Download App

Environmental Issues — BIOLOGY STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceBIOLOGYEnvironmental Issues3 Marks
Question
Biological Oxygen Demand or BOD increases with increase in water pollution. In this reference, answer the questions that follow:
  1. At a particular segment of the river near a sugar factory, the BOD is much higher than the normal level. What is it indicative of?
  2. What will happen to the dissolved oxygen and living organisms in this part of the river?
✓

Answer

  1. It indicates that the sugar factory releases organic waste in the water body. To degrade the organic matter, microbes utilise the dissolved oxygen in the water, thereby, reducing the levels of dissolved oxygen and increasing the BOD.
  2. In this part of river, the dissolved oxygen will be depleted making it difficult for aquatic species to survive. It can result in death of fishes in severe cases.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "3 Marks Question" from Environmental Issues→Environmental Issues — all question types→BIOLOGY STD 12 Science question papers→Gujarat Board STD 12 Science question papers→Gujarat Board question paper generator→

Similar questions

Define the following terms and give one example for each:
a. Commensalism
b. Parasitism
c. Camouflage
d. Mutualism
e. Interspecific competition
→
$F_1$ progeny of pea plant bearing violet flowers and snapdragon plant bearing red flowers were selfed to produce their respective $F_2$ progeny. Compare the phenotypes, the genotypes and the pattern of inheritance of their respective $F_2$ progeny.
→
The broadly utilitarian argument for the services provided by biodiversity. Describe.
→
  1. State the type of gametes shown in the diagram.
  2. Identify the process taking place and the resultant structure.
  3. Name an organism that reproduces in this manner.
→
Discuss in your own words why the government is popularising the slogan-'Hum Do Humare Do' in both rural and urban areas of the country.
→
Secondary treatment of the sewage is also called Biological treatment. Justify this statement and explain the process.
→
Given below is a list of six micro-organisms. State their usefulness to humans.
  1. Nucleopolyhedrovirus.
  2. Saccharomyces cerevisiae.
  3. Monascus purpureus.
  4. Trichoderma polysporum.
  5. Penicillium notatum.
  6. Propionibacterium sharmanii.
→
When someone buys packets of cigarettes, cannot miss the statutory warning that is present on the packing which warns against smoking and says how it is injurious to health. Yet, smoking is very prevalent in our society, both among young and old. Advise the adolescents about the importance of avoiding smoking. (Mention any six points.)
→
  1. Define pioneer species.
  2. Among bryophytes, lichens and fern, which one is a pioneer species in a xeric succession? And why?
→
The below image shows is the headquarter of Eli Lilly company. Eli lily is one of the first pharmaceutical companies to produce human insulin using RDT technology by cell-based fermentation method.
Image
i. How did Eli Lilly synthesize human insulin?
ii. Mention one difference between this insulin and the one produce by the human pancreas.
→