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Questions and Answers
What is the first stage of germination in a seed?
What is the first stage of germination in a seed?
Which method of seed dispersal helps plants spread their offspring over a larger area?
Which method of seed dispersal helps plants spread their offspring over a larger area?
What does seed structure refer to?
What does seed structure refer to?
Which stage of germination involves the start of the visible growth phase?
Which stage of germination involves the start of the visible growth phase?
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What helps dandelion seeds fly great distances?
What helps dandelion seeds fly great distances?
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What distinguishes naked seeds from enclosed seeds?
What distinguishes naked seeds from enclosed seeds?
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What is the significance of light requirements in seed germination?
What is the significance of light requirements in seed germination?
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How does temperature sensitivity affect seed germination?
How does temperature sensitivity affect seed germination?
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Which type of seed requires darkness to break dormancy?
Which type of seed requires darkness to break dormancy?
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What does dormancy refer to in terms of seed germination?
What does dormancy refer to in terms of seed germination?
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Study Notes
Seed
Seeds play a crucial role in plant reproduction and survival. They contain all the necessary components for a new plant to grow from a single cell called a zygote. There are three main aspects of seeds: germination, seed dispersal, and seed structure.
Germination
Germination is the process by which a seed begins to develop into a young plant. It involves several stages: imbibition, embryo growth, radicle emergence, and shoot elongation. Imbibition occurs when water enters the seed's dry cells, causing them to expand. Embryo growth follows, where the embryo starts to increase in size, forming a root (radicle) and a stem (epicotyl). Radicle emergence marks the start of the visible growth phase, with the radicle breaking through the seed coat. Finally, shoot elongation continues until a complete plant has emerged.
Seed Dispersal
Seed dispersal is the method plants use to spread their offspring over a larger area. This ensures genetic diversity, reduces competition between siblings, and helps colonize new areas. Some common methods of seed dispersal include wind, water, animals (zoochory), insects (entomochory), bacteria (bacteriochory), and gravity (barochory). For example, dandelion seeds can fly great distances due to puffballs filled with wind-blown seeds.
Seed Structure
Seed structure refers to the physical characteristics of a seed that determine its ability to survive and establish itself as a new plant. There are two main types of seeds based on structure: naked seeds and enclosed seeds. Naked seeds lack a protective covering (testa) around their embryo, while enclosed seeds have a testa that protects them from desiccation. Other factors affecting seed structure include dormancy, light requirements, and temperature sensitivity.
Dormancy and Light Requirements
Dormancy refers to the period during which a seed cannot germinate, while light requirements indicate whether a seed needs light to initiate germination. Some seeds, like avocado seeds, need light to break dormancy before they can begin germinating. Others, such as sweet potato seeds, require darkness to break dormancy and germinate.
Temperature Sensitivity
Temperature sensitivity determines the range of temperatures under which a seed can germinate successfully. Temperature plays a vital role in determining germination rate, directionality, and depth. For instance, northern lupine seeds will only germinate if the soil temperature remains consistently below freezing.
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Description
Learn about the key aspects of seeds: germination, seed dispersal, and seed structure. Explore the stages of germination, methods of seed dispersal, and the different types of seed structures. Understand concepts like dormancy, light requirements, and temperature sensitivity in seeds.
