Please wait...
/
-
Read the following text and answer the any four questions on the basis of the same:
Large quantities of sewage is generated every day in cities and towns, which is treated in Sewage Treatment Plants (STPs) to make it less polluted. Given below is the flow diagram of one of the stages of STP.
Observe the given flow diagram and answer the questions accordingly.
Q. Primary effluent is passed into large aeration tanks:
The primary effluent is transferred into large aeration tanks where it is constantly agitated mechanically and the air having oxygen is pumped into it which allows fast growth of useful aerobic microbes into flocs (masses of bacteria associated with fungal filaments to form mesh-like structures).
Q. Identify the correct set of gases produced during digestion of sludge:
During this digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide, and carbon dioxide. These gases form biogas and can be used as a source
of energy. The treated effluent from the secondary treatment plant is generally released into natural water bodies like rivers and streams.
Q. Technical term used for sediment formed in sewage treatment is:
The effluent after primary treatment is passed into the settling tank where the bacterial 'flocs' are allowed to settle down and this sediment is called Activated sludge. A small part of the activated sludge is pumped back into the aeration tank to serve as the inoculum(starter).
Q. The technology of biogas production from cow dung was developed in India largely due to the efforts of :
The technology of biogas production from cow dung was developed in India largely due to the efforts of Indian Agricultural Research Institute (IARI) and Khadi & Village Industries Commission (KVIC) .
So, the correct option is 'Option C' .
Q. The significance of the above sediment formed is that:
The activated sludge is pumped back into the aeration tank to serve as the inoculum(starter).
Read the following text and answer any four questions on the basis of the same :
Ecological Indicators : The presence of dragonflies can reveal changes in the water ecosystems more quickly than studying other animals or plants. In fact, from the nymph to the adult stage, the dragonfly has a significant, positive ecological impact. Dragonfly eggs are laid and hatched in or near water, so their lives show an impact on both water and land ecosystems. Once hatched, dragonfly nymphs can breathe in the air or underwater which enables them to eat mosquito larvae, other aquatic insects and worms, and even small aquatic vertebrates like tadpoles and small fish. Adult dragonflies capture and eat adult mosquitoes.
Community wide mosquito control programs that spray insecticides to kill adult mosquitoes also kill dragonflies.
Q. The approach to biological control includes :
The approach to biological control includes Preservation of natural enemies(predators & parasites) that are already established in an area.
Q. The most effective stages in the life cycle of dragonfly are eradicating mosquitoes area.
Dragonflies are large and heavy bodied insects. The larvae (or Nymphs), which live in water, eat almost anything living that is smaller than themselves. The adult dragonfly larvae are even known to catch and eat small fish. Usually they eat bloodworms or other aquatic insect larvae. Dragonfly nymphs are such good hunters because they move really fast - by what looks like jet propulsion. One of the benefits of having dragonflies live nearby is that they eat many times their weight in mosquitoes every day. Dragonflies also eat many different kinds of flies. Using a basketlike arrangement of their legs, adult dragonflies can actually catch and eat other bugs while they are flying.
Q. Two diseases less likely to occur in a region with plenty of dragonflies are_____
Directions : In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :
Assertion : Releasing dragonflies in areas where there is an outbreak of malarial diseases can be an environment friendly method of control.
Reason : Dragonflies are dominant species and will not allow mosquitoes to reproduce.
Dragonflies have a role in controlling the mosquitoes population and ultimately malarial disease as they are predators on them but they have no role to allow mosquitoes to reproduce.
Q. Dragonflies indicate positive ecological impact as :
Adult dragonflies are beneficial because they eat pests, flying insects, particularly midges and mosquitoes and help to decrease the probability of diseases spread by vectors.
Read the following and answer the question given below:
Villagers in a place near Chembur started planning to make power supply for agricultural purposes from cow dung. They have started a biogas plant for the purpose.
Study the flow chart for biogas production given below and answer the following questions.
Q. Biogas is composed of majorly:
Biogas is composed of Methane(50-70%), CO2(30-40%) with traces of hydrogen sulphide and hydrogen.
Read the following and answer the following question: Microorganisms include bacteria, viruses, fungi and protozoa. In our mind, we presume, most of the time, that microbes are always harmful. Microbes are, of course, the causal agents of many infections diseases of plants and animals including humans but they also have lots of beneficial role. Lactic acid bacteria (LAB) are one of this kind of useful group. These are Gram positive, non-sporulating, either rod shaped or spherical bacteria. They produce lactic acid in milk products as major metabolic end product of carbohydrate fermentation. LAB are considered as natural fermentors. Lactobacillus is a common LAB which converts lactose sugar of milk into lactic acid, that causes coagulation and partial digestion of milk protein casein. Milk is then changed into curd, yoghurt and cheese. Lactobacillus is also used in probiotics which have potentially beneficial effect on gut ecosystem of humans. Some other probiotic strain used belong to the Genus Bifidobacterium.
Q. Which of the following is not a lactic acid producing bacteria?
Microbes such as. Lactobacillus and others commonly called lactic acid bacteria (LAB) grow in milk and convert it into curd. During growth, such bacteria produce adds (mainly lactic add) that coagulate and partially digest the milk proteins. A small amount of curd, known as starter, is added to the milk and kept at a suitable temperature, where lactic acid bacteria multiply in millions and converts milk into curd that also improves its nutritional quality by increasing vitamin BI2. It also checks the growth of disease-causing microbes in the stomach.
Q. In the given flow chart, 'A' denotes :
The methanogenic bacteria are anaerobic organisms that convert CO2 to methane via a sequence of reactions.
Q. If 'A' is not added in the procedure
If methanogenic bacteria is not added in the procedure methane formation will not take place.
Q. What is represented by 'B' in the flow chart?
In the second stage of biogas production, the simple soluble compounds or monomers are acted upon by fermentation causing microbes and converted into organic acids especially acetic acid.
Correct (-)
Wrong (-)
Skipped (-)
Time Taken: - 
×
Bank
SSC
Railway
State
Other
Teaching
Insurance
Medical
Engineering
Defence
GATE
NTA CUET
UPSC
MBA Entrance
LAW
JEE Advanced 2025
CUET UG 2025
RRB NTPC 2024-25
Railway Group D 2025
Bihar Police Constable 2025
RRB ALP CBT-I 2025
Get latest Exam Updates 
