Life and Earth Sciences quiz

More questions about Life and Earth Sciences

These visible examples show the question style. LearnClash turns the full topic into ranked duels and spaced repetition.

1. 1 Easy

   Which organelle arose from an engulfed bacterium through endosymbiosis?

   Answer: Mitochondrion

   Why: Mitochondria still retain their own circular DNA and replicate independently inside eukaryotic host cells.

2. 2 Medium

   What creates new crust at mid-ocean ridges?

   Answer: Divergent boundary

   Why: These spreading ridges form a chain nearly 65,000 km long, the longest mountain range on Earth, and almost all of it sits underwater.

3. 3 Hard

   What RNA molecule can catalyze biochemical reactions?

   Answer: Ribozyme

   Why: Ribozymes showed that RNA can act as both an information carrier and a functional catalyst without proteins.

4. 4 Easy

   How do decomposers primarily sustain an ecosystem's food web?

   Answer: By recycling nutrients into soil

   Why: Without decomposers, essential elements like nitrogen and phosphorus would remain permanently locked in dead biomass.

5. 5 Medium

   Which ancient organisms made the oxygen that formed banded iron formations?

   Answer: Cyanobacteria

   Why: Ocean iron absorbed cyanobacterial oxygen for hundreds of millions of years, so free oxygen only began building up in the air 2.4 billion years ago.

6. 6 Hard

   Which supercontinent broke apart before Pangaea formed?

   Answer: Rodinia

   Why: Breaking apart Rodinia opened fresh coastlines that absorbed vast amounts of carbon dioxide and cooled the planet.