PLANT RESPONSE TO EXTERNAL STIMULI
6.L.5B.5 Analyze and interpret data to describe how plants respond to external stimuli (including temperature, light, touch, water, and gravity).
It is essential for students to know that plants respond to changes in their environments. These responses (the reply to the change in the environment) vary depending on the specific environmental stimulus (a change in the environment that causes a response or a reaction).
● Temperature, along with day length, can be used to manipulate flowering.
● Temperature alone can also influence flowering in some plants.
● For example, many bulb plants (like daffodils) must be exposed to cold temperature to force the bulb to mature.
● Many plants require a daily change of temperature between night and day to ensure photosynthesis and respiration reactions occur at optimal temperatures which will result in maximum plant growth.
● Under certain conditions (frequent temperature changes), when a mature plant or seed becomes or remains dormant (inactive).
○ is a period of time when the growth or activity of a plant or seed stops due to changes in temperature or amount of water.
○ allows various species to survive in particular environments. It helps to ensure that seeds will germinate when conditions are favorable for survival of the small seedlings.
○ For example, leaves fall from trees prior to the conditions of winter and the leaf buds do not open again until conditions are favorable in the spring.
● Plants respond to changes in the environment by growing their stems, roots, or leaves toward or away from the stimulus. This response, or behavior, is called a tropism.
● Examples of plant tropisms include:
○ Phototropism - The way a plant grows or moves in response to light.
○ Gravitropism - The way a plant grows or moves in response to gravity; also called geotropism.
○ Hydrotropism - The way a plant grows or moves in response to water.
○ Thigmotropism - The way a plant grows or moves in response to touch.
• Students can analyze and interpret weather data to see how similar species of plants respond to changes in temperature in different regions of the state and country.
• Students can conduct an experiment where seeds are placed in different directions in order to see how roots and stems respond to gravity.
The objective of this indicator is to analyze and interpret data to describe how plants respond to external stimuli. Therefore, the primary focus of assessment should be for students to analyze and interpret data from informational texts, observations, measurements, or investigations to construct scientific explanations describing how plants respond to changes in their environments. This could include but is not limited to students observing growing plants and describing how they have grown in response to light, touch, water, and gravity. Students may also be able to gather evidence that would support the hypothesis that plants grow in response to light, tough, water, and gravity (see 6.L.5B.4).
In addition to analyze and interpret data, students should be asked to ask questions; plan and carry out investigations; use mathematics and computational thinking; engage in argument from evidence; construct explanations; develop and use models; obtain, evaluate, and communicate information; and construct devices or define solutions.