Question

Membrane-bound organelles are absent in-
a. Plasmodium
b. Saccharomyces
c. Streptococcus
d. Chlamydomonas

Answer 1

Streptococcus is a heterogeneous group of Gram-positive bacteria that belongs to prokaryotic organisms and is a single-celled organism that does not have a separate nucleus with a membrane or other complex organelles. The Prokaryotes include the archaea and bacteria.

_Complete answer: _

Option A is incorrect. Plasmodium is a eukaryotic unicellular organism that belongs to Kingdom Protista. They are essential vertebrate and insect parasites. Plasmodium species are spread globally anywhere they can find suitable hosts. Most commonly, insect hosts are mosquitoes of the Culex and Anopheles genera.
Option B is incorrect. Saccharomyces is a genus of fungi containing several yeast species. They are both saprotrophic and unicellular fungi. Many members of this genus are presumed very important in the production of food. Saccharomyces cerevisiae (Yeast) is eukaryotic since it has a well-defined nucleus and organelles bonded to the membrane.
Option C is correct. Streptococcus is a genus of gram-positive coccus that is characteristically round or ovoid in shape, non-motile, non-spore forming bacteria, lacking an organelle-bound membrane and belonging to the Streptococcaceae family. They live in different pairs or chains. Most Streptococci are optional anaerobes while some are obligatory anaerobes.
Option D is incorrect. Chlamydomonas Is a cup-shaped oval green alga, unicellular flagellates found in polluted water and saturated soil, in fresh water, in seawater and even in snow as "snow algae." They include membrane-bound organelles, indicating that these organelles (e.g. mitochondria, lysosome, etc.) are surrounded by a bilayer (membrane) of phospholipids.

>So, the correct answer is Option C.

Additional information:
Prokaryotes are unicellular species that lack a true nucleus, such as chloroplast, mitochondria, golgi complex, membrane-bound organs. They have chosen nucleoid, a genetic material without a nuclear shell. They have walls of cells. Examples include Streptococcus bacteria, Blue-green algae. Plasmodium is a blood sucking protozoan species that injects parasites into the bloodstream of their host, destroying the host's red blood cells and contributing to sickness, called malaria. Chlamydomonas is a eukaryote which is a single cell. Saccharomyces is a yeast. All these are eukaryotes and have organelles attached to the membrane.

Note: In Streptococcus, the membrane bound organelles are absent. Since they are spherical gram-positive bacteria belonging to the prokaryotic organism group and compared to a eukaryotic cell, the only comparable organelles found in prokaryotes are naked nucleoprotein particles ribosomes.