In plants, the entry points of necessary substances for photosynthesis to proceed are primarily through the leaves. The leaves contain specialized structures called stomata, which are small openings on the surface of the leaf. These stomata allow for the exchange of gases, including the entry of carbon dioxide (CO2) and the exit of oxygen (O2) produced during photosynthesis.
Carbon dioxide, a vital component for photosynthesis, enters the leaves through the stomata. It diffuses into the intercellular spaces within the leaf and eventually reaches the chloroplasts, the site of photosynthesis within plant cells.
Water, another essential substance for photosynthesis, is absorbed by the roots of the plant. It travels through the vascular tissues, known as xylem, and is transported upward to the leaves. The movement of water through the plant is driven by a process called transpiration, where water is lost through the stomata, creating a "pull" that draws more water up from the roots.
In addition to carbon dioxide and water, plants also require sunlight for photosynthesis. Sunlight is absorbed by pigments, such as chlorophyll, located in the chloroplasts within plant cells. These pigments capture the energy from sunlight, initiating the process of photosynthesis.
Overall, the entry points for necessary substances for photosynthesis in plants are the stomata for carbon dioxide, the roots for water, and the chloroplasts for sunlight.