Nucleoid is present in

Identify the correct group of prokaryotic cells from the following list:
$1.$ Egg of ostrich,$2.$ $PPLO$,$3.$ Tracheid,$4.$ Blue-green algae,$5.$ Bacteria,$6.$ Animal cells.

In photosynthetic bacteria,pigments are present in ..........

Read the sentences properly and select the correct option for mesosome.
$(i)$ Mesosome is an extension of the plasma membrane.
$(ii)$ These extensions are only in the form of spheres.
$(iii)$ Mesosomes help in cell wall formation and $DNA$ replication (not $RNA$ synthesis).
$(iv)$ They help in respiration.

Infoldings of the plasma membrane of gram-positive bacteria give rise to:

The $DNA$ of $E. coli$ is