1.

What is the style of reproduction

Answer» \tModes of Reproduction used by Single Organisms:The production of a new organism from a single parent without the involvement of *** cells or gametes is called asexual reproduction.Fission, fragmentation, regeneration, budding, vegetative propagation and spore formation are various modes of asexual reproduction.\xa0\xa0\xa0Various methods of asexual reproduction are:\xa0\xa0\tBinary FissionFission in which the parent cell divides to form two similar daughter cells. Example - Amoeba.Multiple FissionFission in which the parent cell divides to produce more than two daughter cells. Example - Plasmodium.BuddingThe reproductive method in which an organism produces an outgrowth on its body surface, which then matures and develops into a new individual. Example - Hydra.Spore FormationSpore formation is an asexual mode of reproduction found in certain multicellular organisms like Rhizopus. The thick walled spores have the capacity to develop into new individuals under suitable conditions.RegenerationRegeneration is found in many completely differentiated simple organisms, like Hydra and Planaria. If such an organism is split into several parts, most of the parts will develop into complete organisms.FragmentationThe reproductive method in which certain multi-cellular organisms, on maturation, break up into smaller fragments, each of which develops into new individual. Example - Spirogyra.Vegetative PropagationThe reproductive method in which new plants are produced asexually from roots, stems or leaves of the parent plant. Example - Buds on leaf of Bryophyllum.\t\xa0\xa0The process of growing many plants from one plant by man-made methods is called artificial propagation. The three common methods of artificial propagation are:\xa0\tCuttingA small part of a plant which is removed by making a cut with a sharp knife is called cutting. Example - rose.LayeringIn this method, a branch of the plant is pulled towards the ground and a part of it is covered with moist soil leaving the tip of the branch exposed above the ground. After some time, new roots develop from the part of the branch buried in the soil. The branch is then cut off from the parent plant. The part of the plant which has developed roots grows to become new plant. Example - Jasmine plant.GraftingGrafting is the method in which cut stems of two different plants are joined together in such a way that the two stems join and grow as a single plant. The cut stem of a plant having roots is called stock whereas the cut stem of another plant without roots is called scion.\t\xa0\xa0\xa0\tSexual Reproduction:The reproduction which takes place by the combination of special reproductive cells called \'*** cells\' is called sexual reproduction.\xa0\xa0\tWhy the Sexual mode of Reproduction?Advantages of sexual reproduction over asexual reproduction:(i) Sexual reproduction combines DNA from two individuals (male and female) due to which the offspring has lot of variations. On the other hand, in asexual reproduction, only the DNA of one individual is copied due to which the variations in the offspring are extremely small.(ii)Due to lot of variations, sexual reproduction allows species to change to more advanced forms from one generation to the next and speed up evolution whereas asexual reproduction does not allow a species to change much from one generation to the next and hence, evolution becomes very slow.\xa0\xa0The sexual reproduction in animals takes place in the following steps:(i) The male parent produces male gamete called sperms. The sperm is a small cell with a long tail (flagellum) for movement.(ii) The female parent produces female gamete called ova which is much bigger cell than the sperm, having a lot of cytoplasm.(iii) The sperm enters into the ovum and fuses with it to form a new cell called zygote and this process is called fertilisation.(iv) The zygote then divides again and again to form a large number of cells and ultimately the zygote grows and develops to form a baby.


Discussion

No Comment Found

Related InterviewSolutions