Biological Classification Test - 13

Their peptidoglycan layer is thin and does not retain crystal violet stain like Gram- positive bacteria do.

Protists do not have a unifying characteristic other than being eukaryotic; they do not fit into the kingdoms of Plantae, Animalia and Fungi.

Endospores are able to survive a wide range of conditions.

All viruses are characteristically obligate parasites and nucleo-protein in nature. But the nature of genetic material may vary among viruses. In plant viruses, the genetic material is characteristically RNA, except cauliflower mosaic virus, where it is DNA.

Pseudomycelium is characteristic feature of yeast.

The kingdoms were named Monera, Protista, fungi, plantae and Animalia. Four kingdoms contain eukaryotes except kingdom Monera, which contains prokaryotes.

The symbiotic association of fungi and algae is called lichen.

Rhizopus (pin mould or black mould) grows on bread and hence also called bread mould.

It is the first stage of sexual reproduction in which the cytoplasm of two sex cells fuse with each other. The nuclei of sex cells come close to each other but do not fuse. Thus, the resulting cell becomes binucleate or dikaryon.

Robert Koch (1882) working on bacterial diseases, postulated certain fundamental laws of diseases known as Koch's postulates.

Claviceps purpurea is a fungus which causes ergotism in rye (Secale cereale) and other plants. It also yields a hallucinogenic drug called LSD.

Virus is a small infectious agent that replicates only inside the living cells of other organisms. Viruses can infect all types of life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses can pass through bacterial proof filters as they are smaller than bacteria.

Archaebacteria is a primitive group of bacteria. The three main groups of archaebacteria are methanogens, halophiles and thermoacidophiles. Methanogens are found in the musk of swamps and marshes, the rumen of cattle sewage, sludges and gut of termites. Halophiles are named so because they usually occur in salt rich substrata like salt pans, salt beds and salt marshes.

Thermoacidophiles have dual ability to tolerate high temperature as well as high acidity. They often live in hot sulphur springs where the temperature may be as high as 80°C and pH as low as 2.

Generation time is 40 minutes.

∴ Number of divisions is \({\frac{240}{40}}\)

Number of bacteria are

\(2^n = 2^6\times10^7\)

= \(64\times10^7\)

Oscillatoria is a photosynthetic cyanobacterium. In this cyanobacterium during photosynthesis water is electron donor and oxygen is a by-product. i.e. oxygenic photosynthesis occurs.

Rhodospirillum and Chlorabium are non-oxygenic photosynthetic, purple non-sulphur and green-sulphur bacterium.

Chromatium is purple sulphur bacterium, also a non-oxygenic photosynthetic.

Mesosomes are areas in the cell membrane of prokaryotic (bacterial) cells that fold inward. They play a role in cellular respiration, the process that breaks down food to release energy. Instead, they use the mesosomes as a site for the electron transport chain.

Amoebiasis or amoebic dysentery is caused by protozoan parasite Entamoeba histolytica that resides in the upper part of large intestine. It spreads through contaminated water and food contaminant form (trophozoite) or cyst of Entamoeba.

Trophozoite damages intestinal wall by engine histolysis, reaches blood capillaries and feed on RBCs, bacteria, tissue debts, resulting in abdominal. pain, acidic motions with mucus and blood. The disease can be prevented by drinking boiled and clean water and intake of fresh and hygienic food.

All bacteria possess cell wall. However, the bacteria are classified as Gram positive bacteria and Gram-negative bacteria on the basis of their cell wall. Cell wall of Gram-positive bacteria consist of multiple layer of peptidoglycan. Cell wall of Gram-negative bacteria is made up thin layer of peptidoglycan. In addition, they have one more outer layer of lipopolysaccharide (LPS).