Final answer:
Tropism refers to a plant's directional response to stimuli, critical for survival and growth, while turgor pressure maintains plant structure by the pressure of cell contents against the wall, important for support and stomatal function.
Step-by-step explanation:
Tropism and Turgor Pressure in Plants
Tropism is the directional growth or movement that plants exhibit in response to environmental stimuli such as light, gravity, touch, or chemicals. For instance, when a plant is tipped on its side, the gravitropic response will cause the roots to grow downwards and the shoots upwards due to their respective positive and negative gravitropism. Similarly, the tendril of a bean encountering a metal pole will display thigmotropism by wrapping around it. Leaves and stems often grow towards light because of phototropism, which is critical for photosynthesis.
Turgor pressure is the pressure exerted by the fluid contents of a plant cell against its cell wall. It arises mainly due to osmotic pressure, which occurs when water moves into a cell by osmosis, making the cell turgid. This pressure is essential for keeping the plant cells rigid and upright, contributing to the overall plant structure and support. If a plant cell is placed in a hypotonic solution, water enters the cell, increasing the turgor pressure, while in a hypertonic solution, it decreases as the cell loses water.
Both tropism and turgor pressure are crucial for the survival and adaptability of plants. Tropism guides the plant towards favorable environmental conditions while turgor pressure maintains plant structure and facilitates the opening and closing of stomata for gas exchange. Hormones, such as auxins, play a significant role in tropisms and growth, while water potential and osmotic pressure influence turgor.