An average normal range is between 4,500 and 10,000 white blood cells per microliter
The correct answer is 'If molecules are small enough, then they can pass through the semipermeable membrane because they can cross the semipermeable membrane from their small pores or openings'.
The semipermeable membrane is permeable to few molecules, and the smaller molecules pass through the molecules from small pores present in the semipermeable membrane. The size of the big molecules are large, so, they cannot cross through semipermeable membrane.
I don't know exactly what you mean but the size of a group affects its defense because there is a larger group. Therefore, more people would be protecting it, adding more to its defense.
ECM is the extracellular matrix, or the set of extracellular molecules secreted by cells with the purpose to support surrounding cells. In plants the cell wall is the ECM and in mammals ECM can be in the form of fibrils and may constitute a significant portion of the bulk of the organism and it also referred as connective tissue.
