What experiments demonstrate plant tropic responses?

Experiments demonstrating plant tropic responses include phototropism, geotropism, thigmotropism, and hydrotropism experiments.

Phototropism is the growth of a plant in response to light. An experiment to demonstrate this could involve growing a plant in a box with a small hole on one side. Over time, the plant will grow towards the light source, demonstrating phototropism. This is because the plant's cells on the side away from the light elongate more, causing the plant to bend towards the light. This is a survival mechanism, allowing the plant to maximise its exposure to sunlight for photosynthesis.

Geotropism, also known as gravitropism, is the growth of a plant in response to gravity. An experiment to demonstrate this could involve growing a plant on its side. Over time, the roots will grow downwards, and the shoots will grow upwards, demonstrating geotropism. This is because the plant's cells in the roots and shoots respond differently to gravity. The cells in the roots elongate on the upper side, causing the roots to grow downwards, while the cells in the shoots elongate on the lower side, causing the shoots to grow upwards.

Thigmotropism is the growth of a plant in response to touch. An experiment to demonstrate this could involve growing a climbing plant near a support. Over time, the plant will grow around the support, demonstrating thigmotropism. This is because the plant's cells on the side touching the support elongate less, causing the plant to grow around the support.

Hydrotropism is the growth of a plant in response to water. An experiment to demonstrate this could involve growing a plant between two water sources. Over time, the roots will grow towards the water sources, demonstrating hydrotropism. This is because the plant's cells in the roots elongate more on the side closer to the water, causing the roots to grow towards the water.