Question

Which one is stained using carmine?
a. Bacteria
b. Diatoms
c. Chromosomes
d. Viruses

Answer 1

Hint: Carmine is a basic dye which is extracted from some scale insects and finds its use in reflectance spectroscopy as it reflects bright red light. It is used to stain various cell organelles.

Complete answer:
Carmine is a bright red-purple colour pigment/dye/stain which is obtained from an insect called Cochineal belonging to the family Dactylopius. Its red colour is due to the aluminium complex present in the carminic acid. This stain finds its use in the production of artificial flowers, rogues, paints, cosmetics, medications, food colour and inks.
It is used in histology to stain glycogen, mucopolysaccharides, cell organelles like cell nuclei, chromosomes.

Hence, the correct answer is option (C).

Additional information:
Chemically carmine is a derivative of anthraquinone.
Purity of carmine is checked by the absence of iron.
Biggest exporter of carmine is Peru.
70,000 cochineal insects are killed to produce one pound of carmine.
It is mostly obtained from the bodies of female insects Dactylopius coccus cacti.
Bacteria are stained by Gram staining which is based on checking the retention of crystal violet dye in the cell wall of the bacteria.
Diatoms are stained by using a dilute solution of methyl blue or Bengal rose.
Viruses are stained by using acridine orange staining.

Note: Sometimes carmine is confused with red 40 which is made by refining coal tar and other petroleum products and is also suitable for consumption. Carmine and red 40 both are used in food colouring but they both are obtained from different sources though their colour is the same.