What differentiates evolutionary from incremental life cycle models?

Which kind of sun tan lasts longer?

Chemical sunscreens (e.g. avobenzone) are rich in C=C and C=O groups. Why are these groups particular useful in absorbing UV rays?

Based on genetic analysis of the MC1R gene, biologists estimate that body hair loss and brown skin appeared in the human line around:  

Which type of melanin has two forms: black (DHI) and brown (DHICA)?  

Achromotrichia refers to the __________ of hair.

Keratinocytes have a photoreceptor protein that detects UV light and is responsible for forming and positioning:  

What element in pheomelanin (derived from cysteine) is the primary reason why it appears lighter in color than eumelanin?  

Two common chemical sunscreens, oxybenzone and octinoxate, have been banned in Hawaii, Palau, nature reserves in Mexico, Bonaire, Aruba, The US Virgin Islands, the Marshall Islands, and Thailand’s marine natural parks. Experiments have shown these sunscreens are toxic to:

The same cell types that make eyelashes curve are the same as those that make hair curly.