Plant Tropisms

Plant Responses

Today we will learn how plants respond to external stimuli and how hormones have an effect on their growth.

Multiple Choice

The image shows a picture of a garden with flowers that exhibit incomplete dominance. The first year the garden has the same species of red and white flowers. The second year has the garden has red, white, and pink flowers of the same species. What most likely caused the pink flowers to be produced?

• cross-pollinization by white and red flowers

• self-pollinization by red flowers

• cross-pollination by the white flowers

• self-pollinization by e white and red flowers

Fill in the Blanks

Multiple Choice

Considering the process of osmosis, what conditions must the external environment, in the soil, be for water to move into the plant passively?

• high solute

• low solute

• equal solute

• nucleus

Multiple Choice

Some desert plants respond to darkness by opening their flowers at night to lure in pollinators. In this situation, a plant's response system is working in conjunction with the 

• immune system

• reproductive system

• vascular system

• root system

Open Ended

What is a stimulus?

1 minute and 30 seconds.

Don't forget to submit your answer!

How does a plants ability to respond to a stimulus play a role in its evolution through Natural Selection?

Natural Selection

Like Animals, plants have developed a system that will help them regulate cellular responses to external stimuli.

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​Plant Stimuli

Animals have a nervous and endocrine system that help them regulate the internal environment through elecrtic impulses and chemical signals called hormones.

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Control and Regulation

While plants do not have a nervous or specific endocrine system, they do produce and secrete hormones that are used to ensure the growth of the plant organism.

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Plant Hormones

Phototropism

• Stimulus: Light Energy

• Positive Tropism: Shoots grow towards light.

• Negative Tropism: Roots grow away from light.

Gravitropism or
(Geotropism)

• Stimulus: Gravity

• Positive Tropism: Roots grow towards gravity

• Negative Tropism: Shoots grow away from gravity.

Thigmotropism

• Stimulus: Touch

• Positive Tropism: Growth toward touch

• Negative Tropism: Growth away from touch.

Match

Match the following

Phototropism

Gravitropism

Thigmotropism

• Phototropism

• Gravitropism

• Thigmotropism

Hydrotropism

• Stimulus: Water

• Positive Tropism: Root growth toward water

• Negative Tropism: Stem growth away from water.

Match

Match the following tropisms

• stimulus to touch

• stimulus to gravity

• stimulus to water

• stimulus to light

Thigmatropism

Geotropism

Hydrotropism

Phototropism

• Thigmatropism

• Geotropism

• Hydrotropism

• Phototropism

Multiple Choice

Plants adjust their growth patterns to respond to water availability in their environment.

 

Which of the following BEST demonstrates hydrotropism?

• A cactus spreads its spines outward to reduce water loss

• Sunflower stems turn to follow the movement of the Sun across the sky.

• A seedling's roots grow towards a wet patch of soil in a garden.

• Tree leaves curl during a dry season to conserve moisture.