Question

(a) What does a stem (or shoot) do in response to gravity? What is this phenomenon known as?
(b) What does a root do in response to light? What is this phenomenon known as?

Answer 1

(a) Stem always grows up and away from the pull of gravity. This phenomenon is known as negative geotropism.
(b) Root always grows downwards and away from light. This phenomenon is known as negative phototropism.