You have isolated two mutations in the Lac operon that cause constitutive expression of Lac genes. You designate these mutants Lac1– and Lac2–. Making use of an F' that carries the Lac operon with the LacY gene mutated, you construct strains that you test for both ß-galactosidase activity and Lac permease activity with results shown below.

     

Classify each mutation as dominant or recessive and as cis- or trans-acting, giving the experimental result that allows you to arrive at each conclusion. Finally, deduce what type of Lac mutation best fits the properties of Lac 1– and of Lac 2–.

#Question id: 10959

#SCPH28 | Zoology

 Which of the following would best explain a prolonged bleeding time test?

#Question id: 10960

#I Life Science/ Life Sciences Group – I-V

Why do some malnourished patients bleed excessively when injured?

#Question id: 10961

#I Life Science/ Life Sciences Group – I-V

Over the past 12 weeks, a 75-year-old man with a moderate aortic stenosis has developed shortness of breath and chest pains during exertion. He appears pale. Test of his stool for blood is positive. Laboratory studies show the following: hemoglobin 7.2 g/dL, and mean corpuscular volume 75. A blood smear shows microcytic, hypochromic erythrocytes. Which of the following is the most likely diagnosis?

#Question id: 10962

#I Life Science/ Life Sciences Group – I-V

A 24-year-old man came into the ER with a broken leg. A blood test was ordered and his WBC count was 22 × 10^3/μl. Five hours later, a second blood test resulted in values of 7 × 10^3/μl. What is the cause of the increased WBC count with the first test?

#Question id: 10963

#I Life Science/ Life Sciences Group – I-V

During an inflammatory response, which is the correct order for cellular events?

#Question id: 10964

#I Life Science/ Life Sciences Group – I-V

A patient visits his dentist, who notices a sore on the patient’s lip. The sore was unusual in that there was no pain or drainage from the sore. The patient was subsequently admitted to the hospital with a violent shaking chill. His lab values were Hct 30%, platelets 400,000/μl, WBC 4200/μl, 68% lymphocytes, and 20% neutrophils. What is the diagnosis of this patient?