Quiz of the Day
Trees & Nature
Friday, 24 April 2026
Arbor Day — tree records, forests of the world, plant science
1. What is the tallest tree species in the world?
- Sitka spruce
- Douglas fir
- Giant sequoia
- Coast redwood
The tallest known tree, a coast redwood named Hyperion in California, stands 115.92 metres tall — taller than the Statue of Liberty. Its exact location is kept secret to protect it from tourists.
2. How old is the oldest known living tree?
- About 5,000 years
- About 10,000 years
- About 1,000 years
- About 3,000 years
A bristlecone pine named Methuselah in California is over 4,856 years old — it was already ancient when the Egyptian pyramids were being built. An even older bristlecone was discovered but remains unnamed for protection.
3. What process do trees use to convert sunlight into energy?
- Fermentation
- Osmosis
- Cellular respiration
- Photosynthesis
During photosynthesis, a single large tree can produce enough oxygen for 2-4 people daily. The green colour of leaves comes from chlorophyll, the pigment that captures light energy.
4. What is the largest rainforest in the world?
- Daintree Rainforest
- Congo Rainforest
- Tongass Rainforest
- Amazon Rainforest
The Amazon covers 5.5 million square kilometres across nine countries. It contains about 390 billion individual trees belonging to roughly 16,000 species — and scientists discover new species every year.
5. What are the rings inside a tree trunk used to determine?
- The tree's species
- The tree's age
- The tree's weight
- The tree's height
Each ring represents one year of growth. Wide rings indicate good growing years with plenty of rain, while narrow rings show drought or stress. Scientists use this data to reconstruct climate conditions thousands of years back.
6. Which country has the most forest cover by total area?
- United States
- Russia
- Brazil
- Canada
Russia's forests cover about 815 million hectares — roughly 20% of the world's total forest area. That's larger than the entire land area of Australia.
7. What is the world's largest living organism by area?
- A honey fungus
- A giant sequoia
- A quaking aspen grove
- A blue whale
Pando in Utah is a single quaking aspen that has cloned itself into roughly 47,000 stems across 43 hectares. The entire grove shares one root system and is estimated to be 80,000 years old.
8. What do deciduous trees do in autumn?
- Lose their leaves
- Stop growing roots
- Grow new leaves
- Produce fruit
Autumn leaf colours aren't new pigments — the yellows and oranges (carotenoids) are there all year but masked by green chlorophyll. When chlorophyll breaks down in autumn, the hidden colours are revealed.
9. Which tree produces acorns?
- Maple
- Elm
- Oak
- Birch
A single oak tree can produce up to 70,000 acorns per year, but only about 1 in 10,000 will grow into a new tree. Oak trees typically don't start producing acorns until they're 20-50 years old.
10. What is the 'Wood Wide Web'?
- An online forestry database
- A network of underground fungal connections between trees
- A satellite monitoring system
- A type of spider web found in forests
Trees communicate and share nutrients through mycorrhizal fungal networks in the soil. Mother trees have been shown to send extra carbon to their seedlings and even warn neighbouring trees of pest attacks.
11. Which tree's bark is used to make the spice cinnamon?
- Eucalyptus
- Birch
- Cinnamomum
- Cork oak
Cinnamon is harvested by stripping the inner bark of Cinnamomum trees. In ancient times, it was more valuable than gold — Arab traders kept its source secret for centuries, claiming it came from giant birds' nests.
12. How many trees are estimated to be on Earth?
- About 400 million
- About 3 trillion
- About 3 billion
- About 3 quadrillion
A 2015 Yale study estimated 3.04 trillion trees on Earth — about 400 trees per person. However, the number has decreased by 46% since the start of human civilisation.
13. Which tree is the national symbol of Canada?
- Spruce
- Maple
- Pine
- Cedar
The maple leaf has appeared on Canadian flags since the 1700s. Canada produces about 71% of the world's maple syrup — it takes approximately 40 litres of sap to make just 1 litre of syrup.
14. What is the fastest-growing tree in the world?
- Willow
- Eucalyptus
- Empress tree (Paulownia)
- Bamboo
While bamboo grows fastest (technically a grass), the Empress tree is the fastest-growing true tree, capable of growing 3-5 metres in a single year. It can reach 15 metres in just 5 years.
15. What unusual defence mechanism do some acacia trees in Africa use against herbivores?
- They produce thorns that grow longer
- They release toxic gas to warn nearby trees
- They secrete sticky sap
- They drop their leaves instantly
When giraffes browse on acacia leaves, the trees release ethylene gas, which signals neighbouring trees to pump bitter tannins into their leaves within minutes. Giraffes have learned to walk upwind to find unwarned trees.