Shannon is making a Venn diagram to organize the characteristics of cell walls and cell membranes. Which pair of characteristics
both belong in the two areas of the Venn diagram that do not intersect? (A) helps with communication; contains mostly cellulose
(B) contains mostly cellulose; forms the outer layer of animal cells
(C) is found in plant cells; is found in animal cells
(D) is semipermeable; found in animal cells
The right answer is (B) contains mostly cellulose; forms the outer layer of animal cells.
The so-called pectocellulosic cell wall (consisting of pectin and cellulose) completely surrounds the cells and thereby plays the role of an internal medium of the plant or an inter-cellular medium. It is therefore involved in intercellular exchanges and communications (just like the cell membrane in animals, so A is false).
The cytoplasmic membrane or plasmalemma is located in contact with the cytoplasm, at the boundary between the inside and the outside of the cell.
The fact that only cells are able to produce more cells is part of cell theory. The idea that organisms can develop independently of cells is called spontaneous generation, and it isn't supported by cell theory. Spontaneous generation suggests that living organisms develop from non-living matter.
