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.

americans began to notice growing differences between the northern and southern sections of the country. there were more people living in cities in the north, which made it more urban. more people lived on farms in the south, which made it more rural. while many people were farmers in the northern states, there were now other ways to make a living, such as working in mechanical cotton gins factories manufacturing cloth, tools and other goods. people in the north supported high tariffs on goods imported from europe because the extra cost encouraged people to “buy american” instead. in the southern states, planters did not like tariffs because they sold most of their production to europe and bought their tools from there as well. southerners believed the protective tariff was something that only northern factory owners keep their profits high. so the southern politicians came up with an idea. they would opt out. they would simply ignore the protective tariff. it was ‘null and void’ in south carolina. the state would not collect the taxes on goods imported into south carolina, no matter what the president said they had to do. this decision led to the nullification crisis.