The symbiotic nitrogen-fixing cyanobacterium in Azolla is: MCQ with Answer and Explanation

Explanation:
Transcription is the synthesis of mRNA from the DNA template strand by RNA polymerase. It occurs in the nucleus (eukaryotes). Replication is DNA duplication. Translation is protein synthesis from mRNA. Transformation is the uptake of foreign DNA by bacteria. The central dogma: DNA → RNA → Protein. Transcription produces mRNA, tRNA, rRNA. The mRNA carries the codon sequence for protein assembly.

Explanation:
Telomerase is a ribonucleoprotein enzyme that adds repetitive nucleotide sequences to the ends of chromosomes (telomeres), preventing them from shortening during DNA replication. It is highly active in germ cells, stem cells, and most cancer cells, granting them replicative immortality. In most normal somatic cells, telomerase is inactive, leading to gradual telomere shortening and cellular aging.

Explanation:
Antonie van Leeuwenhoek, using his hand-crafted single-lens microscopes, was the first to observe and describe living sperm cells, bacteria, protozoa, and red blood cells in the 1670s. Hooke saw dead cork cells, Pasteur and Koch later advanced microbiology with germ theory and pure culture techniques.