NEET Important Chapter - Reproduction in Organisms

This article includes the reproduction in organisms as per the NEET syllabus for biology. It will result in being extremely useful for those NEET aspirants who are looking for last-minute revision notes.

Reproduction in organisms includes all of the important topics and provides insight into the exam pattern. Here you’ll find the answer to all the important questions of the chapter such as what is reproduction, how it takes place, what are the types of reproduction and how is the reproduction different in organisms to that of the plants. 

Important Topics of Reproduction in Organisms

• Sexual and Asexual Reproduction

• Gametogenesis

• Pollination

• Double fertilization

• Karyogamy and plasmogamy

• Events in Sexual Reproduction

• Importance of reproduction in organisms

Important Concepts

• Definition and Features of Reproduction

The process by which an organism multiplies and gives birth to another organism of the same species is known as reproduction. Because each individual has a finite lifespan, reproduction is critical for sustaining variation and perpetuating a race.

Reproduction's Fundamental Characteristics:

• DNA replication is the process by which DNA is replicated. 

• Cell division is the process by which cells divide (only mitotic, or both mitotic and meiotic).

• Reproductive bodies or units are formed.

• Reproductive bodies develop into progeny.

• Types of Reproduction

1. Asexual Reproduction: Asexual reproduction is defined as the formation of new individuals without the use of meiotic division or gamete fusion.

• Given by apomixis. 

• Term suggested by Winkler.

• Rate of reproduction is observed to be faster in asexual reproduction.

• No formation of gametes takes place.

• Common asexual reproductive structures are conidia (Penicillium), buds (Hydra) and gemmules (sponge).

• Asexual reproduction occurs in various types but the most important are budding, binary fission, fragmentation, Parthenogenesis and vegetative propagation. 

The Table Represents The Different Types of Asexual Rreproduction with Example.

Below Given Table Represents The Vegetative Parts Along With Their Examples.

2. Sexual Reproduction

The process of sexual reproduction entails the fusion of male and female gametes which leads to embryogenesis and finally results in the formation of the genetically distinct progeny.

Phases in Sexual Reproduction

• Juvenile Phase: The period between birth and sexual maturity. In plants, it is termed as the vegetative phase.

• Reproductive Phase: The end of the juvenile/vegetative phase marks the beginning of the reproductive phase.

• Senescent Phase: This starts with the end of the reproductive phase, and eventually leads to death.

Events in Sexual Reproduction : Pre-fertilisation, Fertilisation, Post-fertilisation

• Pre-Fertilisation: It involves the processes called Gametogenesis and gamete transfer. 

• Gametogenesis: The production of male and female gametes is known as gametogenesis. Gametes are haploid cells with a structure that might be similar or distinct. 

Isogametes: Both the gametes have a similar structure..

Heterogametes: Both the sexes have distinctly structured gametes.

In fungi and plants, homothallic and monoecious terms are used to denote the bisexual condition and heterothallic and dioecious are used for the unisexual conditions. In flowering plants, the unisexual male flower is staminate, i.e., bearing stamens, while the female is pistillate or bearing pistils.

In animals, species which possess both male and female reproductive organs in the same individual are called bisexual or hermaphrodites (earthworm, sponges, tapeworm etc.) and both have either male or female reproductive organs called unisexual (cockroach, human).

• Gamete Transfer: It can be described as the transfer of gamete which leads to fusion. In the majority, only male gametes are motile while fungi and algae have both gametes motile. 

• Fertilization: It is also called Syngamy, wherein the fusion of male and female gametes occurs. 

• Pollination: Pollination is the transmission of pollen from a plant's anther to its stigma. Pollination may be self (another to the stigma of the same flower) or cross (another to the stigma of a different flower). Factors affecting: wind, water, rain and pollinators. 

• The process of the development of new organisms without fertilization of female gametes is called parthenogenesis. For example: honey bees.

• External fertilization occurs when Syngamy occurs outside the body of the organism and Internal fertilization occurs when Syngamy occurs inside the body of the organism).

• Post Fertilisation Events: Events in the sexual reproduction after the formation of the zygote.

• Embryogenesis- It is the process of development of an embryo from the zygote wherein the zygote undergoes mitotic division and cell differentiation. 

• Oviparous - Zygote develops outside the body of organisms and lays fertilized or unfertilized eggs. Ex – Reptiles and birds.

• Viviparous - Zygote develops inside the body of organisms and produces young ones. Examples of reproduction in living organisms: Human, dog, horse etc.

• In flowering plants, a zygote is formed inside the ovule. After fertilization, sepals, petals and stamens of flowers fall off. The zygote develops into embryos and ovules into seeds. The ovary develops into fruits which develop a thick wall called the pericarp, protective in function.

Solved Examples of the Chapter Reproduction in Organisms

1. Explain why meiosis and gametogenesis are always interlinked?

Ans: Gametogenesis is the process of producing gametes, whereas meiosis is the act of having chromosomes. Meiosis is required for gametes to generate haploid cells. The number of chromosomes is reduced to half after two meiotic cycles. Because of this, gametogenesis and meiosis are related.

Key point to remember: Meiosis is required for gametes to generate haploid cells.

2. Differentiate between a zoospore and a zygote.

Ans: 

3. Higher organisms have resorted to sexual reproduction in spite of its complexity. Why? 

Ans: Sexual reproduction is seen in all higher creatures. Male and female gametes fuse together to produce a zygote in this kind of reproduction. The zygote develops into a properly grown embryo. Because of meiotic cell division, sexual reproduction aids in the introduction of variety in organisms. As a result, all higher creatures exhibit sexual reproduction. This allows the offspring to better adapt to their surroundings and survive.

Key point to remember: Sexual reproduction aids in the introduction of variety in organisms and provides adaptability to the changing environment.

4. Identify the sequence of events shown in the diagram below.

(Image will be updated soon)

1. Fission of Gametes → New Individual → Zygote

2. Fusion of Gametes → Zygote → New Individual (Cell 2n)

3. Fission of Gametes → Zygote → New Individual (Cell 2n)

4. Stages in the gametogenesis

Ans: b. Fusion of Gametes → Zygote → New Individual (Cell 2n)

The first figure represents the fusion of male and female gametes. In the second figure, there is the zygote formation as it represents two nuclei that are in a completely fused situation. Figure three shows the complete cell after the completion of the process of fusion.

Trick: Haploid male gamete(n) + Haploid female gamete (n)= New Individual (2n)

Solved Problems of Previous Year Questions Related to Reproduction in Organisms

1. Which of the following plants is monoecious?

1. Marchantia Polymorpha

2. Cycas Circinalis

3. Carica Papaya

4. Chara

Ans: d. Chara

Chara is a monoecious alga. It has both male and female sex organs antheridium and oogonium at the same node. Marchantia polymorpha, Cycas circinalis, and Carica papaya are all dioecious.

2. Vegetative Propagule in Agave is as:

1. Rhizome

2. Bulbil

3. Offset

4. Eye

Ans: b. Bulbil

Bulbils are used in Agave's vegetative reproduction. Bulbils are vegetative or floral specialized buds that swell into a swollen structure. It splits from the parent plant and produces new plants when favorable conditions arise.

3. Select the correct sequence of events.

1. Gametogenesis → Gamete Transfer → Syngamy → Zygote → Cell division (Cleavage) → Cell differentiation → Organogenesis

2. Gametogenesis → Gamete Transfer → Syngamy → Zygote → Cell division (Cleavage) → Organogenesis → Cell differentiation 

3. Gametogenesis → Syngamy → Gamete Transfer → Zygote → Cell division (Cleavage) → Cell differentiation → Organogenesis  

4. Gametogenesis → Gamete Transfer → Syngamy → Zygote → Cell differentiation → Cell division (Cleavage) → Organogenesis  

Ans: a. Gametogenesis → Gamete Transfer → Syngamy → Zygote → Cell division (Cleavage) → Cell differentiation → Organogenesis.

Trick to Solve: Production of gametes is the first step, followed by the transfer of gametes and this ultimately leads to the fusion that is syngamy. Syngamy causes the production of zygote and further zygote undergoes meiosis ( cell division) followed by cell differentiation. Lately, Organogenesis happens.

Practice Questions for Reproduction in Organisms

We request all NEET aspirants to attempt as many practice questions as they can. You can also attempt reproduction in organisms neet mock test (chapter wise test series).

1. If the gametes are similar in their appearance they are called as

1. Isogametes

2. Anisogametes

3. Homogametes

4. Both A and C 

Ans: d. Both A and C, i.e., Isogametes and Homogametes. So if the gametes are similar in their appearance, they can be called by both of these names.

Key to remember: The words ‘Iso’ and ‘Homo’ both mean ‘similar’.  

2. Identify A to D in given diagrams showing asexual reproductive structure:

1. A- Zoo Gamete, B- Bud, C- Conidia, D- Gemmule

2. A- Zoospore, B- Conidia, C- Bud, D- Gemmule

3. A- Zoospore, B- Conidiosporangium, C- Bud, D- Gemmule

4. A- Aplanospore, B- Conidia, C- Bud, D- Gemmule

(Image will be updated soon)

Ans: b. A- Zoospore, B- Conidia, C- Bud, D- Gemmule

Key points to remember: These structures are to be thoroughly learned by the aspirant.

Conclusion

This article carries Reproduction in Organisms: NEET notes of all the important topics for the NEET aspirant. It can be very helpful for a quick and at the same time effective revision. It includes all the important concepts and topics of Biology NCERT, questions from previous years’ NEET question papers and some practice questions. Make sure to try the Practice question on your own to test your learnings. 

To score good marks in the Neet Exam, you must prepare wisely. You can take chapter wise mock tests such as reproduction in organisms-NEET mock tests and prepare accordingly.