The normal pH of blood is around 7.3, which means blood is normally slightly basic. A truly neutral pH is 7.0. Whenever the pH of blood is under 7.3 (not 7.0) it is considered acidosis, and so our answer is either 7.2 or 6.8.

The AB⁺ blood type is known as the "universal recipient" type, therefore, people with any blood type can donate to an AB⁺ individual.

As for the incorrect answers, a person with O^- blood has the "universal donor" type, and can only receive blood from other O^- individuals. Erythroblastosis fetalis, also known as hemolytic disease of the newborn, cannot occur during a woman's first pregnancy because her body has not yet produced anti-Rh antibodies. Finally, Rh factor presence is a genetically dominant condition.

Human blood contains 55% plasma and 45% cells. The cells include erythrocytes (red blood cells), leukocytes (white blood cells), and thrombocytes (platelets). Plasma is largely composed of water, protein (albumin), and clotting factors.

Note that blood serum is simply blood plasma with the clotting factor elements (fibrinogen) removed.

Thromboplastin is released when damage occurs to a tissue. Prothrombin and fibrinogen are both present in the blood. When thromboplastin interacts with the blood, it converts prothrombin to its active state, thrombin. Thrombin then cleaves fibrinogen, converting it to its active state, fibrin. Fibrin is exceptional at forming cross-linked mesh-like interactions, and in doing so traps passing blood cells and plasma proteins. This blockage and accumulation of blood elements becomes the clot.

When centrifuged, blood will divide into three parts: the plasma layer, the buffy coat layer, and the red blood cell layer. The plasma layer contains albumin, immunoglobulins, and blood clotting factors. The buffy coat is composed of leukocytes, and the red blood cell layer is composed of erythrocytes.

Low-density lipoprotein (LDL) cholesterol are considered to be "bad cholesterol" because it transports fat molecules to arteries and attracts macrophages, leading to atherosclerosis. Alternatively, high-density lipoprotein (HDL) cholesterol is considered to be "good cholesterol" because it removes fat molecules from macrophages, decreasing the risk of atherosclerosis.

Coagulation Factor II (prothrombin) is a protein produced in the liver. Prothrombin is modified after translation to produce thrombin. Thrombin is an enzyme that catalyzes coagulation reactions and results in reduced blood loss. Factor II deficiency is an autosomal recessive mutation that can result in defects in blood clotting.

The buffy coat is so-named because it has the majority of white (immune) cellular material, while the hematocrit contains most of the red cell material (hemoglobin), and the plasma has the fluid and circulating proteins, such as antibodies.

Erythrocytes are found in the hematocrit, lymphocytes are found in the buffy coat, and clotting factors, albumin, and fluids are found in the plasma.

Albumin is the protein that is involved in transporting a variety of products throughout the blood as well as the protein factors involved in blood clotting. Albumin makes up about 50% of the plasma protein distribution. It is responsible for binding insoluble molecules to transport them through the aqueous blood stream. Albumin is also the main driver of oncotic pressure in the arteries and veins to keep water from moving to the tissues via osmosis.

Plasminogen, thrombin, and thromboxane are all proteins involved in the clotting process and are also found in the blood.

Fibrinogen is converted to fibrin by the action of thrombin, and fibrin is the protein that actually forms a blood clot. An inability to properly form clots, such as is seen in hemophilia, could arise from a defect in fibrinogen, resulting in a problem with the clotting pathway.

Renin is an enzyme released by the kidney, which creates angiotensin to help raise blood pressure. Vasopressin is a posterior pituitary hormone that acts on the kidney to retain water. Albumin is a plasma protein that functions to maintain the oncotic pressure in the blood, as well as to transport fatty acids. Major histocompatibility complex (MHC) proteins are used to present antigens to the immune system.