https://www.khanacademy.org/science/biology/ecology/intro-to-ecology/v/ecology-introduction 2024-01-22T05:31:37.90910307Z Ecology introduction Ecology studies how life interacts with other life and their environment, focusing on both living (biotic) and non-living (abiotic) factors. It explores different scales, from individual organisms to populations, communities, ecosystems, and the biosphere. Each level offers unique insights into the complex, often balanced systems that form our world. Ecology also considers potential biospheres beyond Earth. Sal Khan video https://cdn.kastatic.org/googleusercontent/O4k8YUHqHveXQCpe_S5aKD6CJVBtEqIC7-5wGkOGArzdfopMoLqzjoPvhAHZNQ-JWdJj32BbUmqA8rJFjfcv_AxLEw Ecology introduction Ecology studies how life interacts with other life and their environment, focusing on both living (biotic) and non-living (abiotic) factors. It explores different scales, from individual organisms to populations, communities, ecosystems, and the biosphere. Each level offers unique insights into the complex, often balanced systems that form our world. Ecology also considers potential biospheres beyond Earth. https://cdn.kastatic.org/ka-youtube-converted/OfV3VNgjpvw.mp4/OfV3VNgjpvw.mp4 589 Ecosystems and biodiversity https://www.khanacademy.org/science/ms-biology/x0c5bb03129646fd6:interactions-in-ecosystems/x0c5bb03129646fd6:populations-communities-and-ecosystems/v/ms-populations-communities-and-ecosystems 2022-10-21T22:40:33.613234713Z Populations, communities, and ecosystems Organisms, and populations of organisms, are dependent on their environmental interactions both with other living things and with nonliving factors. Sal Khan video https://cdn.kastatic.org/ka_thumbnails_cache/5672b967-c8cc-46f0-ba8b-431eb788378e_1280_720_base.png Populations, communities, and ecosystems Organisms, and populations of organisms, are dependent on their environmental interactions both with other living things and with nonliving factors. https://cdn.kastatic.org/ka-youtube-converted/xzINev2Bd8s.mp4/xzINev2Bd8s.mp4 226 Ecosystems and biodiversity https://www.khanacademy.org/science/hs-bio/x230b3ff252126bb6:biodiversity-and-human-impacts/x230b3ff252126bb6:biodiversity/v/biodiversity 2024-05-08T17:59:40.799210289Z Biodiversity Biodiversity encompasses genetic, species, and ecosystem diversity. Biodiversity is dynamic and changes over time, influenced by speciation and extinction events. However, human actions—such as climate change and overexploitation—are increasing extinction rates. As extinction rates increase, ecosystems experience a loss in biodiversity. Khan Academy video https://cdn.kastatic.org/ka_thumbnails_cache/238e0cd1-b6f5-4aa3-aa56-5cab1b704c2e_1280_720_base.png Biodiversity Biodiversity encompasses genetic, species, and ecosystem diversity. Biodiversity is dynamic and changes over time, influenced by speciation and extinction events. However, human actions—such as climate change and overexploitation—are increasing extinction rates. As extinction rates increase, ecosystems experience a loss in biodiversity. https://cdn.kastatic.org/ka-youtube-converted/TZ-S9sc6HYM.mp4/TZ-S9sc6HYM.mp4 471 Ecosystems and biodiversity https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:relationships-of-organisms-with-one-another-and-with-the-environment/x2a084a90105205d2:ecosystems-and-biodiversity/v/predator-prey-population-cycles-in 2025-06-10T19:22:53.658409675Z Predator-prey population cycles Let's understand predator prey population cycles! Skyloom (Dubbing) video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw Predator-prey population cycles Let's understand predator prey population cycles! https://cdn.kastatic.org/ka-youtube-converted/PxsnFQ_zzAQ.mp4/PxsnFQ_zzAQ.mp4 347 Ecosystems and biodiversity https://www.khanacademy.org/science/ap-biology/ecology-ap/population-ecology-ap/v/density-dependent-and-density-independent-population-regulation 2024-05-06T19:22:43.24334365Z Population regulation There are two types of population regulation: density-dependent and density-independent. Density-dependent factors, like competition for resources, predation, disease, and waste accumulation, limit population growth based on population density. Density-independent factors, such as natural disasters, affect populations regardless of density. Understanding these factors helps us consider human population growth and potential carrying capacity. Sal Khan video https://cdn.kastatic.org/googleusercontent/aowVW739U5AOhvKG8kQdvlwy8fNmRKnQqcx1yn1OXju_YjMV2JFSLAKXaL840jkOZMn8_rg_1RC7BYhwvGCJQyiY Population regulation There are two types of population regulation: density-dependent and density-independent. Density-dependent factors, like competition for resources, predation, disease, and waste accumulation, limit population growth based on population density. Density-independent factors, such as natural disasters, affect populations regardless of density. Understanding these factors helps us consider human population growth and potential carrying capacity. https://cdn.kastatic.org/ka-youtube-converted/6IS_M6CX7FE.mp4/6IS_M6CX7FE.mp4 633 Ecosystems and biodiversity https://www.khanacademy.org/science/ms-biology/x0c5bb03129646fd6:interactions-in-ecosystems/x0c5bb03129646fd6:resources-and-population-growth/v/ms-resources-and-population-growth 2022-10-21T22:40:33.613234713Z Resources and population growth In any ecosystem, organisms and populations with similar requirements for food, water, oxygen, or other resources may compete with each other for limited resources, access to which consequently constrains their growth and reproduction. Growth of organisms and population increases are limited by access to resources. Sal Khan video https://cdn.kastatic.org/ka_thumbnails_cache/ba4594ec-059f-4dbf-a12c-734bb6177b33_1280_720_base.png Resources and population growth In any ecosystem, organisms and populations with similar requirements for food, water, oxygen, or other resources may compete with each other for limited resources, access to which consequently constrains their growth and reproduction. Growth of organisms and population increases are limited by access to resources. https://cdn.kastatic.org/ka-youtube-converted/i5uF5inpY7s.mp4/i5uF5inpY7s.mp4 218 Ecosystems and biodiversity https://www.khanacademy.org/science/ap-biology/ecology-ap/population-ecology-ap/a/hs-population-ecology-review 2025-03-13T12:19:34.272335663Z Population ecology review article https://www.khanacademy.org/science/hs-bio/x230b3ff252126bb6:ecology-and-natural-systems/x230b3ff252126bb6:population-growth-and-carrying-capacity/a/describing-populations 2024-05-28T21:41:02.467178644Z Describing populations Learn about population density and dispersion and populations grow and change over time. article https://www.khanacademy.org/science/ms-biology/x0c5bb03129646fd6:interactions-in-ecosystems/x0c5bb03129646fd6:resources-and-population-growth/a/resources-and-population-growth 2026-04-15T05:40:45.550331962Z Key points: Resources and population growth Review your understanding of resources and population growth in this free article. article https://www.khanacademy.org/science/biology/ecology/intro-to-ecology/a/what-is-ecology 2021-04-29T08:03:21Z What is ecology? Overview of ecology. Biotic and abiotic factors. The different levels of ecology. article https://www.khanacademy.org/science/ms-biology/x0c5bb03129646fd6:interactions-in-ecosystems/x0c5bb03129646fd6:populations-communities-and-ecosystems/a/populations-communities-and-ecosystems 2026-02-27T17:50:36.702607024Z Populations, communities, and ecosystems Review your understanding of populations, communities, and ecosystems in this free article aligned to NGSS standards. article https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:relationships-of-organisms-with-one-another-and-with-the-environment/x2a084a90105205d2:ecosystems-and-biodiversity/e/intro-to-ecology 2026-04-08T00:54:09.631945657Z Intro to ecology Test your knowledge on the basics of ecology! Ashley exercise https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:relationships-of-organisms-with-one-another-and-with-the-environment/x2a084a90105205d2:ecosystems-and-biodiversity/e/understand-biodiversity 2021-07-30T23:14:05.129780946Z Understand: biodiversity Check your understanding of biodiversity in this set of free practice questions aligned to NGSS standards. exercise https://www.khanacademy.org/science/ap-biology/ecology-ap/biodiversity/e/biodiversity-ap 2023-08-07T17:09:37.131449861Z Biodiversity Test your knowledge of biodiversity! exercise https://www.khanacademy.org/science/ms-biology/x0c5bb03129646fd6:interactions-in-ecosystems/x0c5bb03129646fd6:populations-communities-and-ecosystems/e/apply-populations-communities-and-ecosystems 2026-02-27T17:50:36.702607024Z Apply: populations, communities, and ecosystems Apply your understanding of populations, communities, and ecosystems in this set of free practice questions aligned to NGSS standards. Khan Academy exercise https://www.khanacademy.org/science/ms-biology/x0c5bb03129646fd6:interactions-in-ecosystems/x0c5bb03129646fd6:resources-and-population-growth/e/understand-resources-and-population-growth 2026-04-15T05:40:45.550331962Z Understand: Resources and population growth Check your understanding of resources and population growth in this set of free practice questions. Khan Academy exercise https://www.khanacademy.org/science/ms-biology/x0c5bb03129646fd6:interactions-in-ecosystems/x0c5bb03129646fd6:resources-and-population-growth/e/apply-resources-and-population-growth 2026-04-15T05:40:45.550331962Z Apply: Resources and population growth Apply your understanding of resources and population growth in this set of free practice questions. Khan Academy exercise