| CIRCADIAN | Relating to the biological cycle of 24 hours (9) |
| PRELUDE | Any one of a cycle of 24 piano pieces by Chopin including his Op. 28, No. 15, or "Raindrop" (7) |
| BIENNIAL | Plant with a two-year biological cycle (8) |
| COGNITION | The symbolic, or top-down, approach in AI research seeks to replicate intelligence by analyzing _________ independent of the biological structure of the brain, in terms of the processing of symbols (9 |
| OVULATION | In females, the biological release of eggs (9) |
| DETRIMENT | In physics, the ratio of the amplitudes in successive cycles of a damped oscillator (9) |
| OFTHEKING | See 53 Cycle of twelve narrative poems by Alfred, Lord Tennyson retelling the legend of King Arthur (6,2,3,4) |
| SOLARYEAR | Total time taken for a full cycle of the seasons |
| LUNARYEAR | Period of 12 full cycles of the moon |
| DESERTIFICATION | The process that reduces the biological productivity of drylands (arid and semiarid lands), which may be the result of climate change, deforestation, overgrazing, poverty, political instability, or un |
| LIGHT | Photoreception is any of the biological responses of animals to stimulation by ___ (5) |
| TRIENNIUM | Period or cycle of three years, commonly used in academic and theological contexts (9) |
| PERENNIAL | Plant with a life cycle of more than two years |
| SPIRITUAL | Unworldly, one union trapped in cycle of decline? |
| SEMESTERS | Rest seems disturbed in cycles of about fifteen weeks (9) |
| PATERNITYTEST | Procedure to determine whether a man is the biological father of a child (9,4) |
| TELOMERE | Sometimes described as the biological equivalent of an aglet that prevents a shoelace from fraying, the protective tip of a chromosome (8) |
| DELAY | Hold up the Spanish in the course of 24 hours |
| YOYODIETS | Goes through cycles of weight fluctuation |
| RANIDAE | The biological family of "true frogs" |
