Biological Classification Test 7

Methanogens , Halophiles , Thermoacidophils , all belong to ARCHAEBACTERIA. They are primitive organisms which means they were the first to inhabit earth . They are often called LIVING FOSSILS. Methanogens are found in Rumen of cattles , Halophiles are found in salt lakes , Thermoacidophils are found in hot sulphur springs and Archaebacteria are found in some of the harsh climatic conditions where no other life form could survive.

In blue green algae, photosynthesis takes place in Lamellasome.

These are a result of blue-green algae, which are actually bacteria (cyanobacteria). Some algal blooms are the result of an excess of nutrients (particularly phosphorus and nitrogen) in waters and higher concentrations of these nutrients in water cause increased growth of algae and green plants.

Fungi are eukaryotic, multicellular organisms while Streptomyces is a prokaryotic, unicellular filamentous bacterium that reproduces by fission or conidia and hence, placed under Actinomycetes and not under Fungi, Eubacteriales (rod-shaped and reproduce by endospores) and virus. 

Cyanobacteria is the modern name of Myxophyceae. It is also called blue-green algae. It is a prokaryotic photosynthetic organism.

Since cyabobacteria belongs to kingdom monera, it also has 70S type ribosome like other bacteria, so, option a is correct. As for the dna it is double stranded, circular & naked, so option b is also correct. Being a gram -ve moneran, its wall has peptidoglycan like other gram -ve bacterias, so option c is also correct. Therefore correct answer is option d.

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 a common constituent of cell walls of all types of fungi; option C is incorrect. 
The yeast cell wall itself is mainly composed of glucans mannoproteins and chitin; option D is incorrect. 

Mesosomes are structures of prokaryotic cells formed by folded invaginations (sometimes described simply as "infoldings") of the plasma membrane. Enzymes associated with respiration of the prokaryotic cell, e.g. a bacterium, are located on the infoldings.

Nitrogen fixation is utilized by numerous prokaryotes, including bacteria, actinobacteria, and certain types of anaerobic bacteria. Microorganisms that fix nitrogen are called diazotrophs. Some higher plants, and some animals (termites), have formed associations (symbioses) with diazotrophs. 

Heterocysts are larger cells with thick walls and one or more pores. They are the active site of protein synthesis and rich in nitrogenase and hydrogenase enzymes which in turn serve in nitrogen fixation. 

All the prokaryotic organisms lack membrane bound organelles. They lack true nucleus i.e. nuclear membrane, mitochondria, golgi body, endoplasmic reticulum, vacuoles, lysosomes and others because they are membrane bound organelles. Now cell division in prokaryotic organisms occurs by the process of amitosis which does not include spindle fibre formation. Chromosomes do not differentiate. The nucleus elongates and constricts in the middle and divides into 2 daughter nuclei. so prokaryotic cells do not contain the Golgi body and also do not form spindle fibres.

A prokaryote is a unicellular organism that lacks a membrane bound nucleus mitochondria ,or any other membrane bound organelle.

Trichodesmium erythraeum is a red coloured blue-green alga which is responsible for the red colour of the Red Sea. Its cell wall is made up of several layers of mucoprotein and other polysaccharides and lipopolysaccharides but lack cellulose and mannans which are the chief components of cell walls of red algae; this makes option B incorrect and option A correct.

Unlike bacteria, archaea cell walls do not contain peptidoglycan. Archaea have different membrane lipid bonding compared to Bacteria and Eucarya.

The most numerous intracellular structure is the ribosome which is the site of protein synthesis in all living organisms. All prokaryotes have 70S (where S=Svedberg units) ribosomes while eukaryotes contain larger 80Sribosomes in their cytosol. The 70S ribosome is made up of a 50S and 30S subunits.

Nostoc, is genus of blue-green algae with cells arranged in beadlike chains that are grouped together in a gelatinous mass. Like most blue-green algae,Nostoc contains two pigments, blue phycocyanin and red phycoerythrin, as well as chlorophyll, and has the ability to fix nitrogen in specialized cells called heterocysts. This makes them photosynthetic.

Mycoplasma is a prokaryote having no cell wall so they are also called "bacteria with their coats off".They are resistant to penicillin because penicillin acts as a cell wall and they are wall less.

Heterocyst is a transparent thick walled empty cell which is present in intermittent position in filaments of BGA. They are the site of nitrogen fixation and hence, carry the enzymatic machinery for the same. Nitrogenase is a multi-subunit enzyme complex containing iron, sulphur, molybdenum. It catalyzes reduction of nitrogen to ammonia. 

Binary fission ("division in half") is a kind of asexual reproduction. It is the most common form of reproduction in prokaryotes such as bacteria. It occurs in some single-celled Eukaryotes like the Amoeba and the Paramoecium. In binary fission, DNA replication and segregation occur simultaneously.

A cell wall is a layer located outside the cell membrane found in plants, fungi, bacteria, algae, and archaea. A peptidoglycan cell wall composed of disaccharides and amino acids gives bacteria structural support. The bacterial cell wall is often a target for antibiotic treatment.

Actinomyces is a genus of the Actinobacteria class of bacteria. They are all gram-positive. Actinomyces species may form endospores, and, while individual bacteria are rod-shaped, Actinomyces colonies form fungus-like branched networks of hyphae.

Prokaryotes have no well defined nucleus. The genetic material is basically naked, not enveloped by nuclear membrane.Cell wall of prokaryotes is made up of peptidoglycan which is a type of mucopeptide.

Diaminopimelic acid (DAP) is an amino acid, representing an epsilon-carboxy derivative of lysine. DAP is a characteristic of certain cell walls of some bacteria. DAP is often found in the peptide linkages of NAM-NAG chains that make up the cell wall of gram-negative bacteria.

Some blue-green algae can produce toxins, some do not. However, exposure to any blue-green algae blooms can cause health effects in people and animals when water with blooms is touched, swallowed, or when airborne droplets are inhaled.

Mesosome is an extension of the cell membrane presence in cytoplasm as infolding and serves to increases surface area in photosynthetic prokaryotes, cyanobacteria, wherein it carries the photosynthetic pigments. Mesosomes serve in DNA replication and guide distribution of duplicated bacterial chromosomes into the two daughter cells during cell division. They also carry the enzymes for aerobic respiration and increase the surface area for the same. This makes option C correct answer. Mesosomes do not contain the enzymes for nitrogen fixation which makes option D incorrect. Thus, the correct answer is option C..

Anabaena is a free living nitrogen fixing BGA. But with azolla pteridophyta, it can be a symbiotic nitrogen fixing cyanobacteria, mainly used as bio fertilizer in paddy fields.

Prokaryotic cells contain a single compartment enclosed within the cell membrane. Prokaryotes lack a well defined nucleus (which is where DNA and RNA are stored in eukaryotic cells), mitochondria, ER(Endoplasmic reticulum), Golgi apparatus, and so on.

Blue-green algae are oxygenic phototrophic bacteria with mucopeptide cell wall. Their cell wall is covered with a gelatinous sheath which makes the ground surface in rainy seasons slippery. Fungi have a tough chitinous cell wall and bryophytes have a cellulosic cell wall, they do not have any gelatinous covering on it. Slime moulds are amoeboid protists that lack cell wall but have slime layer. Being chemoheterotrophs, they are found among the decaying organic matter. Bryophytes are amphibians of the plant kingdom. They can survive on land as well as water.

Cyanobacteria (blue-green algae) are oxygenic phototrophic bacteria carrying out water-splitting, O₂ -releasing (viz., plant-type) photosynthesis and water-forming, O₂ -reducing respiration in one and the same “noncompartmentalized” prokaryotic cell .

The algal form myxophyceae or commonly called blue green algae do not have any sexual organs and no motile reproductive bodies have been observed till now .