1. Ch 13-3: Plant Development and Responses
Stimulus: anything that causes a reaction or change in an organism or any part of an organism.
Tropism: growth of all or part of an organism in response to an external stimulus, such as light.

2. Hormone: chemical that causes cells to react in certain ways
Hormone: chemical that causes cells to react in certain ways. Growth: process of increasing in size. Development: process that an organism goes thru as it increases in ability or skill.

3. Phototropism: change in the direction of plant growth in response to light. Gravitropism: change in the direction of plant growth in response to gravity.

4. If a plant gets light from only one direction, the shoot will likely…… Grow toward the light source. *Plant cells can differentiate many times thruout a plant’s life.