Biological membranes are selectively permeable, allowing certain molecules to cross the membrane, but not others. Classify the molecules or ions depending on how they cross a biological membrane. a. Simple Diffusion
b. Facilitated Diffusion

1. steroid hormones
2. K+
3. retinol etinol
4. N2
5. glucose

Identify one disadvantage to each of the following models of electron configuration: -dot structures -arrow and line diagrams -written electron configurations type in your answer below. (answer) -dot structures do not show the distribution of electrons in orbitals and take up a lot of space. -arrow and line diagrams take up a lot of space and make it difficult to count electrons. -written configurations make it easy to lose count of electrons and do not show the distribution of electrons in orbitals.