CBSE 12 Biology Question Paper-2020 Set-1 by Pavan | Practice Test to Test Your Knowledge
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  3. CBSE 12 Biology Question Paper-2020 Set-1
CBSE 12 Biology Question Paper-2020 Set-1

CBSE 12 Biology Question Paper-2020 Set-1

This mock test includes actual CBSE Class 12 Biology board exam questions from the year 2020 Set 1, helping students understand exam trends and practice real paper format

2025-08-06
Pavan Pavan
CBSE Class 12 Biology 2020 Grade 12

Duration

30 min

Questions

30

Marking

Negative

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Questions Preview

Nematode specific genes were introduced into the tobacco host plant by using the vector.

A
Plasmid
B
Bacteriophage
C
pBR 322
D
Agrobacterium

The principle of vaccination is based on the property of.

A
Specificity
B
Diversity
C
Memory
D
Discrimination between ‘self’ and ‘non-self’

Opioids act as.

A
Depressants
B
Pain killers
C
Euphoria providers
D
Stimulants

After spermiogenesis, the sperm heads get embedded in which of the following cells?

A
Leydig cells
B
Sertoli cells
C
Germinal epithelium
D
Seminal vesicle

Introduction of an alien DNA into a plant host cell is achieved by making them.

A
Competent with bivalent ions
B
Using microinjections
C
Using gene gun
D
Using lysozymes and chitinase

The principle of vaccination is based on the property of.

A
Specificity
B
Diversity
C
Memory
D
Discrimination between ‘self’ and ‘non-self’

Opioids act as.

A
Depressants
B
Pain killers
C
Euphoria providers
D
Stimulants

After spermiogenesis, the sperm heads get embedded in which of the following cells?

A
Leydig cells
B
Sertoli cells
C
Germinal epithelium
D
Seminal vesicle

Introduction of an alien DNA into a plant host cell is achieved by making them.

A
Competent with bivalent ions
B
Using microinjections
C
Using gene gun
D
Using lysozymes and chitinase

One of the ex situ conservation methods for endangered species is.

A
Biosphere reserves
B
National parks
C
Cryopreservation
D
Wildlife sanctuaries

Hormones released in human females only during pregnancy are.

A
hCG, hPL, Progesterone
B
Relaxin, hCG, hPL
C
hCG, hPL, Oxytocin
D
hPL, Thyroxine, hCG

The principle of vaccination is based on the property of.

A
Specificity
B
Diversity
C
Memory
D
Discrimination between ‘self’ and ‘non-self’

Cotton bollworms enjoy feeding on cotton plants, but get killed when they feed on Bt cotton plant. Justify the statement.

A
Genetically modified cotton plants produce toxins that are harmful to bollworms.
B
Bollworms have a high tolerance to cotton plant toxins.
C
Bt cotton is resistant to bollworm infestation.
D
Bollworms cannot digest Bt cotton plants.

Spirulina is a rich source of proteins. Mention the two ways by which large scale culturing of these microbes is possible.

A
Bioreactors and pond farming
B
Ocean farming and bioreactors
C
Pond farming and artificial lakes
D
Bioreactors and algae tanks

What is the action of EcoRI on a DNA molecule?

A
Cuts DNA at specific sequences
B
Cleans DNA strands
C
Denatures DNA to separate strands
D
Ligates two DNA molecules together

Which of the following is true about the interaction between mycorrhizae and plants?

A
Mycorrhizae enhance water and nutrient absorption for the plant.
B
Mycorrhizae reduce water absorption from the soil.
C
Mycorrhizae act as pathogens to plants.
D
Mycorrhizae produce toxins that help the plant.

What is the scientific name of methanogen bacteria and their role in biogas production?

A
Methanobacterium; they convert organic waste into methane.
B
Methanobacterium; they use nitrogen to produce biogas.
C
Bacillus; they break down glucose to produce methane.
D
Methanogen; they produce methane through anaerobic processes.

Which of the following is true about the mechanism of sex determination in humans?

A
Humans have XY sex chromosomes.
B
Humans have XO sex chromosomes.
C
Humans have ZW sex chromosomes.
D
Humans have XXY sex chromosomes.

Differentiate between Dominance, Incomplete dominance, and Co-dominance with suitable examples.

A
Dominance involves one allele completely masking another. Incomplete dominance results in a blending of traits, and Co-dominance results in both traits being expressed.
B
Dominance involves no expression of traits. Incomplete dominance results in a blending of traits, and Co-dominance results in the suppression of one trait.
C
Dominance involves both traits being expressed. Incomplete dominance results in blending, and Co-dominance results in full masking of the other allele.
D
Dominance has equal expression of both alleles. Incomplete dominance results in dominant expression, and Co-dominance suppresses alleles.

How is the gamete formation comparable in humans and honeybees with respect to chromosome number?

A
Humans have 46 chromosomes and undergo meiosis. Honeybees have 32 chromosomes, and males are produced from unfertilized eggs.
B
Humans have 46 chromosomes, and males produce sperm with half the chromosomes. Honeybees have 32 chromosomes, and males are produced by fertilized eggs.
C
Humans and honeybees both have 46 chromosomes and produce identical gametes.
D
Humans and honeybees both have 32 chromosomes, and males and females are identical.

Which of the following is true about the chemical nature of antibodies and the cells that produce them?

A
Antibodies are proteins produced by plasma cells.
B
Antibodies are lipids produced by T-cells.
C
Antibodies are sugars produced by B-cells.
D
Antibodies are proteins produced by red blood cells.

How is the principle of Hardy-Weinberg equilibrium applied to population genetics?

A
It is used to predict the genetic variation within a population under equilibrium conditions.
B
It is used to measure the rate of mutation in a population.
C
It is used to assess the dominance of traits in a population.
D
It is used to identify the extinct species in a population.

What is the process of natural selection?

A
It is the process where organisms better adapted to their environment tend to survive and reproduce more offspring.
B
It is the process where all organisms in a population are equally likely to survive.
C
It is the process of genetic mutation causing immediate changes in an organism.
D
It is the process by which new species are created from one ancestral species.

Which of the following processes is responsible for the transfer of genetic material between two prokaryotic cells?

A
Conjugation
B
Replication
C
Mutation
D
Fertilization

What is the role of enzymes in biological reactions?

A
They increase the rate of reactions by lowering the activation energy.
B
They decrease the rate of reactions by raising the activation energy.
C
They serve as a source of energy for cells.
D
They are responsible for maintaining homeostasis in the body.

Which of the following is not a characteristic of a prokaryotic cell?

A
Presence of a nucleus
B
Lack of membrane-bound organelles
C
Small size
D
Circular DNA

In which part of the cell does glycolysis occur?

A
Cytoplasm
B
Mitochondria
C
Nucleus
D
Endoplasmic Reticulum

What is the final electron acceptor in the electron transport chain?

A
Oxygen
B
NADH
C
ATP
D
FADH2

Which of the following processes occurs during the light-independent reactions of photosynthesis?

A
Carbon fixation
B
Production of ATP
C
Splitting of water molecules
D
Absorption of sunlight

Which of the following best describes the function of ribosomes?

A
They synthesize proteins.
B
They store genetic material.
C
They break down cellular waste.
D
They produce ATP.