The Big Science Crossword

Click on a number in the grid to see the clue for that number, then enter your answer into the box and click on "Check" to see if your answer is correct. If you are stuck, you can click on "Hint" to get a free letter.
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 3            4           
                    
 5           6            
         7             
                    
      8                
 9     10                 11   
                    
 12               13        
                    
          14            
15                   16     
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    18                  
                    
 19              20         
                    
 21                     

Across:

1. An organism that lives on or in another organism.
4. German physicist - the answer is relatively easy!
5. Italian physicist and astronomer - invented telescope.
7. A natural body that revolves around a planet.
8. The science that deals with the properties of substances.
9. A linear sequence of nucleotides along a segment of DNA.
12. An increase of speed or velocity.
14. The positively charged mass within an atom.
15. Polish astronomer whose theory describes how planets move around the sun.
17. A large system of stars or a bar of chocolate.
18. English scientist founder of falling apples.
19. A scientific trial or test.
20. English physicist who wrote 'A brief history of time'.
21. The interaction between living organisms in a particular area.

Down:

2. The bones of a human or an animal considered as a whole.
3. It all started here or TV series. (3,4)
6. The process in which energy is emitted as particles or waves.
10. An elementary particle that has a negative charge.
11. The science of life or living matter.
12. In your speaking exam you'll say 'ambient', but you mean this word.
13. mc2 = ??
16. British naturalist- a bit of a monkey!