How Plants Work
How Plants Work
Plants may look still, but they are constantly moving water, gases, sugars and signals inside their bodies. They need light, water, carbon dioxide and mineral nutrients to grow. Different parts of a plant do different jobs, but those parts work together. Roots take in water and minerals from the soil. Leaves usually capture most of the light used for photosynthesis. Stems connect the roots and leaves and help move materials around the plant.
Photosynthesis turns light into stored energy
Photosynthesis is the process plants use to capture light energy. In most plants, much of this happens inside cells in the leaves. The plant uses carbon dioxide from the air and water from its roots to make sugars. Those sugars store chemical energy that the plant can use later. Oxygen is released as a by-product of the process. Plants also use cellular respiration, just like animals, to release usable energy from stored food.
How water moves through a plant
Water enters a plant mainly through its roots. It then moves upward through tubes called xylem. Water can travel from the roots all the way to the highest leaves of a tall tree. Evaporation from leaves helps pull water upward through the plant. This movement also carries dissolved minerals from the soil. If a plant loses water faster than it can replace it, it can wilt and become damaged.
Leaves also control gas exchange
Leaves need carbon dioxide for photosynthesis, but gases cannot simply flow in without control. Tiny openings called stomata can open and close on the leaf surface. When stomata open, carbon dioxide can enter the leaf. Water vapor can also escape through those openings. This creates a trade-off between getting enough carbon dioxide and losing too much water. Plants adjust their stomata depending on light, water supply and other conditions.
Plants can sense their environment
Plants do not have brains, but they can still respond to the world around them. Shoots often grow toward light, while roots respond strongly to gravity. Some plants change growth after being touched or damaged. Plants also respond to drought, temperature and attacks from insects or microbes. Hormones help carry many of these signals through the plant. These responses can change growth, flowering, leaf movement and other parts of plant life.
Plants are far more diverse than one simple model
A cactus and a fern do not solve the same problems in the same way. Mosses, conifers and flowering plants also differ in how they reproduce and move water. Some plants live in deserts, while others grow almost entirely in water. A few plants even trap and digest small animals to gain extra nutrients. That means broad plant rules are useful, but they always have exceptions. Paleon uses simple explanations first and then shows how unusual species can break the basic pattern.