Q. Which of them is/are correct regarding pressure flow model for translocation? I. Sugar is transported through phloem as glucose II. Movement of sugar is carried out through sieve tube near the source region III. Concentration of sugar is always highest near the sink region IV. Water from the adjacent xylem moves into phloem by osmosis
A) II and IV
B) II and III
C) I, II and III
D) Only IV
Explanation
According to pressure flow hypothesis, sieve tube system show better adaptation for mass flow of organic nutrients. Due to the process of photosynthesis, source region is always rich in osmotic concentration. So, they pass organic nutrient into sieve tube by active process which in turn produce high osmotic concentration in sieve tube. Sieve tube absorbs water from adjacent xylem and develop a gradient of turgor pressure. Now, the organic nutrients are transported from an area of higher turgor pressure to the region of lower turgor pressure (sink or utilisation site)
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.