Movement of phloem sap from a source to a sink
-occurs through the apoplast of sieve-tube elements.
-depends on tension, or negative pressure potential.
-results mainly from diffusion.
-depends on pumping water into sieve tubes at the source.
-depends ultimately on the activity of proton pumps-

Silver nanoparticles exhibit significantly physical, chemical and biological properties for applications in biological engineering.https://www.cd-bioparticles.com/t/Properties-and-Applications-of-Silver-Nanoparticles_60.html

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.

the three components of a nucleotide are the nitrogenous base, the phosphate group and the five-carbon sugar.