0.2 mls of a 10-4 dilution of a virus preparation yields 90 plaques. What is the number of PFU per ml in the undiluted virus preparation?
A. 9.0 × 108
B. 4.5 × 106
C. 4.5 × 107
D. 9.0 × 105
Answer: B
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The prevalence rate of tuberculosis in one particular county in Texas is 7/1000 people, while the incidence rate for 2011 is 2/1000 people. Analyze this data and summarize the situation.
A. Incidence rate should really be higher than prevalence rate because it includes all new cases for the year. B. The data were collected incorrectly because the two values should match. C. Prevalence rate is higher than incidence rate because the number of people still alive with tuberculosis is higher because of better treatments. D. Prevalence rate and incidence rate cannot be determined for the same disease.
Which of the following do NOT contain endoplasmic reticulum?
A. noneukaryotes B. animal cells C. eukaryotic cells D. All of the choices are correct.
Habitat fragmentation poses severe threats to many species because of:
A) small size of local populations. B) undesirable edge effects. C) barriers to movement in response to changing conditions. D) all of the above.
If you want to avoid skin cancer, the safest thing to do is ________
Fill in the blank(s) with correct word