Test: Biological Classification 6 - From Past 28 Years Questions - NEET MCQ

Plasmodium transmitted through female Anopheles mosquito to Human and the most favourite dwelling place for Anopheles is water or moist places like ponds and puddles.

Schizogont or Asexual stage occurs in human erythrocytes and liver cells.

H. Temin and D. Baltimore (1970) discovered that tumor viruses contain RNA as genetic material and replicate by synthesizing complementary DNA. This process is called reverse transcription and it is carried by an RNA dependent DNA polymerase called as reverse transcriptase.

All viruses are nucleoprotein (Nucleic acid + Protein) in the structure. The nucleic acid (DNA and RNA) is genetic material. In a particular virus either DNA or RNA is genetic material never both are present in a virus. Hence viruses are : (i) Double stranded  DNA or ds DNA - Hepatitis B (ii) Single stranded DNA or ss DNA - coliphage (iii) Double stranded RNA or ds RNA - Reo virus, wound Tumor virus (iv) Single stranded RNA or ss RNA - Tobacco mosaic virus (TMV)

Besides Nuclear DNA, bacteria possesses extranuclear DNA (outside the nucleoid region) called as plasmid which can replicate independently. Due to this property plasmid holds great importance in genetic engineering. Plasmid can be taken out of bacteria and made to combine with desired DNA segment. A plasmid carrying DNA of other organism now it is known as cosmid which can be introduced into any desired cells. This is the basis of genetic engineering.

The term antibiotics was coined by Waksman but the first known antibiotic, penicillin was extracted from fungi  Penicillium notatum by A Flemming 1944. Antibiotics are the chemicals that are produced from the living organisms, used to  kill another living organisms. About 2300 antibiotics discovered so far e.g. Streptomycin, Tetracycline etc.

Some of the blue green algae can tolerate extremes of temperature due to presence of gelatinous sheath, and compactness of protein molecules in protoplasm.

Azotobacter is nonsymbiotic, free living nitrogen fixing bacteria.

Rickettsias are tiny obligate, intracellular parasites found in blood sucking insects like lices, mites, ticks. They were first observed by Ricketts 1909 but it was properly described by Rocha-lime 1916, who named them as  Rickettsia. They have mucopeptide cell wall with DNA as genetic material and are independent entity produces diseases like Q-fever, typhus etc

Only some bacteria and Blue green algae (cynobacteria) has capacity to fix atmospheric nitrogen.         

• Bacteria     :     Azotobacter, Rhizobium, Frankia etc.   
• Blue    green    algae    :        Nostoc, Oscillatoria, Anabaena etc.

Protistans are eukaryotes and their genetic material is organised in form of nucleus. DNA is associated with histone protein.

 Pyrrhoea is caused by bacterial infections along with other factor, Diarrhoea by caused by rotavirus along with many other factor. Dysentery by Entamoeba histolytica.

Members of kingdom Protista have diverse mode of nutrition. They are photosynthetic, saprophytic parasitic and ingestive. They are major  heterotroph.

Kingdom Protista includes flagellates (euglenophyceae), diatoms, dinoflagellates, slime moulds, sarcodines, ciliates, sporozoans. They are photosynthetic, chemotrophic, heterotropic in mode of nutrition.

The genus Ustilago includes the group of fungi producing lack, sooty powder mass of spores on the host pl(mt peris imparting them a burnt appearance, hence, the name, the black dusty masses of spores produced by these fungi resemble soot or smut, so these are also known as smut fungi.

So, the correct answer is 'They develop sooty masses of spores.'.

The fungus that causes the disease ‘Ergot of Rye’ is  Claviceps purpurea.  It contains many poisonous alkaloids. The hallucinogenic drug LSD is extracted from this fungi.   

• Rust     of      wheat     is     used     by     Puccinia graminis.
• Powdery     Mildew     of      Pea     is     caused     by  Erysiphae.

Decomposers act on dead bodies converting complex organic constituents into simple soluble form.
They obtain their energy from dead organisms. Decomposers themselves are organisms (often fungi, earthworms, or bacteria) that break down organic materials to gain nutrients and energy. Decomposers accelerate the natural process of decomposition. They supply the required nutrients for other trophic levels.

The fungi on the tree are decomposers.
When an organism dies, it leaves behind nutrients that are locked tightly together. A scavenger might eat the carcass, but its feces would still contain a considerable amount of unused energy and nutrients. Decomposers will later induce further breakdown. This last step releases raw nutrients (such as nitrogen, phosphorus and magnesium) in a form usable to plants, which quickly incorporate the chemicals into their own cells. This process greatly increases the nutrientload of an ecosystem, in turn allowing for greater biodiversity. 

Mycorrhiza is symbiotic association between fungi and roots of higher plants. Mycorrhiza form wooly covering of fungal hyphae on the surface and remain in upper layers. It is of two types Ecto and Endomycorrhiza. In some endomycorrhiza, the fungal hyphae develop some organs called vesicles within the root cortical cells, such mycorrhizae are called VAM (vesicular arbuscular mycorrhizae) . It is meant for phosphate nutrition.

The term ‘plasmid’ was  introduced by Lederberg in 1952 for extragenomic DNA segment. It is a small circular molecule of DNA found in bacterial cell in addition to the larger circular bacterial DNA.

The Euglena is an organism, which possesses both the characteristics of plants and animals, as it can move with a flagella and also contains chlorophyll. Its nutrition is mixotrophic.

In protozoa, the function of contractile vacuole is the removal of excretory substances, carbon dioxide etc. It is very essential to regulate water content i.e., osmoregulation.

The macronucleus lacks nuclear membrane and is formed of trophochromatin. It regulates the metabolic activities of the body and it is also known as trophonucleus. The micronucleus has a definite nuclear membrane and controls the reproductive activities of Paramecium and Vorticella.

The conractile vacuole is supposed to assist excertion in Amoeba, as its watery contents possess traces of carbon dioxide and urea. The CO₂ diffuses directly through plasmalemma.

Fermentation refers to the breakdown of organic substances, particularly carbohydrates, under anaerobic conditions. Saccharomyces cerevisiae is used for fermenting carbohydrate. The ethyl alcohol and carbon dioxide are formed at the end of the process.

Covered smut of barley is caused by Ustilago hordei, not by Ustilago nuda. This disease is purely externally seed borned.