Gravitropism
This video presents the same text shown beside it, spoken and on screen. It adds nothing the text does not say.
State
Gravitropism orients growth to gravity: shoots show negative gravitropism, growing upward, while roots show positive gravitropism, growing downward, both mediated by settling starch-filled amyloplasts.
Show
A plant laid on its side redirects shoot growth upward within hours as amyloplasts settle to the new lower cell wall.
Watch for
"Positive" and "negative" describe direction relative to gravity's pull, not a value judgment about usefulness.