CBSE Ch 1 Important Question Class 12 Biology 2025 PDF

Reproduction in Organisms Class 12 Important Questions is very important for the students as many questions are framed from this chapter in competitive and board examinations. Imagine a world where living beings couldn’t create new life—life on Earth would simply vanish with each passing generation. But thanks to the process of reproduction, life continues to thrive, evolve, and adapt. Reproduction is nature’s way of ensuring the survival of species, from the tiniest microorganisms to the most complex mammals, including humans.

In this blog, we’ll dive into the fascinating world of reproduction, exploring how organisms bring new life into existence. Whether it’s through the simplicity of a single-celled organism dividing into two or the intricate dance of gametes fusing in sexual reproduction, the variety and beauty of reproductive processes are truly astounding. Below, we have provided the links to Class 12 Biology Important Questions and Answers PDFs. You can download them without having to share any login info.

Reproduction in Organisms Important Questions

Offsprings produced by asexual reproduction are called clones. Justify by giving two reasons.

Answer:

Offspring produced by asexual reproduction are called clones because they are genetically identical to the parent. Here are two reasons to justify this:

1. Single Parent Involvement

• In asexual reproduction, only one parent is involved in producing offspring.
• There is no fusion of gametes or genetic material from another source, so the DNA remains unchanged from the parent.

2. No Genetic Variation

• Asexual reproduction occurs through processes like binary fission, budding, or fragmentation, which replicate the parent’s genetic material exactly.
• Since there is no mixing or recombination of genes, the offspring are exact copies of the parent, making them genetically identical.

Thus, the lack of genetic diversity and single-parent involvement result in offspring being called clones.

Meiosis is an essential event in the sexual life cycle of any organism. Give two reasons.

Answer:

Meiosis is an essential event in the sexual life cycle of any organism due to the following reasons:

1. Formation of Haploid Gametes

• Meiosis reduces the chromosome number by half (from diploid to haploid), ensuring that gametes (sperm and egg) have only one set of chromosomes.
• This is crucial because, during fertilization, the fusion of gametes restores the diploid chromosome number in the offspring, maintaining the species’ chromosome count across generations.

2. Genetic Variation

• Meiosis introduces genetic diversity through processes like crossing over (exchange of genetic material between homologous chromosomes) and independent assortment (random distribution of chromosomes into gametes).
• These variations are essential for evolution, as they provide the raw material for natural selection and adaptation.

Thus, meiosis is indispensable for maintaining chromosome stability and fostering genetic diversity in sexually reproducing organisms.‍

Differentiate between oviparous and viviparous animals. 

Answer:

Oviparous animals rely on external egg development, while viviparous animals ensure internal protection and nourishment of the embryo, leading to better survival rates for their offspring.

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Offsprings formed due to sexual reproduction have better chances of survival. Why? Is this statement always true?

Answer:

Offsprings formed due to sexual reproduction have better chances of survival. 

‍Genetic Variation

• Sexual reproduction involves the fusion of male and female gametes, resulting in offspring with genetic material from both parents.

• This genetic recombination introduces variations, which increase the adaptability of the offspring to changing environmental conditions.

Better Evolutionary Potential

• Variations produced through sexual reproduction provide the raw material for natural selection.
• Offspring with advantageous traits are more likely to survive, reproduce, and pass on those traits to the next generation.

Disease Resistance

• Genetic diversity reduces the chances of inheriting harmful mutations or being uniformly vulnerable to diseases, as seen in populations with limited genetic variability.

Is This Statement Always True? Not always. Here’s why:

Environmental Stability

In stable environments, offspring from asexual reproduction may have equal survival chances because they are already well-adapted to their surroundings.For example, organisms like bacteria thrive through asexual reproduction in consistent environments.

Time and Energy

‍Sexual reproduction requires significant energy and time for mating, gamete production, and development. Asexual reproduction is faster and more efficient, especially in organisms where rapid reproduction is necessary for survival.

‍Unfavorable Variations

‍Not all genetic variations are beneficial; some may reduce the survival chances of the offspring. While sexual reproduction generally enhances survival chances due to genetic diversity and adaptability, it is not universally advantageous. The benefits depend on the organism and its environment.

What is a bisexual flower? Collect five bisexual flowers from your neighbourhood and write their scientific names.

Answer:

‍A bisexual flower is one that contains both male (stamens) and female (carpels) reproductive structures within the same flower. This allows the flower to carry out self-pollination or cross-pollination.

‍Examples of Bisexual Flowers contains

‍Here are five common bisexual flowers you might find in your neighborhood, along with their scientific names:

1. Hibiscus (China Rose)
   • Scientific Name: Hibiscus rosa-sinensis
2. Rose
   • Scientific Name: Rosa indica
3. Lily
   • Scientific Name: Lilium spp.
4. Mustard
   • Scientific Name: Brassica juncea
5. Sunflower
   • Scientific Name: Helianthus annuus

Key Features of Bisexual Flowers

• Contain both stamens (male part) and carpels (female part).
• Promote reproductive efficiency as both sexes are present in one flower.
• Found in many plant species and are often highly evolved for pollination.

By identifying and collecting these flowers, you can observe their structural adaptations for pollination. Make sure to handle flowers responsibly and avoid damaging plants in your neighborhood!

Reproduction in Organisms: Chapter 12 Summary

Reproduction is the process by which living organisms create offspring to ensure the continuation of their species. It’s a fundamental characteristic of life and can occur in two main forms: asexual and sexual reproduction. The chapter explains how different organisms reproduce and the significance of this process.

Lifespan of Organisms

• Every organism has a specific lifespan, which is the period from birth to natural death.
• Lifespans vary greatly across species. For example:some text
  • Mayfly: A few hours
  • Tortoise: Over 100 years
  • Humans: Around 70–80 years
• Lifespan is not related to the complexity of an organism.

Types of Reproduction

1. Asexual Reproduction

• In asexual reproduction, only one parent is involved, and the offspring are genetically identical to the parent (clones).
• Common in unicellular organisms and some plants and animals.
• Methods of asexual reproduction:some text
  • Binary Fission (e.g., in Amoeba)
  • Budding (e.g., in Hydra, yeast)
  • Fragmentation (e.g., in algae like Spirogyra)
  • Vegetative Propagation (e.g., in plants like potato and mint)

2. Sexual Reproduction

• In sexual reproduction, two parents (male and female) are involved, and the offspring show variations.
• It involves the formation of gametes (sperm and egg) and their fusion (fertilization).
• Occurs in most plants, animals, and humans.
• Key stages:some text
  1. Pre-fertilization: Gamete formation and transfer.
  2. Fertilization: Fusion of male and female gametes.
  3. Post-fertilization: Development of the zygote into a new individual.

Reproductive Phases

1. Juvenile Phase: The period of growth before an organism becomes capable of reproduction.
2. Reproductive Phase: When the organism is sexually mature.some text
   • Seasonal breeders (e.g., frogs) reproduce at specific times.
   • Continuous breeders (e.g., humans) reproduce throughout their lifespan.
3. Senescence: The phase of ageing after reproduction.

Events in Sexual Reproduction

1. Pre-fertilization Events:some text
   • Gametogenesis: Formation of male and female gametes.
   • Gamete Transfer: Movement of gametes to the site of fertilization (e.g., pollination in plants).
2. Fertilization (Syngamy):some text
   • Fusion of gametes to form a zygote.
   • Can be external (e.g., in frogs) or internal (e.g., in humans).
3. Post-fertilization Events:some text
   • Zygote Formation: The single-celled zygote is the first stage of a new individual.
   • Embryogenesis: Development of the zygote into an embryo.

Reproduction in Plants and Animals

• In Plants:some text
  • Asexual methods include vegetative propagation.
  • Sexual reproduction involves flowers, which are the reproductive organs.
• In Animals:some text
  • Lower animals use asexual methods.
  • Higher animals (like mammals) reproduce sexually.

Significance of Reproduction

• Reproduction ensures the survival of species over time.
• It introduces variations (in sexual reproduction), which are crucial for evolution and adaptation.

Why Practicing Important Questions on "Reproduction in Organisms" is Important?

The chapter "Reproduction in Organisms" is foundational for understanding biology at an advanced level. Here's why practising important questions from this chapter is essential for students:

1. Builds Conceptual Clarity

• Reproduction is a fundamental concept in biology, linking topics like genetics, evolution, and ecology.
• Practicing questions helps solidify your understanding of key concepts such as asexual vs. sexual reproduction, lifespan, gametogenesis, and the reproductive phases.

2. Prepare for Exams

• The chapter often features board exams, NEET, and other competitive exams.
• Solving questions ensures familiarity with the question patterns, improving confidence and performance.

3. Improves Application Skills

• Many questions test your ability to apply theoretical knowledge to real-life scenarios or diagrams.
• Practising helps you learn how to answer application-based and diagrammatic questions effectively.

4. Enhances Retention

• Revisiting concepts through practice reinforces memory and ensures you remember critical details like definitions, examples, and processes.

5. Builds a Strong Foundation

• This chapter is a base for other topics in biology, such as reproduction in animals and plants, and human reproduction.
• A solid grasp of this chapter will make learning advanced topics easier.

6. Develops Time Management

• Regular practice improves your ability to answer questions quickly and accurately, a critical skill for timed exams.

7. Boosts Confidence

• Solving a variety of questions familiarizes you with all possible question types, reducing exam stress and boosting confidence.

Practising questions from "Reproduction in Organisms" isn’t just about scoring marks—it’s about mastering a fundamental concept in biology that connects to the bigger picture of life on Earth. So, grab your pen, open your notebook, and start solving! We hope that you practice the above Reproduction in Organisms Class 12 Biology Extra Questions and achieve your dream marks.

All the best!