Sea anemone is a cylinfrical and radially symmetrical animal measuring about 5 to 7cm. Body is divided into orl disc, peadal disc and column. It is brownish or yellowish in colour.

Body cavity of Ascaris is called pseudocoel. It is the space between body wall and the alimentary canal which is not lined by mesoderm.

Haemocoel is the primary body cavity of most invertebrates, containing circulatory fluid.

Amphicoel or amphicoelous consists of both anterior and posterior surfaces of the centrum concave.

Schizocoel is a coelom present in the body cavity lying between the digestive tract and the musculature of the body wall.

Homeostasis is the condition in which body's internal environment remains relatively constant within limits. Homeostatic mechanisms protects an environment from harmful fluctutations.

Chloragogen cells ofPheretima posthuma are analogous to liver of vertebrates. They are said to be excretory. They may also store the reserve food material and manufacture glycogen from fatty acids.

The term enzyme was given by W. Kuhne in 1678. J.B. Sumner (1926) purified and crystallised urease enzyme and suggested that enzymes are proteins.J.H. Northrop and M. Kunitz (1930) prepared pure crystalline pepsin and trypsin and showed that these enzymes were also proteins.

Parasphenoid bone is a flattened and inverted T-shaped bone which lies in the median line along the floor of cranium.

Mammalian prolactin is secreted by adenohypophysis. ACTH or Adrenocorticotrophic hormone is secreted by adenohypophysis or anterior pituitary.

Oxytocin is secreted by posterior pituitary or neurohypophysis.

Coanocytes are the characteristic cells of sponges not coelenterates.

In Hydra, epitheliomuscular cells, cnidoblasts,interstitial cells, nerve cells, sensory cells, epithelio musculonutritive cells are found.

Cretinism is caused by the deficiency of thyroid hormone in infants. Myxoedema is caused by the deficiency in adults. Graves disease or exophthalmic goitre is caused by the hypersecretion of thyroid hormone.

The glomerular filtrate contains a large amount of water and other dissolved substances such as urea, uric acid, creatinine, amino acids, glucose, sodium, potassium, vitamins etc. Both glomerular filterate and blood plasma are similar except former does not consists of proteins.