Long-bodies, limb-less coecilion, skin compact, roofed with bone, vertebrae many, ribs long skin smooth, provided with transverse furrows, both slime glands and squid glands are present in the skin. In some scales are embedded in the skin, while in other specialized genera, scales are lost.
Head one trunk fused, neck not found, tail less, two pairs of limbs, hind legs with toes, vertebrae are ten, the last one is a urostyle, ribs reduced or absent, fertilization is external.
True crabs are mainly cancer, carcinus, portumus etc. Crabs reach the highest degree of cephalization among crustaceans. They remain buried among rocks and mud in shallow water. The cephalothorax is broader than longer, flat and disc-like.
Urodela is an order of subclass stego cephalia of class amphibian. (1) These are lizard like amphibians with distinct tail. (2) Two pairs of equal limbs are present. (3) Skin without scales and tympanum.
The retina of bird is the innermost layer and is sensory in nature. It is supplied by optic nerve projecting through the retina at they eye is a prominent vascular, pigmented fan shaped, vascular ridged plates called pectin, which protrudes, from the region of the blind spot, where the optic nerve enters.
Hairs are epidermal structures, which are found in the mammals. Each hair develops as a thickening of the stratum germination, of the epidermis and is distinguished in to two parts, the basal part, laying in the dermis is called root and the upper part traversing the dermis and projecting from the epidermis is called shaft.
An antibody (Ab) reacts with the concerned antigen (Ag) in a highly specific manner (i.e. an antibody reacts only with that determinant or region of an antigen for which it is specific) to produce an Ag-Ab complex.
The preservation of cells, tissue and organs in liquid nitrogen is called cryobiology. Many studies have been carried out on cryopreservation of plant cells and organs and the approach appears to have considerable promise in germplasm conservation.
A recombinant DNA molecule is produced by joining together two or more DNA segments usually originating from different organisms. More specifically, a recombinant DNA molecule is a vector) e.g. a plasmid, phage or virus) in to which the deserted DNA fragment has been inserted to enable its cloning in an appropriate host.
There are some viral disease namely small pox, influenza, polio, measles, jaundice, rabbis and hydrophobia trachoma and chicken pox. A list of some viral disease is given below: