Knowledge Point 01: The Three Essential Elements for Seed Germination
Seed germination requires sufficient water, air, and an appropriate temperature, which are the three indispensable conditions for seed sprouting.
Water is necessary for cell division and growth during seed germination, as it activates enzymes within the seed and promotes the conversion and utilization of nutrients. Air provides oxygen for the seed to support its respiration, generating energy. An appropriate temperature accelerates the seed’s metabolism, enabling biochemical reactions within the seed to proceed smoothly. When these three conditions are met simultaneously, the seed can successfully germinate and begin its growth journey.
Knowledge Point 02: The Structure of Broad Bean Seeds
Broad bean seeds are composed of parts such as the seed coat, plumule, radicle, and cotyledons, which collectively form the complete structure of the seed.
The seed coat serves as a protective layer for the seed, wrapping around the internal plumule, radicle, and cotyledons like a “suit of armor” to prevent damage from the external environment. The plumule is the primitive structure that forms the stems and leaves after seed germination, containing the potential for future plant growth.
The radicle is the primitive structure that forms the root system after seed germination, responsible for absorbing water and nutrients from the soil to provide the foundation for plant growth. The cotyledons store nutrients, providing energy support for seed germination.
Knowledge Point 03: The Earliest Green Plants on Earth
The earliest green plants on Earth were blue-green algae, which brought the first vitality and vigor to the planet.
Blue-green algae are prokaryotes that can synthesize organics using sunlight, water, and carbon dioxide through photosynthesis and release oxygen. This ability not only provides the energy and substances necessary for the survival of blue-green algae themselves but also creates conditions for the emergence and reproduction of other organisms on Earth.
Therefore, blue-green algae are considered the earliest green plants on Earth, and their appearance marks the initial formation of the Earth’s ecosystem. Over the course of long geological history, blue-green algae gradually evolved into more complex and diverse plant forms, laying a solid foundation for Earth’s biodiversity.
