Which of these statements describes a constraint imposed on scientific researchers by the antarctic treaty system? a. tourist activities are carefully controlled. b. the safety of scientists is ensured. c. some activities are banned. d. scientific knowledge is not shared.

A constraint imposed on scientific researchers by the Antarctic Treaty System is that some activities are banned. So, option C is correct.

The Antarctic Treaty System is a treaty with several related agreements. Here the environment is fully protected and research is given priority. The environmental conditions are very inhospitable for visitors. The main aim is to keep the environment protected and hence several activities are banned even for scientific research purposes such as establishing military bases and use of the weapons, disposal of radioactive waste and nuclear explosion etc. Tourist activities are controlled and safety of visitors is ensured including the scientists. Many recent research developments have taken place in the twentieth century.

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.