Question

5.

Microbial growth in a test tube leads to

	A.	decreasing turbidity.
	B.	increased nutrients.
	C.	increasing amounts of alkaline waste products.
	D.	an increasing pH.
	E.	None of the above is correct.

6.

Which of the following is TRUE of microbial growth?

	A.	Growth increases gradually up to the optimal temperature, then drops sharply from optimum to maximum temperature.
	B.	Physical growth considerations include moisture, radiation, and hydrostatic pressure.
	C.	Thermoduric organisms are mesophiles that can survive brief exposure to higher temperatures.
	D.	A facultative halophile could grow in salt concentrations that would prevent the growth of other organisms.
	E.	All of the above are true.

7.

Which of the following is an indirect method for estimating the number of microbes in a sample?

	A.	turbidity
	B.	pour plate counts
	C.	membrane filtration
	D.	spread plate counts
	E.	direct microscope count

8.

Which of the following is NOT a membrane-disrupting toxin?

	A.	A-B toxin
	B.	Streptolysin
	C.	Leukocidin
	D.	Hemolysin
	E.	All of the above are membrane-disrupting toxins

9.

Which of the following is NOT a method of avoiding host antibodies?

	A.	Antigenic change
	B.	Membrane-disrupting toxins
	C.	Invasins
	D.	Inducing endocytosis
	E.	IgA protease

10.

Which of the following is a fomite?

	A.	Insects
	B.	A hypodermic needle
	C.	Droplets from a sneeze
	D.	Water
	E.	Pus

11.

Which of the following statements is FALSE?

	A.	Kinase digests clots.
	B.	Leukocidins destroy neutrophils.
	C.	Coagulase destroys blood clots.
	D.	Hemolysins lyse red blood cells.
	E.	Hyaluronidase breaks down substances between cells.

Answer 1

5) Ans: D.Microbial growth in a test tube leads to increasing pH

Soln: A- As Microbial growth in a test tube leads to increasing turbidity. higher the turbidity higher the number of cell.

B. As Microbial growth in a test tube leads to decreasing nutrients. due to consumption of nutrients by microbes.

C. Microbial growth doesn't leads to the formation of alkaline waste products.

D.Microbial growth in a test tube leads an increasing pH. Yes, the products, byproducts, and waste produced by the bacteria during growth and metabolism will alter pH of the medium.

6) Ans: All of the above are true.

A: Growth increases gradually up to the optimal temperature, then drops sharply from optimum to maximum temperature. The optimum growth temperature is the temperature at which an organism exhibits the highest growth rate.

B: Physical growth considerations include moisture, radiation, and hydrostatic pressure.

C:Thermoduric organisms are mesophiles that can survive brief exposure to higher temperatures.

D: A facultative halophile could grow in salt concentrations that would prevent the growth of other organisms.

7) Ans: A- Turbidity

Soln: As the cell number increases in the solution so does the turbidity.

8) Ans: A-  A-B toxin.

Soln: The A-B toxin are produced by the proteins of pathogenic organisms such as the bacteria Botulinum toxin.

A membrane-disrupting toxin is toxin that affect the cell membrane. they are also called as exotoxins. they mainly effect by altering the phospholipid layer structure by forming a small pores which causes the leakage of cytoplasmic contents and leads to cell death.

examples: Leukocidin, Hemolysin.

9) Ans:  D- Inducing endocytosis

Soln: By inducing endocytosis host antibodies cannot be avoided instead it activates the host antibodies.

10) Ans: B- A hypodermic needle

soln: Fomite is an object contaminated with the pathogen and has the ability to infect the person who come in contact with that.

11) Ans: C - Coagulase destroys blood clots.

Soln: coagulase is a bacterial enzyme that reacts with a cofactor found in blood plasma to catalyze the formation of fibrin from fibrinogen. It helps in the formation of blood cloths.