Presence of myoglobin
They are red due to presence of haemoglobin.
Iodine turns blue-black in the presence of starch.
The red color comes from the presence of iron oxide.
Laterite soil is red in colour due to the presence of oxides of iron.
due to presence of green colour photosynthetic pigment known as Chlorophyll
chloroplast has green color due presence of green pigment that is chlorophyll
Phenolphthalein turns pink/magenta in the presence of an alkali.
Methyl orange turns red in the presence of calcium hydroxide.
It is a substance(chemical or natural) which changes colour in the presence of an acid or base.
Fehling's A solution is blue in color due to the presence of copper sulfate.
Carotene from a grass-based diet. Milk will lack carotene (not be a yellowish colour) if she is fed a grain-based diet.