Which of the following is true about environmental hazards to humans? A)
Children are more at risk than adults because they take in more air per unit mass than adults.
B)
Adults are most at risk because they have the highest exposure to environmental hazards.
C)
Elderly people are most at risk because their immune systems do not perform efficiently.
D)
Children are least at risk because they have well functioning immune systems.
E)
Adults are most at risk because they take in more pollutants relative to their size than children.

as resources become scarce because of population growth, the growth decreases after few years due to lack of resources and food.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.

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.