Question

Each cell is enclosed by its plasma membrane, which
provides a selective barrier to substances entering or
leaving. This property, called selective permeability, allows
the cell (plasma) membrane (see p. 32) to control the entry
or exit of many substances, thereby regulating the com-
position of its internal environment; several mechanisms
are involved. Particle size is important as many small
molecules, e.g. water, can pass freely across the mem-
brane while large ones cannot and may therefore be con-
fined to either the interstitial fluid or the intracellular
fluid (Fig. 1.3A). Pores or specific channels in the plasma
membrane admit certain substances but not others
(Fig. 1.3B). The membrane is also studded with special-
ised pumps or carriers that import or export specific sub-
stances (Fig. 1.3C). Selective permeability ensures that the
chemical composition of the fluid inside cells is different
from the interstitial fluid that bathes them.​

Answer 1

Answer:

Yes, what you've said is all scientifically true and correct. Plasma membrane only allows selectively permeable substances inside the cell.