7 th Grade Unit 1: Organism Response to the Environment Lesson 2: Seedling Science Vocabulary of Instruction:

Gravity The force that pulls objects toward each other.

Stimuli Something causing or regarded as causing a response.

Response A change in an organisms surroundings that cause the organism to react.

Tropism Is a biological phenomenon, indicating growth or turning movement of a biological organism, usually a plant, in response to an environmental stimulus.

Geotropism Is the term applied to the consequent orientation response of growing plant parts.

Hydrotropism Is a directional growth response in which the direction is determined by a stimuli in water concentration.

Phototropism Is directional growth in which the growth is determined by the direction of the light source.

Thigmotropism Is a movement in which an organism moves or grows in response to touch or contact stimuli.