CBSE Questions for Class 7 Biology Wastewater Story Quiz 2 - MCQExams.com

• Anthropogenic (environmental pollution originating in human activity) sources of water pollution include domestic waste, sewage, soaps, detergents, run-off from agricultural fields having fertilizers and pesticides, industrial wastes as effluents, heat, waste from animal sheds and slaughterhouses, oil spills etc. 

• Vermi-processing toilets is a design of a toilet in which humans excreta is treated by earthworms and redworms.
• In this process, human excreta is completely converted to cake-like structures called vermi cakes by earthworms. Vermi cakes are used as manure and fertilizers.

• A disease can spread from one person to population by improper sanitation in public places because many disease-causing organisms can survive on the surface of the improperly sanitized public toilet seat, and for an infection to occur, the germs(bacteria, virus) would have to be transferred from the toilet seat to your urethral or genital tract, or through a cut or sore on the buttocks or thighs, which is possible.
• Hence A disease can spread from one person to population by improper sanitation in public places.
• So, the correct answer is 'improper sanitation in public places'.

• Sanitation refers to public health conditions related to clean drinking water and adequate treatment and disposal of human wastes and sewage. Preventing human contact with feces is part of sanitation.
  
• Poor sanitation is linked to transmission of diseases such as cholera, diarrhea, dysentery, hepatitis A, typhoid and polio because these diseases can be transmitted through the fecal-oral route when food or water is contaminated.
• Hence Disease caused due to poor sanitation is typhoid and polio.
• So, the correct answer is 'Both B and C'.

• The chemicals present in paints, solvents, insecticides, motor oils, may kill microbes that help purify water. 
• Hence, it is recommended not to throw them down the drain.
• The other options mentioned are biodegradable and hence won't kill the microorganism.
• So, the correct answer is option A.

• Sanitation refers to public health conditions related to clean drinking water and adequate treatment and disposal of human wastes and sewage. Preventing human contact with feces is part of sanitation.
• Sanitation at public places can be maintained by Proper drainage,Garbage management and Sufficient public toilet facilities.
  
• So, the correct answer is 'All the above'.

• An endemic disease is a disease that exists permanently in a particular region or population. Poor sanitation is linked to transmission of some endemic diseases such as cholera, diarrhea, dysentery, hepatitis A, typhoid and polio
• Hence the disease caused due to improper sanitation in public place is endemic diseases.
  
• So, the correct answer is 'Endemic'.

• Vermi-processing toilets is a design of a toilet in which humans excreta is treated by earthworms.
• In this process, human excreta is completely converted to cake like structures called vermi cakes by earthworms. Vermi cakes are used mostly in the soil as manure and fertilizers.
• The vermi-processing toilets do not use water for flushing and therefore called dry toilets. 
• Hence vermi-processing toilets are associated with Low water use toilet because they do not use water for flushing.
• So, the correct answer is 'Low water use toilet
  

• All the cooking oils should not be thrown in drains because it can harden and block the pipes. In an open drain, the fats clog the soil pores reducing its effectiveness in filtering water. 
• Throw oil and fats in the dustbin.
• Hence Cooking oil should not be thrown down the drain because they block the drainage pipes.
• So, the correct answer is 'They block the drainage pipes'.

$$\textbf{Correct option: B}$$

$$\textbf{Solution:}$$

Option B:

$$\bullet$$ Bar screening is a technique used to filter large products from the waste water.

$$\bullet$$ A mechanical filter is formed in the way of waste water flow, so that the large solid wastes like rags, plastics, etc can be removed from the waste water.

$$\bullet$$ It is used in the primary filtration level of the wastewater treatment plant.

Hence the correct option is option B.

• Wastewater goes to a grit and sand removal tank. The speed of the incoming wastewater is decreased to allow sand, grit and pebbles to settle down.
• Thus, Sand and Grit filters are used for filtration of wastewater.