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Split view of tropical rainforest and coral reef: sea turtle, tropical fish, toucan, blue butterfly under a cloudy sky
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NatureHard

Biodiversity and Ecosystems

Which ecosystem produces the most oxygen, which giant fungus holds the record for the largest living being, which tree nears 5,000 years, and how long can a tardigrade survive without water? 20 questions on a living world that often outstrips fiction, from the deep sea to records of longevity.

20

Questions

4

Minutes

Tip: Use keys 1-4 to answer quickly

The 20 quiz questions

Question 1 : What is the largest land mammal?

Possible answers:

  • African elephant
  • Hippopotamus
  • Giraffe
  • White rhinoceros

Explanation: The African elephant is the largest land mammal, reaching up to 4 meters at the shoulder and weighing up to 7 tons.

Question 2 : What process allows plants to transform CO2 into oxygen?

Possible answers:

  • Transpiration
  • Photosynthesis
  • Fermentation
  • Respiration

Explanation: Photosynthesis allows plants to convert carbon dioxide and water into glucose and oxygen, using sunlight and chlorophyll.

Question 3 : Which marine animal has three hearts and blue blood?

Possible answers:

  • Jellyfish
  • Squid
  • Octopus
  • Lobster

Explanation: The octopus has three hearts (two for the gills, one for the body) and its blood is blue because it contains copper (hemocyanin) instead of iron.

Question 4 : What is the largest coral reef in the world?

Possible answers:

  • New Caledonia Reef
  • Great Barrier Reef
  • Maldives Reef
  • Belize Reef

Explanation: The Great Barrier Reef, off Australia, stretches over 2,300 km. It is visible from space and harbors exceptional biodiversity.

Question 5 : How long can a tardigrade survive without water?

Possible answers:

  • 1 week
  • 1 month
  • 1 year
  • 10 years

Explanation: Tardigrades can enter cryptobiosis and survive up to 10 years without water. These micro-animals also resist the vacuum of space and radiation.

Question 6 : Which fungus is the largest known living organism on Earth?

Possible answers:

  • Fly agaric
  • Truffle
  • Bolete
  • Armillaria ostoyae

Explanation: The Armillaria ostoyae (honey fungus) in Oregon spans 965 hectares and is over 2,400 years old. Its underground mycelium makes it the largest known organism.

Question 7 : Which animal produces the strongest known substance (silk)?

Possible answers:

  • Silkworm
  • Mussel
  • Snail
  • Darwin's bark spider

Explanation: Darwin's bark spider silk (Caerostris darwini) is 10 times stronger than Kevlar and more elastic than nylon, making it the strongest known biomaterial.

Question 8 : What natural phenomenon causes bioluminescence in fireflies?

Possible answers:

  • Static electricity
  • Phosphorescence
  • Fluorescence
  • Luciferin-luciferase

Explanation: Bioluminescence in fireflies is caused by a chemical reaction involving luciferin and the enzyme luciferase, producing cold light without heat.

Question 9 : What percentage of marine species remains to be discovered according to scientists?

Possible answers:

  • 10%
  • 20%
  • 50%
  • 80%

Explanation: It is estimated that 80% of ocean species remain to be discovered. The deep sea, representing more than 95% of Earth's habitable space, is largely unexplored.

Question 10 : Which tree can live nearly 5,000 years?

Possible answers:

  • Giant sequoia
  • Bristlecone pine
  • Olive tree
  • Baobab

Explanation: Bristlecone pines (Pinus longaeva) are the oldest trees in the world. One of them, named Methuselah, is over 4,850 years old.

Question 11 : Which ocean contains the deepest point on Earth?

Possible answers:

  • The Arctic Ocean
  • The Indian Ocean
  • The Pacific Ocean
  • The Atlantic Ocean

Explanation: The Pacific Ocean contains the Mariana Trench, whose Challenger Deep reaches 10,994 meters in depth.

Question 12 : Which meteorological phenomenon is measured on the Fujita scale?

Possible answers:

  • Hurricanes
  • Tornadoes
  • Tsunamis
  • Earthquakes

Explanation: The Fujita scale (F0 to F5) measures tornado intensity based on damage caused. It has been replaced by the Enhanced Fujita scale (EF).

Question 13 : Which gas makes up about 78% of Earth's atmosphere?

Possible answers:

  • Carbon dioxide
  • Oxygen
  • Nitrogen
  • Argon

Explanation: Nitrogen (N₂) makes up 78% of the atmosphere, followed by oxygen (21%), argon (0.9%), and CO₂ (0.04%). It is an inert gas essential to the nitrogen cycle in nature.

Question 14 : Which animal can fully regenerate its heart?

Possible answers:

  • Axolotl
  • Lizard
  • Starfish
  • Salamander

Explanation: The axolotl can regenerate not only its limbs but also its heart, brain, and spinal cord, fascinating researchers in regenerative medicine.

Question 15 : Which animal has fingerprints most similar to those of humans?

Possible answers:

  • Chimpanzee
  • Orangutan
  • Koala
  • Gorilla

Explanation: Koalas have fingerprints so similar to ours that they can even fool forensic experts. This is a case of convergent evolution.

Question 16 : What phenomenon causes the Northern Lights?

Possible answers:

  • Reflection of moonlight
  • Light pollution
  • Solar particles and Earth's magnetism
  • Volcanic eruptions

Explanation: The Northern Lights are caused by the interaction between charged solar particles and gases in the upper atmosphere, channeled by Earth's magnetic field.

Question 17 : How many liters of water can an elephant drink per day?

Possible answers:

  • 20 liters
  • 50 liters
  • 100 liters
  • 200 liters

Explanation: An adult elephant can drink up to 200 liters of water per day and uses its trunk to suck up to 10 liters at a time.

Question 18 : Which ecosystem produces the most oxygen on Earth?

Possible answers:

  • Oceans
  • Tropical forests
  • Grasslands
  • Tundra

Explanation: Ocean phytoplankton produces 50 to 80% of Earth's oxygen, much more than tropical forests. These microorganisms are essential to life on Earth.

Question 19 : What is a relationship between two species where both benefit from each other called?

Possible answers:

  • Symbiosis
  • Parasitism
  • Commensalism
  • Predation

Explanation: Mutualistic symbiosis is a win-win relationship. Example: clownfish and sea anemones protect each other.

Question 20 : What do you call a species that exists in only one place in the world?

Possible answers:

  • An endemic species
  • An invasive species
  • A migratory species
  • A protected species

Explanation: An endemic species lives only in a limited geographic area. Madagascar is home to 90% endemic species, such as lemurs.

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