NEET Practice Questions (MCQs) with Answers & Solutions

All statements are true except II.

Conjugation is process of transfer of genetic material that involve cell to cell connection. It was first reported in E. coli by Tatum and Lederberg in 1946. Transduction is a process of transfer of DNA by bacteriophage virus in bacteria. It was first reported in the Salmonella by Zinder and Lederberg in 1952. Gram staining is based on the composition or size of bacterial cell wall as gram +ve bacteria has thick cell wall compare to gram –ve bacteria.

Total number of bacteria produced = 2ⁿ

$n=\frac{\mathrm{Total} \mathrm{time}}{\mathrm{Time} \mathrm{of} \mathrm{division}}=\frac{175}{35}=5$

Thus, after 5 divisions total number of bacteria will 2⁵ = 32. Initially there are 10⁵ bacteria/mL and therefore, after 175 minutes, the concentration of bacterial cell will be 32 × 10⁵ or 3.2 × 10⁶ cells/mL.

In the fungus Agaricus, dikaryotisation (n + n) is brought about by two processes: clamp connections and somatogamy between two hyphae of different strains. Clamp connections allow the transfer of nuclei between adjacent cells, while somatogamy involves the fusion of two compatible hyphae.

Heterothalism was discovered by AF Blackeslee (1904) in Rhizopus stolonifer. In this phenomenon, fungi shows fusion of gametes which belong to genetically, morphologically and physiologically dissimilar mycelia normally referred as positive and negative strains.

The slime moulds (or moulds) make up two unique and interesting phyla of kingdom-Protista. The cellular slime moulds are now classified with Protozoa (Amoeba) due to their evolutionay closeness and having amoeboid stage.

The other phyla of slime moulds are Plasmodial. Slime moulds belongs to Myxomycota.

Spirochaetes are spiral-shaped or helically coiled bacteria belonging to the phylum Spirochaetes. They are gram-negative, motile, and have unique endoflagella enclosed within the outer sheath.

Clamp connections are specialized structures found in the hyphae of Basidiomycetes. They facilitate the transfer of nuclei during the sexual reproduction process, ensuring the maintenance of a dikaryotic state.

Diatoms have unique double shells made up of opaline silica.

Ergotamine tartrate is an ergot alkaloid derived from the fungus Claviceps purpurea, which infects rye and other cereals. It is primarily used in the treatment of migraine headaches and other vascular headaches.