NCERT Class 10 Science Science: Chapter 7 — How do Organisms Reproduce?
This chapter delves into the fundamental question of why organisms reproduce, a process essential for species survival but not individual life. It explains that reproduction involves creating copies of the DNA blueprints that dictate body designs. The process begins with DNA copying within a cell, followed by the creation of additional cellular apparatus and cell division, resulting in two new cells. While these cells are similar, variations in DNA copying mean they are not always identical. These variations, though sometimes leading to non-viable cells, are crucial for the survival of species over time, especially when environmental conditions change. The chapter highlights that consistency in DNA copying maintains body design features, but variations provide a chance for survival in altered niches, as seen with heat-resistant bacteria. It concludes by posing questions about the importance of DNA copying and the benefit of variation for species survival.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 10 |
| Subject | Science |
| Book | Science |
| Chapter | Chapter 7 — How do Organisms Reproduce? |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 4 minutes |
| Word count | 661 |
Learning outcomes
- Understand the necessity of reproduction for species survival.
- Explain the role of DNA copying in creating new individuals.
- Recognize that DNA copying is not always exact, leading to variations.
- Appreciate the importance of variation for the survival of species in changing environments.
Vocabulary
| Word | Meaning |
|---|---|
| Reproduction | The biological process by which new individual organisms – offspring – are produced from their parents. |
| DNA | Deoxyribonucleic Acid, a molecule carrying genetic information from parents to offspring. |
| Chromosomes | Structures in the cell nucleus that contain DNA and genes. |
| Proteins | Molecules made by cells based on DNA information, essential for body design and function. |
| Variation | Differences in characteristics between individuals of the same species, arising from DNA copying. |
| Niche | The role and position a species has in its environment; how it meets its needs for food and shelter, how it survives, and how it reproduces. |
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Practice questions
- Why is reproduction not essential for the survival of an individual organism? Answer: Reproduction is not essential for the survival of an individual because essential life processes like nutrition, respiration, and excretion are required for an individual to stay alive, while reproduction is for the continuation of the species.
- What is the basic event in reproduction? Answer: The basic event in reproduction is the creation of a DNA copy.
- Why are the DNA copies generated during reproduction not always identical to the original? Answer: The DNA copies are not always identical because no bio-chemical reaction is absolutely reliable, and the process of copying DNA has some variations each time.
- How does variation help in the survival of a species? Answer: Variation is beneficial for species survival because if the environment changes, individuals with variations suited to the new conditions are more likely to survive and reproduce, ensuring the species' continuation.
Frequently asked questions
Why do organisms reproduce?
Organisms reproduce to create new individuals, which ensures the continuation of their species, even though it's not necessary for an individual's immediate survival.
What is the role of DNA in reproduction?
DNA contains the genetic information or blueprints for an organism's body design. Reproduction involves making copies of this DNA to pass on to new individuals.
Are the new individuals created through reproduction exact copies of the parents?
No, the new individuals are similar but not always exactly identical to the parents due to natural variations that occur during the DNA copying process.
What is variation in the context of reproduction?
Variation refers to the small differences that arise in the DNA copies during reproduction, leading to subtle differences in the new individuals.
Why is variation beneficial for a species?
Variation is beneficial because it increases the chances of a species' survival if the environment changes. Some individuals with advantageous variations may survive and reproduce.
Does variation always help the individual?
Not necessarily. While variation is crucial for species survival, some variations might be drastic and lead to the death of the new individual.
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NCERT Class 10 Science — Science — Chapter 7 — How do Organisms Reproduce?. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.