6 Most FAQ’s of Reproduction Chapter in Class 10th Biology (TS/AP)

8 Marks

LAQ-1 : What are the different modes of a sexual reproduction? Cite them with examples.

Introduction

Asexual reproduction is widespread in the plant kingdom, and various methods of this type of reproduction are evident in different organisms.

Different Modes of Asexual Reproduction

1. Binary Fission:
   A cell splits into two parts, each growing into a complete organism. Example: Paramecium.
2. Multiple Fission:
   A cell splits into more than two parts. Example: Lactobacillus bacteria.
3. Budding:
   A small cyst-like structure called a bud develops into a new individual. Examples: Hydra and yeast.
4. Fragmentation:
   An organism breaks into parts, with each part growing into a new individual. Examples: Flatworms, molds, lichens, Spirogyra.
5. Parthenogenesis:
   New individuals form from unfertilized gametes or ovules. Examples: Spirogyra, ants, bees, wasps.
6. Regeneration:
   New individuals arise from the body parts of the parent. Each piece of a cut organism can grow into a new one.
7. Vegetative Propagation:
   Formation of new plants from leaves, stems, and roots.
8. Natural Propagation:
   New plants emerge naturally from the parent plant. Examples: Bulbs in onions, Rhizome in ginger.
9. Artificial Propagation:
   Human intervention in the growth of new plants. Examples: Grafting in mango and citrus, Cutting in rose.
10. Spore Formation:
    The parent plant produces reproductive units called spores, often in a sac-like structure called a sporangium. Examples: Fungi like Rhizopus, ferns, mosses.

Summary

Asexual reproduction is a fascinating and diverse mode of reproduction. It can occur through various methods such as fission, budding, fragmentation, parthenogenesis, regeneration, vegetative propagation, and spore formation. Understanding these methods provides insight into the incredible adaptability and survival strategies of many organisms, especially in harsh or changing environments. It also has applications in agriculture, where many plants are propagated asexually for uniformity and specific desirable traits.

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LAQ-2 : Observe the following table.

Reproduction System	Organisms
Fission	Paramecium, Bacteria
Budding	Yeast, Hydra
Fragmentation	Flatworms, Spirogyra
Rhisozome	Ginger, Tumeric
Cutting	Rose, Hibiscus
Grafting	Citrus, Apple

1. Paramecium, yeast, flatworms, Spirogyra (any two can be mentioned as all the above organisms carry out asexual reproduction).
2. (a) Cutting (b) Grafting
3. (a) Ginger (b) Turmeric
4. a. In binary fission, two organisms can be obtained.
   b. In multiple fission, more than two organisms can be obtained.

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LAQ-3 : Explain the methods of artificial propagation in various plants.

Introduction

Artificial propagation is used to reproduce and multiply plants that have specific, desirable characteristics. This can be achieved through several methods, including cutting, layering, and grafting.

Methods of Artificial Propagation

Cutting:

1. Process of Cutting:
   Cutting is a process where a part of a plant, containing a bud, is cut from the parent plant and grown individually to form a new plant.
2. Methodology and Growth Medium:
   In this method, the cut part, typically a stem or leaf, is planted in soil or another growing medium. It is then nurtured until it forms roots and begins to grow as a new plant.
3. Common Examples:
   Common examples of plants propagated this way include Rose and Hibiscus.
4. Advantages of Cutting:
   The advantages of cutting are that it’s a quick and easy method, and it allows for the cloning of plants with specific traits.

Layering:

1. Process of Layering:
   Layering involves selecting a weak branch from a plant, burying it in the soil while leaving the tip above ground, to encourage root generation.
2. Development and Independence:
   Over time, the buried branch develops roots. Once these roots are established, the branch is severed from the parent plant and grown independently.
3. Common Applications:
   This method is commonly used for plants like Nerium and Jasmine.
4. Advantages of Layering:
   The key advantages of layering include its effectiveness for plants that are challenging to propagate through cuttings and its ability to maintain the characteristics of the parent plant.

Grafting:

1. Method of Grafting:
   Grafting is a method that combines two plants of closely related varieties to produce a single plant with desirable characteristics.
2. Procedure and Components:
   It involves attaching a shoot or bud (known as the scion) from one plant to the rooted stem (rootstock) of another plant. These two parts are bound together until they fuse and grow into a single plant.
3. Common Usage in Plant Varieties:
   This technique is commonly used in plants like Mango, Citrus, Apple, and Rose.
4. Advantages of Grafting:
   The main advantage of grafting is that it allows for the combination of traits from two different plants, such as incorporating disease resistance from one plant and superior fruit quality from another.

Summary

Artificial propagation methods like cutting, layering, and grafting are essential tools in modern horticulture. These techniques enable the reproduction of plants with specific desirable traits, the combination of characteristics from different plants, and the conservation of valuable or endangered plant species. They offer more control over plant growth and development and contribute significantly to the agriculture and gardening industries.

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LAQ-4 : Explain any two natural and two artificial vegetative propagation methods to produce more number of plants in less time period with examples. (OR) Explain the artificial methods of vegetative propagation in plants. (OR) Explain the method of artificial propagation in various plants.

Introduction

Vegetative propagation is a method of plant reproduction that doesn’t involve seeds or spores. This approach can occur both naturally and artificially, facilitating the reproduction and growth of new plants from existing ones. Below is an explanation of two natural and two artificial vegetative propagation methods:

1. Natural Vegetative Propagation:
   This occurs without human intervention, where new plants grow naturally from the parent plant. Here are two methods:
   • Leaves: In natural vegetative propagation through leaves, small plants grow from the edges of the leaves, as seen in the case of Bryophyllum. This method allows for rapid reproduction and the spread of the plant without relying on seeds, making it an efficient way to propagate and expand plant populations.
   • Stem: In natural vegetative propagation through stems, when structures like runners or stolons touch the ground, they produce adventitious roots. If the connection to the parent plant is severed, the stem portion with these roots grows into a new, independent plant. This method is exemplified by plants with stolons, bulbs, and tubers. The primary advantage of this approach is that it enables plants to expand their territory quickly.
2. Artificial Vegetative Propagation:
   This involves human intervention to facilitate the reproduction of specific plants with desirable characteristics. Here are two methods:
   • Cutting: Cutting is an artificial vegetative propagation method where a part of the plant, typically containing a bud, is cut from the parent plant and grown individually to form a new plant. This technique is commonly used in plants like Rose and Hibiscus. The primary advantage of cutting is that it allows for the propagation of plants that might be difficult to grow from seeds and effectively preserves the genetic characteristics of the parent plant.
   • Layering: Layering is an artificial vegetative propagation method where a weak branch from the plant is buried in the soil, with the tip left above ground. Once roots form in the buried section, the branch is detached from the parent plant and grown independently. This technique is used in plants like Nerium and Jasmine. The key advantage of layering is that it is useful for plants that are difficult to propagate through cuttings and it effectively maintains the characteristics of the parent plant.

Summary

Vegetative propagation, both natural and artificial, allows for the reproduction and growth of new plants from existing ones. Natural methods, such as propagation through leaves and stems, enable plants to spread without human intervention. Artificial methods, like cutting and layering, empower gardeners and farmers to reproduce plants with specific desirable traits. These techniques offer the advantage of producing more plants in less time and are vital in the conservation of plant species, cultivation of crops, and beautification of gardens.

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LAQ-5 : Describe the process of double fertilization in plants. Explain the uses of endosperm that is formed.

Introduction

Double Fertilization is a unique and vital process in flowering plants that leads to the formation of both the zygote and a nutritive tissue called endosperm. Here’s a detailed breakdown of the process and the significance of endosperm:

Double Fertilization Process:

The process of double fertilization involves several sequential steps:

1. Pollen Grain Germination:
   When a pollen grain reaches the stigma (the female part of the flower), it germinates to form a pollen tube. This germination marks the initial step in the process of sexual reproduction in plants, setting the stage for the subsequent stages of fertilization.
2. Rupture of Pollen Tube:
   The end of the pollen tube ruptures and releases two male nuclei into the embryo sac. This critical step sets the stage for the subsequent fusion of male and female gametes, a fundamental process in plant reproduction.
3. Fusion with Female Gamete (First Fertilization):
   One of the two male nuclei fuses with the female gamete to form the zygote. This fusion of gametes, known as fertilization, is a crucial process that leads to the creation of a new organism.
4. Fusion with Fusion Nucleus (Second Fertilization):
   The second male nucleus fuses with another nucleus in the embryo sac to form endosperm tissue. This event marks the occurrence of double fertilization, a distinctive process in which the second act of fertilization leads to the formation of nutritive tissue alongside the zygote.

Uses of Endosperm:

The endosperm, formed through the process of double fertilization, serves several vital roles in plant reproduction:

1. Supports Embryonic Growth:
   Endosperm provides essential nutrients and energy which are crucial for supporting the growth of the embryonic plant, enabling it to develop properly.
2. Supplies Nutrients:
   The endosperm contains a store of starch, proteins, and fats, acting as a vital food reserve that nourishes the embryo during its growth.
3. Protects and Controls Embryo Growth:
   The endosperm surrounds the embryo and may influence its development, providing not only nourishment but also protection and potentially controlling the growth pattern of the embryo.

Summary

Double fertilization is a critical process in the reproductive cycle of flowering plants. It ensures the formation of the zygote, which will grow into the new plant, and leads to the creation of the endosperm. This special tissue nourishes, supports, and protects the growing embryo, playing a key role in the successful development of the next generation of the plant. Understanding this process is essential for botanists, gardeners, and farmers alike, as it underpins the life cycle of many plants that we rely on for food, medicine, and beauty.

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LAQ-6 : Make a flow chart to show the cell cycle and explain cell division describing different stages of mitosis.

Cell Cycle Flow Chart

1. Interphase
   • G1 Phase: Cell grows, prepares for DNA replication.
   • S Phase: DNA replication, chromosomes duplicate.
   • G2 Phase: Cell prepares for division.
2. Mitotic Phase (M Phase)
   • Prophase
   • Metaphase
   • Anaphase
   • Telophase
   • Cytokinesis: Cytoplasm divides, two daughter cells formed.

Stages of Mitosis Explained

Prophase:

1. Chromosome Condensation in Prophase:
   In the Prophase stage of mitosis, Chromosome Condensation occurs, where chromosomes condense into visible structures.
2. Chromatid Formation:
   Simultaneously, Chromatid Formation takes place as each chromosome forms sister chromatids connected by centromeres.
3. Nuclear Membrane Disintegration:
   This phase also involves Nuclear Membrane Disintegration, where the nuclear membrane disappears.
4. Centrosome Division in Animal Cells:
   In animal cells, Centrosome Division occurs, with centrioles dividing to form the spindle apparatus.

Metaphase:

During the Metaphase stage of mitosis, Chromosome Alignment occurs where chromosomes attach to spindle fibers and align at the cell’s equator.

Anaphase:

In the Anaphase stage of mitosis, Centromere Splitting occurs, where centromeres split and sister chromatids separate. Concurrently, Chromatid Movement takes place as spindle fibers contract, moving chromatids towards opposite poles of the cell.

Telophase:

1. Chromatid Extension in Telophase:
   During the Telophase stage of mitosis, Chromatid Extension occurs, where chromatids extend to form new chromosomes.
2. Nuclear Membrane Formation:
   This is followed by Nuclear Membrane Formation, where new nuclear membranes develop around the daughter nuclei.
3. Cell Division in Animal Cells:
   In animal cells, Cell Division is marked by the cell membrane dividing to form two daughter cells.
4. Cell Wall Formation in Plant Cells:
   In plants, a new cell wall forms, effectively dividing the cell.
5. Culmination of Mitosis:
   Concurrently, both the nucleus and cytoplasm divide, culminating in the formation of two separate daughter cells.

Summary

The cell cycle includes both growth and division phases, beginning with the cell preparing for division, replicating its DNA, and entering mitosis. Mitosis consists of four key stages (Prophase, Metaphase, Anaphase, and Telophase), culminating in the formation of two identical daughter cells. This process is essential for the growth, development, and repair of multicellular organisms, and understanding it is fundamental to grasping biological concepts and its implications in medicine and genetics.