Biology Class 12 NCERT Solutions: Chapter 1 Reproduction in Organisms Part 1

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Q.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.

  • Reproduction is required for extension of life of a species at a given time. Reproduction is the only method by which the continuity of the thread of life is maintained. It enables the species to live generation after generation.

Image of Organisms Reproduce

Image of Organisms Reproduce

Image of Organisms Reproduce

Q.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.

Q.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 off springs so produced are morphologically and genetically similar to their parents and are thus, called clones.

  • In asexual reproduction, offsprings that are produced are not identical to one another but also exact copies of their parent. Such offsprings are genetically also identical.

Q.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.