Using the law of superposition
Explanation:
The dog salivating is an example of responding to stimuli
Answer;
-Skin cells do not need crystallin for their function.
-Skin cells have the crystallin gene but do not express it.
Explanation;
-The crystallin proteins are water-soluble structural proteins that occur in high concentration in the cytoplasm of eye lens fibre cells. It has also been identified in other places such as the heart, and in aggressive breast cancer tumors.
-The main function of crystallins at least in the lens of the eye is probably to increase the refractive index while not obstructing light. The skin cell does not make crystallin protein because the skin cells do not need crystallin for their function and also they have the crystallin gene but do not express it.
