Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!

Many species of animals and plants that once inhabited the Earth have died out or become . If selection takes place, then the less well-adapted will become extinct. Perhaps they can't compete for so well, or they don't avoid so well.
Humans are responsible for the extinction of thousands of . As the human population rises they need more food. This has meant the destruction of natural to give room to grow crops.
Other animals have been to extinction. Often these animals breed and usually live for a long time.