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HUW DV V O KEPKODUCE Y, To Revised Edition 2015 |, 68, What is Asexual reproduction ? What are the different methods of asexual, Q2:, reproduction ?, Ans: The production of a new organism from a single parent without the involvement of sex, cells (gametes) is called asexual reproduction., The different methods of asexual reproduction are as under:, · Fission, i), Budding, i), Regeneration, iv), Spore formation, Fragmentation, vi), Vegetative propagation, Q3:, Describe the various methods of asexual reproduction ?, Ans.: The different methods of asexual reproduction are described below:, Fission: Many single-celled organisms like protozoa and bacteria just split into, two identical halves during cell division leading to the creation of new arganisms., This is called Fission. The nucleus divides first and then cytoplasm. Fission is of two, types:, a), Binary Fission : When two individuals are formed from the parent during, fission, the process is called Binary Fission. E.g., amoeba , paramecium,, bacteria, etc reproduce by binary fission., Multiple Fission: In multiple fission, the parent splits into many, new, b), organisms at the same time. Eg., Plasmodium reproduces by multiple, fission., Fully, grown, Amoeba, Nuclous, Twa amaler, Amoebae, Nucleus, Nucleus divides, Into two parts, Cyloplasm, divides, løngthens, Cylopleam, /produced, (e) Two daughter, ceile, (6), (8) Parent, col, Figure, Amoeba reproducing by binary fission., Daughter, celis, ralassed, Mamy daughter oelie, produced by, multiple, esion, Nueteus, Oyiopfasm, Cul, Cyat, tprotoctive wall), Cyat breaks, (e), (A), Reproduction by multiple fission., (a), Figure, 1

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3 HOW DO ORGANISMS REPRODUCE, ii), observed in Hydra and Yeast., Mouth, Tentacies, New Hydra, Parent, Hydr, New, Bud ie, formed, separates, Hydra, (c), Hydra reproducing by the method of budding., Figure, New, yeast, oell, Parent, yenet, cell, Bud, forming, Bud nipped off, Buds remain attached, (D), (a), Long chain, of, yeast cells, formed, Flgure, Yehst reproducing by the method of budding., iii), Regeneration: In some organisms (plants as well as animals) small cut parts of, their body can grow to form whole new organism complete in all respects. This, process of getting back a full organism from its body parts is called Regeneration., Simple animals like Hydra and Palnaria show regeneration., Regeneration, Planaria gels out, inte three plece, Regenaration, Papeneration, Panan, iv), Spore Formation: In spore formation, the parent plant produces hundreds of, microscopic reproductive units called 'spores'. When the spore case (sporangium), bursts, then the spores spread into air. When these air born spores land on food, or soil under favourable conditions (warmth, moisture), they germinate and, produce new plants. Most of the fungi ( like Rhizopus, Mucor, etc.), Bacteria and, non-flowering plants such as ferns and mosses reproduce by spore formation., * Notes Compiled, Designed & Printed By C

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70, v), Fragmentation: The breaking up of the body of a simple multicellular organism, into two (or more) pieces on maturing, each of the which subsequently grows to, form a complete new organism, is called Fragmentation., Amature, Spirogyra, Fragmentation, Three Spingy, produced, Pigure Spirogyra (a filament-type green alga plant) reproduces by the method of, fragmentation., vi), Vegetative Propagation: The vegetative propagation occurs only in plants. In, vegetative propagation, new plants are obtained from the parts of old plants (like, stems, roots and leaves), without the help of any reproductive organs. Vegetative, propagation usually involves the growth and development one or more buds, present on the old plant part to form a new plant., ome plants like Bryophyllum have bud, on le, When these leav, fall on, the ground, they produce new bryophyllum plants. Money plant can be reproduced, by cutting stem pieces containing atleast one leaf. Tubers (modified underground, stems) have a number of buds (called 'eyes'). These tubers also help in the, propagation of many plants such as Potato., Q4:, What is Tissue Culture?, Ans.: Tissue culture is the advanced technique used to propagate the plants for commercial, purposes, In tissue culture, new plants are grown by removing or separating cells (or, tissue) from the growing tip of a plant. These cells are then placed in an artificial medium, where they divide rapidly to from a small group of cells or callus. The callus is then, transferred to another medium containing hormones for growth and differentiation which, results in the formation of small plantlets (saplings). These plantlets are then placed in the, soil so that they can grow into mature plants. Many plants can be grown in a disease-free, conditions by using the technique of tissue culture. This technique is commonly used for, growing ornamental plants., 3

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3 HOW DO ORGANISMS REPRUDUV, Explain the process of reproduction in Rhizopus (Bread Mould)?, Q5:, Ans.: Rhizopus or Bread mould reproduces by spore, formation. Rhizopus consists of fine, thread like, Sporanglum, Spore case, bursts, Spores being, dispersed, Into ak, horizontal projections called hyphae and thin raised, Stem, stems having knob-like projections called sporangia., Each sporangium contain hundreds of minute spores, enclosed in a spore case. When the spore case, Hyphae, This is a common bread mould plunt, (or Rhizopus fungus). It reproduces, by forming spores., bursts, the tiny spores are dispersed in air. These, Figure, spores are the asexual reproductive units which can, produce more rhizopus under suitable conditions., Spore formation method of asexual reproduction is also found in mucor and non-, flowering plants like ferns and mosses., Q6:, What is sexual reproduction?, Ans.: The production of a new organism from two parents by making use of their sex cells, (gametes) is called Sexual Reproduction. In sexual reproduction , the sex cell of one parent, fuses with the sex cell of other parent to form a new cell called ' Zygote '. This zygote, grows and develops to form a new organism ., Q7:, What are the different parts of a flower ? Draw a neat and clean diagram., Ans.: Flower is the reproductive organ of the flowering plants. The main parts of a flower are:, a) Receptacle : The base of a flower at which all the parts of a flower are attached is, called Receptade., b) Sepals: It is the outermost, green leaf like circle of a flower., c) Petals: The colourful parts (coloured leaves) of a flower are called Petals., d) Stamen: The little stalks with swollen tops just inside the ring of petals in a flower, are called Stamens., 4

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-UILIU n Z015 O, 72, Stamen is the male reproductive part of the plant. Stalk of a stamen is called, Filament and the swollen top is called Anther containing pollen grains., Stamen, Petal, (Male part of flower), Сагрel, (Fernale part of flower), Sepal, Receptacle, Flower, stem, Figure, Diagram to show the parts of a flower., e) Carpel ( or Pistil) :, The flask shaped part in the centre of a flower is called, Carpel. Carpel is the female reproductive part of the flower. The terminal sticky part, of the carpel is called Stigma. The middle elongated part is called style and the swollen, part at the bottom of a carpel is called Ovary. Ovary contains ovules., Q8:, What is pollination ? What are its types ?, Ans.:, The transfer of pollen grains from the anther of a stamen to the stigma of a carpel is called, Pollination. Pollination is done by agents like insects (like bees, butterflies), birds, wind, and water., Pollination is of two types :, a) Self Polination: The transfer of pollen grains from the anther of a flower to the, stigma of the same flower ( or another flower on the same plant), is called Self-, Pollination., The transfer of pollen grains from anther of a flower on one, b) Cross Pollination:, plarit to the stigma of a flower on another similar plant is called Cross- Pollination.