Educational worksheet on plant tropisms, featuring definitions, examples, and interactive activities for learning about plant responses to stimuli.

Let’s go step by step to fill out this worksheet about plant tropisms. We’ll answer each part clearly and simply, like we’re talking to a friend who’s learning this for the first time.

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Tropism is _a plant’s growth response to a stimulus (like light, gravity, touch, or water)._
They can be positive or negative.

- Positive Tropism: When the plant grows *toward* the stimulus.
*(Example: roots growing down toward gravity = positive gravitropism)*

- Negative Tropism: When the plant grows *away from* the stimulus.
*(Example: stems growing up away from gravity = negative gravitropism)*

Remember a stimulus is a _change in the environment that causes a reaction._

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Plants sense and respond to change! How??

- Seasonal Responses: Plants living in cold regions detect shorter days and colder temps → they drop leaves or go dormant.
*Example: Maple trees losing leaves in fall.*

- Short-day plants: Grow better when nights are longer than days.
*Example: Poinsettias (they bloom around Christmas when nights are long).*

- Long-day plants: Grow better when nights are shorter than days.
*Example: Spinach or lettuce (they grow well in spring/summer with long daylight).*

- Can humans manipulate plants to grow differently?
*Yes!* We use artificial lights in greenhouses to trick plants into thinking it’s summer (long days) so they flower earlier. Or we cover them to make short days and trigger blooming in poinsettias.

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Now let’s fill in the four boxes with definitions and meanings:

Phototropism

- “Photo” means light
- Definition: Growth of a plant in response to light. Usually, stems grow toward light (positive phototropism).

Gravitropism

- “Gravi” means gravity
- Definition: Growth of a plant in response to gravity. Roots grow down (positive), stems grow up (negative).

Thigmotropism

- “Thigmo” stands for touch
- Definition: Growth in response to touch or physical contact. Like vines wrapping around a trellis.

Hydrotropism

- “Hydro” means water
- Definition: Growth of roots toward water sources. Helps plants find moisture in soil.

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Now the table with movies/examples:

| Movie / Example | Tropism | Stimulus | Plant Response | Illustration (draw or describe) |
|-----------------------------|-------------------|------------------|------------------------------------|----------------------------------------|
| 1. “Sunflower Phototropism” | Phototropism | Light | Sunflower turns head to follow sun | Draw sunflower facing the sun |
| 2. “Sensitive Plant” | Thigmotropism | Touch | Leaves fold when touched | Draw Mimosa pudica closing its leaves |
| 3. “Corn root gravitropism” | Gravitropism | Gravity | Corn roots grow downward | Draw corn roots going straight down |

*(Note: The “Sensitive Plant” actually shows thigmonasty — a rapid movement, not slow growth — but since the worksheet says “Thigmotropism,” we’ll go with that for now. In real science, it’s a nastic movement, not tropism. But for school level, it’s often grouped here.)*

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4. Explain what’s the nastic and put the photo and one type of nastic

- What is the nastic?
Nastic movements are fast, reversible responses to stimuli — NOT growth-based. They happen quickly and don’t depend on direction of stimulus.

- One type of nastic:
*Thigmonasty* – like the sensitive plant (Mimosa pudica) folding its leaves when you touch it.

- Photo:
*(You would draw or paste a picture of Mimosa pudica with closed leaves after being touched.)*

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Final Answer:

Tropism is a plant’s growth response to a stimulus. Positive tropism = toward stimulus; Negative = away. Stimulus = environmental change.

Examples:
- Seasonal: Maple drops leaves in fall.
- Short-day: Poinsettia blooms in winter.
- Long-day: Spinach grows in summer.
- Humans can use lights to control flowering.

Phototropism: “photo” = light → plant grows toward light.
Gravitropism: “gravi” = gravity → roots down, stems up.
Thigmotropism: “thigmo” = touch → vines wrap around things.
Hydrotropism: “hydro” = water → roots grow toward water.

Table filled as above.

Nastic = fast, non-growth movement. Type: Thigmonasty (e.g., sensitive plant). Photo: Mimosa pudica closing leaves.