The compound lecithin is classified as a phospholipid. Phospholipids are a major component of cell membranes and are essential for various cellular functions. They consist of a glycerol backbone, two fatty acid tails (which are hydrophobic), and a phosphate group head (which is hydrophilic). This unique structure allows them to form bilayers, which are critical in cell membrane formation.
In contrast, the other options such as amino acids, glycerides, and carbohydrates refer to different types of biological molecules:
Therefore, the correct classification for lecithin is Phospholipids.
| Pair of skeletal parts | Category | |
|---|---|---|
| (a)$\,\,$ | Sternum and ribs$\,\,$ | Axial skeleton |
| (b)$\,\,$ | Clavicle and glenoid cavity$\,\,$ | Pelvic girdle |
| (c)$\,\,$ | Flumerus and ulna$\,\,$ | Appendicular skeleton |
| (d)$\,\,$ | Malleus and stapes$\,\,$ | Ear ossicles |