Answer:
Active uptake (which I think you mean active transport) is important when the concentration gradient is against that of a certain substance, so it doesn't cross the membrane through diffusion or passive transport. It is sometimes necessary if a substance needs to move across a membrane but can't do so due to electrical charge or that there is a substance on the other side of the membrane preventing diffusion.
Explanation:
Answer:
<u>d. the cells in primary cell cultures do not divide.</u>
A key difference between primary cell cultures and secondary cell lines is that<u> the cells in primary cell cultures do not divide.</u>
<u>hope</u><u> </u><u>it</u><u> </u><u>helped</u><u> </u><u>you</u><u> </u>
Explanation:
<em>The main difference between primary and secondary cell culture is that the primary cell culture contains the cells directly obtained from host tissue, whereas the secondary cell culture contains sub-cultured cells from primary cell culture.</em>