Grapes growing on a vine are observed to shrink slightly during the day and increase in size at night. This is because: a. developing fruits, such as grapes, transpire a lot of water to stay cool.
b. photosynthesis to produce sugar occurs in the light, but respiration and, therefore, the growth of new cells occurs mostly in the dark.
c. in leaves, phloem flow to growing sinks only occurs when the stomata are closed, because the transport capacity of the xylem is too small to supply water for both transpiration and phloem flow.
d. during the day, transpiration pulls on the water in the whole plant, causing the grapes to shrink slightly.