The scientist who isolated the first antibiotic, penicillin, from Penicillium notatum was:
A. Alexander Fleming
B. Howard Florey
C. Ernst Chain
D. Selman Waksman
Answer: Option A
Solution (By JKSSB Mock Tests)
Alexander Fleming discovered penicillin in 1928. Florey and Chain later purified it and demonstrated its therapeutic potential. Waksman discovered streptomycin. The discovery of penicillin revolutionized medicine.
Consider statements about microorganisms: 1. Bacteria reproduce by binary fission. 2. Viruses have their own metabolic machinery. 3. Fungi have a cell wall made of chitin. Which are correct?
Explanation:
Bacteria are prokaryotes that primarily reproduce asexually through binary fission, where a single cell divides into two identical daughter cells. Fungi are eukaryotes characterized by having cell walls primarily composed of chitin, a tough polysaccharide. Viruses lack cellular structure and metabolic machinery; they are obligate parasites that rely entirely on the host cell's machinery for replication. Thus, statements 1 and 3 are correct.
Explanation:
Estrogen promotes ductal growth in breasts and deposition of fat, contributing to breast development at puberty. Progesterone develops alveoli, prolactin synthesizes milk, oxytocin ejects milk.
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