Medulla oblongata is the primary respiratory control center. Its main function is to send signals to the muscles that control respiration to cause breathing to occur.

Photosystem- I is found in the non appressed part of grana thylakoids as well as stroma thylakoids. Chlorophyll : carotenoid content is high. Its photocenter is P₇₀₀. This photosystem receives electrons from Photosystem II. It is involved in both cyclic and non- cyclic photophosphorylation.

WBCs can change their shape like amoeba and are thus, capable of amoeboid movement. This enables them to squeeze out of blood capillaries into the tissues. This process is called diapedesis.

Valium is a benzodiazephine (sedative) that gives a feeling of relaxation, calmness or drowsiness in the body.

Morphine is the main opium alkaloid that depresses respiratory centre and contributes to the fall in blood pressure.

Amphetamines are synthetic drugs and are stimulant in nature.

Hashish is a hallucinogen.

Ciliated epithelium is a region of epithelium consisting of columnar or cuboidal cells bearing hairlike appendages that are capable of beating rapidly. It performs the functions of moving particles of fluids over the epithelial surface.

Cuboidal epithelium is found in ducts of glands and tubular parts of nephrons in kidney.

Columnar ciliated epithelium occurs in fallopian tubules, nasal passages, bronchioles, small bronchi and buccopharyngeal cavity of frog.

Secretin and cholecystokinin are secreted by Brunner's gland located in duodenum. Secretin causes the pancreas to secrete alkaline pancreatic juice and stimulates bile production in the liver. Cholecystokinin induces the gall bladder to contract and eject bile into the intestine and stimulates the pancreas to secrete its digestive enzymes.

The ventral nerve cord is a cord of nervous tissue that runs the length of the animal in the lower part of its body. It is the charcateristic of lower chordates like leech, cockroach and scorpion.

Patella is a sesamoid bone. Sesamoid bones are small rounded masses of bones formed in tendons at the joints where they are subjected to great pressure.

The organ of Corti consists of outer hair cells, inner hair cells, inner pillar cells, outer pillar cells, tunnel of Corti, phalangeal cells (cells of Deiters), cells of Hensen and cells of Claudius. The sensory hair project from the outer ends of the hair cells into the scala media, while from the inner end of the cells nerve fibres arise, which unite to form the cochlear nerve.

Entamoeba histolytica is a monogenetic parasite, i.e., living in a single host, in the large intestine of humans. It causes amoebiasis or amoebic dysentery.