Question

The translocation of organic solutes in sieve tube members is supported by-

• A. Cytoplasmic streaming
• B. Root pressure and transpiration pull
• C. P-proteins
• D. Mass flow involving a carrier and ATP

Answer 1

Answer: (D)

Mass flow involving a carrier and ATP

Answer 2

P-proteins (Phloem proteins) are components found in large amounts in phloem sieve tubes. The main function of these bodies is to seal off the sieve tube element or sieve cell by bringing about the blockage of sieve plate. These bodies perform this function when ; the sieve element is injured. These bodies and cal lose together block the pores of sieve tube elements. P-Protein bodies and callose form blocking plugs. These bodies remain along the walls of sieve tube elements. P-Protein bodies are assigned some in the translocation of food material in the sieve tubes but is not universally accepted.