{"slug":"cbse-class-10-science-how-do-organisms-reproduce","title":"How do Organisms Reproduce?","description":"Variation, asexual modes of reproduction, reproduction in flowering plants and in humans, and reproductive health, weighted towards fission, chromosome number in the zygote, the flower and sexually transmitted diseases, all set in the 2026 papers.","board":"CBSE","grade":"Class 10","subject":"Science","chapter":"How do Organisms Reproduce?","url":"https://www.flipnlearn.app/deck/cbse-class-10-science-how-do-organisms-reproduce","studyUrl":"https://www.flipnlearn.app/deck/cbse-class-10-science-how-do-organisms-reproduce/study","cards":[{"id":"why-variation-helps-a-species","kind":"concept-question","front":"Why is variation useful for a species, even though it does not help every individual?","back":"Niches can change beyond an organism's control, through changes in temperature or water levels, or even meteorite hits. A population suited to one niche could be wiped out, but a few variants may survive, just as heat-resistant bacteria would if global warming heated their waters."},{"id":"binary-fission","kind":"term-definition","front":"Binary fission","back":"Division of a single-celled organism into two halves. In Amoeba the split can happen in any plane, while in Leishmania, which has a whip-like structure at one end, it happens in a definite orientation. In multiple fission, as in Plasmodium, a cell divides into many daughter cells at once."},{"id":"regeneration","kind":"term-definition","front":"Regeneration","back":"The ability of some fully differentiated organisms, such as Hydra and Planaria, to grow a complete organism from each piece they are cut into. It is carried out by specialised cells, but it is not the same as reproduction, since organisms do not normally depend on being cut up."},{"id":"budding","kind":"term-definition","front":"Budding","back":"Asexual reproduction in which an outgrowth forms by repeated cell division at one specific site, develops into a tiny individual and detaches when mature. Hydra reproduces this way using regenerative cells, and yeast also puts out small buds."},{"id":"spore-formation","kind":"term-definition","front":"Spore formation","back":"Reproduction by spores, as in the bread mould Rhizopus, whose blob-like sporangia on stalks contain them. The spores have thick walls that protect them until they reach a moist surface on which they can grow."},{"id":"vegetative-propagation","kind":"term-definition","front":"Vegetative propagation","back":"Growing new plants from roots, stems or leaves, as done by layering or grafting for sugarcane, roses and grapes. Such plants flower and fruit earlier than those from seed, are genetically similar to the parent, and allow propagation of plants like banana and orange that have lost the capacity to produce seeds."},{"id":"why-sexual-reproduction-creates-more-variation","kind":"concept-question","front":"Why does sexual reproduction generate more variation than asexual reproduction?","back":"DNA copying is precise enough that new variations arise slowly. Sexual reproduction combines DNA from two individuals who each carry different accumulated variations, already tested in living organisms, so every offspring receives a novel combination."},{"id":"gamete","kind":"term-definition","front":"Gamete","back":"A germ cell carrying half the number of chromosomes of body cells, which fuses with another in sexual reproduction. In complex organisms the two differ: the male gamete is smaller and motile, while the female gamete is larger and contains stored food."},{"id":"how-the-chromosome-number-is-restored","kind":"concept-question","front":"If gametes from two parents fuse, why does the offspring not end up with twice the DNA of its parents?","back":"Germ cells are formed by a special cell division, meiosis, so each carries just half of a body cell's chromosomes and DNA. When two gametes fuse, the normal chromosome number and DNA content are re-established in the new individual."},{"id":"parts-of-the-pistil","kind":"diagram-label","front":"In the longitudinal section of a flower, what are the three parts of the pistil and what does each do?","back":"The stigma, the terminal part that may be sticky and receives pollen; the style, the elongated middle part through which the pollen tube grows; and the ovary, the swollen bottom part containing ovules, each with an egg cell."},{"id":"pollination","kind":"term-definition","front":"Pollination","back":"The transfer of pollen from the stamen to the stigma. Transfer within the same flower is self-pollination; transfer from one flower to another is cross-pollination, achieved by agents such as wind, water or animals."},{"id":"fertilisation","kind":"term-definition","front":"Fertilisation","back":"The fusion of the male germ cell produced by a pollen grain with the female gamete in the ovule, giving a zygote. To reach it, a tube grows out of the pollen grain on the stigma and travels through the style to the ovary."},{"id":"what-happens-in-a-flower-after-fertilisation","kind":"concept-question","front":"What happens in a flower after fertilisation?","back":"The zygote undergoes repeated division, producing an embryo inside the ovule, which develops a tough coat and becomes a seed. The ovary grows rapidly and ripens into a fruit, while other flower parts such as petals, sepals and stamens may wither and drop away."},{"id":"puberty","kind":"term-definition","front":"Puberty","back":"The period in adolescence when reproductive tissues begin to mature as general body growth slows down. Changes such as new hair growth, breast development and menstruation in girls, and facial hair and a cracking voice in boys, are signs of this sexual maturation."},{"id":"role-of-seminal-vesicles-and-prostate","kind":"concept-question","front":"What is the role of the seminal vesicles and the prostate gland?","back":"Along the path of the vas deferens they add their secretions to the sperms, so the sperms travel in a fluid that eases their transport and nourishes them."},{"id":"how-the-embryo-is-nourished","kind":"concept-question","front":"How does the embryo get nourishment inside the mother's body?","back":"Through the placenta, a disc embedded in the uterine wall. Villi on the embryo's side are surrounded by blood spaces on the mother's side, giving a large surface for glucose and oxygen to pass to the embryo and for its wastes to pass back into the mother's blood."},{"id":"why-menstruation-occurs","kind":"concept-question","front":"Why does menstruation occur?","back":"Each month the uterus lining thickens and becomes spongy and rich in blood, ready to nourish an embryo. If the egg released is not fertilised it lives about one day, the lining is no longer needed, so it slowly breaks down and leaves the body through the vagina, as blood and mucous."},{"id":"contraception","kind":"term-definition","front":"Contraception","back":"Methods of avoiding pregnancy: barriers such as condoms that stop sperm reaching the egg; oral pills that change hormonal balance so eggs are not released; devices such as the copper-T placed in the uterus; and surgery that blocks the vas deferens or the fallopian tubes."},{"id":"sexually-transmitted-diseases","kind":"concept-question","front":"Which sexually transmitted diseases are caused by bacteria and which by viruses, and how can transmission be reduced?","back":"Gonorrhoea and syphilis are bacterial infections; warts and HIV-AIDS are viral. Wearing a condom during sex reduces, to some extent, the spread of many of these infections."}]}