Review the vocabulary words listed. Distinguish between the vocabulary words in each pair. Climax community, limiting factor, primary succession, secondary succession, succession, tolerance, aphotic zone, biome, desert, estuary, grassland, intertidal zone, photic zone, plankton, taiga, temperate/deciduous forest, tropical rain forest, tundra. photic zone—aphotic zone

a. Photic zone: Upper layer of water where sunlight penetrates, supporting photosynthesis.
b. Aphotic zone: Deeper layer where sunlight cannot penetrate, resulting in lower levels of photosynthesis and primarily inhabited by deep-sea organisms.