VI. Solve the crossword puzzle

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Across:

1. The sum of all chemical reactions (energy exchanges) in cells; 4. Protein molecule that acts as catalysts in biochemical reactions; 6. The complex of chemical compounds and structures within a plant or animal cell excluding the nucleus; 7. A microorganism that lacks a nucleus and has a cell wall composed of peptidoglycan, a protein-sugar molecule; 10. An organism that obtains its nutrition by breaking down organic molecules in foods; the group includes animals and fungi; 11. A structure along which chomosomes are distributed and drawn apart during cell division; 14. A polymer of amino acids linked together by peptide bonds; 16. The natural world within which people, plants, and animals live; 18. An organism that synthesizes its nutrients and obtains its energy from inorganic raw materials; 19. A human child or an animal's baby; 20. Something used as a model for making another thing.

Down:

2. Scientific study of people; their societies, culture, etc.; 3. The process whereby all living organisms produce offspring; 5. The study of the behaviour of animals in their natural habitat; 8. Tendency of an organism to suit to its environment; 9. Composed of many cells and exhibiting some division of labor and specialization of cell structure and function; 12. A group of individuals of the same species living in the same area at the same time and sharing a common gene pool; 13. The science that studies the way in which the bodies of living things work; 15. An interactive association between two or more species living together; 17. The physical environment in which a population lives.