In regards to the intrinsic clotting mechanism, the hageman factor (factor xii) is activated: by the sticking of platelets to damaged tissue by the sticking of platelets to other platelets when blood comes in contact with a foreign substance such as collagen when a tissue factor is released by damaged endothelium with agglutination

The right answer is by the sticking of platelets to other platelets.

The platelets attach to the injured walls of the endothelium via the von Willebrand factor. Once fixed, the platelets will be activated and conformational change to attract more platelets to the injured site so as to form a white clot. Then the coagulation factor will intervene including the factor XII which is activated in contact with the negatively charged platelet membrane, and will activate the rest of the coagulation factors.

Proposals 1 and 3 trigger primary hemostasis and not coagulation.

Proposition 4 concerns the exogenous pathway of activation of coagulation.

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.