The first antibiotic, Penicillin, was extracted from which microorganism?
A. Virus
B. Fungus (Penicillium notatum)
C. Actinomycete
D. Bacterium
Answer: Option B
Solution (By JKSSB Mock Tests)
Penicillin, the first true antibiotic, was discovered by Alexander Fleming in 1928. He observed that a mold contaminating a Staphylococcus culture plate was inhibiting bacterial growth. The mold was identified as Penicillium notatum (now P. chrysogenum). Penicillin is extracted from this fungus and is effective against many Gram-positive bacteria.
Consider statements about ecology: 1. A population includes all species in an area. 2. A community includes only interacting populations. 3. An ecosystem includes both biotic and abiotic components. Which are correct?
Explanation:
A population consists of individuals of a single species living in a specific area, not all species. A community comprises all the interacting populations of different species living together in a defined area. An ecosystem is a functional unit of nature encompassing both the biotic (living community) and abiotic (physical environment) components, interacting as a system. Only statement 2 is strictly correct in its definition.
Explanation:
Poliovirus attacks motor neurons in the spinal cord and brainstem, causing paralysis. It spreads via the fecal-oral route. Vaccination (IPV/OPV) has almost eradicated it globally. The virus replicates in the intestine and then invades the nervous system. Polio survivors may suffer post-polio syndrome later.
Explanation:
Mycoplasma is a genus of bacteria that naturally lack a cell wall; they are the smallest known free-living organisms. Their membrane contains sterols providing some rigidity. Other bacteria typically have peptidoglycan cell walls. Fungi have chitinous walls, plant cells have cellulose walls. The absence of cell wall makes Mycoplasma pleomorphic and resistant to antibiotics targeting cell wall synthesis like penicillin.
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