Ascientist is comparing the outer structure of an onion cell, structure x, to the outer structure of a human skin cell, structure y. which generalization is true about the types of structures being examined?
a) structure x is not living, and structure y is living.
b) structure x can be found in some human cells, and structure y can be found in some plant cells.
c) structure x is only found in plant cells, and structure y is found in plant and animal cells.
d) structure x is semipermeable, and structure y is selectively permeable.

The correct option is C.

The outer structure of an onion is made up of cellulose cell wall. Cellulose is a material that is found only in plant cells, it is not present in the animal cells. The plant cell wall is made up of cellulose; cellulose is a polysaccharide, which gives the cell wall its form and rigidity. Structure Y on the other hand, which is cell membrane is found in both plants and animals cells.

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.