Question

all living things are made of at least one cell. most single - celled organisms are microscopic in size. larger organisms are composed of many cells - adult humans contain trillions of them!
what limits the size of single - celled organisms? why are large organisms made of many tiny cells instead of one giant cell?
a cell cannot continue growing forever because the needs of a growing cell tend to increase faster than the ability of the cell to meet those needs. for example, as a cell grows, it needs more and more proteins to build structures and to carry out processes. but proteins are made using the genetic information in a cells dna, and no matter how large a cell grows, the amount of dna in its nucleus stays the same. if the cell becomes too large, it wont be able to keep up with its own protein needs. so before a growing cell becomes too large, it splits into two cells in a process called cell division.
select the true statements.
large complex organisms, like humans, are made of trillions of cells.
cell addition is the process by which cells split in two.
if a cell grows too large, it will not be able to make enough proteins for itself.
as a cell grows larger, the amount of dna in its nucleus increases at the same rate.

Explanation:

• The text clearly states "adult humans contain trillions of them (cells)" which supports the first statement.
• The text mentions "it splits into two cells in a process called cell division", not "cell addition", so the second statement is false.
• The text says "If the cell becomes too large, it won't be able to keep up with its own protein needs", which validates the third statement.
• The text states "no matter how large a cell grows, the amount of DNA in its nucleus stays the same", so the fourth statement is false.

Answer:

Large complex organisms, like humans, are made of trillions of cells.
If a cell grows too large, it will not be able to make enough proteins for itself.