Microbial Taxonomy and Diversity (GATE)

Correct answer:
1. Bacteria have closed circle of double-stranded DNA.
2. Bacteria have single chromosome without associated histones.
4. Bacterial ribosomes have a sedimentation rate of 70S.

Bergey's Manual of Systematic Bacteriology is known as Bible of bacterial taxonomy. Bacterial taxa, which have been correctly described, are reviewed in Bergey's Manual of Systematic Bacteriology, which aims to aid in the identification of species and is considered the highest authority.

Chemoheterotroph is the most common nutritional mode in prokaryotes. They use organic molecules as an energy source (for example, sugar) and use organic molecules as a carbon source (for example, proteins, sugars, fats, nucleic acids, etc.).

Correct answer.
Thiomargarita namibiensis and Epulopiscium fishelsoni are up to half a millimetre long and are visible to the unaided eye; Epulopiscium fishelsoni reaches 0.7 mm.

Amphitrichous: One flagellum attached at each end. It is of rare occurrence. For example, Nitrosomonas.

Bacteria were first observed by Antonie van Leeuwenhoek in 1676, using a single-lens microscope of his own design. He called them 'animalcules' and published his observations in a series of letters to the Royal Society.

In 1898, Nocard and Roux reported the cultivation of the causative agent of CBPP, which was at that time a grave and widespread disease in cattle herds. The disease is caused by M. mycoides subsp. mycoides SC (small-colony type) and the work of Nocard and Roux represented the first isolation of a mycoplasma species.

When starved of amino acids, Myxobacteria detect surrounding cells in a process known as quorum sensing. They migrate towards each other and aggregate to form fruiting bodies up to 500 micrometres long and contain approximately 1,00,000 bacterial cells. About one in 10 cells migrate to the top of these fruiting bodies and differentiate into a specialised dormant state called myxospores, which are more resistant to drying and other adverse environmental conditions than ordinary cells.

This is the correct answer because Q and S both are false statements. Correct statements are:

Q. Fimbriae are found in both motile and non-motile forms of bacteria.
S. F-pili or sex pili occur in donor bacteria having F^₊ or fertility factor.

A and R both are correct and R is not the correct explanation of A.

The botulism toxin has the effect of inhibiting the neurotransmitter, acetylcholine, which is required by a nerve to stimulate a muscle. As a result, a person who has ingested the botulism toxin suffers from flaccid paralysis, which can lead to death.

All the given characteristics are found in Bacillus thuringiensis; so this is a wrong answer.

Mycoplasma laboratorium is a chemically synthesised genome of a mycoplasmal cell based entirely on synthetic DNA which can self-replicate.

Correct answer because both P and R are true:

P. Cell membrane has ether-linked lipids and pseudopeptidoglycan.
R. Metabolism methods are methanogenesis and its various types.

Archaeal Richmond Mine acidophilic nanoorganisms (ARMAN) are archaea which were discovered in 2006 and are some of the smallest organisms known. They occasionally connect with other archaeal cells in acid mine drainage biofilms.