These proteins allow substances to enter that wouldn't be able to otherwise. Only small hydrophobic substances can enter cells. However, these proteins aid crucial substsances in entering the cell.<span />
Answer:
Which of the following properties describes a direct current system but not an alternating current system?
The current always flows it the same direction.
Explanation:
When current flows in the same direction, it is described to have flow in a direct manner rather than an alternate system
Answer:The real answer is D
Explanation:
<span>The mammalian sperm cell consists of a head, a midpiece and a tail. The head contains the nucleus with densely coiled chromatin fibres, surrounded anteriorly by an acrosome, which contains enzymes used for penetrating the female egg.</span>