Question

Which of the following store proteins?
(a) Chromoplasts
(b) Aleuroplasts
(c) Amyloplasts
(d) Elaioplasts

Answer 1

Hint: Plastids are cell organelles found in plant cells and euglenoids that are easily observed by microscope as they are large in size. Plastids contain pigments in them which are responsible for giving color to the cells. On the basis of pigments, plastids are characterized into chloroplasts, chromoplasts, and leucoplasts.

Complete Answer:
The chloroplasts contain green colored pigments in them known as chlorophyll which is essential for trapping light during photosynthesis. Chromoplasts also store pigments but other than green pigments, such as carotenoids like carotene, xanthophylls, etc. They are responsible for giving red, yellow, or orange color to the plant. Leucoplasts do not store pigments and thus are colorless, but they store nutrients such as amyloplasts store starch, elaioplasts store oils and fats, and aleuroplasts store proteins.

Additional information: Let us look at the structure of chloroplast in detail.
Chloroplasts are double membrane-bound cell organelles. The inner membrane of the chloroplast is relatively less permeable.

The space inside the inner membrane of the chloroplast is known as stoma and it contains flattened membranous sacs called thylakoids in it. The thylakoids are arranged in stacks like piles of coins known as grana.
Stroma lamellae are the structures that connect the thylakoids of different grana.
The membrane of the thylakoids encloses a space known as lumen in which a hydrogen gradient is developed.
The stroma also contains enzymes for the synthesis of carbohydrate and proteins, double-stranded circular DNA, and ribosomes.
So, the correct option is ‘(b) Aleuroplasts’.

Note: Chloroplasts are mostly found inside the mesophyll cells of the leaves. Their number varies from 1 cell in Chlamydomonas which is a green alga to 20-40 chloroplasts in mesophyll cells. The shape of chloroplasts can be lens-shaped, oval, spherical, discoid, or even ribbon-like.