Force & Response Notes TEKS 7.7C demonstrate and illustrate forces that affect motion in everyday life, such as emergence of seedlings, turgor pressure, and geotropism TEKS 7.13A investigate how organisms respond to external stimuli found in the environment such as phototropism and flight or fight

A force is a push or pull on an object in a specific direction.

Forces can be used by living organisms to perform basic functions.

Forces are used in many ways by humans.

For example, interactions between the muscular & skeletal systems allow the body to apply forces needed for movement.

Humans use the force of their heart muscles contracting to keep blood flowing through their bodies.

The roots of plants use force to push through the soil.

Plants use force in other ways by changing their growth in response to their environment.

These changes are called tropisms.

Geotropism occurs when a plant grows or bends in response to gravity.

A plant’s stem will grow up and its roots will grow down.

The way a plant grows or bends in response to light is called phototropism.

The plant will grow toward light, even if it must grow sideways.

When a plant takes in water, the vacuole exerts pressure the plant’s cell wall.

This pressure is called turgor pressure.

Turgor pressure allows a plant to become rigid causing the plants to stand upright.