Which structure is not unique to plant cells ?

There are several common structures that are found between animal and plant cells, but plant cells have features that are not present in animal cell

Cell wall : It is a protective layer outside the cell membrane and it also provides support for the cell's structure

Chloroplast : act as the main center for photosynthesis

Plastids : they are organelles that store or manufacture food

Central vacuole : it is the largest organelle in the cell and it's main function is to hold materials and waste of the cell

the correct answer is b

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!