Jointed appendages are the defining characteristic of which phylum? MCQ with Answer and Explanation

Explanation:
Genes are specific sequences of DNA that code for proteins or RNA, and they are arranged linearly on chromosomes within the nucleus. DNA replication is semi-conservative, meaning each newly synthesized DNA molecule consists of one original parental strand and one newly synthesized strand, as proven by the Meselson-Stahl experiment. RNA is typically single-stranded, allowing it to fold into complex shapes and perform various functions, unlike the double-stranded DNA helix. Thus, statements 1 and 2 are correct.

Explanation:
Typhoid fever is caused by Salmonella typhi, transmitted via contaminated food/water, causing high fever, abdominal pain, and rose spots. Widal test is used for diagnosis. Cholera is Vibrio cholerae, TB Mycobacterium, dysentery Shigella or Entamoeba.

Explanation:
Louis Pasteur developed the first rabies vaccine in 1885, using dried spinal cords from infected rabbits. Jenner developed smallpox vaccine, Koch identified tuberculosis bacterium, Salk developed inactivated polio vaccine.