A pulse of sugars labelled with a fluorescent dye is supplied to leaves of young plants. After a brief interval, tissue sections are obtained from the plant and examined under the fluorescence microscope. Tissues are scored for the presence of fluorescence and ranked from very high to low fluorescence. Which cells would contain the most fluorescence

A pulse of sugars labelled with a fluorescent dye is supplied to leaves of young plants. After a brief interval, tissue sections are obtained from the plant and examined under the fluorescence microscope. Tissues are scored for the presence of fluorescence and ranked from very high to low fluorescence. Which cells would contain the most fluorescence

a. xylem

b. companion cells

c. sieve elements

d. epidermis

b. companion cells

Explanation:

The xylem and phloem are the vascular tissues in plants. Their function is to transport water and sugars respectively to all the parts of the plant body. Xylem is only involved in water transport. Companion cells and sieve elements are the two components of the phloem. The companion cells are the storage house of sugars they have a role in movement of the sugars in and out of the sieve elements. They take up sugars via active transport by using their transmembrane proteins. The companion cells will show major fluorescence as these are the reservoir of sugars.

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