Tag: non cellular organism : virus

  E. coli , a gram negative rod shaped bacteria has since the time of discovery have been commonly used for biological lab experiment and research. The simple cell structured E. coli has one circular chromosome and a ds circular DNA molecule with 4.6 million base pairs in length and 4288 protein coding genes.

The cell walls of bacteria are composed of a macromolecule peptidoglycan which is a repeating framework of long glycan chains having alternate N-acetyl glucosamine and N-acetyl muramic acid; these glycan chains are cross-linked by short peptide fragments to provide a strong but flexible support framework. This makes option A correct. The green algal cell wall is composed mainly of cellulose which makes option B incorrect. Chitin is common constituent of cell walls of all type of fungi; option C is incorrect. The yeast cell wall itself is mainly composed of glucans ($\beta$$-glucans), mannoproteins and chitin; option D is incorrect. Thus, the correct answer is option A.

Amoeba is a protozoan belonging to the kingdom Protista. They are unicellular eukaryotic organisms and thus, made up of single cell.

Microorganisms are the organisms that we cannot see by our naked eyes. It can be prokaryotic unicellular like bacteria, eukaryotic unicellular like protozoa, eukaryotic multicellular like fungi and algae and even acellular like viruses.

Thus, the correct answer is option C.

Unicellular organisms are made up of a single cell and perform all the life processes for survival and independent existence.  Hence, the cell is called as the fundamental structural and functional unit of life.

Pili are minute hair like appendages, that emerges from suface of Gram -ve bacteria. They have similar structure as flagella and often involved in attachment to surface and making of biofilm. They also help in DNA exchange. They are involved in conjugation which results in transfer or exchange of genetic material. 

The reproduction in amoeba is asexual, called binary fission, where it replicated its cells by mitosis and its cell divide in two equal daughter cells. Amitosis is similar to binary fission. Meiosis does not take place in amoeba.

The correct answer is B. 

Amoeba takes its food by the method of phagocytosis (i.e ingesting or engulfing the food particles), also by means of pinocytosis (wherein amoeba wraps around its membranes around the food forms vesicles and pinch it inside the membrane and then gradually digests it) and by endocytosis (in which the outermost the membrane of amoeba either stretches inwards or projects outwards to obtain nutrition.

The correct answer is D.