Which of the following diseases is caused by a virus?
A. Malaria
B. Cholera
C. Anthrax
D. Measles
Answer: Option D
Solution (By JKExamLibrary)
Measles (rubeola) is a highly contagious viral disease caused by the measles virus (a paramyxovirus), characterized by fever, cough, and a distinctive red rash. Anthrax is bacterial (Bacillus anthracis), malaria is protozoan, cholera is bacterial. Measles can be prevented by the MMR vaccine. It is a leading cause of child mortality in unvaccinated populations.
Explanation:
Oxytocin, produced in the hypothalamus and released from the posterior pituitary, triggers the milk let-down reflex by causing myoepithelial cells around alveoli to contract upon suckling. Prolactin stimulates milk synthesis. Estrogen and progesterone are involved in breast development during pregnancy but not the immediate ejection reflex.
Explanation:
A peptide bond is a covalent bond formed between the carboxyl group (-COOH) of one amino acid and the amino group (-NH₂) of another, releasing a water molecule (condensation reaction). Glycosidic bonds link monosaccharides, phosphodiester bonds link nucleotides in DNA/RNA, hydrogen bonds stabilize secondary structures. Peptide bonds create the polypeptide backbone.
Explanation:
Robert Koch identified Bacillus anthracis as the causative agent of anthrax in 1876, establishing Koch's postulates for proving microbial disease causation. Pasteur developed vaccines, Jenner smallpox vaccine, Lister antiseptic surgery.
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