It is directly composed of organs, and each organ works independently, so there is no system.
Only animals have a systematic hierarchy, and plants have no systematic hierarchy. Roots, stems, leaves, flowers, fruits and seeds all belong to the structural level of organs, and they form a complete plant, so the plant has no system.
Extended data
The concept of each level:
① Fine cell: Cell is the basic structure and functional unit of organism and the most basic life system.
② Tissue: It consists of a group of cells and interstitial cells with similar morphology, structure and function.
(3) Officials: Different organizations are grouped together in a certain order.
④ System: refers to a whole composed of interacting and interdependent components regularly. * * * Whether it can be combined with multiple organs that perform one or more physiological functions in a certain order.
⑤ Individual: The most intuitive organism, such as a human or a horse, is the one whose complex life activities are coordinated by different organs or systems.
⑥ Species: In a natural area, all individuals of the same organism are a population, like carp in a fish pond or poplar in the same forest.
⑦ Population: In a certain natural area, all populations form a community. For example, all living things in a forest are a community, and all living things in a grassland are also a community.
⑧ Ecosystem: It can reflect the whole life phenomenon and the law of life activities, and it is hierarchical. In a certain natural area, biological community and inorganic environment form a unified whole, such as forest ecosystem, grassland ecosystem, marine ecosystem and fresh water ecosystem (divided into lake ecosystem, pond ecosystem and river ecosystem, etc.). ). It is divided into biological system and abiotic system, in which biological system includes animals, plants and microorganisms.
(9) Biosphere: It consists of all living things on the earth and the inorganic environment in which these living things live. Is the largest living system.