Biochemistry and Clinical Pathology Questions and Answers

Answer: C

The father of cytopathology is Dr. George Papanicolaou.

Papanicolaou, a Greek-born physician working in the United States, showed that cancer of the cervix could be detected from cells shed into vaginal smears. His Pap smear and the Papanicolaou stain founded diagnostic cytology as a discipline.

Hans Christian Gram devised the Gram stain for bacteria. Charles Darwin proposed the theory of evolution by natural selection. Robert Brown described the cell nucleus in 1831, an early contribution to cell biology but not to cytopathology.

Answer: C

The average lifespan of a human red blood cell is 120 days.

A red cell has no nucleus and cannot repair itself. After about 120 days in the circulation its membrane becomes rigid, and it is removed by macrophages, mainly in the spleen. The haemoglobin is broken down, its iron is reused, and the haem becomes bilirubin.

Sixty and ninety days are too short for a normal cell, though red cell survival is shortened in haemolytic anaemias. 150 days exceeds the normal lifespan. For comparison, platelets live about 7-10 days.

Answer: D

The one that is not a method of haemoglobin estimation is the Coombs test.

The Coombs (antiglobulin) test detects antibodies or complement attached to red cells, and is used in autoimmune haemolytic anaemia, haemolytic disease of the newborn and cross-matching. It does not measure haemoglobin.

Haemoglobin can be estimated by colorimetric methods (Sahli's acid haematin, cyanmethaemoglobin), gasometric methods (from the oxygen-combining capacity of blood), and physical methods such as the copper sulphate specific gravity test used to screen blood donors. So the other three are genuine methods.

Answer: D

Red blood cells are also known as erythrocytes.

The name comes from the Greek erythros, red, and kytos, cell. Erythrocytes carry oxygen bound to haemoglobin.

The other options are laboratory tests, not names of cells. The total leukocyte count measures white blood cells. The packed cell volume (haematocrit) is the fraction of blood occupied by red cells, a measurement made on them. The platelet count measures thrombocytes.