How would you recognise red blood cells when looking at a colour photograph of blood taken with a light microscope?

Erythrocytes, or red blood cells, are by far the predominant cell type in the blood smear. They appear as biconcave discs of uniform shape and size (7.2 microns) that lack organelles and granules. Red blood cells have a characteristic pink appearance due to their high content of haemoglobin.

Genes

Explanation:

Genes are sequences of nucleotides that determine characteristics. They are passed from parents to offspring.