| A | B |
|---|
| External Stimulus | a change in the environment outside of the organism |
| Feedback mechanism | a response within a system that influences the activity of that system |
| Force | push or pull |
| Geotropism | growth that happens in organisms in response to gravity, such as the downward growth of plant roots |
| Homeostasis | the body’s ability to keep the internal balance of the body stable |
| Internal stimulus | a change within the organism |
| Motion | a change in the position of an object |
| Phloem | conducting tissue in plants that transports nutrients through the plant |
| Phototropism | growth that happens in organisms in response to light, such as a stem bending toward a light source |
| Root system | below-ground part of a plant that includes the organs such as roots, tubers, and rhizomes |
| Shoot system | above-ground part of a plant that includes the organs such as leaves, buds, stems, flowers (if the plant has any), and fruits (if the plant has any) |
| Stable | balanced; unchanging |
| Simulus | a thing or event that causes a response or reaction |
| Transpiration | process of water moving through plants and evaporating from the leaves and stems into the atmosphere |
| Tropism | turning of all or part of an organism in a particular direction in response to an external stimulus |
| Turgor pressure | pressure exerted by water inside the cell on the cell wall |
| Xylem | vascular tissue in plants that transports fluid through the plant |
