This set of Marine Biotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Recirculating Aquaculture System – Set 2”.
1. Sand, dense plastic, glass beads, minerals etc. are employed in ___________________
a) trickling filter
b) rotating contactors
c) fluidized bed reactor
d) emerged bed filters
View Answer
Explanation: The biofilters can have following two types of configurations – emerged bed filters and submerged bed filters. The fluidized reactor is a common type of submerged bed filter in which sand, minerals etc. are used.
2. Trickling filters and rotating biological contactors are types of emerged bed filters.
a) True
b) False
View Answer
Explanation: Trickling filters also commonly known as packed columns and rotating biological filters are types of emerged bed filters. These are usually employed in RAS.
3. __________________ is directly correlated with density of fish in the tank.
a) Turbidity
b) Aerobic bacteria
c) Hydrogen potential
d) Oxygen demand
View Answer
Explanation: There are a number of factors governing oxygen demand in a culture tank. There is a direct correlation between the density of fish in the tank and oxygen demand, along with such other factors as water temperature and flow rates.
4. Amount of water exchanged per unit of time is ________________
a) turnover time
b) carrying capacity
c) baseline
d) compartmentalization
View Answer
Explanation: The amount of water exchanged i.e. the amount of water that can be re-circulated per unit of time is termed as recirculating rate or turnover time. It can be calculated by dividing the volume of water in the tank with capacity of the pump.
5. __________________ is designed as a settling basin in an RAS.
a) Mechanical filter
b) Rearing tank
c) Rotating drum
d) Sump
View Answer
Explanation: A sump or clarifier tank is used in RAS to preclude accumulation of waste products and uneaten feed. It is designed as a settling tank with a slow flow rate to increase sedimentation.
6. A hydroclone is used for _____________________
a) waste settling
b) nitrification
c) denitrification
d) oxygen saturation
View Answer
Explanation: A hydroclone is a cone-shaped device used to increase settling of waste particles by employing centrifugal force that increases gravitational force thereby reducing the settling time.
7. What cannot be used for pure oxygen diffusion into liquid?
a) Hydroclone
b) U-tube
c) Counter-current injector
d) Micro-bubble device
View Answer
Explanation: U-tube oxygenation, counter-current flow injectors and micro-bubble devices are used to diffuse pure oxygen into culture water. The amount of oxygen bubbled out and lost to the atmosphere is very low.
8. ____________________ is a powerful oxidizing agent used for disinfection.
a) Ozone
b) Hydrogen sulfide
c) Carbon monoxide
d) Carbon dioxide
View Answer
Explanation: Ozone (O3) is a powerful oxidizing agent that aids in breaking down compounds. It is a naturally found gas used for disinfection in aquaculture systems provided appropriate injection apparatus.
9. Carbon dioxide removal in aquaculture systems can be accomplished by ____________________
a) decreasing pH
b) decreasing air-water contact
c) increasing air-water contact
d) increasing pH
View Answer
Explanation: Carbon dioxide removal can be accomplished by increasing air-water contact using such devices as RBC and packed columns. The CO2 level should be maintained below 30 mg/L for good fish growth.
10. Different fish species have different feed requirements.
a) True
b) False
View Answer
Explanation: Different fish species have different feed requirements just as they have different tolerance for temperature and crowding. Particularly the protein content is variable and differs depending on the marketable growth size.
11. Which of the following is true for RAS?
a) Little heat required for maintaining temperature
b) No need of biofilters
c) Mostly aquaponics is not feasible
d) Warm water fish cannot be reared
View Answer
Explanation: Energy conservation is an advantage of recirculating aquaculture systems. After initial heating of the water to optimal temperature only little amount of heat is required to maintain that temperature.
Sanfoundry Global Education & Learning Series – Marine Biotechnology.
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