helpful in increasing the yield?

   ›Reveal solutionSolution

   Sonalika, a semi-dwarf, disease-resistant, early-maturing wheat variety from the Green Revolution, boosted yield mainly by resisting lodging under heavy fertiliser use.

   Sonalika is one of the high-yielding wheat varieties developed in India as part of the Green Revolution, using semi-dwarf wheat germplasm originally introduced from Mexico (associated with Dr Norman Borlaug's breeding programme). Being semi-dwarf, it has a short, strong stem that does not fall over (lodge) even when it produces a heavy grain head and is grown with generous doses of fertiliser and irrigation — a major limitation of earlier tall varieties, which would lodge under such conditions and lose yield. It is also comparatively rust-resistant and early-maturing, allowing farmers to harvest sooner and sometimes fit in an additional crop cycle. Together, these traits substantially raised wheat yield per unit area compared with traditional tall varieties.

   ✓Final answer

   Sonalika increases yield because its short, lodging-resistant stem tolerates heavy fertiliser/irrigation input without falling over, and it is disease-resistant and early-maturing.

3. CBSE 2023Set ANNUAL1 markMCQ
   Q.Which plant breeding method is used by human from ancient time?

   (a) Hybridization

   (b) Selection

   (c) Mutation

   (d) None of these

   ›Reveal solutionSolution

   Selection — repeatedly choosing and propagating plants with desirable traits from a mixed population — is the oldest plant breeding technique, used by farmers long before genetics was understood.

   Early farmers, without any knowledge of genetics, improved their crops simply by observation and selection:

   • They would identify individual plants in their fields showing desirable characters (higher yield, better grain size, disease resistance, taste), and
   • Save and sow the seeds from only those selected plants for the next season, generation after generation.

   This continuous selection of superior plants over many generations gradually improved crop varieties — long before hybridization (deliberate cross-breeding of different varieties) or induced mutation techniques were developed as scientific breeding methods.

   ✓Final answer

   (b) Selection.

4. CBSE 2023Set ANNUAL1 markMCQ
   Q.Autopolyploidy can be artificially induced

   (a) by colchin

   (b) by chloroform

   (c) by colchicine

   (d) by chloroquine

   ›Reveal solutionSolution

   Colchicine induces autopolyploidy.

   Colchicine, an alkaloid from Colchicum autumnale, binds tubulin and prevents the assembly of spindle microtubules during cell division. As a result, the duplicated chromosomes are not separated to opposite poles and the cell ends up with a doubled (or multiplied) chromosome set — inducing autopolyploidy. This is widely used in plant breeding to create polyploid varieties. ('Colchin' is a misspelling of colchicine.)

   ✓Final answer

   (c) by colchicine.

5. CBSE 2022Set ANNUAL1 mark
   Q.Why is the South Indian sugarcane preferred by agriculturists?

   ›Reveal solutionSolution

   Saccharum officinarum (South Indian sugarcane) has thicker stems and far higher sugar content than North Indian cane, making it agriculturally preferred.

   India grows two broad groups of sugarcane: North Indian canes (largely Saccharum barberi), which are thinner-stemmed with comparatively lower sugar content but are better adapted to the cooler North Indian climate; and South Indian canes (Saccharum officinarum), which have thick, juicy stems and a much higher sugar (sucrose) content, but are less tolerant of North Indian growing conditions. Because sugar yield per plant is the key economic trait for agriculturists, thick-stemmed, high-sucrose South Indian S. officinarum is the more commercially preferred type. In practice, plant breeders hybridise S. officinarum with S. barberi to combine officinarum's superior sugar yield with barberi's hardiness/adaptability, producing the high-yielding sugarcane varieties widely cultivated across India today.

   ✓Final answer

   South Indian sugarcane (Saccharum officinarum) is preferred for its thick stems and high sugar content, and is used in hybridisation with the hardier North Indian S. barberi to develop high-yield commercial cane varieties.

6. CBSE 2022Set ANNUAL1 markMCQ
   Q.Emasculation is related to?

   (a) mass selection

   (b) clonal selection

   (c) hybridization

   (d) pure line

   ›Reveal solutionSolution

   Emasculation is part of artificial hybridisation in plant breeding, so the answer is (C).

   In plant breeding, artificial hybridisation is done to cross two selected parents with desirable traits. When the female parent bears bisexual flowers, its own anthers must be removed before they mature and shed pollen, to prevent self-pollination. This removal of anthers is called emasculation. The emasculated flower is then bagged and later dusted with pollen from the chosen male parent.

   Mass selection, clonal selection and pure-line breeding are other methods that do not specifically involve emasculation, so hybridisation is the correct link.

   ✓Final answer

   (C) hybridization.

7. CBSE 2022Set ANNUAL1 markMCQ
   Q.Pusa Shubhra is a variety of

   (a) wheat

   (b) cauliflower

   (c) chilli

   (d) cabbage

   ›Reveal solutionSolution

   Pusa Shubhra is a cauliflower variety, so the answer is (B).

   Many improved vegetable varieties have been bred in India for disease and pest resistance. Pusa Shubhra (and Pusa Snowball K-1) are cauliflower varieties resistant to diseases such as black rot and curd blight. These are outcomes of plant breeding for improved quality and disease resistance.

   Hence Pusa Shubhra is a variety of cauliflower.

   ✓Final answer

   (B) cauliflower.

8. CBSE 2022Set ANNUAL1 markMCQ
   Q.Triticum aestivum, which is a hexaploid wheat, contains

   (a) 7 chromosomes

   (b) 14 chromosomes

   (c) 30 chromosomes

   (d) 42 chromosomes

   ›Reveal solutionSolution

   Hexaploid wheat has 2n = 42, so the answer is (D).

   The basic (monoploid) chromosome number for wheat is x = 7. Common bread wheat, Triticum aestivum, is a hexaploid — it carries six sets of chromosomes. Therefore its chromosome number is 6 × 7 = 42 (2n = 42). Polyploid crops like hexaploid wheat are important in agriculture because polyploidy often gives larger, more vigorous and higher-yielding plants.

   ✓Final answer

   (D) 42 chromosomes.

9. CBSE 2020Set ANNUAL1 mark
   Q.Which variety of Brassica is resistant to Aphid?

   ›Reveal solutionSolution

   The aphid-resistant variety of Brassica (rapeseed-mustard) is Pusa Gaurav.

   Among the crop varieties bred for insect-pest resistance, the rapeseed-mustard (Brassica) variety Pusa Gaurav is resistant to aphids. It was developed by conventional plant breeding (hybridisation and selection), enabling the crop to resist aphid infestation and reduce yield losses without relying on chemical insecticides. (This topic belongs to the plant-breeding section of the older chapter 'Strategies for Enhancement in Food Production'.)

   ✓Final answer

   Pusa Gaurav (a Brassica / rapeseed-mustard variety) is resistant to aphids.

10. CBSE 2020Set ANNUAL1 mark
    Q.State one Programme to improve chances of successful production of hybrids.

    ›Reveal solutionSolution

    Careful emasculation and bagging of the female parent flower is a key programme step that ensures a hybridisation cross is not contaminated by unwanted pollen.

    To successfully produce a hybrid by crossing two selected parent plants in a breeding programme, it is essential to prevent the female parent flower from being pollinated by any unwanted pollen (its own or from an unintended source). This is achieved through emasculation (removing the anthers of the bisexual flower before they mature and shed pollen) followed by bagging (covering the emasculated flower with a bag to exclude all other pollen carried by wind/insects), and later, deliberately dusting the stigma with the desired pollen from the selected male parent — this careful, controlled procedure greatly improves the chances of obtaining a genuine, successful hybrid cross rather than accidental self- or open-pollination.

    ✓Final answer

    Emasculation followed by bagging of the female parent's flower — this prevents unwanted pollination and ensures only the deliberately chosen pollen fertilises it, improving the chances of a successful, genuine hybrid cross.

11. CBSE 2019Set ANNUAL1 markMCQ
    Q.Which one of the following is an exotic fish?

    (a) Labeo rohita

    (b) Cyprinus carpio var. communis

    (c) Tilapia massambica

    (d) Both

    (b) and (c)

    ›Reveal solutionSolution

    Exotic fishes are those introduced from other countries; both common carp and Tilapia are exotic, so the answer is (d).

    An exotic fish is a species brought into India from a foreign country (as opposed to an indigenous/native one).

    • (a) Labeo rohita (Rohu) — an indigenous Indian major carp.
    • (b) Cyprinus carpio var. communis (common carp) — introduced from Europe/Asia → exotic.
    • (c) Tilapia mossambica — introduced from Africa → exotic.

    Since both (b) and (c) are exotic, the answer is (d).

    ✓Final answer

    (d) Both (b) and (c) — common carp (Cyprinus carpio) and Tilapia mossambica are exotic fishes, while Labeo rohita is indigenous.

12. CBSE 2019Set ANNUAL1 mark
    Q.What is Biofortification?

    ›Reveal solutionSolution

    Biofortification = breeding crop plants for improved nutritional quality (more vitamins, minerals, proteins) to combat 'hidden hunger'.

    Biofortification is a plant-breeding strategy for improving the nutritional value of food crops. Breeders develop varieties with higher content of vitamins and minerals, better-quality proteins, and healthier oils, so that ordinary staple crops themselves supply more nutrition and help fight micronutrient malnutrition ('hidden hunger') in the population.

    Examples: protein-rich wheat (Atlas 66), vitamin-A-enriched 'golden rice' and carrots/pumpkin, iron- and calcium-rich spinach and beans, and vitamin-C-rich bitter gourd.

    ✓Final answer

    Biofortification is the breeding of crops for higher nutritional quality — more vitamins, minerals and better proteins (e.g. golden rice, protein-rich wheat) — to improve human nutrition.