This set of Marine Biotechnology Multiple Choice Questions & Answers (MCQs) focuses on “Sustainable Marine Food Production Systems – Set 4”.
1. Which is optional in RAS?
a) Ozonation
b) Nitrifying biofilter
c) Aeration
d) Solid removal
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Explanation: Recirculating aquaculture systems (RAS) are a technology used for intensive fish or shrimp farming. Ozonation and UV radiation are optional processes in RAS which aim at disinfecting the culture water before recirculating.
2. Choose the correct option.
| a. Freshwater | 1. Tilapia |
| b. Marine | 2. African catfish |
| 3. Sea bass | |
| 4. Turbot |
a) 1-a, 2-a, 3-b, 4-b
b) 1-a, 2-b, 3-a, 4-b
c) 1-b, 2-a, 3-b, 4-a
d) 1-b, 2-b, 3-a, 4-a
View Answer
Explanation: Over 10 different species of marine and freshwater fish are farmed in recirculating aquaculture systems (RAS) word over. Tilapia, African catfish are freshwater fish while Seabass and turbot are marine fish.
3. Low dissolved oxygen results in ______________
a) stress in fish
b) phytoplankton growth
c) phototrophic bacteria
d) heterotrophic bacteria
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Explanation: Dissolved oxygen (DO) levels are the most important water quality parameter that should be controlled in intensive fish farming. Low dissolved oxygen levels in RAS result in nitrifying biofilter malfunction and stress amongst fish.
4. Oxygen requirement in intensive fish farming is not determined by ________________
a) temperature
b) feed addition
c) autotrophic bacterial count
d) tolerance to hypoxia
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Explanation: A wide range of factors govern the oxygen requirement of an intensive fish farming unit (or an RAS system). Autotrophic bacterial count however is natural as well as beneficial and does not influence oxygen needs of the system.
5. Oxygen supersaturation is possible in RAS.
a) True
b) False
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Explanation: Supersaturation refers to transferring oxygen to water at concentration higher than its saturation concentration under atmospheric conditions. Diverse range of devices can be incorporated in intensive farming units to achieve supersaturation.
6. Aeration can elevate DO to supersaturation level.
a) True
b) False
View Answer
Explanation: Aerators can only elevate dissolved oxygen (DO) concentration to atmospheric levels. To elevate dissolved oxygen to supersaturation, pure oxygen must be supplied through cascade devices or oxygen cylinders.
7. Which is not associated with gas-to-liquid type oxygenator?
a) Blower
b) Compressor
c) Perforated pipes
d) Aspirator
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Explanation: To maintain dissolved oxygen levels in recirculating aquaculture systems, two types of oxygenators/ aerators are employed. Gas-to-liquid are diffuse aeration systems where air or oxygen is transferred to water column creating bubbles, aspirators are not used in these.
8. Which is not a type of liquid-to-gas aerator?
a) Speece cone
b) Packed column
c) Paddlewheel
d) Low-head oxygenator
View Answer
Explanation: Speece cone is a gas-to-liquid type oxygen transfer device that creates bubbles during the process. Packed column aerator, low-head oxygenator, and paddlewheel aerators are types of liquid-to-gas aerators.
9. Select the incorrect option regarding aqueous media ammonia.
a) Ammonia exists in 2 forms in water
b) Both forms are equally toxic
c) Non-ionized form is toxic
d) Total ammonia nitrogen is sum of 2 forms
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Explanation: In aqueous media ammonia exist in two forms – ionized (NH3) and unionized (NH4+). Total ammonia nitrogen (TAN) is the sum of ionized and ionized forms. Unionized ammonia is more toxic to fish.
10. Ratio of unionized and ionized forms of ammonia is not controlled by ________________
a) dissolved oxygen
b) pH
c) salinity
d) temperature
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Explanation: Ammonia (unionized form) is highly toxic to fish and must be controlled to levels below 2 mg/L. factors governing the ratio between ionized and non-ionized forms of ammonia include pH, salinity, and temperature.
11. Species of the genera Nitrosomonas, Nitrospira and Nitrobacter are ___________________
a) denitrifying bacteria
b) sulfide oxidizing bacteria
c) nitrifying bacteria
d) sulfate oxidizing bacteria
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Explanation: Species of the genera Nitrosomonas, Nitrospira, Nitrosococcus, Nitrococcus and Nitrobacter are nitrifying bacteria that utilize the toxic ammonia as source of electrons and hydrogen ions. These are therefore useful for application in aquaculture.
Sanfoundry Global Education & Learning Series – Marine Biotechnology.
To practice all areas of Marine Biotechnology, here is complete set of 1000+ Multiple Choice Questions and Answers.
