The diagrams shown represent an investigation concerning the growth of bean plants. The roots
of three identical bean plants were each placed
through a hole in covered tubes containing water
as shown in the diagrams. Nothing was done to
plant A. Vaseline was used to cover the upper
surface of the leaves of plant B. Vaseline was used
to cover the lower surface of plant C The water
level of each tube was marked and the plants were
placed together near a window. Aller 24 hours,
the water level in each tube was measured,
Vaseline
Volion
Cover
西
water level
at the art
А
с
Which tube represents the control for this
investigation?
i