Oxyntic cells or parietal cells are large and rounded cells located upon the surface of the gastric gland and secrete HCl and CIF (Castle's Intrinsic Factor). This HCl gives the gastric fluids, a pH of about 2.0.

Kingdom - Monera includes all prokaryotes (autotrophic of heterotrophic) viz, mycoplasmas, bacteria, Actinoomycetes (mycelial bacteria) and photosynthetic vyanobacterial while all unicellular eukaryotic organisms like flagellates, diatoms, dinoflagellates, slime moulds, sarcondina etc. are included in Kingdom - Protista.

Glycolysis is an essential and first path of respiration. It is common in both aerobic andanaerobic respiration and occurs in the cytosol of all living cells of prokaryotes as well as Eukaryotes.

The basophils are probably like mast cells of connective tissue. They release heparin histamine and serotonin. Their nucleus is usually three-lobed and their granules take basic stain strongly.

Monocytes are the largest of all types of leucocytes. Their nucleus is bean-shaped. They are motile and phagocytic in nature. Theyengulf bacteria and cellular debris. Generally, they will change into macrophages after entering tissue spaces. Eosinophils have a two-lobed nucleus. They are non-phagocytic and help in dissolving a blood clot. Their number increases in people with allergic conditions such as asthma or high fever.

Neutrophils are most numerous of all leucocytes They eat harmful germs and are, therefore, phagocytic in nature. Their nucleus is many lobed and strain weakly with both and basic stains.

Nearly a century ago TH Huxley called birds 'glorified reptiles' thereby meaning that birds have evolved from some reptilian ancestor. Both birds and reptiles lay the same type of eggs, which are deposited outside water. Eggs are large and telolecithal. The ovum is surrounded by albumen, an egg membrane and a thick hard calcareous shell, which are all secreted by special gland located int he walls of oviduct.

Birds like mammals have completely four chambered heart with double circulation, in which there is no mixing of pure and impure bloods. Whereas the ventricle is imperfectly divided in reptiles, resulting in partial mixing of bloods.

All birds have horny epidermal scales confined to the lower parts of their legs and feet, which are exactly like the epidermal scales of the reptiles. Besides birds are covered by feathers, which are homologous to the reptilian horny scales as they have a similar origin and develop from similar germ buds.

The members of phylum-Arthropoda show bilateral symmetry, three germ layers in body wall, external metamerism, jointed and paired appendages, haemoocel and open type of circulatory system with dorsal heart.

Hypersecretion of Growth Hormone (GH) or Somatotropin Hormone (STH) from adenohypophysis of pituitary gland causes gigantism in children and acromegaly in adulthood. Gigantism involves excessive growth (lengthening) of bones with enlargement of internal organs as well. Acromegaly causes abnormal thickening of bones (due to ossification of periosteum) especially at face and margins of hand and feet.

With regard to transfusion of whole blood or packed red blood cells, individuals with O type negative blood are often called universal donors and those with type AB positive blood are called universal recipients. The person with blood group O^–­ do not have any type of antigen present on the surface of the RBC so the recipient will not form any antibody against it.

The genotype of a person with blood group 'B' may be I^BI^B or I^O1^B, person with genotype I^BI^B cannot produce offsprings with blood group 'O' in any case but if the person's genotype is I^O1^B, then its offsprings may have blood group O.

Pinctada sp. is the bivalve molluscs, commonly known as pearl oysters. These belong to sub-class-Lamellibranchia, class-Bivalvia or Pelycipoda, phylum-Mollusca and Kingdom-Animalia.