The excretory and osmoregulatory organs of the fishes are the gills and kidney. Excretion in bony fishes is ureotelic (i.e., they excrete urea) but some freshwater bony fishes are ammonotelic (i.e., excrete ammonia).

Import involves passive sucking of food into body by rapture of plasmalemma e.g., ingestion of algae.

Haemocoel is the body cavity of most of the vertebrates, containing circulatory fluid. It is filled with blood. It is well developed in arthropodes (e.g. cockroach) and molluscs (e.g., Pila).

Hormones regulate the different colour of frog skin (under hormonal control) ,metachrosis is the condition of changing in skin colour which protect frog from enemies.

Slime moulds are characterized by the presence of capillitium. Itis a branched system of sterile fibres present inside the fruit body.Elaters and pseudoelaters are present in some bryophytes whereas capitulum is a type of inflorescence.

Ecdysone is a steroid hormone. It controls moulting and metamorphosis in insects. It is a major insect moulting hormone.

Anamniote are an informal group comprising the fishes and the amphibians.Amnion is an extraembryonic membrane that surrounds an embryo in reptiles, birds and mammals. Anamniotes are vertebrate animals as they lack amnion membranee.g., fishes and amphibians.

Pepsin is an endopeptidase enzyme or protein digesting enzyme. It is produced in the stomach. It breaks down proteins into smaller peptides. It acts in acidic medium,i.e. pH 2.

Trypsin is a serin protease. It hydrolzes proteins in the digestive system of many vertebrates. It is formed in the small intestine.

During early embryonic development of frog a blastula stage comes after morula stage which contain a small irregular excentric space or cavity called blastocoel or segmentation cavity appear in the animal hemisphere.

Apoenzyme is the proteinaceous part of an enzyme. The apoenzyme plus non- protein aceous part is called holoenzyme.

Co-enzyme is a non- protein compound that is necessary for the function of an enzyme.

Prosthetic group is a non- protein group, forming a part of or combined with a protein.