Sternal angle marks the joint between the sternum and the 2nd rib.
Option E.
<h3><u>Explanation:</u></h3>
Sternum is the breast bone which is a dorsi ventrally flattened bone present in thorax of human. It gives the support for the ribs where the ribs join. A sternum has three parts - Manubrium sterni, body of sternum and the xyphoid process.
The sternum has attachments of a total of 10 ribs and clavicle. The clavicle and the first rib joins in the Manubrium sterni, and the 3rd to 10th rib joins in the body of sternum. The 2nd rib joins in a facet which is partly in Manubrium sterni and partly in body of sternum. This place id also called the sternal angle. So the sternal angle marks the joint of 2nd rib to sternum.
In your cells, cellular respiration happens in a special organelle called the mitochondrion. But as mentioned, prokaryotic organisms don't have organelles. Rather than taking place in the mitochondrion, cellular respiration happens either in the cytoplasm or across the plasma membrane of the cell.
There are four classes of macromolecules (polysaccharides or carbohydrates, triglycerides or lipids, polypeptides or proteins, and nucleic acids such as DNA & RNA). Carbohydrates and lipids are made of only carbon, hydrogen, and oxygen (CHO). Proteins are made of carbon, hydrogen, oxygen, and nitrogen (CHON).
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It is so important because complex carbohydrates give you the most energy