# Bioprocess Engineering Questions and Answers – Medium Optimization

This set of Bioprocess Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Medium Optimization”.

1. What does X in “Xn” represents in the large number of experiments?
a) Number of variables
b) Number of levels
c) Representation of any element
d) Number of elements

Explanation: To make a full factorial search which would examine each possible combination of independent variable at appropriate levels could require a large number of experiments, xn, where x is the number of levels and n is the number of variables. This may be quite appropriate for three nutrients at two concentrations but not for six nutrients at three concentrations.

2. In the Plackett-Burman method, the evaluation of x-1 variables by x experiments, where x must be the multiple of?
a) 2
b) 4
c) 6
d) 8

Explanation: The Plackett-Burman method allows for the evaluation of x-1 variables by x experiments, x must be a multiple of 4, e.g. 8, 12, 16, 20, 24, etc. Normally one determines how many experimental variables need to be included in an investigation and then selects the Plackett-Burman design which meets that requirement most closely in multiples of 4.

3. Experimental error and dummy variables in Placket-Burman method are linked.
a) True
b) False

Explanation: Any factors not assigned to a variable can be designated as dummy variables. Alternatively, factors known to not have any effect may be included and designated as dummy variables. The incorporation of dummy variables into an experiment makes it possible to estimate the variance of an effect (experimental error).

4. The response surface optimization technique is also given by Plackett- Burman, which is another stage in medium optimization.
a) True
b) False

Explanation: The response surface optimization techniques were introduced by Box and Wilson in 1951.

5. The contour plot is __________
a) 1-D
b) 2-D
c) 3-D
d) Any dimension

Explanation: The axes of the contour plot are the experimental variables and the area within the axes is termed the response surface. To construct a contour plot, the results of a series of experiments employing different combinations of variables are inserted on the surface of the plot at the points delineated by the experimental conditions. Points giving the same results are then joined together to make a contour line. In its simplest form two variables are examined and the plot is two dimensional.
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6. Is there any serum named as “Chicken serum”?
a) True
b) False

Explanation: Chicken serum is collected from healthy birds slaughtered for human consumption. Chicken serum is tested specifically for cytotoxicity. Test samples are examined for the ability to support the attachment and proliferation of three adherent cell lines. The test and reference cultures are monitored for evidence of nutritional deficiency, abnormal morphology, or cytotoxicity.

7. Is serum-free media beneficial?
a) True
b) False

Explanation: The advantages of removing serum from media include:
i) More consistent and definable medium composition to reduce batch variation.
ii) Reduction in potential contamination to make sterility easier to achieve.
iii) Potential cost savings because of cheaper replacement components.
iv) Simplifying downstream processing because the total protein content of the medium has been reduced.

8. What do you mean by the term “Trace elements”?
a) Needed in small amount
b) Needed at medium amount
c) Needed at very high amount
d) The elements which are discovered

Explanation: A chemical element required only in minute amounts by living organisms for normal growth.

9. Hybridoma technique is not required for antibody production.
a) True
b) False

Explanation: Hybridoma technology is a method for producing large numbers of identical antibodies (also called monoclonal antibodies).The myeloma cell line that is used in this process is selected for its ability to grow in tissue culture and for an absence of antibody synthesis.

10. What is Hepes?
a) An animal culture
b) A buffer
c) A type of non-ionic element
d) A horse serum

Explanation: HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) is a zwitterionic organic chemical buffering agent; one of the twenty Good’s buffers. HEPES is widely used in cell culture, largely because it is better at maintaining physiological pH despite changes in carbon dioxide concentration (produced by cellular respiration) when compared to bicarbonate buffers, which are also commonly used in cell culture.

11. Which of the following is not a foaming agent?
a) Sodium lauryl sulfate
b) Ammonium lauryl sulfate
c) Titanium hydride
d) Pluronic f-68

Explanation: Pluronic F68 is used in cell culture as a stabilizer of cell membranes protecting from membrane shearing and additionally acts as an anti-foaming agent.

12. Casein is converted to yoghurt because of _____________
a) Lactic acid
b) Salicylic acid
c) Benzoic acid
d) Picric acid

Explanation: Compared to other milk products such as cheese, ice cream, or butter, yogurt contains all milk proteins and salts whereas the milk sugar (lactose) is mostly converted into lactic acid which gives yogurt a pleasant acidic flavor.

13. A trickling filter is used for –
a) Antibiotic production
b) Beer production
c) Waste water treatment
d) Citric acid manufacturing

Explanation: A trickling filter, also called trickling biofilter, biofilter, biological filter and biological trickling filter, is a fixed-bed, biological reactor that operates under (mostly) aerobic conditions. Pre-settled wastewater is continuously ‘trickled’ or sprayed over the filter.

14. Blood agar is an example of which type of media?
a) Selective
b) Differential
c) Enriched
d) Enrichment

Explanation: Blood agar is a differential medium that distinguishes bacterial species by their ability to break down the red blood cells included in the media. Blood agar is often used to distinguish between the different species of pathogenic Streptococcus bacteria.

15. Sodium carboxy methyl cellulose is not a type of non-nutritional media supplements.
a) True
b) False

Explanation: Sodium carboxy methyl cellulose may be added to media at 0.1% to help to minimize mechanical damage caused by the shear force generated by the stirrer impeller.

Sanfoundry Global Education & Learning Series – Bioprocess Engineering.

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