What structure in a animal cell acts as barrier between the cell and the external environment?
Select one:
O a. Cell membrane
O b. Nucleus
O c. Cell wall
O d. Cytoplasm

O a. Cell membrane

Explanation:

Cell membrane is the boundary of the cell in animals while cell wall is the boundary of cell in plants. Cell wall is absent in animal cell so cell membrane protects the inner portion of the cell from the external environment. Cell membrane is a semipermeable membrane through which substances are diffused in or out i. e. Oxygen, glucose, nutrients and carbondioxide etc.

protist eukaryotes that are not plants, animals, or fungi ("misfits")

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.