Answer:
C. They produce and use adenosine triphosphate (ATP).
Explanation:
ATP is the energy currency for the cells of all living beings. It is produced by aerobic or anaerobic respiration in both prokaryotes and eukaryotes. Complete or incomplete oxidation of nutrients obtains ATP. ATP is used by cells to perform all the vital functions. ATP synthesis occurs when phosphate is added to ADP during substrate-level phosphorylation or oxidative phosphorylation. Hydrolysis of ATP includes the release of terminal phosphate and lots of energy which in turn is used by cells.
Ectopic focus or ectopic pacemaker happens when an excitable group of cells outside the normal sinoatrial node causes premature heartbeat. Sinoatrial node (SA node) is the pacemaker of the heart. Most people experience ectopic focus but persistent occurrence may need the client/patient to visit the doctor. If a client or patient complains of ectopic focus, it is better to consider his/her activity before visiting the clinic. Ask, for example if the client/patient had a vigorous exercise because it might be causing the irregular heartbeat, how often is he/she experiences such irregularity in his/her heartbeat (acute ectopic foci is usually non-life threatening, however, chronic type requires medical help), his/her lifestyle (he/she might be using illegal drugs, smokes and/or drinks alcohol,had too much coffee etc). Again, history taking is very vital.
A DNA molecule is like a ladder because there are two sides (the sugar-phosphate backbones of the two strands) and rungs (each rung being a pair of complementary bases). Twisted, because the molecule is twined in a coil called a helix - or rather, a double helix because there are two strands.
