Test: Biological Classification 5 - From Past 28 Years Questions - NEET MCQ

Phytoalexins are non-specific antibiotic substances produced by plants in response to infection by a fungus.

Albugo candida is an obligate parasite causing white rust on members of family Cruciferae and other hosts.

Azotobacter and Bacillus polymyxa are the examples of non-symbiotic nitrogenfixers.

Sex-factor or F-factor in bacteria results in high frequency conjugation. It allows bacteria to produce sex pilus necessary for conjugation.

Influenza virus is a retrovirus wherein, the genetic material comprises of  RNA.
There are three genera of influenza virus, identified by antigenic differences in their nucleoprotein and matrix protein:   

• Influenza     virus     A     are     the     cause     of      all flu pandemics and are known to infect humans, other mammals and birds (see also avian influenza).         
• Influenza     virus     B     are     known     to     infect humans and seals.         
• Influenza     virus     C     are     known     to     infect humans and pigs. 

Bacterial chromosomes comprise of circular DNA.

Interferons are virus induced proteins produced by cells infected with viruses. They are antiviral  in action.

Lichens are composite dual organisms formed by the association between a  fungus and a photosynthetic symbiont. The bulk of lichen body is formed of fungus.

Association of algae and fungi is referred to as lichen. Symbiotic association of Rhizobium with roots of leguminous plants is referred to as symbiosis. Mycorrhiza is symbiotic association between fungi and roots of higher plants. The fungal partner of mycorrhiza obtains food from roots of the higher plant and in return supplies mineral elements to it.

In any kind of Bacteria (E.coli) double stranded DNA is present.

Plasmids are the extrachromosomal DNA.

Viruses have either DNA or RNA as the genetic material. Viruses having RNA as the genetic material are known as Retroviruses.

The lichen fungus is typically a member of the Ascomycota rarely a member of the Basidiomycota. The algal or cyanobacterial cells are photosynthetic, and as in higher plants they reduce atmospheric carbon dioxide into organic carbon sugars to feed both symbionts. Both partners gain water and mineral nutrients mainly from the atmosphere through rain and dust. The fungal partner protects the alga by retaining water, serving as a larger capture area for mineral nutrients and, in some cases, provides minerals obtained from the substratum. If a cyanobacterium is present, as a primary partner or another symbiont in addition to green alga as in certain tripartite lichens, they can fix atmospheric nitrogen, complementing the activities of the green alga.

Escherichia and Agrobacterium are both used as vectors in genetic engineering. Nitrobactor converts nitrites to nitrates. Azotobacter is a free living nitrogen fixing bacteria. Nitrosomonas converts ammonia to nitrite. Rhizobium is a symbiotic nitrogen fixing bacteria living in the root nodules of  leguminous plants Diplococcus pneumoniae causes pneumonia.

Bacteria acts as decomposers in the carbon cycle.

These are archaebacteria  which can tolerate high temperature.

Transfer of genetic information from one bacterium to another by physical contact is called conjugation while if it takes place by some other medium like virus than it is called transduction.

Puccinia causes black rust of wheat . It completes  its life cycle in two hostswheat and barberry. Two types of spores are produced on  wheat - uredospores and teleutospores. 

Aspergillus niger is known as guinea pig of kingdom fungi. The main source of commercial preparation of citric acid is the fermentation of sugar with Aspergillus niger.

Yeast performs alcoholic fermentation because of enzyme ‘Zymase’. It is used in the production of ethyl alcohol or ethanol.

Azolla is a freshwater fern harbouring a bluegreen alga - Anabaena in its leaf cavities. The alga fixes atmospheric nitrogen and releases nitrogenous compounds in leaf cavities. This symbiotic system is the main source of algal biofertilizer in rice fields. When rice paddies are flooded in the spring, they can be inoculated with Azolla, which then quickly multiplies to cover the water, suppressing weeds. As the plants die, they contribute nitrogen to the rice plants, and as the rice paddy dries out, the Azolla all eventually die, making an exceptional green manure.

Chloroplasts, chromoplasts and leucoplasts are the types of plastids found in higher plants. Chloroplasts contain the green pigment chlorophyll. Chromoplasts contain coloured pigments. Leucoplasts are colourless and store starch granules.

In prokayotes nucleoid consist of double stranded circular DNA without histone protein.

Aspergillus is a fungus, Mucor is also a fungus. Azolla harbours blue-green algae Anabaena which fixes N2, increasing fertility.

Enzymes are absent in viruses because they are unable to transmit their nucleic acid from one host cell to another.