When seeds germinate, roots grow downward and stems grow upward in response to gravity. This response to gravity is called .

conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. the objects must be in physical contact.

the ratio of the conjugate base to the acid required to attain the desired ph.