Question 11 of 20 : Select the best answer for the question.

11. During the Middle Ages, central Europe was subject to invasions by people pushed out of

O A. Norse.

O B. Anglo-Saxons.

O C. Visigoths.

O D. Magyars.

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1 digestive system

2 stomach

3 bladder

4 carbon deoxide

5 tiger

mammal

explanation:

1. amino acid refers to the fundamental building block of proteins, comprising of an amino group and a carboxyl group.

2. catalyst refers to any substance, which increases the rate of chemical reaction without being used up in the reaction.

3. a complex molecule containing he genetic code is dna or deoxyribonucleic acid.

4. an enzyme refers to a molecule of protein, which is unique in accelerating up a particular chemical reaction in the biological systems.

5. nucleic acid refers to an sequence of sugars, phosphates, and nitrogenous bases, for example, dna and rna.

6. a protein refers to a large, composite organic molecule comprising of a huge number of amino acids associated together with the of peptide bonds.

7. rna refers to a nucleic acid that takes part in the production of proteins.

8. substrate refers to a compound, which takes part in a chemical reaction, and is chemically modified by the reaction.