Name: Human Excretory System
Uploaded: 2019-07-19
Duration: 2 min 16 s
Description: This video briefly introduces the Human Excretory System and the organs associated with the same. It defines the excretion process and highlights kidneys, ureters, urinary bladder, and urethra.

Question

Xylem transports sap upwards only whereas phloem transports food in both directions. Why do you think there is a difference?

Accepted Answer

The loss of water through the aerial part of the plant is known as transpiration. It occurs mainly through the stomata, present on the surface of the leaves. It helps in the upward movement of water and minerals from roots to the leaves by generating a suction pull.

Xylem transports water and minerals from the roots to all the other plant parts. It transports sap upwards only because all other parts of the plant are in the upward direction. Therefore, the movement of water and minerals in the xylem is unidirectional.

Phloem transports food prepared by the leaves in both upward and downward directions, as each part of the plant needs energy food. Since the leaves located above performs photosynthesis and prepare food, it needs to be travelled to all other parts of the plant. Therefore, the movement of food in phloem is bidirectional.

Xylem transports sap upwards only whereas phloem transports food in both directions. Why do you think there is a difference?

Important Questions on Transportation in Animals and Plants

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