13. Which procedure would most likely provide valid results in a test to determine if drug A would be effective in treati cancer in white mice?
A) injecting 1 mL of drug A into 100 white mice with cancer
B) injecting 1 mL of drug A into 100 white mice with cancer and 0.5 mL of drug X into 100 white mice without can
C) injecting 1 mL of drug A into 100 white mice with cancer and 0.5 mL of drug X into another group of 100 white
with cancer
D) injecting 1 mL of drug A into 100 white mice with cancer and 1 mL of distilled water into another group of 100
mice with cancer

Consider the model of the oxygen cycle on earth. the majority of earth's oxygen reservoirs are found in the a) atmosphere. b) biosphere. c) hydrosphere. d) lithosphere.

In 1959, doctors began using the powerful antibiotic methicillin to treat infections of staphylococcus aureus, but within two years, methicillin-resistant strains of s. aureus (mrsa) appeared. how did the resistant strains of s. aureus emerge? in 1959, doctors began using the powerful antibiotic methicillin to treat infections of staphylococcus aureus, but within two years, methicillin-resistant strains of s. aureus (mrsa) appeared. how did the resistant strains of s. aureus emerge? staphylococcus aureus bacteria that were able to synthesize cell walls using a protein that was not affected by methicillin survived the methicillin treatments and reproduced at higher rates than did other individuals. over time, these resistant individuals became increasingly common. in response to treatment of staphylococcus aureus infections with methicillin, some bacteria began to synthesize cell walls using a protein that was not affected by methicillin. these bacteria survived the methicillin treatments and reproduced at higher rates than did other individuals. over time, these resistant individuals became increasingly common. in response to treatment of staphylococcus aureus infections with methicillin, bacterial populations gradually began to synthesize cell walls using a protein that was not affected by methicillin.

The normal shape of an enzyme is as shown in structure a. if the enzyme’s shape changes to that shown in structure b, what are two consequences of this change?