https://www.khanacademy.org/science/biology/ecology/biogeochemical-cycles/a/introduction-to-biogeochemical-cycles 2025-06-30T13:17:39.587845569Z Intro to biogeochemical cycles Get an overview of how atoms are recycled through Earth's ecosystems via biogeochemical cycles. article https://www.khanacademy.org/science/bmc-grade-9-science/x345505a97fc4a662:energy-flow-in-an-ecosystem/x345505a97fc4a662:bio-geo-chemical-cycle/a/hs-biogeochemical-cycles-review 2021-04-29T08:02:39Z Biogeochemical cycles review article https://www.khanacademy.org/science/biology/ecology/biogeochemical-cycles/v/biogeochemical-cycles 2024-05-06T19:22:43.24334365Z Biogeochemical cycles overview Biogeochemical cycles are nature's way of recycling essential elements for life, like water, carbon, nitrogen, and phosphorus. These cycles circulate these molecules through ecosystems and the entire biosphere. From the water cycle to the carbon cycle, these processes ensure the constant reuse of matter, while energy flows through the ecosystem. Sal Khan video https://cdn.kastatic.org/googleusercontent/RkZfK_GfyQENMLzn91OXdJD-6fcWtW4iD5D2jYN8t2sSGSm9SmuUbQpyotrMYkzgCLJGmJfw0BnooTWMjSSGNWw Biogeochemical cycles overview Biogeochemical cycles are nature's way of recycling essential elements for life, like water, carbon, nitrogen, and phosphorus. These cycles circulate these molecules through ecosystems and the entire biosphere. From the water cycle to the carbon cycle, these processes ensure the constant reuse of matter, while energy flows through the ecosystem. https://cdn.kastatic.org/ka-youtube-converted/ccWUDlKC3dE.mp4/ccWUDlKC3dE.mp4 475 Bio-geo-chemical cycle https://www.khanacademy.org/science/how-we-interact-with-our-environment/x049400914d70a1b7:ecosystem/x049400914d70a1b7:nutrient-cycling/e/hs-biogeochemical-cycles 2026-04-08T00:16:02.937952483Z Biogeochemical cycles Test your knowledge of the water cycle, carbon cycle, and nitrogen cycle! Ashley exercise https://www.khanacademy.org/science/bmc-grade-9-science/x345505a97fc4a662:energy-flow-in-an-ecosystem/x345505a97fc4a662:bio-geo-chemical-cycle/v/the-carbon-cycle 2025-07-01T18:08:15.179962416Z The carbon cycle Carbon moves through the environment in a continuous cycle, shifting between reservoirs such as plants, animals, soil, air, water, and rocks. Key processes—photosynthesis, respiration, decomposition, and combustion—drive this movement. While the biological carbon cycle happens quickly, the geological carbon cycle takes millions of years. Human actions can disrupt this cycle, contributing to climate change. Mahesh Shenoy video https://cdn.kastatic.org/ka_thumbnails_cache/45df2542-dadf-4897-977d-715d87892a21_1280_720_base.png The carbon cycle Carbon moves through the environment in a continuous cycle, shifting between reservoirs such as plants, animals, soil, air, water, and rocks. Key processes—photosynthesis, respiration, decomposition, and combustion—drive this movement. While the biological carbon cycle happens quickly, the geological carbon cycle takes millions of years. Human actions can disrupt this cycle, contributing to climate change. https://cdn.kastatic.org/ka-youtube-converted/XynPVsE1fd4.mp4/XynPVsE1fd4.mp4 284 Bio-geo-chemical cycle https://www.khanacademy.org/science/bmc-grade-9-science/x345505a97fc4a662:energy-flow-in-an-ecosystem/x345505a97fc4a662:bio-geo-chemical-cycle/e/understand-the-carbon-cycle 2025-07-13T07:33:51.252224157Z Understand: the carbon cycle Check your understanding of the carbon cycle in this set of free practice questions aligned to NGSS standards. exercise https://www.khanacademy.org/science/hs-bio/x230b3ff252126bb6:energy-and-matter-in-biological-systems/x230b3ff252126bb6:biogeochemical-cycles/e/apply-the-carbon-cycle 2025-06-13T16:17:46.628796572Z Apply: the carbon cycle Apply your understanding about the carbon cycle in this set of free, standards-aligned practice questions. Wieteke Holthuijzen exercise https://www.khanacademy.org/science/bmc-grade-9-science/x345505a97fc4a662:energy-flow-in-an-ecosystem/x345505a97fc4a662:bio-geo-chemical-cycle/v/the-nitrogen-cycle 2025-07-13T07:33:51.252224157Z The nitrogen cycle Let's learn about nitrogen cycle Skyloom (Dubbing) video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw The nitrogen cycle Let's learn about nitrogen cycle https://cdn.kastatic.org/ka-youtube-converted/iX9yoVkps4s.mp4/iX9yoVkps4s.mp4 320 Bio-geo-chemical cycle https://www.khanacademy.org/science/hs-bio/x230b3ff252126bb6:energy-and-matter-in-biological-systems/x230b3ff252126bb6:biogeochemical-cycles/e/apply-the-nitrogen-cycle 2024-05-28T21:41:02.467178644Z Apply: the nitrogen cycle Apply your understanding about the nitrogen cycle in this set of free, standards-aligned practice questions. Wieteke Holthuijzen exercise https://www.khanacademy.org/science/ap-college-environmental-science/x0b0e430a38ebd23f:the-living-world-ecosystems-and-biodiversity/x0b0e430a38ebd23f:biogeochemical-cycles/a/ap-es-the-nitrogen-cycle 2022-09-07T01:03:50.067296221Z The nitrogen cycle Review your understanding of the nitrogen cycle in this free article aligned to AP standards. article https://www.khanacademy.org/science/revision-term-2-tg-biology-class-8/x04828215b460a495:week-2/x04828215b460a495:the-world-of-microorganisms-part-i-ii/e/nitrogen-fixing-and-nitrogen-cycle 2026-04-09T13:10:38.304888012Z Nitrogen fixing and nitrogen cycle Let answer some questions! Shankar R exercise