two strands of DNA are held together by weak hydrogen bonds.
Answer:
A
Explanation:
The pulmonary artery carries de-oxygenated blood from the right ventricle of the heart to the lungs. It is the only artery that carries de-oxygenated blood. This blood is usually from the tissues and has a lot of carbon dioxide from the cellular respiration of cells around the body. The blood is pumped to the lungs to be oxygenated and the carbon dioxide expelled.
The enzymes are the special types of proteins which decreases the activation energy of the chemical reaction. The activation energy is the minimum amount of energy required to start a chemical reaction. Hence the enzymes are the special type of proteins that catalyses or speed up the chemical reaction by decreasing the activation energy of the reaction. Hence the correct answer is option C. Enzymes.
