10 most difficult biology riddles A list of ten (out of 30) biology related questions that are the most often answered incorrectly Biology quiz Which animal doesn't belong to odd-toed ungulates?Rhinoceros. Odd-toed ungulates include the horse, the tapir, and the rhinoceros.very hard 24% hippopotamushippopotamus27%rhinocerosrhinoceros24%camelcamel15%okapiokapi32%Created by: Paweł Kołodziejczyk. Statistics based on 2156 answers in 2 languages »animals riddles » How deep is the root system of a giant sequoia?4 meters (13 feet). The sequoias root system is wide spreading, but shallow. There is no taproot. A mature sequoia's roots can occupy over 1 acre of earth and contain over 90,000 cubic feet of soil. very hard 32% 4 meters (13 feet)4 meters (13 feet)32%20 meters (60 feet)20 meters (60 feet)15%40 meters (130 feet)40 meters (130 feet)23%80 meters (260 feet)80 meters (260 feet)28%Created by: globalquiz.org. Statistics based on 5602 answers in 4 languages »trees riddles » What was included in the original Pepsi-Cola recipe?Digestive enzyme. Pepsi Cola, first introduced in 1898, was named after pepsin (enzyme) and kola (nuts). In 1931, the company entered bankruptcy and changed hands. The new owners changed the recipe to resemble more Coca-Cola.very hard 35% coke from coalcoke from coal6%saltpetersaltpeter16%digestive enzymedigestive enzyme35%heroinheroin40%Created by: Kasia. Statistics based on 11448 answers in 4 languages »beverages riddles » Where do coast redwoods grow?In the west of the United States. Common names of sequoia sempervirens include coast redwood, coastal redwood and California redwood. It is an evergreen, long-lived, monoecious tree living 1,200–1,800 years or more. This species includes the tallest living trees on Earth. It comes from coastal mountains of Oregon and California. (the west of the USA).hard 44% In Central America onlyIn Central America only15%In the west of the United StatesIn the west of the United States44%in the eastern Brazilin the eastern Brazil16%in the entire North and Central Americain the entire North and Central America22%Created by: Paweł Kołodziejczyk. Statistics based on 4599 answers in 4 languages »plants riddles » Where do gharials live?In the Ganges River. The gharial (Gavialis gangeticus), also known as the gavial, and the fish-eating crocodile, is a crocodilian of the family Gavialidae, native to the northern part of the Indian Subcontinent. It is harmless to humans.hard 47% In the NileIn the Nile13%In the Ganges RiverIn the Ganges River47%In the AmazonIn the Amazon19%In the entire Central Africa (Congo and its tributaries)In the entire Central Africa (Congo and its tributaries)19%Created by: Paweł Kołodziejczyk. Statistics based on 8428 answers in 2 languages »reptiles riddles » How is the soilless cultivation of plants called?Hydroponics is a subset of hydroculture and is a method of growing plants using mineral nutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite or gravel.hard 49% hydrologyhydrology9%hydroculturehydroculture20%hydroponicshydroponics49%hydrofarminghydrofarming19%Created by: Paweł Kołodziejczyk. Statistics based on 8558 answers in 2 languages »crops riddles » If you were forced to feast along the tribe of cannibals, which part of the human body should you avoid at most?Brain. Eating your own and closely related species is generally a bad idea, as there are species-specific parasites and germs that might get transmitted. But eating brain, bone marrow, and the spinal cord is particularly dangerous, as you may get deadly prion diseases like kuru. hard 52% heartheart4%musclesmuscles6%liverliver35%brainbrain52%Created by: life-o-holic. Statistics based on 16249 answers in 2 languages »cannibalism riddles » What it is an autotomy?Self amputation (e.g. of a tail). Autotomy (from the Greek auto- "self-" and tome "severing") or self amputation is the behaviour whereby an animal sheds or discards one or more of its own appendages, usually as a self-defense mechanism to elude a predator's grasp or to distract the predator and thereby allow escape. The lost body part may be regenerated later.hard 56% eating only one kind of spieces (e.g. the koala is eating leaves of the eucalyptus)eating only one kind of spieces (e.g. the koala is eating leaves of the eucalyptus)10%self amputation (e.g. of a tail)self amputation (e.g. of a tail)56%hunting of its own kindhunting of its own kind23%in-breeding (small gene pool)in-breeding (small gene pool)10%Created by: Paweł Kołodziejczyk. Statistics based on 8977 answers in 4 languages »human anatomy riddles » How is the branch of zoology concerned with aphibians and reptiles called?Herpetology. "Herp" is a vernacular term for reptiles and amphibians. It is derived from Greek 'herpien' meaning 'to creep'.hard 57% ichthyologyichthyology18%herpetologyherpetology57%malacologymalacology9%entomologyentomology15%Created by: Paweł Kołodziejczyk. Statistics based on 9981 answers in 2 languages »names riddles » What are hedgehog's spines made of?Keratin is a fibrous protein, a key structural component of the hair, nails, horns, claws and hooves of mammals. Hedgehog spines are hollow hairs made stiff with keratin.hard 58% bonesbones4%keratinkeratin58%chitinchitin21%cartilagecartilage15%Created by: globalquiz.org. Statistics based on 10186 answers in 4 languages »mammals riddles » Play biology quiz and see all the questions.