Most plants have a vascular structure, which means they receive their nutrients through a series of tubes. These plants have three basic parts: roots, stems and leaves. Roots are at the bottom of the plants and usually stay below the ground. They pull water and minerals from the soil for the plant to eat. Stems are above the ground and transport the water and minerals from the roots to the leaves. Leaves are responsible for photosynthesis, which means they absorb carbon dioxide for the plant and create food molecules.
Photosynthesis requires sunshine. The sun's light is energy that plants absorb through their leaves. Plants do this with chloroplasts, which are inside the cells of plants. Chlorophyll is a compound inside the chloroplasts. The chlorophyll breaks down the sun's energy into water, carbon dioxide and sugar to fuel the plant. Just as people breathe oxygen, plants breathe carbon dioxide, so the chlorophyll has a very important job.
The system of tubes that transport nutrients through a plant is made up of two parts: the xylem and the phloem. Xylem is made of vessels that are connected end to end to transport water from the roots of a plant to the leaves. Xylem dies after a year, which is why the rings inside the trunk of a tree can tell you how old the tree is. The rings are dead xylem tissue. Phloem is also made up of vessels laid end to end, but these run throughout the entire plant and deliver the sugar that the leaves have created through photosynthesis. Unlike xylem, phloem is always alive.
Like humans and other animals, plants must reproduce in order to keep their species from becoming extinct. Plant reproduce with their seeds. The small kernels in the middle of an apple or an acorn from a tree are two examples of seeds. Seeds are planted in the ground, and with the help of the sun, water and nutrients from the soil, the seeds grow into new plants. These new plants have their own seeds, and the whole process starts all over again.