CBSE Term 2 Class 12 Biology Sample Paper 2021-22: Paper Pattern & Marking Scheme
The sample question paper consists of three sections and 13 questions.
It is expected the paper would be similar.
All the questions would be compulsory.
Section–A consists of 6 questions of 2 marks each.
Section–B would consist of 6 questions of 3 marks each.
Section–C consists of a case-based question of 5 marks.
This paper unlike other many has no overall choice.
However, internal choices have been provided in some questions.
A student can attempt only one of the alternatives in such questions.
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CBSE Term 2 Class 12 Biology Sample Paper 2021-22: Questions & Answers
Q.1 Humans have innate immunity for protection against pathogens that may enter the gut along with food. What are the two barriers that protect the body from such pathogens?
Ans. Microbial pathogens enter the gut of humans along with food:
Physical barriers: Mucus coating of the epithelium lining the gastrointestinal tract helps in trapping microbes entering our body.
Physiological barriers: Acid in the stomach, saliva in the mouth prevent microbial growth.
Q.2 A patient admitted to ICU was diagnosed to have suffered from myocardial infarction.
Name two bioactive agents and their mode of action that can improve this condition.
Ans.
Streptokinase (produced by the bacterium Streptococcus) is used as a ‘clot buster’ for removing clots from the blood vessels of patients who have undergone myocardial infarction. Statins (produced by the yeast Monascus purpureus) act as blood cholesterol-lowering agents.
Q.3 Substantiate by giving two reasons as to why a holistic understanding of the flora and fauna of the cropland is required before introducing an appropriate biocontrol method.
Ans: Eradication of pests will disrupt predator-prey relationships, where beneficial predatory and parasitic insects which depend upon flora and fauna as food or hosts, may not be able to survive.
A holistic approach ensures that various life forms that inhabit the field, their life cycles, patterns of feeding and the habitats that they prefer are extensively studied and considered.
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Q.4 Identify the compound chemical structure is shown below. State any three of its physical properties
Ans.
It is Morphine.
Physically it appears as a white, odourless, crystalline compound.
Q.5 An ecologist study an area with population A, thriving on unlimited resources and showing exponential growth, introduced populations B and C to the same area. What will be the effect on the growth pattern of the population A, B and C when living together in the same habitat?
Ans.
This interaction will lead to competition between the individuals of populations A, B and C for resources.
Eventually, the ‘fittest’ individuals will survive and reproduce.
The resources for growth will become finite and limiting, and population growth will become realistic.
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