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6. Seeds: Structure and Germination

Seeds play a crucial role in the continuity of plant life, providing a means for dispersal and germination. Understanding seed structure, including differences between monocotyledonous and dicotyledonous seeds, is key to comprehending their growth. Germination, influenced by water, oxygen, temperature, and seed viability, leads to the development of a young plant from a dormant seed. The process involves significant changes in the seed that facilitate the emergence of the plant.

Sections

  • 6

    Seeds: Structure And Germination

    This section covers the structure of seeds and the process of germination, highlighting the differences between monocot and dicot seeds.

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  • 6.1

    Introduction

    A seed is the mature ovule that contains an embryo, essential for the continuity of plant life and dispersal.

    Learning Practice

  • 6.2

    Structure Of A Seed

    The section discusses the structural differences between monocotyledonous and dicotyledonous seeds, detailing their respective components.

    Learning Practice

  • 6.2.1

    Types Of Seeds

    This section categorizes seeds into monocotyledonous and dicotyledonous types, highlighting their key features and examples.

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  • 6.2.1.1

    Monocotyledonous (Monocot)

    Monocot seeds are characterized by a single cotyledon and are an essential component of plant biology, illustrated through examples like maize.

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  • 6.2.1.2

    Dicotyledonous (Dicot)

    Dicotyledonous seeds contain two cotyledons and differ from monocots in several structural aspects.

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  • 6.2.2

    General Parts Of A Dicot Seed

    This section describes the essential parts of a dicot seed, such as the seed coat, hilum, micropyle, cotyledons, and embryo, emphasizing each part's function.

    Learning Practice

  • 6.2.2.1

    Seed Coat

    The seed coat is the outer protective layer of a seed, consisting of two layers that help protect the embryo inside.

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  • 6.2.2.2

    Hilum

    The hilum is a scar on the seed coat marking the attachment point to the fruit, playing a crucial role in seed structure and functionality.

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  • 6.2.2.3

    Micropyle

    The micropyle is a small pore in the seed coat that facilitates water and oxygen entry during germination.

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  • 6.2.2.4

    Cotyledons

    Cotyledons are the seed's embryonic leaves crucial for nutrient storage and plant development.

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  • 6.2.2.5

    Embryo

    The embryo is the developing plant within the seed, crucial for the formation of a new plant post-germination.

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  • 6.2.2.5.1

    Radicle

    The radicle is the part of the seed embryo that develops into the root, playing a crucial role in anchoring the plant and absorbing nutrients and water.

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  • 6.2.2.5.2

    Plumule

    The section discusses the plumule, which is the part of the seed embryo that develops into the shoot of a new plant.

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  • 6.2.3

    Structure Of A Monocot Seed

    Monocot seeds, such as maize, have a unique structure featuring one cotyledon and specialized food storage tissues.

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  • 6.2.3.1

    Single Cotyledon (Scutellum)

    The scutellum is a key structure in monocot seeds, serving as the single cotyledon that aids in nutrient absorption and supports the embryo during germination.

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  • 6.2.3.2

    Endosperm

    The endosperm is a crucial part of the seed that provides nutritional support to the developing embryo.

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  • 6.2.3.3

    Embryo

    The embryo is a vital part of a seed, responsible for developing into a new plant.

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  • 6.2.3.4

    Coleoptile

    Coleoptile is a protective sheath that encases the plumule in a monocot seed, aiding its emergence during germination.

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  • 6.2.3.5

    Coleorhiza

    Coleorhiza is a protective sheath surrounding the radicle in monocot seeds, facilitating germination and growth into a new plant.

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  • 6.3

    Types Of Seeds

    Seeds are classified into monocotyledonous and dicotyledonous based on the number of cotyledons they possess.

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  • 6.4

    Germination Of Seeds

    Germination is the process by which seeds grow into seedlings under suitable conditions.

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  • 6.4.1

    Types Of Germination

    Germination involves two main types: epigeal and hypogeal, each characterized by the position of cotyledons during seedling development.

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  • 6.4.1.1

    Epigeal Germination

    Epigeal germination is the process where the cotyledons of a seed emerge above the soil as the plant grows.

    Learning Practice

  • 6.4.1.2

    Hypogeal Germination

    Hypogeal germination is a process where cotyledons remain below the soil surface during seedling development.

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  • 6.5

    Conditions Necessary For Germination

    Germination requires specific conditions, including water, oxygen, suitable temperature, and viable seeds.

    Learning Practice

  • 6.6

    Changes During Germination

    Germination involves crucial changes as seeds absorb water and convert food, leading to the growth of roots and shoots.

    Learning Practice

  • 6.7

    Significance Of Germination

    Germination is crucial for the growth of new plants, allowing seeds to develop into independent organisms.

    Learning Practice

References

b9-6.pdf

Class Notes

Memorization

What we have learnt

  • Seeds are the mature ovules...
  • There are two main types of...
  • Germination requires specif...

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