Answer:
a. allow a variety of molecules to cross the cytoplasmic membrane
Explanation:
The cells have different molecules in its membrane. As a membrane the main function of it is to regulate the income and outcome of substances that the cell needs or the cell has like some wastes.
Some of these molecules can be some proteins like the permeases, that is going to regulate the solutes that can enter the cell, but since they are non specific, that means that can not make the difference among one carbohydrate and another (as an example).
All food chains begin with producers
I think the correct answer from the choices listed above is the third option. The DNA is used as a molecular clock in the sense that the <span>percent of carbon in DNA is compared between parent and offspring. Hope this answers the question. Have a nice day.</span>