AbstractThe idea that quantum-mechanical phenomena can play nontrivial roles in biology has fascinated researchers for a century. Here we review some examples of such effects, including light-harvesting in photosynthesis, vision, electron- and proton-tunneling, olfactory sensing, and magnetoreception. We examine how experimental tests have aided this field in recent years and discuss the importance of developing new experimental probes for future work. We examine areas that should be the focus of future studies and touch on questions such as biological relevance of quantum-mechanical processes. To exemplify current research directions, we provide some detailed discussions of quantum-coherence in photosynthetic light-harvesting and highlight the crucial interplay between experiment and theory that has provided leaps in our understanding. We address questions about why coherence matters, what it is, how it can be identified, and how we should think about optimization of light-harvesting and the role coherence plays.