https://www.khanacademy.org/science/biology/biology-of-viruses/virus-biology/v/viruses 2021-03-18T10:33:24Z Viruses Introduction to viruses. Sal Khan video https://cdn.kastatic.org/googleusercontent/Y2goQonuPymd0AbVnv5A_J2p_tFV9xQOSXJSE3jjI24wWdtWF6HSQLnL064BIg4AnlgVzV1kDhSu5XwzA6C22hY Viruses Introduction to viruses. https://cdn.kastatic.org/ka-youtube-converted/0h5Jd7sgQWY.mp4/0h5Jd7sgQWY.mp4 1397 Features of organisms https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:classification/x2a084a90105205d2:features-of-organisms/v/what-are-viruses-pk 2025-12-18T03:40:48.390254156Z What are Viruses? Created by Khan Academy video https://cdn.kastatic.org/googleusercontent/ZCdwTudJg6e6n-P2gsaUborP4izvMsGo71pvEVlX9dNYWcLXcP7VHkWpn2grt4TUP1KoJLQP9NswyHBuBLSFTBw What are Viruses? Created by Khan Academy https://cdn.kastatic.org/ka-youtube-converted/oKCWnuJ6OAo.mp4/oKCWnuJ6OAo.mp4 417 Features of organisms https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:classification/x2a084a90105205d2:features-of-organisms/e/vertebrates 2026-04-08T00:54:09.631945657Z Vertebrates This exercise tests the salient features of vertebrates and the differences between Chondrichthyes, Osteichthyes, Amphibia, Reptilia, Aves, and Mammalia. Moumita Sen exercise https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:classification/x2a084a90105205d2:features-of-organisms/e/vertebrata-i 2026-03-06T17:50:38.494926415Z Vertebrata - I This exercise is about the classes Cyclostomata, Pisces, and Amphibia. Nivedhitha exercise https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:classification/x2a084a90105205d2:features-of-organisms/e/vertebrata-ii 2026-03-06T17:50:38.494926415Z Vertebrata - II This exercise is on the vertebrate classes Reptilia, Aves, and Mammalia. Nivedhitha exercise https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:classification/x2a084a90105205d2:features-of-organisms/e/arthropoda 2025-11-01T07:40:37.451595137Z Arthropoda This exercise tests your understanding of the structural and functional diversity within Arthropoda. It assesses knowledge of exoskeleton composition and molting, open circulation, and different respiratory systems like book gills, book lungs, and tracheae. It also examines how major subphyla differ in body structure and appendages, and how various arthropods adapt to aquatic and terrestrial environments. Khan Academy exercise https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:classification/x2a084a90105205d2:features-of-organisms/e/classification-of-phylum-arthropoda 2025-12-14T15:30:39.162517042Z Classification of Phylum Arthropoda This exercise tests how different arthropod groups are identified and classified using key structural and functional traits. Through short fossil and living-animal scenarios, you will apply sub-phylum and class characteristics—such as body lobes, limb type, respiratory organs, and appendage arrangements—to determine each organism’s correct taxonomic placement. Khan Academy exercise https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:classification/x2a084a90105205d2:features-of-organisms/e/protista 2025-01-27T11:20:52.400099217Z Protista Overview of kingdom Protista, and plant-like protists and fungi-like protists in-depth Moumita Sen exercise https://www.khanacademy.org/science/cambridge-o-level-biology-cie/x2a084a90105205d2:classification/x2a084a90105205d2:features-of-organisms/e/viruses-viroids-and-prions-up 2025-09-03T06:00:49.033224489Z Viruses, viroids, and prions This exercise has questions on viruses, viroids, and prions. Moumita Sen exercise