Final answer:
The forces that support the upward movement of water in plants are osmotic pressure and root pressure. These forces work at the cellular level to move water into the plant and through its tissues. Buoyancy also affects aquatic plants in water but does not directly influence water transport within the plant.
Step-by-step explanation:
The forces that support the upward movement of water in plants are osmotic pressure and root pressure. Osmotic pressure is the main driving force that moves water into plants and through plant tissues. As a plant cell in a hypotonic environment takes up water, the resultant osmotic pressure can build up turgor pressure, acting against the cell wall, supporting the cell's structure and contributing to the vertical movement of water. On the other hand, root pressure develops in the roots as water moves into root cells, helping to push water upwards through the plant's vascular system.
Buoyancy is also a force that can influence the movement of water and objects in water. Due to pressure differences across an object, there is a net upward force or buoyant force on any object in a fluid. While this does not directly contribute to the transport of water within plant tissues, it can affect the overall floating or sinking behavior of aquatic plants.