Which of the following is a bacterial STD? MCQ with Answer and Explanation

Explanation:
HIV attacks CD4+ T helper cells, progressively weakening the immune system, leading to AIDS, characterized by opportunistic infections and cancers. Hepatitis is liver inflammation often viral, tuberculosis is bacterial, leukemia is cancer of white blood cells. Antiretroviral therapy (ART) controls HIV replication.

Explanation:
Angiosperms are flowering plants where seeds are enclosed within a mature ovary (fruit). They are characterized by double fertilization, where one male gamete fuses with the egg and the other with the secondary nucleus. They exhibit immense diversity in habit, ranging from tiny aquatic Wolffia to massive trees, so not all are trees. Statements 1 and 2 are correct.

Explanation:
The central dogma, proposed by Francis Crick, describes the flow of genetic information from DNA to RNA (transcription) and then to protein (translation). Information cannot flow from protein to nucleic acid. However, exceptions exist: reverse transcription (RNA → DNA) in retroviruses, and some regulatory RNA functions. The fundamental principle still holds.