Biological Classification Test - 9

Sex factor of bacteria is F-factor or fertility factor. It is present in its plasmid. F-factor contains genes for producing sex pili and other characters needed for gene transfer. It has a molecular mass of about 250,000 daltons. These are transfer factor and possessed by male or donor cells.

Lichens are formed by the symbiotic association between algae and fungi and have a unique morphology distinct from both partners. Litmus is a blue dye extracted from various species of lichens especially Rocella tinctoria. Lichens are very sensitive to sulphur dioxide pollution in the air. If air is very badly polluted with sulphur dioxide there may be no lichens present. They are sensitive to sulphur dioxide, because their efficient absorption systems result in rapid accumulation of sulphur when exposed to high levels of sulphur dioxide pollution. The growth rate of lichen is very slow even less than a millimeter per year and this property is used to determine the age of exposed rock.

A 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. All viruses are obligate parasites; i.e., they lack metabolic machinery of their own to generate energy or to synthesize proteins, so they depend on host cells to carry out these vital functions. Thus, option C is correct.

Viruses do not possess their own metabolic system. So, depends on host machinery. Thus, option A is wrong.

All viruses contains either DNA or RNA as genetic material but, not both. Thus, option B is wrong.

The protein coat of virus is called as capsid. Thus, option D is wrong.

Carbon is a component of all organic compounds of protoplasm like carbohydrates, lipids, proteins, etc. It constitutes 49% of dry weight of organisms and is next only to water in abundance. Carbon cycling occurs through atmosphere, ocean and through living and dead organisms. Bacteria also play a very important role in carbon cycle. Decomposers contribute substantially to CO_2​ pool by their processing of waste materials and dead organic matter of land or oceans. The main role of bacteria in the carbon cycle involves digestion or breakdown of these waste organic compounds.

Thermoacidophiles (temperature and acid loving) archaebacteria are found .in hot sulphur springs. Although they are microscopic, single-celled organisms, they flourish under conditions which would kill higher organisms. These are aerobic bacteria and have the capacity to oxidize sulphur to H2S04 at high temperature and high acidity (pH = 2.0). Some of them are also able to reduce sulphur to H2S under anaerobic conditions. As a rule, they grow best between 80° and 100°C and several species do not grow below 80°C.

Fungal spores produced asexually at tops or sides of hyphae are called Conidia. The tips of these conidiophores fragment into hundred of tiny haploid spores called Conidia.

The sexual reproduction of fungi involves three phases, namely plasmogamy, karyogamy and meiosis.

In plasmogamy, there is a fusion of two protoplasts that brings together two compatible nuclei within the same cell. This pair of nuclei is called as a dikaryon (resulting cell becomes bi-nucleate).

Thus, there is fusion of two haploid cells without nuclear fusion.

In case of lower fungi, plasmogamy is almost immediately followed by karyogamy but in higher fungi these two processes may be separated in time.

Fungi differ from Algae as they do not have chlorophyll and possess chitinised wall .

Algae belong to kingdom Protista while Fungi belong to kingdom Fungi. 

Algae are autotrophs having chlorophyll for photosynthesis where as Fungi are heterotrophs having no chlorophyll for photosynthesis as they obtain organic material from the souses in external environment. The cell wall of Algae is mainly composed of cellulose whereas the wall of Fungi is mainly composes of chitin.

The sexual reproduction of fungi occurs by means of oospores, ascospores and basidiospores. Spores are produced in distinct structures called fruiting bodies. The sexual cycle involves the following three steps:

(i) Fusion of protoplasms of two motile or non-motile gametes called plasmogamy.

(ii) Fusion of two nuclei called karyogamy.

(iii) Meiosis in zygote resulting in haploid spores

An RNA virus is a virus that has RNA (ribonucleic acid) as its genetic material. This nucleic acid is usually single-stranded RNA (ssRNA), but may be double-stranded RNA (dsRNA). In some viruses, RNA is present instead of DNA indicating that RNA can act to transfer heredity. They use RNA to transfer genetic information..