CBSE Class 12 Previous Year Question Paper for Biology (2022)

CBSE Class 12 Previous Year Question Papers for Biology help you to understand the level of questions asked in the previous exams, along with the changes in pattern. Practicing the past year’s question papers of Class 12 enhances time-management skills while appearing in the examination. It makes you understand the importance of different topics that have been asked previously.

Previous year’s CBSE Class 12 Biology Question Papers will boost your confidence level to appear in the examination with proper knowledge of different topics that are going to be asked. It enhances the understanding of the topic and acts as a checkpoint to see the level of preparation that you have done. 

Overview of CBSE Class 12 Biology Paper

A detailed overview of the CBSE Class 12 Biology paper – 2022 is given below:

Number of Questions Asked	13
Maximum Marks	80
Total Time Allotted	3 hours
Paper Section	3 Sections (A, B and C) – All Compulsory
Types of Questions Asked	Short Answer Types, Long Answer Types, Case Study, and MCQs

Section A (2 Marks)

Question 1: Mention the parts of the human body that get affected by Pneumonia and common cold infections. Write the causative agents of the two diseases.                                                                                     

Answer: 

Pneumonia

• Parts of Human body affected- alveoli as well as air sacs of the lungs
•  Causative agent- Streptococcus pneumoniae / Haemophilus influenza

Common cold

•  Parts of Human body affected-nose and respiratory passage
•  Causative agent- Rhinovirus

Question 2: State the impact of constant mechanical agitation and pumping of air in the aeration tank on the sewage during the biological treatment.

Answer: 

The constant mechanical agitation allows vigorous growth of microbe. Furthermore, it is required for the formation of flocs to form mesh-like structures and reduces BOD of the affluent / reduces polluting potential while the microbes consume the major part of organic waste in the sewage. 

or

(a.)  Cattle excreta is an important source for producing domestic fuel.  Name the fuel and write its main components. 

(b.)  Write the biological process that is responsible for the production of this fuel.

Answer:

• a.) Cattle excreta is known for producing Biogas (Gobar Gas), which has main components such as Methane, CO₂, H₂, N₂ and O₂
• b.) Anaerobic digestion of cellulose

Question 3:

• (a.) Give an example of a viral biocontrol agent. 
• (b.) Why are they considered to be desirable when an ecologically sensitive area is being treated?

Answer:

(a.) Baculoviruses  

(b.) They work in a species-specific manner in a narrow range with a minimal impact on plants, animals, fishes, and non-targeted insects, making them suitable candidates for integrated pest management.

Question 4:  What is the importance of female Anopheles mosquitoes in the life of a malarial Parasite, Plasmodium?  

Answer:

 Female Anopheles act as a vector as well as the primary host for Plasmodium. The Plasmodium completes its sexual life cycle in female Anopheles.

Question 5: Study the graph given below, showing the population growth curves ‘A’ and ‘B’, respectively. Answer the following questions:

• (a.) What is ‘Carrying Capacity’ in respect of Curve ‘B’ indicative of?                                                                                     
• (b.) Mention the action of possible natural forces that could have led to curve ‘B’.

 Answers:

• a.) Carrying Capacity is the maximum capacity of an organism to have offspring in a particular habitat. Furthermore, it is the maximum growth to be achieved by an organism.
• b.) Natural selection, survival of the fittest. 

Question 6:  The histogram given below represents the data for the annual shark harvest in the Great Barrier Reef/ coral reef, located on the east coast of Queensland, Australia. Study the histogram and answer the questions that follow.

• (a.) Write your interpretation of the data given.
• (b.) Write the impact on the biodiversity of the area that you can interpret on the basis of given data.

Answer:

• a.) The graph represents an exponential increase in the shark harvesting.
• b.)  Since the environment is over exploited to increase the shark harvest, it will directly cause a decrease in the biodiversity of east coast.  

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Question 6: The stability of a community depends upon its species richness.”   How did David Tilman show this experimentally? 

Answer:

Tilman conducted these experiments in an outdoor plot. He founded that plot with more species shows less year to year variation in the stability.  

 Section B (3 Marks)                     

Question 7: The data collected based on the survey conducted for species richness of groups of mammals in three different climatic regions of the world is shown in the bar graph given below. Panama has nearly 560 species of mammals, Canada has nearly 301 species of mammals, and Denmark has 67 species of mammals.                                                                                                                                     

• (i) Based on the species richness, identify the location of these countries in the respective climatic regions given.
• (ii) Plants and animals do not have a uniform diversity in the world.  Write the term given to this pattern of diversity, and why?    

Answer:

(i) As the graph represents the Taxonomic richness is directly proportional to the different regions. Therefore, following are the locations corresponding with their regions. 

• Panama with 560 species of mammals- Tropic region 
• Canada with 301 species of mammals- Temperate region
• Denmark with 67 species of mammals- Polar region

(ii)   

• Latitudinal gradient. 
• A decrease in species diversity can be seen as we move away from equator towards the pole. 
• This change in species diversity can be explained by different climatic conditions and different latitudes.

Question 8: Biodiversification of life started to occur almost 3 billion years ago. Since then, new species have been evolving and then disappearing en masse from the earth.    

• (a.) How many episodes of mass extinctions of species have already taken place, and which one is in progress in the current era? 
• (b.) How is a current episode in progress different from the previous episodes, and why? Explain. 

Answer:

(a.) There are five mass extinctions have been occurred and the sixth one is going to occur in this era that means it is in progress. 

(b.) The current episode of mass extinction is the sixth episode that is much more approximately 100- 1000 times faster than the previous ones. Reason behind this could the industrialization, the loss of habitat, over exploitation etc.  

Question 9: Name two naturally occurring sources, one that transfers pathogenic genes into plant cells and the other into an animal cell, respectively, for their benefit.  Write how have these naturally occurring sources been used for the benefit of the human race by the biotechnologies. 

Answer:

Following are the naturally occurring sources, that transfer pathogenic genes:

• Plant- Agrobacterium tumefaciens, it transfers the disarmed Ti Plasmid that is used as a vector to introduce the gene of interest in the variety of plants.
• Animal- Retrovirus, the disarmed retroviruses can be used for transferring the genes of interest into mammalian host cells

Question 10: Enumerate the main sources of bio-fertilizers, giving one example of each. 

Answer:

Following the natural resources of fertilizers:

• Bacteria—Rhizobium, Azospirillum, Azotobacter 
• Fungi—Mycorrhiza, Glomus 
• Cyanobacteria—Anabaena, Nostoc, Oscillatoria 

Question 11: Explain giving the reason for the action plan followed by organic farmers that support their key belief “biodiversity furthers health of crop lands”

Answer:

“Biodiversity furthers health of crop lands”- The reason behind this could be not to eradicate the pests and keep them at negotiable or at a manageable level by using the various check and different type balances between the crop and the pests. 

• The pest can be further used as food for example: lamb’s-quarter (Bathua) is a pest wheat crop.
• Furthermore, various types of pests act as a beneficiary predators and parasites who would suffer and not survive. 

Question 12:

1. State the role of a selectable marker in rDNA technology. 
2. Name one such selectable marker which is considered to be useful for E. coli.
3. Give one reason why is it considered to be a useful marker. 

Answer:

(i.) Selectable markers plays a huge role in the transformed and non-transformed colonies of bacteria or in other words in helps in identifying the recombinant and non-recombinant bacteria. 

(ii.) The antibiotic selectable markers can be used for screening. Example: Ampicillin resistance, tetracycline resistance etc. 

(iii.) These markers are useful in identifying or isolating a transformed colony

or                  

Q12. What are plasmids? How are they different from cloning vectors? Give one example each for a viral and a bacterial cloning vector.                                                                                                                                                                                                                                                                    (3 marks)

Answer:

A plasmid is an extra-chromosomal circular DNA present in the prokaryotes(bacteria). It has the ability of self-replication. The plasmid is an extra-chromosomal DNA which is present inside the bacteria naturally whereas a vector can be a natural or synthetic plasmid which we can use as a vehicle to insert our gene of interest. 

Example:

• Bacterial cloning vector: pBR322
• Viral cloning vector: Bacteriophage

Section C (4 Marks)

Question 13: To save crop plants from the attack of various insect pests, biotechnologists have developed many pest-resistant plants.  One such example is the Bt corn plant.  In this plant ‘cry’ genes were introduced which produce cry­ proteins in the plant that has a toxic effect on the pest (corn borer). This saves the corn plant from the attack of the corn borer.  An experimental field study was conducted by the scientists to see the efficacy of the Bt corn plant against the attack of corn borers.  Three different species of corn borers namely ‘A’, ‘B’, and ‘C’ were collected and were independently fed on non-Bt corn plants and Bt corn plants separately for the same period.  The extent of the damage caused to the leaf area of the plant was observed and noted down.  With the help of the observations and data collected, the following bar graph was plotted.  Study the graph and answer the questions that follow. 

(i.) Identify the species of the corn borer that was most successfully controlled by the Bt corn plant. Give an appropriate reason for your inference.

(ii.) Identify the species of the corn borers which show the least impact of toxin produced by  Bt genes.

(iii.) What would be your advice, as a Scientist, to the farmers for growing this particular Bt corn variety in an area which is infested by species of corn borers?

(iv.) Name one Bt gene that encodes a protein in corn plants to control corn borers.

Answer:

(i.) As represented in the graph Species A has the least impact on the Bt-crop. The graph itself represents that species A causes least damage to the leaves.

(ii.) Species B shows a comparable stat in both non-Bt and Bt crops. Therefore, Species B shows least impact of toxin produced by  Bt genes

(iii.) Since the area is already infested by Species B. Furthermore, the coast of Bt-crop is also high and the yield is low as compared to non-Bt crop. Therefore, the farmer should go for non-Bt variety because the overall results are going to be the same. 
(iv.) CryIAb is one of the known Bt gene that encodes protein in corn plants to control corn borers.

Or 

Question 13: A gene was identified in a fungus by a research worker in a lab which was considered to be of great importance in the field of agriculture. As a student of biotechnology, write the steps you would suggest to: 

• (i) Isolate this gene of interest from the fungus and 
• (ii) amplify this gene for further experimentation and research. 

Answer:

(i.)  Following are the steps for the isolation of gene of interest from the fungus:

• Fungal cells should be treated with chitinase to break the cell wall.
• The RNA and Proteins contaminations can be removed by the treatment of RNase, and proteases respectively. 
• Restriction digestion of whole DNA isolate by the site-specific restriction Enzyme. 
• The fragments can be separated by gel electrophoresis.  

(ii.) Amplification of the gene of interest can be achieved by the following steps:

• Multiple copies can be generated by the PCR amplification
• Furthermore, a clone of this gene can be generated to see the function of this gene as a protein. 

Points to Remember While Solving Class 12 CBSE Biology Previous Year Question Paper

Some points to focus on while practising CBSE Class 12 previous year question papers for biology are:

• Understand the question paper format and marking scheme.
• Review important concepts and topics covered in the syllabus.
• Practice time management to answer all questions within the allotted time.
• Read each question carefully and understand what is being asked.
• Answer questions using appropriate diagrams, if necessary.
• Double-check answers for accuracy and clarity before submission.
• Seek clarification from teachers or peers if any doubts arise during solving.
• Use Class 12 previous year question papers as a tool for revision and understanding exam patterns.

Conclusion – CBSE Class 12 Biology Question Paper 2022

The previous year question paper are an important tool while preparing for CBSE class 12 board examinations. They give you a chance to judge your preparations before examinations. CBSE Class 12 Biology Question Papers 2022 are available here. The main purpose of providing the previous year question papers is to give an idea about exam pattern and the types of questions asked in exam. Questions are ofvten repeated in exams as well. Hence, solving class 12 previous year question paper for biology is important while studying.

FAQs – CBSE Class 12 Previous Year Question Paper for Biology (2022)

Is it Necessary to Solve the CBSE Biology Previous Year Papers of Class 12?

Yes, solving CBSE Class 12 Previous Year Question Papers for Biology after completing topics from NCERT textbook helps in gaining in-depth knowledge of the chapter that will ultimately help in scoring good marks in the exams.

Do the CBSE Class 12 Biology Previous Year Papers Provide the Exact Exam Pattern According to the Latest Syllabus?

Yes, CBSE Class 12 Biology Previous Year Papers provide the exact exam pattern as per the latest syllabus. This helps students in getting a better understanding of types of questions asked in board exams.

Why Should a Student Solve the CBSE Class 12 Biology Previous Year Papers

Solving previous year question papers of Class 12 Biology familarise them with the CBSE exam patter, marks distribution, and practise finishing writing answers within alloted time.

Is Previous Year Questions Enough for CBSE Class 12?

Yes, solving the last 5-7 years previous question paper of Class 12 is enough for CBSE board exams but it is advisable to understand the topics before starting to solve the questions.