A seed begins the germination process when it gets the , temperature, and oxygen that it needs. As the seed
absorbs water, the tiny seedling inside of the seed begins to grow and expand,
against the seed coat. The seedling
must exert enough
to break through the seed coat and
through the soil. There must also be enough
for the shoot to move against the force of
is the force that attracts all objects with
to each other.
occurs when a plant turns toward or away from the pull of gravity. Because of
geotropism, plant
grow toward the pull of gravity as they push deeper into the soil. The plant
grow
away from the pull of gravity as they break through the soil and the stem grows into the air. Through the forces resulting from
pressure and geotropism, plants are able to do a lot of
Plant roots can break apart rock and
concrete as they grow
the pull of gravity. A seed can break apart rock-hard soil as it expands due to
turgor pressure and the
of the seedling emerging from the seed coat.