Question

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

Answer 1

Membrane bound organelles are the structures within the cell that are bound by a membrane such as the mitochondria, chloroplast, etc they are present in the eukaryotic cells but are absent in the unicellular prokaryotes. For example- bacteria.

Complete answer:
Membrane bound organelles such as mitochondria and chloroplasts are generally not seen in unicellular prokaryotic organisms which belong to the kingdom monera. They are absent in bacterial species known as streptococcus.

Bacteria belong to the kingdom monera and are prokaryotic organisms and hence the membrane bound cell organelles are absent in them.

Hence, the correct answer is option (C).

Additional information:
• Chlamydomonas is a species of unicellular eukaryotic organisms that were formerly classified under the kingdom protista.
• Plasmodium is also a unicellular eukaryotic organism belonging to the kingdom protista. Since it is a eukaryotic organism it processes membrane bound cell organelles.
• Saccharomyces is a species of unicellular eukaryotic fungi which belong to the kingdom mycota. Some examples of membrane bound organelles are mitochondria , chloroplast, golgiapoartus, lysosomes etc.
• According to the endosymbiotic hypothesis, the membrane-bound organelles i.e. the mitochondria and the chloroplasts were used to be prokaryotic cells which were engulfed by the eukaryotic cells and over a long period of time they developed a symbiotic relationship. This can be supported by the fact that their DNA and 70s ribosomes are present in them which is the characteristic feature of prokaryotic cells.

Note: All the eukaryotic cells do not possess all the membrane bound organelles.
• Mitochondria which are present in almost all of the eukaryotic cells, acts as the energy producing machinery. Moreover, they are absent in certain cells that do respire anaerobically, one such example is mammalian RBCs.
• Chloroplasts are also membrane bound organelles that are found only in the plant kingdom and in some certain unicellular eukaryotes like euglena which do perform photosynthesis.