A) gravitropism is how they "know"
The umbra is the innermost and dark part of the shadow where like it’s created by any light source and is completely blocked by the occluding body. It’s a Latin term hope this helps man!
Metamorphic rocks are formed from other rock that has been subjected to very high temperature and pressure.
When one of the earth's plates comes in contact with another either by both traveling opposite directions, straight into each other, or from one slipping under the other (subduction zone), the pressure/friction of the plates against each other melts the rocks and after they cool they are metamorphic. Example is in Washington state when the Juan de fuca plate is going under the North American plate the pressure/friction of this melts the rocks which then form metmorphic rock.
Answer:
a plant hormone which promotes leaf detachment, induces seed and bud dormancy, and inhibits germination.