Question

Orange-yellow colours of flowers and fruits are due to
A. Chloroplasts
B. Leucoplasts
C. Aleuroplasts
D. Chromoplasts

Answer 1

Hint: The plastids are cell organelles that provide colour to various organs present in plants. Plastids are exclusively present in plant cells only. They are the double-membranous cell organelles. They are semi-autonomous cell organelles in nature.

Complete answer:
a) Chloroplasts: Chloroplasts are green plastids. They contain the chlorophyll pigment and some other pigments all of which are concerned with photosynthesis. The chlorophyll is, however, the main photosynthetic pigment. It is fat-soluble.
b) Leucoplasts: Leucoplasts are colourless plastids. They are mostly present in the underground parts of plants like roots and underground stems. They are mainly concerned with food storage in plants. Leucoplasts are further classified into three types on the basis of the kind of food they store.
i. Aleuroplasts: Aleuroplasts are a type of leucoplasts. They are concerned with the storage of proteins in plants. The other types of leucoplasts are elaioplasts associated with the storage of fats and amyloplasts associated with the storage of starch.
ii. Chromoplasts: Chromoplasts are coloured plastids. These plastids are coloured other than green. They contain pigments other than chlorophyll like carotenes and xanthophylls. Carotenes are orange or red-coloured pigments. On the other hand, the xanthophylls are yellow in colour.
Thus, based on the above information we can conclude that the orange-yellow colours of flowers and fruits are due to chromoplasts.
Hence, the correct answer is option D.

Note: Carotenes and xanthophylls are together termed as carotenoids. The carotenoids are fat-soluble pigments. They are the secondary pigments and are also known as the shield pigments. This is because they protect the chlorophyll molecules from photooxidation or solarization.