https://www.khanacademy.org/science/biology/ecology/biogeochemical-cycles/v/carbon-cycle 2024-05-06T19:22:43.24334365Z The carbon cycle Carbon is crucial for life, forming molecules like glucose, ATP, amino acids, and DNA. The carbon cycle involves plants taking in carbon dioxide, fixing carbon, and creating organic molecules. Animals eat plants, metabolize the molecules, and release carbon dioxide. This cycle keeps carbon circulating in the biosphere. Sal Khan video https://cdn.kastatic.org/googleusercontent/PANHGUsQ7xlmTUmBIQ5gOGmQph_QMC3IukyvEWtMqz7ynXac-nf0w-2gbg0-Lsah0_bhu8pJPMKf_GMxQJUfwO3B The carbon cycle Carbon is crucial for life, forming molecules like glucose, ATP, amino acids, and DNA. The carbon cycle involves plants taking in carbon dioxide, fixing carbon, and creating organic molecules. Animals eat plants, metabolize the molecules, and release carbon dioxide. This cycle keeps carbon circulating in the biosphere. https://cdn.kastatic.org/ka-youtube-converted/_dYkByQ9Kmg.mp4/_dYkByQ9Kmg.mp4 517 Nutrient cycles 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/hs-bio/x230b3ff252126bb6:energy-and-matter-in-biological-systems/x230b3ff252126bb6:biogeochemical-cycles/a/nitrogen-cycle 2024-05-09T17:42:08.599818576Z The nitrogen cycle Learn about the nitrogen cycle and how nitrogen moves from the atmosphere to living organisms through different chemical forms. article https://www.khanacademy.org/science/biology/ecology/biogeochemical-cycles/v/nitrogen-cycle 2024-05-06T19:22:43.24334365Z The nitrogen cycle The nitrogen cycle is a crucial process that converts atmospheric nitrogen into a form that plants and other organisms can use. This process, known as nitrogen fixation, is primarily carried out by bacteria. Nitrogen is essential for life, forming a key component in amino acids, ATP, and DNA. The cycle also includes the return of nitrogen to the atmosphere through decomposition. Sal Khan video https://cdn.kastatic.org/googleusercontent/gQTO9JBwADmey2m_RcYCR_nTXRtFSeKzD8OmiRJn46LlNov4Q7sqsF2imvMCMS8i7OccArqSUWSxktBugc1seihb0g The nitrogen cycle The nitrogen cycle is a crucial process that converts atmospheric nitrogen into a form that plants and other organisms can use. This process, known as nitrogen fixation, is primarily carried out by bacteria. Nitrogen is essential for life, forming a key component in amino acids, ATP, and DNA. The cycle also includes the return of nitrogen to the atmosphere through decomposition. https://cdn.kastatic.org/ka-youtube-converted/DsCMYyQ0NWU.mp4/DsCMYyQ0NWU.mp4 345 Nutrient cycles https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:relationships-of-organisms-with-one-another-and-with-the-environment/x2a084a90105205d2:nutrient-cycles/e/understand-the-carbon-cycle-tx 2025-07-01T18:08:15.179962416Z Understand: the carbon cycle Check your understanding of the carbon cycle in this set of free, standards-aligned practice questions. Wieteke Holthuijzen exercise https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:relationships-of-organisms-with-one-another-and-with-the-environment/x2a084a90105205d2:nutrient-cycles/e/apply-the-carbon-cycle-teks 2026-04-15T18:00:48.584286558Z Apply: the carbon cycle Apply your understanding of the carbon cycle in this set of free, standards-aligned practice questions. Wieteke Holthuijzen exercise 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/the-carbon-cycle-article 2022-09-07T01:03:50.067296221Z The carbon cycle Review your understanding of the carbon cycle with this free article aligned to NGSS and AP standards. article