Environmental Biotechnology Questions on “The Process of Toxicants Uptake: Kinetic Aspect”.
1. Which of the following phases doesn’t lead to bio accumulation in aquatic organism?
a) Accumulation phase
b) Steady-state
c) Elimination phase
d) Death phase
Answer: d
Clarification: In aquatic organism, bio accumulation of toxic materials in organisms occurs via several phases like Accumulation phase, Steady-state, Elimination phase, whereas death phase is not included in the uptake phase as this leads to the decline phase.
2. The initial phase of uptake of toxicant is very fast.
a) True
b) False
Answer: a
Clarification: In case of bioaccumulation, it follows Michaelis-Menten kinetic in which the initial phase of uptake of toxicant is very fast.
3. The toxicant accumulation can occur by direct absorption from the medium and ________
a) Toxification
b) Food chain transfer
c) Biochemical degradation
d) Potassium
Answer: b
Clarification: The toxicant accumulation can occur by direct absorption from the medium and Food chain transfer and transportation to the sorption zones inside the organism, Toxification is the result of several toxicants that can only be imposed if it is able to cross the several sub cellular structures, biochemical degradation is the degradation of bio-accumulated chemicals stored in the organism, whereas, Potassium are the metals that can be found in an organism.
4. In young organism, steady state can be achieved very fast.
a) True
b) False
Answer: a
Clarification: In young organisms, within hours of exposure to acute concentration of toxicants, steady state can be achieved very fast.
5. The time to reach half of the concentration of the toxicant is a function of environmental concentration and _______________
a) Membrane permeability rate
b) Partial coefficient
c) Rate of active transport
d) Rate of active transport
Answer: b
Clarification: The half time i.e. the time to reach half of the concentration of the toxicant can be expressed as a function of environmental concentration and Partial coefficient, whereas Membrane permeability rate, rate of active transport, and rate of active transport are the factors that influence the uptake of toxicants during bio accumulation.
6. Which of the following factor doesn’t influence the rate of Bioaccumulation by food?
a) Temperature
b) Pressure
c) Food type
d) Size of animal
Answer: b
Clarification: The rate of Bioaccumulation by food is influenced by several factors like Temperature, Food type and Size of animal but it does not depend on the pressure component.
7. At plateau of bio accumulation, rate of uptake is equal to rate of elimination.
a) True
b) False
Answer: a
Clarification: When steady state is reached, at plateau of bio accumulation, rate of uptake is almost equal to rate of elimination.
8. Sometimes organism metabolizes the accumulated toxicant to facilitate its own growth.
a) True
b) False
Answer: a
Clarification: Sometimes organism can metabolize the accumulated toxicant to facilitate its own growth and recover from toxic stress.
9. What does ∆t depicts in the given formula: C = Cmax Δt/B + Δt?
a) t-t0
b) t0-t
c) C-C0
d) C0-C
Answer: a
Clarification: ∆t=t-t0 i.e. the difference in exposure time to exposure beginning time.
t=Exposure end time
t0=Exposure beginning time C=0
C=Concentration of xenobiotic in organism, at steady-state
B=The initial concentration of the xenobiotic present in the organism at the time of exposure.