<u>arteries carry oxygenated blood and veins carry de-oxygenated blood.</u>
<h3><u>Answer and explanation;</u></h3>
- DNA is a double stranded molecule. Covalent and hydrogen bonds pray important roles in the functioning of DNA molecules.
- <em><u>Covalent bonds occur within each linear strand and strongly bond the nucleotide bases, sugars, and phosphate groups occurring both within each component and between components.</u></em>
- <em><u> Hydrogen bonds occur between the two strands and involve a base from one strand with a base from the second in complementary pairing.</u></em>
- Hydrogen bonds helps the complementary base pairs in DNA; guanine with cytosine and adenine with thymine to connect to one another. The hydrogen bonds between these complementary pairs helps keep the two strands of DNA helix together.
Answer: Vaccines give you immunity to a disease without you getting sick first. They are made using killed or weakened versions of the disease-causing germ or parts of the germ (called antigens). For some vaccines, genetic engineering is used to make the antigens used in the vaccine.
Explanation: Vaccines greatly reduce the risk of infection by working with the body's natural defenses to safely develop immunity to disease.
B. Bacteria would be your answer
Organic compound, any of a large class of chemical compounds in which one or more atoms of carbon are covalently linked to atoms of other elements, most commonly hydrogen, oxygen, or nitrogen. ... The few carbon-containing compounds not classified as organic include carbides, carbonates, and cyanides