CBSE Class 10 Science Chapter 8: How do Organisms Reproduce? NCERT Solutions

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NCERT Solutions PDF Class 10 PDF

This comprehensive set of NCERT Solutions for CBSE Class 10 Science, Chapter 8, "How do Organisms Reproduce?", delves into the fundamental processes of reproduction. It explains the critical role of DNA copying in ensuring genetic continuity and the significance of variations for species survival, even if not always beneficial for individuals. The solutions also differentiate between binary fission and multiple fission, illustrating these processes with examples like Amoeba and Plasmodium. Furthermore, it highlights the advantages of reproduction through spores, such as large-scale production, wide distribution, and protection against unfavorable conditions. These solutions are designed to provide clear, step-by-step explanations, aiding students in grasping complex biological concepts and preparing effectively for their examinations.

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Quick info

BoardCBSE
ClassClass 10
SubjectScience
Session2026
LanguageEnglish
TypeNCERT Solutions
ChapterChapter 8: How do Organisms Reproduce

Chapter summary

Chapter 8 of the CBSE Class 10 Science syllabus focuses on "How do Organisms Reproduce?". These NCERT Solutions cover essential topics including the importance of DNA copying for heredity, the role of variations in species evolution, and the mechanisms of asexual reproduction like binary fission and multiple fission. It also explains the process of spore formation as a mode of reproduction. The solutions provide clear explanations and examples to help students understand these vital biological concepts.

Learning outcomes

  • Understand the importance of DNA copying in reproduction.
  • Explain the role of variations in the survival of a species.
  • Differentiate between binary fission and multiple fission.
  • Describe the process of reproduction through spores and its advantages.

Topics covered

Paper topics

  • Importance of DNA copying
  • Role of variations in reproduction
  • Binary fission
  • Multiple fission
  • Spore formation
  • Asexual reproduction

Important topics

  • DNA copying and its significance
  • Variations and species survival
  • Binary fission vs. Multiple fission
  • Advantages of spore formation

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Questions and Solutions

Question 1

What is the importance of DNA copying in reproduction?
Solution: DNA (Deoxyribonucleic acid) serves as the blueprint for an organism's characteristics. It is the molecule that carries the genetic instructions for the development, functioning, growth, and reproduction of all known organisms. During reproduction, DNA copying is crucial because it ensures that the genetic information is accurately transferred from the parent(s) to the offspring. This precise copying mechanism allows the offspring to inherit the traits and body design of their parents, leading to a resemblance between them. Without accurate DNA copying, the genetic continuity would be disrupted, and offspring might not develop the characteristic features of their species.

Question 2

Why is variation beneficial to the species but not necessarily for the individual?
Solution: Variations are changes in the genetic material that can arise during reproduction. These variations are highly beneficial for the survival of a species over time. If the environment changes drastically (e.g., due to climate change, disease outbreak, or resource scarcity), individuals with certain variations might be better adapted to the new conditions. For instance, if a population of bacteria is exposed to a new antibiotic, only those bacteria with a genetic variation conferring resistance will survive. This allows the species as a whole to persist. However, a specific variation may not always be beneficial for an individual organism. It could be neutral, or in some cases, even detrimental, making the individual less suited to its environment. The benefit lies in the increased chances of survival for the species as a whole due to the presence of diverse traits within the population.

Question 1

How does binary fission differ from multiple fission?
Solution: Binary fission and multiple fission are two distinct modes of asexual reproduction. Binary Fission: In this process, a single parent cell divides into two approximately equal-sized daughter cells. The nucleus divides first, followed by the cytoplasm. This is a common method of reproduction in unicellular organisms like Amoeba and bacteria. Multiple Fission: In contrast, multiple fission involves a single parent cell dividing into numerous daughter cells simultaneously. This typically occurs when the organism is under favorable conditions or when it needs to produce many offspring quickly. For example, the parasite Plasmodium reproduces through multiple fission, especially within red blood cells, producing many merozoites at once. The key difference lies in the number of daughter cells produced from a single parent cell: two in binary fission and many in multiple fission.

Question 2

How will an organism be benefited if it reproduces through spores?
Solution: Reproduction through spores offers several significant advantages for an organism, particularly in surviving and spreading to new environments. Advantages of Spore Formation: 1. Large Numbers: A single sporangium (spore-producing structure) can produce a vast number of spores, increasing the chances of at least some of them finding suitable conditions to germinate. 2. Wide Dispersal: Spores are typically lightweight and are easily carried by wind, water, or animals to distant locations. This helps in colonizing new habitats and reduces competition among offspring in the immediate vicinity of the parent organism. 3. Survival in Unfavorable Conditions: Spores are often enclosed within a thick, protective wall. This wall acts as a barrier, preventing dehydration and protecting the spore from extreme temperatures, mechanical injury, and other adverse environmental factors, allowing the organism to survive until conditions become favorable for growth.

Common mistakes

  • Confusing the benefits of variation for the individual versus the species.
  • Not clearly distinguishing the steps involved in binary and multiple fission.
  • Overlooking the protective role of spore walls in unfavorable conditions.

Revision tips

  • Focus on understanding the 'why' behind DNA copying and variation.
  • Draw diagrams to visualize binary and multiple fission processes.
  • List the key advantages of spore formation for quick recall.

Practice MCQs

Q1. What is the primary role of DNA copying in reproduction?

Q2. Why are variations beneficial to a species?

Q3. Which type of fission involves a single cell dividing into two daughter cells?

Q4. In which organism is multiple fission commonly observed?

Q5. What is a key advantage of reproduction through spores?

Frequently asked questions

What is the main function of DNA copying in reproduction?

DNA copying ensures that the genetic information, which determines the body design and characteristics, is accurately passed from parents to their offspring, maintaining continuity of traits.

How do variations help a species survive?

Variations provide diversity within a species. If environmental conditions change drastically, some individuals with advantageous variations are more likely to survive and reproduce, ensuring the continuation of the species.

What is the difference between binary fission and multiple fission?

Binary fission involves one parent cell dividing into two daughter cells, while multiple fission involves one parent cell dividing into many daughter cells simultaneously.

Why are spores useful for reproduction?

Spores are useful because they can be produced in large numbers, are easily dispersed to new locations, and have protective walls that allow them to survive unfavorable conditions.

Are variations always good for an individual organism?

Not necessarily. While variations are crucial for the long-term survival of a species, they may not always be beneficial or even neutral for an individual organism in its current environment.

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