Which solute is least likely to cross a membrane by simple diffusion?

Ions of sodium, potassium, calcium and chloride.

Explanation:

Simple diffusion allows very small, non-polar, fat-soluble molecules to cross the plasma membrane into or out of the cell through a concentration gradient. In addition, it is necessary that these molecules cannot have electrical charges, which prevents sodium, potassium, calcium and chloride ions from crossing the plasma membrane, even if they are very small.

the father in the first generation probably had the recessive colorblind trait in his x chromosome. if he and his wife both had the colorblind trait, even if she had 1 recessive and 1 dominant, then that trait would be passed on to their kids.

(since you didn't attach the family tree this is just an assumption)

1. dermis

2. chemical

3. urine

4. viruses

5. antibodies