Explore the comprehensive NCERT Solutions for Class 12 Science Biology Chapter 1: “Reproduction In Organisms.” These solutions, accompanied by clear step-by-step explanations, are highly favored by Biology students at the 12th-grade level. Whether you need assistance with homework or effective exam preparation, these solutions for Reproduction In Organisms prove to be a valuable resource. All questions and answers from Chapter 1 of the NCERT Book for class 12 Science Biology are conveniently provided here for free, ensuring a convenient and accessible study aid for students. Page No 17: Question 1: Why is reproduction essential for organisms? ANSWER: Reproduction is a fundamental feature of all living organisms. It is a biological process through which living organisms produce offspring’s similar to them. Reproduction ensures the continuance of various species on the Earth. In the absence of reproduction, the species will not be able to exist for a long time and may soon get extinct. Page No 17: Question 2: Which is a better mode of reproduction sexual or asexual? Why? ANSWER: Sexual reproduction is a better mode of reproduction. It allows the formation of new variants by the combination of the DNA from two different individuals, typically one of each sex. It involves the fusion of the male and the female gamete to produce variants, which are not identical to their parents and to themselves. This variation allows the individual to adapt to constantly changing and challenging environments. Also, it leads to the evolution of better suited organisms which ensures greater survival of a species. On the contrary, asexual reproduction allows very little or no variation at all. As a result, the individuals produced are exact copies of their parents and themselves. Page No 17: Question 3: Why is the offspring formed by asexual reproduction referred to as clone? ANSWER: A clone is a group of morphologically and genetically identical individuals. In the process of asexual reproduction, only one parent is involved and there is no fusion of the male and the female gamete. As a result, the offsprings so produced are morphologically and genetically similar to their parents and are thus, called clones. Page No 17: Question 4: Offspring formed due to sexual reproduction have better chances of survival. Why? Is this statement always true? ANSWER: Sexual reproduction involves the fusion of the male and the female gamete. This fusion allows the formation of new variants by the combination of the DNA from two (usually) different members of the species. The variations allow the individuals to adapt under varied environmental conditions for better chances of survival. However, it is not always necessary that the offspring produced due to sexual reproduction has better chances of survival. Under some circumstances, asexual reproduction is more advantageous for certain organisms. For example, some individuals who do not move from one place to another and are well settled in their environment. Also, asexual reproduction is a fast and a quick mode of reproduction which does not consume much time and energy as compared to sexual reproduction. Page No 17: Question 5: How does the progeny formed from asexual reproduction differ from those formed by sexual reproduction? ANSWER: Progeny formed from asexual reproduction Progeny formed from sexual reproduction 1. Asexual reproduction does not involve the fusion of the male and the female gamete. Organisms undergoing this kind of reproduction produce offspring’s that are morphologically and genetically identical to them. Sexual reproduction involves the fusion of the male and the female gamete of two individuals, typically one of each sex. Organisms undergoing this kind of reproduction produce offspring’s that are not identical to them. 2. Offsprings thus produced do not show variations and are called clones. Offspring’s thus produced show variations from each other and their parents. Page No 17: Question 6: Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered as a type of asexual reproduction? ANSWER: Sexual reproduction Asexual reproduction 1 It involves the fusion of the male and female gamete. It does not involves the fusion of the male and the female gamete 2. It requires two (usually) different individuals. It requires only one individual. 3. The individuals produced are not identical to their parents and show variations from each other and also, from their parents. The individuals produced are identical to the parent and are hence, called clones. 4. Most animals reproduce sexually. Both sexual and asexual modes of reproduction are found in plants. Asexual modes of reproduction are common in organisms having simple organizations such as algae and fungi. 5. It is a slow process. It is a fast process. Vegetative propagation is a process in which new plants are obtained without the production of seeds or spores. It involves the propagation of plants through certain vegetative parts such as the rhizome, sucker, tuber, bulb, etc. It does not involve the fusion of the male and the female gamete and requires only one parent. Hence, vegetative reproduction is considered as a type of asexual reproduction. Page No 18: Question 7: What is vegetative propagation? Give two suitable examples. ANSWER: Vegetative propagation is a mode of asexual reproduction in which new plants are obtained from the vegetative parts of plants. It does not involve the production of seeds or spores for the propagation of new plants. Vegetative parts of plants such as runners, rhizomes, suckers, tubers, etc. can be used as propagules for raising new plants. Examples of vegetative reproduction are: 1. Eyes of potato: The surface of a potato has several buds called eyes. Each of these buds when buried in soil develops into a new plant, which is identical to the parent plant. 2. Leaf buds of Bryophyllum: The leaves of Bryophyllum plants bear several adventitious buds on their margins. These leaf buds have the ability to grow and develop into tiny plants when the leaves get detached from the plant and come in contact with moist soil. Page No 18: Question 8: Define (a) Juvenile phase, (b) Reproductive phase, (c) Senescent phase. ANSWER: (a) Juvenile phase: It is the period of growth in …
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