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CBSE 12th Standard Biology Subject Biodiversity and Conservation Ncert Exemplar 3 Marks Questions 2021

Published on: 25/05/2021

QB365 Provides the updated NCERT Examplar Questions for Class 12 Biology, and also provide the detail solution for each and every ncert examplar questions , QB365 will give all kind of study materials will help to get more marks

Download CBSE Class 12th Standard CBSE Biology question papers, sample papers, important questions, and previous year solved papers in PDF format. Get free study materials, NCERT solutions, and exam preparation resources for Class 12th Standard CBSE Biology

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Std: 12th Standard CBSE - Biology

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Questions:

Generic 3

5 x 3 = 15

The gradual increase in the temperature of the world is cause of major climatic changes. These climatic changes affect the different aspects of human physiology. Explain the impact of climate change causing various human diseases with the help of flowchart

The diagram given below shows a river and the types of land uses on two sides of the river in a countryside.

The water quality of the river was studied by measuring the amount of dissolved oxygen and ammonia in the water, collected at sites X, Y and Z. The result is presented in the table below:

Site	Dissolved oxygen cm³/liter	Ammonia(ppm)
X	8.9	0.02
Y	0.3	0.62
Z	1.6	5.30

(i) Explain why site Y has the lowest content of dissolved oxygen
(ii) Why are very few fishes found at site 'Z'?
(iii) Which organism will thrive just after site Z?

What does 'red' indicate in the IUCN red list (2004)?

What could have triggered mass extinction of species in the past?

What are characteristics that make a community stable?

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Answers Key:

Generic 3

5 x 3 = 15

Flow char showing impact of climate change.

(i) Site Y has the lowest content of dissolved oxygen due to increased bacterial population. It is caused by sewage run-off from a pig farm.
(ii) There are very few fisher at size Z due to low oxygen Concentration and choked lake (by algae and weeds)
(iii) Algae and weeds will thrive after site Z.

'Red' in IUCN red list (2004) indicates the threatened species i.e. the species under varying degree of extinction risk categories.

Glaciation, melting of snow, eruption of large volcanoes, earthquakes, movement of continents, large meteorites falling on earth, drought, etc. could have triggered mass extinction.

The characteristics that make a community stable are
(i) Less variation in productivity from year to year.
(ii) Resistance or Resilience to occasional disturbances (natural or man-made).
(iii) Resistance to invasions by alien species.