Phototropism

1. Identify light as the stimulus. 2. Check which plant part is growing. 3. State the direction of growth. 4. Name it phototropism. 5. If needed, add positive or negative depending on direction.

A clean diagram can show a shoot bending towards a light source from one side.

A common wrong answer is to call every bending of a plant phototropism without checking the stimulus. The stimulus must be light.

Phototropism is the growth movement of a plant part in response to light.

Phototropism is the growth movement of a plant part in response to light. Rule: photo means light, so phototropism is directional growth caused by light. A sunflower shoot bending towards sunlight is a common example of phototropism.

Phototropism is seen when plant parts grow towards or away from light. Shoots usually show positive phototropism and grow towards light to get more energy for photosynthesis. Roots generally do not show strong positive phototropism. The key idea is that light acts as the stimulus and the growth direction changes because of it. Rule: photo means light, so phototropism is directional growth caused by light. A plant kept in a dark room with light from one side grows towards the window. The shoot bends because the cells on the shaded side grow more, producing positive phototropism. Board questions may ask for the meaning of phototropism, examples of positive phototropism, or why shoots bend towards light. A common wrong answer is to call every bending of a plant phototropism without checking the stimulus. The stimulus must be light.