Force, Motion and Energy

Forces that affect motion…

This plant is more rigid!

Turgor Pressure:

Plants cells have larger vacuoles because they have to store all of the food they make.

This plant is more wilted!

If a plant cell is immersed in a solution that has a higher salt concentration than that of the cell, water will leave the cell. The loss of water from the cell will cause the cell to lose the pressure exerted by the water in the plant cell’s vacuole, which is called turgor pressure.

If the cell membrane becomes damaged, it will lose the ability to control what goes in and out of the cell.

Turgor Pressure in your skin:

Types of tropisms:

– Phototropism: response to light –

This is why people turn their house plants so they won’t lean.

Thermotropism: response to temperature –

The plants leaves curl in response to the temperature.

Hydrotropism: response to water

The roots grow toward the water

–

Geotropism: response to gravity The roots grow downward due to the

force of gravity.

Geotropism

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The growth of a living organism in response to gravity, as the downward growth of plant roots.

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Roots display positive geotropism when they grow downwards, while shoots display negative geotropism when they grow upwards.

Geotropism

A corn kernel was planted face down and this was the result. You can see how it started to grow downwards and then responded to the external stimulus of the sun and grew upwards.

The root system started to grow upwards toward the sun and then responded to gravity (geotropism) and began to grow downwards.

For a plant to be planted in an upside down planter like this the roots must be started first. Why must the roots must be started first in a regular planter?

Well because… If you just planted the plant upside down first the roots would grow downward as well which would kill the plant. Geotropism is what would cause the plants roots to grow downward.

You must start the plant first so the roots will grow correctly and then just the plant itself will grow downwards.

Emergence of Seedlings:

Seeds respond to stimuli (internal and external). Geotropism is where a seed and its roots respond to the force of gravity. This forces the roots to grow downward. Is this an internal or external stimulus?

It takes force and pressure for the plant to push out Gravity is an of the ground.

external stimulus!

Another external stimuli to the plant is the sun. The plant responds to the sun by growing upwards.

Forces that affect motion…

• • A force is a push or a pull.

Work is done when a force moves an object. •

A seedling: pushing up the dirt :: a person: rolling a boulder up a hill It takes MORE force to move something straight up LESS force is used to move something up a ramp or inclined plane

Forces that affect motion…

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Seeds sprout because the force of water pressure (also called turgor pressure) inflates the emerging shoot. The force of the shoot straightening pulls the seed leaves above ground.

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Forces that affect motion…

Turgor Pressure, and Tropisms are all forces that affect the motion of plants and its cells.

PHOTOSYNTHESIS in plants GEOTROPISM in roots THERMOTROPISM in plants leaves when it is cold HYDROTROPISM in roots TURGOR Pressure in celery and potato