Consider the following statements about the human nervous system:
1. The sympathetic nervous system prepares the body for fight-or-flight.
2. The parasympathetic nervous system has a calming effect.
3. Both are part of the somatic nervous system.
Which of the above is/are correct?
Explanation:
Sympathetic (fight or flight) and parasympathetic (rest and digest) are divisions of the autonomic nervous system, not somatic. Thus, 3 is incorrect.
Explanation:
Cross: TT × Tt. Gametes: T (from TT) and T or t (from Tt). Offspring genotypes: TT and Tt. Both express the dominant phenotype because the recessive allele t is masked by T. No tt offspring are produced, so 0% show the recessive trait.
Explanation:
Fleming accidentally discovered penicillin in 1928 when a mold contaminant (later identified as Penicillium notatum/now Penicillium chrysogenum) inhibited bacterial growth. This led to the first widely used antibiotic. Aspergillus species produce some toxins and acids, Saccharomyces is yeast, Agaricus bisporus is the common mushroom. Penicillin acts by disrupting bacterial cell wall synthesis.
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