Andrea y Jimena son esposas y decidieron procrear un hijo recurriendo a la inseminación in vitro. Identifica el principio de la bioética al que hace referencia el enunciado. A Respeto a la autonomía (B) No maleficencia (C) Beneficencia

An unknown microbial specimen measures 18 millimetres under a total magnification of 400 x , when examined under the microscope. What is the actual size of the unknown specimen? \( \begin{array}{ll}\text { (A) } 45 \text { micrometres. Total magnification }=400 x \\ \text { (B) } 4.5 \text { micrometres. } \quad \frac{18}{400 x}=0.045 \mathrm{~mm} \\ \text { (C) } 0.45 \text { micrometres. } \\ \text { (D) } 0.045 \text { micrometres. } & \text { micrometers }=0.045 \times 1000=45 \text { micrometers }\end{array} \)

23 Which of the following statements is TRUE about the methylene blue reduction test (MBRT) conducted for pasteurised milk samples? \( \begin{array}{ll}\text { (A) } \quad \text { Microbial load of milk samples can be determined quantitatively. } \\ \text { (B) } \quad \text { Decolourization of methylene blue is caused by the loss of electrons. } \\ \text { (C) A UV-Vis spectrophotometer is required to monitor the colour change. } \\ \text { (D) } \quad \text { Milk sample with longer reduction time is of better quality than sample with } \\ \text { shorter reduction time. }\end{array} \) CC)

1.1.6 The main purpose of an engine's air filter is that it ... A controls the engine's air intake volume B reduces the engine's air intake noise. C prevents air from entering combustion chamber D prevents dust and other foreign matter from entering the engine

22 Which of the following statements about Staphylococcus aureus is correct? \( \begin{array}{ll}\text { (A) } & \text { It is a mesophilic microorganism. } \\ \text { (B) } \quad \text { Cells will appear pink after Gram staining. } \\ \text { (C) } \quad \text { Enterotoxins produced are easily destroyed by heat. } \\ \text { (D) } \quad \text { It does not thrive well in an oxygen-rich environment. }\end{array} \)

Suppose there are 30 bacteria in a Petri dish at start time. Seven hours later, there are 360 bacteria in the dish. 1.) Express the number of bacteria, P, as a function of \( t \) hours passed. Note: Round the growth rate to 4 dec. places. \( P(t)= \) 2.) Use the model from part a to determine the number of bacteria, rounded to a whole number, in the dish after 20 hours: