Which direction does Xylem flow? Phloem?

The movement of Xylem is unidirectional and phloem is bidirectional

Explanation:

The tension created by transpiration “pulls” water in the plant xylem, drawing the water upward in much the same way that you draw water upward when you suck on a straw.

Phloem transport is bidirectional because sucrose gets accumulated in the phloem tissue and absorbs water creating a high turgor pressure. ... Hence the water flows from regions of high turgor pressure to low turgor pressure and the direction can be upwards or downwards from the leaves based on the gradient.

not necessarily. higher fitness requires the organism to be reproductive successful. for example, an organism at age 10 with 15 offspring is much more fit than an organism at age 15 with only 5 offspring.