Question

$\alpha $- granules of cyanobacterial cells contain
A. Cyanophycean starch
B. Polyphosphate
C. Cyanophycin
D. Lipid globules

Answer 1

Hint: Cyanobacteria or blue green algae are photosynthetic bacteria. The food stored in cyanobacteria is somewhat different from those of green plants. The stored product is usually a starch like material similar to glycogen and is different from the starch produced in plants. It is called Cyanophycean starch.

Complete answer:
 Cyanobacteria or blue green algae are gram negative photosynthetic prokaryotes which perform oxygenic photosynthesis. Four types of inclusions occur in the cells of cyanobacteria that are α-granules (cyanophycean starch), $\beta $-granules (lipid droplets), volutin granules and polyhedral bodies. After photosynthesis, food is stored in the form of cyanophycean starch, lipid globules and protein granules. Cyanophycean starch granules (alpha-1, 4-linked glucose) are a major part of stored food. It is often found near the cross-walls of filamentous forms.

Among the given options:
In cyanobacteria, general phosphate is stored as polyphosphate in polyphosphate bodies. They are also called volutin granules. Polyphosphate bodies contain metals like potassium, calcium, and magnesium and they are energy-rich compounds that act as a reserve store of energy and of phosphate.

Cyanophycin (CGP) is a nitrogen/carbon reserve polymer present in most cyanobacteria. It is a non-ribosomally manufactured polyamide having aspartate and arginine. It is known as a highly bioavailable source for arginine, lysine, Asp, and perhaps all other amino acids.

Cyanobacterial lipid droplets (LDs) are considered as hydrophobic energy-dense compounds. They are located throughout the cell and have great potential for biotechnological expression and the compartmentalization of high value compounds.

So, the correct answer is option A.

Note: Cyanobacteria are among the most successful autotrophic organisms on earth which exist in all types of environment. They are the most selfed photosynthetic organisms.