Science defines the difference between living and non-living things using seven basic characteristics. For something to be considered living, it must display every one of the seven traits. The core building blocks of all things, atoms, are present even in non-living objects, but there exist seven traits that are exclusive to living things, including all plant life.
Plants are made up of cells that maintain a constant state. That condition of stability, known as homeostasis, is one of the characteristics of life in plants. Plants are made up of many cells, which is one of the seven characteristics of life. Those cells are organized at multiple levels, with cells combining to create tissue, which joins together into organs and organ systems. The cells within a plant are specialized units that perform the different functions that sustain and promote life.
The ability of plants to grow is another essential trait of life. That growth takes place both internally as cells split to create new cells and externally as the plant itself takes advantage of the cell division to get larger. Some cells also get larger over time, even without splitting. Related to the growth of an individual plant, another characteristic that proves plants are living is found in the fact that they also reproduce. An individual plant can survive without this trait, but it cannot perpetuate the species and sustain life long-term without reproduction. Plants use both kinds of reproduction: some use sexual reproduction, known as pollination; and other reproduce asexually.
The ability to respond to their surroundings and the capability to evolve and change to survive are two other characteristics of life in plants. Plants must be able to sense changes in climate and respond by creating defenses that allow them to survive. Trees shed their leaves in the fall as a reaction to the environment that allows them to sustain life. The differences within a species show that they have the ability to adapt, which is a trait of living things. Evergreen coniferous trees in warm-weather climates make the necessary changes to live well there, while other trees of the same species thrive year-round in cold-weather climates.
The ability to find and take in nutrients is another critical characteristic of plant life. Some of those nutrients are supplied by the energy sources that are critical to plant life. The ability of the plant to use cell division for growth is dependent on its ability to take in energy and convert it to make it usable.