CBSE 12 Biology Question Paper-2019 by Pavan | Practice Test to Test Your Knowledge
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CBSE 12 Biology Question Paper-2019

CBSE 12 Biology Question Paper-2019

This mock test includes actual CBSE Class 12 Biology board exam questions from the year 2019, helping students understand exam trends and practice real paper format

2025-08-06
Pavan Pavan
CBSE Class 12 Biology 2019 Grade 12

Duration

30 min

Questions

30

Marking

Negative

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Questions Preview

What is ‘population’ according to you as a biology student?

A
The total number of individuals of a species in a given area.
B
The sum of all living organisms in a particular habitat.
C
The birth rate in a specific geographical region.
D
The total biomass of all species in a region.

What is hydrarch succession?

A
The succession process in water bodies leading to the formation of a climax community.
B
The gradual increase in soil fertility in a desert area.
C
The formation of dry land from waterlogged conditions.
D
The process of vegetative growth in tropical forests.

What are the advantages of the ex-situ conservation method?

A
It allows the conservation of species outside their natural habitat.
B
It provides a permanent solution to environmental degradation.
C
It focuses on preserving habitats and biodiversity within natural ecosystems.
D
It aims at maintaining natural habitats with minimal human intervention.

What is the cause of algal bloom in ponds?

A
Excessive nutrient concentration leading to rapid growth of algae.
B
Lack of water currents and stagnant conditions.
C
Water temperature decline due to seasonal changes.
D
Increased water transparency caused by reduced pollution.

Which of the following is a genetically modified organism (GMO)?

A
Genetically modified cotton with insect resistance.
B
A naturally occurring hybrid of two species.
C
Wild plants adapted to drought conditions.
D
A species bred for enhanced taste.

What is the importance of totipotency in plants?

A
It allows plant cells to develop into a complete plant.
B
It is used to transfer genes from one plant to another.
C
It leads to the formation of specialized plant tissues.
D
It helps in the rapid growth of plants in unfavorable conditions.

What are somaclones in plant biotechnology?

A
Genetically identical plants produced through tissue culture.
B
Plants produced by grafting.
C
Natural hybrids between different plant species.
D
Plants that have developed through seed propagation.

What is the process of PCR (Polymerase Chain Reaction)?

A
A method to amplify specific DNA segments.
B
A technique for transforming bacteria.
C
A process for cloning whole organisms.
D
A method used to extract DNA from cells.

What is the role of B-lymphocytes in the immune response?

A
They produce antibodies to neutralize pathogens.
B
They activate T-cells to fight infections.
C
They directly attack infected cells.
D
They produce interferons to prevent viral infections.

What is the importance of the genetic code in protein biosynthesis?

A
It determines the sequence of amino acids in proteins.
B
It regulates the timing of DNA replication.
C
It controls the transcription of RNA.
D
It prevents mutations during cell division.

What is the principle of vaccination based on?

A
The memory property of the immune system.
B
The prevention of initial infection by pathogens.
C
The use of antibiotics to kill pathogens.
D
The stimulation of T-cell responses.

What is the cause of ‘Swiss Cheese’ developing large holes?

A
Carbon dioxide produced by bacteria during fermentation.
B
Presence of air pockets in the cheese-making process.
C
Fermentation by yeasts in the cheese.
D
The natural separation of fats during aging.

What does genetic drift refer to?

A
Random changes in allele frequencies in a population.
B
The increase in genetic variation due to mutation.
C
Selection of the fittest organisms for reproduction.
D
The migration of individuals between populations.

What is the importance of gene flow in populations?

A
It leads to genetic diversity by introducing new alleles.
B
It decreases the chance of extinction.
C
It allows for the adaptation of species to new environments.
D
It increases the reproductive success of individuals.

At which stage does meiosis occur in organisms with a haploidic life cycle?

A
At the formation of gametes.
B
At fertilization.
C
During embryonic development.
D
At the beginning of mitosis.

What is the role of T-lymphocytes in the immune response?

A
They produce antibodies to neutralize pathogens.
B
They directly attack infected cells.
C
They regulate the immune response and activate other immune cells.
D
They produce interferons to prevent viral infections.

What is the significance of B-lymphocytes in vaccine development?

A
They produce antibodies that provide long-term immunity.
B
They enhance the activity of T-cells.
C
They store memory of pathogens for faster response.
D
They create mutations in pathogens to adapt to vaccines.

What is the importance of gene mapping?

A
To determine the location of genes on a chromosome.
B
To study genetic disorders in individuals.
C
To identify the function of specific proteins.
D
To prevent mutations during cell division.

What is the role of DNA ligase in DNA replication?

A
It unwinds the DNA double helix.
B
It synthesizes new DNA strands.
C
It seals the gaps between Okazaki fragments.
D
It proofreads and repairs DNA.

What is the significance of amniocentesis in genetics?

A
It helps to detect genetic abnormalities in the fetus.
B
It aids in the process of gene editing.
C
It is used to produce genetically modified organisms.
D
It helps to clone cells for research purposes.

What is a key feature of gene therapy?

A
It involves replacing defective genes with functional ones.
B
It increases the rate of cell division.
C
It allows for cloning entire organisms.
D
It enhances the body's ability to fight infections.

What is the function of an enzyme like EcoRI in genetic engineering?

A
It cuts DNA at specific sequences.
B
It amplifies DNA during PCR.
C
It attaches genes to plasmids.
D
It transcribes DNA into RNA.

What is the basic concept of recombinant DNA technology?

A
Combining DNA from different sources to create new genetic combinations.
B
Extracting and studying individual genes.
C
Using viruses to insert foreign DNA into cells.
D
Replicating DNA using cell division.

What is the process of using CRISPR-Cas9 for gene editing?

A
It is a method to make precise alterations in the DNA of living organisms.
B
It involves the use of radiation to induce mutations in genes.
C
It is a method for amplifying DNA for sequencing.
D
It involves cloning entire genes into bacteria.

What is the principle of cloning in biotechnology?

A
Creating genetically identical organisms from a single cell.
B
Inserting foreign genes into a host organism.
C
Amplifying a specific gene segment for research.
D
Sequencing DNA to identify mutations.

What does ‘gene therapy’ aim to treat?

A
Genetic disorders by inserting, altering, or removing genes.
B
Infectious diseases using vaccines.
C
Cancers by inducing cell death.
D
Bacterial infections by modifying the immune system.

What is the role of mitochondria in cells?

A
They produce energy in the form of ATP.
B
They synthesize proteins from amino acids.
C
They maintain the structure of the cell.
D
They store genetic information in the form of RNA.

Which of the following is a type of genetic mutation?

A
Point mutation.
B
Tissue differentiation.
C
Protein folding.
D
Chromosome translocation.

What is the significance of a plasmid in genetic engineering?

A
It is used as a vector to introduce new genes into organisms.
B
It produces proteins for therapeutic use.
C
It is used to remove defective genes from the genome.
D
It repairs damaged DNA in the host organism.

What does a gene promoter do in transcription?

A
It initiates the binding of RNA polymerase to the gene.
B
It terminates the transcription process.
C
It repairs the DNA during transcription.
D
It modifies RNA after transcription.