Page 11 - 7-Sci-2 Transport in Humans and Plants

2. Transport in Humans and Plants eLearn.Punjab

Animation 2.4: Transpiration
Source and Credit: elearn.punjab

2.4: Translocation

Plants prepare food in their leaves. The prepared food is
carried by phloem to all parts of a plant. The movement of
prepared food from leaves to those parts of plant body where
it is needed is called translocation (Fig.2.9). How is solid food
transported from one part of the plant to the other?

Pressure Flow Hypothesis Fig: 2.9 Food moves through phloem in solu-
tion form.
We can explain the movement of solid food through the
phloem by “pressure flow hypothesis”. According to this
hypothesis water from nearby xylem enters the phloem
and mixes with the food forming a solution. This solution
flows under pressure through the phloem. The pressure is
created by the difference in amounts of water in phloem
and nearby xylem.

11