BIOLOGY- REPRODUCTION IN ORGANISM Part 4
Contents
- 0.1 Biology: Reproduction in Organisms – Part 4
- 0.2 Part 4: Sexual Reproduction in Organisms
- 0.3 1. What is Sexual Reproduction?
- 0.4 2. Phases of Sexual Reproduction:
- 0.5 3. Types of Organisms Based on Reproduction:
- 0.6 4. Importance of Sexual Reproduction:
- 0.7 5. Examples of Sexual Reproduction:
- 0.8 BIOLOGY- REPRODUCTION IN ORGANISM Part 4
- 0.9 CHAPTER – How do Organisms Reproduce?
- 0.10 Reproduction-in-organisms.pdf
- 0.11 NCERT-Class-12-Biology.pdf
- 0.12 REPRODUCTION AND POPULATION CONTROL
- 1 Biology – Reproduction in Organisms (Part 4)
- 2 1. Overview of Sexual Reproduction
- 3 2. Pre-fertilization Events
- 4 3. Fertilization (Syngamy)
- 5 4. Post-fertilization Events
- 6 Summary Table:
- 7 Quick Quiz:
Biology: Reproduction in Organisms – Part 4
Reproduction in Organisms
Reproduction is a biological process by which organisms produce their offspring. It ensures the continuity of species.
Part 4: Sexual Reproduction in Organisms
1. What is Sexual Reproduction?
Sexual reproduction involves the fusion of male and female gametes (sperm and egg) to form a zygote, which develops into a new organism.
- Biparental Inheritance: Involves two parents.
- Genetic Variation: Offspring show variations due to recombination of genes.
2. Phases of Sexual Reproduction:
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Pre-fertilization Events:
- Gametogenesis: Formation of male and female gametes.
- Isogamy: Similar gametes (Algae).
- Anisogamy: Dissimilar gametes (Humans).
- Gamete Transfer: Transfer of gametes for fertilization.
- Gametogenesis: Formation of male and female gametes.
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Fertilization (Syngamy):
- External Fertilization: Fusion occurs outside the body (Fishes, Amphibians).
- Internal Fertilization: Fusion occurs inside the body (Reptiles, Mammals).
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Post-fertilization Events:
- Zygote Formation: Fusion of sperm and egg forms a zygote.
- Embryogenesis: Development of the embryo from the zygote.
3. Types of Organisms Based on Reproduction:
- Oviparous: Egg-laying organisms (Birds, Reptiles).
- Viviparous: Give birth to young ones (Humans, Mammals).
- Ovoviviparous: Eggs hatch inside the mother’s body (Some Sharks).
4. Importance of Sexual Reproduction:
- Creates genetic diversity.
- Helps in adaptation and evolution.
- Reduces the accumulation of harmful mutations.
5. Examples of Sexual Reproduction:
- Plants: Pollination and fertilization lead to seed formation.
- Animals: Fertilization between sperm and egg.
Quick Quiz:
- What is the difference between isogamy and anisogamy?
- Name one oviparous and one viviparous animal.
- Why is genetic variation important in sexual reproduction?
अगर आपको किसी और टॉपिक या डिटेल्स में जाना है तो बताइए!
BIOLOGY- REPRODUCTION IN ORGANISM Part 4
CHAPTER – How do Organisms Reproduce?
Reproduction-in-organisms.pdf
NCERT-Class-12-Biology.pdf
REPRODUCTION AND POPULATION CONTROL
Here is Part 4 of the Biology – Reproduction in Organisms chapter, based on NCERT Class 12 syllabus and general biology topics:
Biology – Reproduction in Organisms (Part 4)
Topic: Reproductive Structures and Events in Sexual Reproduction
1. Overview of Sexual Reproduction
Sexual reproduction involves the fusion of male and female gametes (haploid) to form a zygote (diploid), which develops into a new organism.
It occurs in three phases:
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Pre-fertilization Events
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Fertilization
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Post-fertilization Events
2. Pre-fertilization Events
These events happen before fertilization and include:
(a) Gametogenesis – Formation of gametes
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Male gamete: Sperm (in animals), Pollen (in plants)
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Female gamete: Ovum (in animals), Egg cell (in plants)
Types of gametes:
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Isogametes – morphologically similar (e.g., algae)
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Anisogametes – morphologically different (e.g., human)
(b) Gamete Transfer
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In animals: Male delivers sperm to the female via copulation (internal) or external release (in aquatic species).
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In plants: Pollen grain is transferred to stigma (pollination).
3. Fertilization (Syngamy)
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It is the process of fusion of male and female gametes to form a zygote.
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Types:
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External Fertilization – outside the body (e.g., frog, fish)
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Internal Fertilization – inside the body (e.g., humans, birds)
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Importance:
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Restores diploid number.
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Initiates development of the new organism.
4. Post-fertilization Events
(a) Zygote Formation
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Zygote is diploid (2n) and develops into an embryo.
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In higher organisms, zygote undergoes mitosis.
(b) Embryogenesis – Development of embryo
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Cell division (cleavage) and cell differentiation occur.
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In animals:
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Oviparous: Lay eggs (e.g., birds, reptiles)
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Viviparous: Give birth to young ones (e.g., mammals)
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In plants:
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Zygote remains in ovule → develops into embryo
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Ovule becomes seed, and ovary becomes fruit
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Summary Table:
Event | Description |
---|---|
Gametogenesis | Formation of gametes |
Gamete transfer | Male to female |
Fertilization | Fusion of gametes |
Zygote formation | Diploid cell formed |
Embryogenesis | Embryo development |
Quick Quiz:
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What is anisogamy?
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Where does fertilization occur in humans?
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What does ovary convert into after fertilization?
Answers:
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Fusion of dissimilar gametes
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In fallopian tubes (oviduct)
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Fruit
Would you like Part 5: Asexual vs. Sexual Reproduction Comparison, or a PDF revision sheet?