Question

Orange-yellow colour of flowers and fruits are due to
(a) Chloroplasts
(b) Leucoplasts
(c) Aleuroplast
(d) Chromoplast

Answer 1

Hint: Plants are eukaryotes consisting of double-walled plastids. Plastid is the largest organelle in the plant cell, carrying genetic information plastidome which helps to control many characteristics of the plant.

Complete Answer:
Chromoplasts are coloured plastids which synthesize and store carotene, xanthophyll, anthocyanin and lycopene. These pigments are responsible for producing yellow, orange and red colour to fruits and flowers. They formed either from leucoplast or chloroplast.
Chloroplast consists of chlorophyll which is responsible for producing green colour to plants and helps in photosynthesis. Carotenoids in chloroplast protect chlorophyll from photooxidation.

Additional information: Photosynthesis helps in the synthesis of organic food from inorganic raw material. Number, size and shape of chloroplast vary from species to species. Chloroplast consists of stroma, grana, and thylakoid. The function of the chloroplast is under control of the nucleus of the cell. DNA of chloroplast shows replication and transcription both. The chloroplast is considered as a semi-autonomous organelle because they synthesize its enzyme and protein, also the formation of new chloroplast takes place from pre-existing one by division. Chloroplast also stores fat in the form of plastoglobuli.
Leucoplast is white moulded colourless plastid with different types of shape. Leucoplast occurs in fruit, seed, tuber and rhizome for storage of carbohydrates, lipids and protein. Leucoplast is of three types Amyloplast which store starch grains, elaioplast which stores fat and aleuroplast which store protein.
Leucoplast, Chloroplast and chromoplast are interconvertible but chromoplast does not change to other plastids. When chloroplast gets to transform into chromoplast the amount of chlorophyll and starch get decreased which leads to improper function of the stroma. For example, carotene developed from leucoplast but lycopene pigment develops from the chloroplast.
So, the correct answer is ‘(d) Chromoplast’.

Note: Plastids are similar to mitochondria with the presence of their own DNA, RNA and ribosome, both present only in eukaryotes, and synthesise ATP after oxidation. Synthesis of ATP in mitochondria takes place inside the cristae whereas in plastid it takes place inside the thylakoid of the chloroplast.