12. Reproduction in plants by Dilip Kumar Chandra
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Vegetative propagation allows plants to reproduce rapidly without seeds or pollination by producing genetically identical offspring through structures like bulbs, corms, rhizomes and tubers. These structures store food to support new growth. Sexual reproduction involves meiosis and fusion of male and female gametes during pollination and fertilization to produce offspring with genetic variation, aiding species survival. Angiosperms typically reproduce sexually through flowers containing stamens that produce pollen and pistils containing ovules. Successful seed germination requires water, oxygen, and warm temperatures as shown through an experiment with mung bean seeds.
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12. Reproduction in plants by Dilip Kumar Chandra
- 1. 1
- 2. Importance of ReproductionImportance of Reproduction ♣produce new generation of individuals to replace those members that die ♣ensure continuation of the species
- 3. Basic types of ReproductionBasic types of Reproduction ∗Asexual Reproduction ∗Sexual Reproduction
- 4. Asexual ReproductionAsexual Reproduction produce offspring from a single parent without fusion of gametes produce offspring by mitosis new organism exactly like its parent
- 5. Binary Fission (e.g. Amoeba)Binary Fission (e.g. Amoeba) Process: 1. Pseudopodia withdrawn 2. Nucleus divided into two 3. Two daughter Amoebas formed
- 6. Budding (e.g. Yeast)Budding (e.g. Yeast) Process: 1. Parent cell produces small outgrowth 2. Outgrowth detaches from parent cell 3. A new cell formed Size: Daughter cell < Parent cell
- 7. Sporulation (e.g. Mucor)Sporulation (e.g. Mucor) Process: 1. Hyphae develop swellings (sporangium) at the tips 2. Hundreds of spores are formed in sporangium 3. Sporangium bursts open 4. Liberates spores 5. Spores carried by wind 6. Germinates under suitable conditions
- 11. Vegetative PropagationVegetative Propagation Principle: 1. A new bud is developed on parent plant 2. Adventitious roots formed & absorbed water and mineral salts for young plant 3. Parent plant develops green leaves for photosynthesis 4. Food stored in a specialized underground storage organ (not transport to parent plant)
- 12. Principle: 5. Bud formed for growth in next growing season 6. Aerial shoot dies down in dry season 7. Underground storage organ remains dormant till next year Name of storage organs: Perennating Organs Vegetative PropagationVegetative Propagation
- 14. CormsCorms new corm old corm adventitious root contractile root aerial shoot apical budaxillary bud
- 15. RhizomesRhizomes direction of rhizome growth green leaves new rhizome growing from axillary bud node adventitious root
- 16. BulbBulb fleshly scale leaf provides food for the growth of bud axillary bud will give rise to daughter bulbadventitious root green leaf carries out photosynthesis bud will give rise to new shoot
- 18. Name of Perennating Organ Origin of Organ Region of Food Storage Examples Bulb Short, condenced stem Fleshly scale leaves surrounding the vertical stem Onion, daffodil Corm Short, vertical stem Swollen stem base Gladiolus, Crocus Rhizome Horizontal stem The entire length of horizontal stem Ginger, lotus, iris Tuber Side branch of stem At the tip of the side branch of stem Potato, arrowhead Summary of VegetativeSummary of Vegetative Propagation in AngiospermsPropagation in Angiosperms
- 19. Vegetative PropagationVegetative Propagation rapid rate of reproduction can retain desirable characters as offspring are genetically identical to parent large food reserves are provided for daughter plants does not involve external agents or another plants Advantages:
- 20. Vegetative PropagationVegetative Propagation overcrowding may occur which leads to competition for water, space & light no genetic variation occurs which decreases the ability to adapt to changes in the surroundings diseases of the parent plant are rapidly transmitted to the offspring Disadvantages:
- 21. Artificial PropagationArtificial Propagation Plants which can use cutting: Coleus, African Violet, Bryophyllum… E.g. Cutting: a process by which a piece of branch, stem, root or leaf when planted grows into a new individual Other methods: Grafting & Layering
- 22. Artificial PropagationArtificial Propagation Select a healthy leaf Use a razor blade / sharp knife to cut it off Insert the leaf stalk into a small pot containing some suitable soil Tiny new plant will be formed within 6 - 8 weeks Procedures:
- 23. Propagation of Coleus by Stem Cutting
- 24. What is the purpose of removing some of the leaves ? Ans: In order to prevent water loss by transpiration. test tube water
- 25. Do any roots grow out of the branch ? Ans: Roots grow out from the cut end after a few days. test tube water
- 26. Sexual ReproductionSexual Reproduction ♠ provides a mean of survival of the species under unfavourable conditions ♠ have a different genetic make-up from their parents ♠ a good chance for some of the offspring to adapt to the new environment
- 27. Sexual ReproductionSexual Reproduction ♠ sex cells & gametes are produced by meiosis ♠ sometimes an organism can produce both male & female gametes (hermaphrodite) ♠ fertilization (male gamete + female gamete) takes place which produce a zygote
- 28. Sexual Reproduction inSexual Reproduction in AngiospermAngiosperm Reproductive organ: Flower usually bisexual or hermaphrodite sometimes unisexual
- 29. Stigma Style Ovary/ Carpels Ovule Petal (petals = corolla) Receptacle Sepal (sepals = calyx) Pistil (carpels = gynoecium) Anther Filament Stamen (stamens = androecium) Structure of a FlowerStructure of a Flower
- 30. Sepal (sepals = calyx) Structure of a FlowerStructure of a Flower protect flower bud can carry out photosynthesis
- 31. Petal (petals = corolla) attract insects by scent, colour, insect guide, nectary (produce nectar) Structure of a FlowerStructure of a Flower
- 32. Anther Filament Stamen: produce pollen grains support anther Structure of a FlowerStructure of a Flower
- 33. Stigma Style Ovary/Carpels Ovule Carpels : receive pollen grains support stigma protect ovule becomes seed after fertilization Structure of a FlowerStructure of a Flower
- 34. PollinationPollination Pollen Grain: carrier of Male gametes Ovule: carrier of Female gametes Pollination: the transfer of pollen grains from anther to stigma
- 37. Insect Pollinated FlowerInsect Pollinated Flower VSVS Wind Pollinated FlowerWind Pollinated Flower
- 38. Insect-Pollinated FlowerInsect-Pollinated Flower generally larger & conspicuous brightly coloured, often with insect-guide nectaries often present at the base of flower which produces nectar often strongly scented
- 39. anthers found inside the flower stigma found inside the flower having small number of pollen grains which are rougher & heavier with spikes flowers appear in warmer season Insect-Pollinated FlowerInsect-Pollinated Flower
- 40. Wind-Pollinated FlowerWind-Pollinated Flower generally small & inconspicuous green or dull colourd, or no petals at all no nectarties no scent anthers hanging out of the flower
- 41. stigma is large & feathery, exposed for catching pollen grains having large number of pollen grains which are lighter & with smooth surface flowers sometimes appear in colder & drier season Wind-Pollinated FlowerWind-Pollinated Flower
- 42. Prevent Self-pollinationPrevent Self-pollination Different level of stigma & anther Male & female parts mature at different times Unisexual flower Pollen tubes cannot germinate in the same Plant
- 43. FertilizationFertilization fusion of male gamete & female gamete to form a zygote Process pollen grain lands on a stigma and then secretes sugary solution stimulates the development of pollen tube which grows down the style & ovary secretes enzyme to digest a pathway through style liberates male gamete in ovary & fuse with egg cell
- 46. Fate of Flower PartsFate of Flower Parts after fertilizationafter fertilization Φ Sepals, petals & stamens : wither & fall off Φ Ovary : becomes fruit Φ Ovary wall: becomes fruit wall Φ Ovule : becomes seed Φ Integument : becomes seed coat Φ Fertilized egg: becomes embryo surrounded by endosperm which supplies food to it
- 48. FruitsFruitsDifferent types of dispersal: ◦ by animal possess spines & hooks which cling to animals’ fur protected by hard seed coat which resists the action of animals’ digestive juice after eaten ◦ by wind some fruits are light & have large surface area to catch wind - others: by explosion, by water
- 49. SeedsSeeds • Seed coat – a tough protective covering – protect embryo from damage – prevent bacteria & fungi from entering seed – micropyle admits water to the embryo before germination
- 50. Embryo : – cotyledon • contains starch & protein which nourish the embryo during germination • contains enzymes – plumule • forms leafy shoot – radicle • forms root SeedsSeeds
- 51. Structure of SeedStructure of Seed plumule radicle micropyle cotyledon seed coat
- 53. Different forms of seeds
- 54. Conditions necessary forConditions necessary for Seed GerminationSeed Germination Water activates enzyme to break down starch to sugars & proteins to amino acids for growth Warm temperature enables enzymes to work properly Oxygen enables seeds to respire aerobically to supply energy for growth
- 56. Investigation of the conditions necessary for Seed Germination
- 57. Which tube acts as the control in this experiment ? Ans: Tube A. A B C D moist cotton wool dry cotton wool moist cotton wool mung bean seeds Cotton wool soaked in alkaline pyragallol solution refrigerator
- 58. What is the function of the alkaline pyrogallol solution ? Ans: To absorb oxygen in air. A B C D moist cotton wool dry cotton wool moist cotton wool mung bean seeds Cotton wool soaked in alkaline pyragallol solution refrigerator
- 59. What conditions are favourable for the germination of mung bean seeds ? Ans: Water, oxygen and warm temperature. A B C D moist cotton wool dry cotton wool moist cotton wool mung bean seeds Cotton wool soaked in alkaline pyragallol solution refrigerator
- 60. Tabulate your results. Fill in the table to show the conditions in each and state whether germination has occurred. A B C D moist cotton wool dry cotton wool moist cotton wool mung bean seeds Cotton wool soaked in alkaline pyragallol solution refrigerator
- 61. ResultsResults Tube Condition A B C D Water √ X √ √ Oxygen √ √ X √ Warm temperature √ √ √ X Did seeds germinate? √ X X X
- 62. AVOID PLASTICS AS FOR AS POSSIBLE As a responsible citizen remember the 4R principle Reduce Reuse Recycle Recover