Selman Waksman, who discovered streptomycin, coined the term 'antibiotic' in 1942 to describe chemical substances produced by microorganisms that inhibit or kill other microorganisms. Fleming discovered penicillin but did not coin the term. Pasteur developed pasteurization and rabies vaccine, Ehrlich discovered salvarsan (magic bullet) for syphilis.
Explanation:
Ammonia, toxic, is converted to less toxic urea in the liver via the urea cycle, then excreted by kidneys. Thus, humans excrete urea (ureotelic). R explains A.
Explanation:
Synapsis (pairing of homologous chromosomes) and crossing over (exchange of genetic material) occur during prophase I of meiosis, not in mitosis. Mitosis involves one division producing two genetically identical diploid daughter cells. Meiosis involves two divisions producing four haploid gametes with genetic variation. Chromosome duplication and sister chromatid separation occur in both. Spindle fibres form in both divisions. Thus, synapsis and crossing over are unique to meiosis.
Explanation:
Glyoxysomes are specialized peroxisomes found in germinating oil seeds. They contain enzymes of the glyoxylate cycle, converting fatty acids to carbohydrates until the seedling can photosynthesize.
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