Staph infections, caused by the bacterium staphylococcus aureus, are increasing in frequency and are more difficult to treat with antibiotics. many staph infections are now caused by mrsa, and methicillin-resistant strain of s. aureus. what explains the more widespread phenomenon of mrsa prevalence in staph infections? a) vaccines for mrsa have become not effective because of changes to human immune systems. b) the presence of antibiotics induced the bacterial genomes to mutate and develop resistance to the drug. c) decreased hospital sanitation practices to save money have resulted in increased presence of resistant staph infections. d) selective pressures by excessive antibiotic use have increased the frequency of resistant strains of s. aureus over the last few decades.

the nitrogen cycle provides nitrogen to the ecosystem from the atmosphere, ground and oceans. nitrogen is an important component of complex molecules such as amino acids and nucleotides, which lead to the creation of proteins and dna, the building blocks of all life. plants absorb nitrogen in the form of ammonium, nitrate ion and, on rare occasions, as amino acids. animals receive nitrogen necessary for biological processes from feeding on living or dead organic matter.

all these collisions do one thing, and that thing is explained in the last option. when dusst, rocks and ice collide, they harden and form giant layers of rocks or hard ice.

d)   to harden materials to form different parts of earth’s layers

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bioteacher101

answerthe above question is correct(true) hope this ;