Question

Root of which plant comprises a red pigment that has an affinity for oxygen?
A. Soybean
B. Carrot
C. Radish
D. Mustard

Answer 1

Hint:
Pigments are substances produced by living organisms having a colour because of selective colour absorption. Many bodily structures, such as eyes, skin, feathers, hair, and fur contain pigments such as melanin in chromatophores. Chlorophyll is a plant pigment that absorbs blue and red wavelengths of light and reflects green.

Complete step by step answer:
Soybean is a leguminous plant that undergoes nitrogen fixation by bacteria such as Rhizobium. Leghemoglobin is an oxygen-carrying phytoglobin located in the nitrogen-fixing root nodules of leguminous plants. It is produced by leguminous plants because of the nitrogen-fixing bacteria in the root hair, as part of the symbiotic interaction between the bacterium and the plant. Roots that do not contain Rhizobium do not produce Leghemoglobin.
Leghemoglobin has similar chemical and structural properties to haemoglobin. It is a red-coloured pigment. In soybean plants, oxygen in the root nodules reduces the activity of the oxygen-sensitive nitrogenase, which is an enzyme responsible for nitrogen fixation.
Carrots contain a pigment called carotenoids. Orange carrots get their colour from alpha- and beta-carotene, red carrots from lycopene, yellow carrots from lutein, and purple carrots from anthocyanin. The red pigment in radish root skin is an anthocyanin found within the cyanoplasts in the outer layers of the cortex and epidermis. Anthocyanins are the pigments responsible for the red-purple pigmentation of the leaves of red mustard plants.

Option ‘A’ is correct

Note:
The structure of leghemoglobin is similar to that of myoglobins and haemoglobins, although there is little sequence preservation. The protein is mostly alpha-helical, with eight helices providing the scaffold for a heme-binding pocket.