Question

Which one of the following living organisms completely lacks a cell wall?
A. Cyanobacteria
B. Sea-fan (Gorgonia)
C. Saccharomyces
D. Blue-green algae

Answer 1

Some types of cells are equipped with a cell wall which provides the cell rigidity, flexibility, protection, and structural support. Some eukaryotes such as plants, fungi, and protists have a defined cell wall. Whereas, animal cells have membrane-bound organelles and nucleus but lack a cell.

**Complete answer:**Cyanobacteria: Cyanobacteria are small, unicellular bacteria growing in colonies. They live in water-bodies and are photosynthetic in nature. These are also known as blue-green algae. As they are photosynthetic in nature they manufacture their own food. Cyanobacteria are one of the largest and most prominent groups of bacteria on earth and have been known to be as old as 3.5 billion years. They are the oldest known fossils. Cyanobacteria is equipped with a thick, gelatinous cell wall. Since cyanobacteria are living organisms that do have a cell wall. In fact, since cyanobacteria are also known as blue-green algae, one can conclude that option D is not the correct answer to the question.
Sea-fans (Gorgonian): Sea fans are also known as sea whips, sea corals, or Alcyonacea belong to the order of corals that do not participate in the production of calcium carbonate skeletons. These were
formerly known as Gorgonia and are found mostly in tropical and subtropical oceans. These are observed to be sessile colonial cnidarians that belong to the coelenterates phylum under kingdom Animalia. Since these are a group of animals, and as discussed earlier that animal cells lack a cell wall, therefore, Sea fan is a living organism that lacks a cell wall.
Saccharomyces: Saccharomyces belong to the fungi genus and include different species of yeast. It is also known as baker’s yeast or brewer’s yeast and is employed in various food products. Most
species of fungi consist of a distinct cell wall separated from the plasma membrane. The cell wall
determines the integrity and shape of the cell during cell division.
Hence, the correct answer is Option B

Note: Many species of fungi are employed in the production of food such as bread, wine, beer, and also in the production of pharmaceutical products. Saccharomyces cerevisiae var boulardii is a species of saccharomyces fungi used in medicines. Similarly, in the production of bread, wine and
beer the fungi species Saccharomyces cerevisiae.