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Example Question #21 : Immune System
Which of the following is true regarding red blood cells?
They live for about 1 month
They have no nucleus
They are made by the liver
They produce antibodies
They are the target of human immunodeficiency virus (HIV)
They have no nucleus
Red blood cells are made in the bone marrow, and live for about 3-4 months. They are enucleated (lacking a nucleus), which makes more space available for hemoglobin molecules, which function to carry oxygen to the tissues. HIV infects T-helper cells, which are white blood cells, not red blood cells. Thus, the name makes sense since the virus infects cells of the immune system (white blood cells) and causes immunodeficiency. The liver and spleen play roles in recycling the red blood cells once they have carried out their function for about 120 days.
Example Question #22 : Immune System
Which of the following is not an immune cell?
Macrophage
Neutrophils
Keratinocytes
B-cells
Basophils
Keratinocytes
Keratinocytes are not immune cells. Rather, they secrete a protein called keratin which is a large proportion of the extracellular matrix and makes up hair, nails, skin, and other parts of the body. All other cells are immune cells.
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