The basic structure of chlorophyll consists of a porphyrin ring, coordinated to a central atom. This is very similar in structure to the heme group found in hemoglobin, except that in heme the central atom is iron, whereas in chlorophyll it is magnesium. This was discovered in 1906 and was the first time that magnesium had been detected in living tissue.

Correct Option: A

The basic structure of chlorophyll consists of a porphyrin ring, coordinated to a central atom. This is very similar in structure to the heme group found in hemoglobin, except that in heme the central atom is iron, whereas in chlorophyll it is magnesium. This was discovered in 1906 and was the first time that magnesium had been detected in living tissue.

The islets of Langerhans are the regions of the pancreas that contain cells that produce hormones. There are five types of cells in the islets of Langerhans: beta cells secrete insulin; alpha cells secrete glucagon; PP cells secrete pancreatic polypeptide; delta cells secrete somatostatin; and epsilon cells secrete ghrelin.

Correct Option: D

The islets of Langerhans are the regions of the pancreas that contain cells that produce hormones. There are five types of cells in the islets of Langerhans: beta cells secrete insulin; alpha cells secrete glucagon; PP cells secrete pancreatic polypeptide; delta cells secrete somatostatin; and epsilon cells secrete ghrelin.