Question

Pyrenoids are made up of
A.Core of starch surrounded by a sheath of protein.
B.Core of protein surrounded by fatty sheath.
C.Proteinaceous centre and starchy sheath.
D.Core of nucleic acid surrounded by protein sheath.

Answer 1

Hint: Pyrenoids are defined as subcellular micro- compartments or simply the dense bodies of some algae and other plants within the chloroplast. Pyrenoids are composed of biomolecules that have one or more amino acids and a polysaccharide.

Complete answer:
Pyrenoids are composed of a protein-like central, viscous granular core and this core is surrounded by tightly packed minute plates, called starch plates or starch cells. Pyrenoids are made up of a dense proteinaceous region surrounded by a starchy sheath.
This is an unique feature to algae chloroplast and are related to polymerizing sugars into starch (reserve polymers).
At the periphery of pyrenoids, a starch sheath is mostly formed or deposited, also though that starch is synthesised in the cytosol rather than in the chloroplast. An extra concentric layer around the pyrenoid, beyond the starch sheath, forms a high-molecular weight complex of two proteins in

Chlamydomonas, and this is currently speculated to function as a $CO_{2}$ leakage barrier or barrier to recapture $CO_{2}$ that keeps escaping from the pyrenoid.
The pyrenoids remains in association with the carbon- concentrating mechanism to serve as carbon dioxide fixation centres by producing and sustaining an atmosphere rich in carbon dioxide around the ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) photosynthetic enzyme.
Thus, pyrenoids are observed to have an analogous function to that of cyanobacterial carboxysomes. It is considered as the site of starch formation.

Hence, the correct answer is option (D)

Note: The pyrenoid may be a concentrated structure internally or externally chloroplasts of some algae, includes widely of ribulose bisphosphate carboxylase enzymes which is vital in photosynthesis process for carbon fixation and in this way sugar produced.