CBSE Class 12 Question Paper 2026 Biology

FOR CBSE CLASS 12 EXAM PREPARATION

CBSE Class 12 2026
Question Paper ·
Biology
EXAM YEAR TYPE SUBJECT

CBSE Class 12 2026 Question Paper Biology

Notes · Sample Papers · Previous Year Papers · Mock Tests

m
m .co

m .co s e m
se g l a
Series : P1QSR a SET~1
- 
Q.P. Code 57/1/1
 .
 -   - 
Roll No.
-    
m
.co
Candidates must write the Q.P. Code
m
.co
on the title page of the answer-book.
e m
e m l as
l as   () ag
ag
BIOLOGY (Theory)
  : 3    : 70
Time allowed : 3 hours Maximum Marks : 70

 {} NOTE
(I)       -   (I) Please check that this question
 23   o mpaper contains 23 printed pages.
.c
(II) -        m(II) Q.P. Code given on the right
s e hand side of the question paper
gl a
-    - 
should be written on the title
-   
a page of the answer-book by the
candidate.
(III)       -  33 (III) Please check that this question
   paper contains 33 questions.

(IV)         (IV) Please write down the serial
, -      number of the question in the
answer-book at the given place
   
o m before attempting it.
m  -     15   (V) 15 minute time hasmbeenc
. allotted
c. o(V)  s e paper. The
to read this question
e m     -  
l
question paper awill be distributed
l as   10.15     10.15
at 10.15 ag
a.m. From 10.15 a.m. to
ag   10.30    
  -
        
10.30 a.m., the candidates will
read the question paper only and
-       will not write any answer on the
answer-book during this period.

57/1/1
2401-1
_________ Page 1 of 24 *P.T.O.

m .
.co s e m
s em l a
g la ag
a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 1 of 24

  
         :
(i)  -  33        
(ii) -      –  , , ,    
(iii)   –   1  16          1    
(iv)   –   17  21   -        2  
 
(v)   –   22  28  -        3    
(vi)   –   29  30 -      4      -
    -         
(vii)   –   31  33  -        5    
(viii) -         ,       
                 
(ix)         -  
(x)    , -          

 – 

  1  16          1       
  

1.               1

(A)  () (B) 

(C)  (D) 

2.           ? 1

(A)  () (B)  

(C)   ()  (D)   ( )

57/1/1 _________ Page 2 of 24 {} *P.T.O.

For more Question Papers, Sample Papers, Notes & Syllabus visit Page 2 of 24

m
m .co

m .co s e m
se g l a
a
General Instructions :
Read the following instructions carefully and follow them :
(i) This question paper contains 33 questions. All questions are compulsory.
(ii) Question paper is divided into FIVE sections – Section A, B, C, D and E.
(iii) Section A – questions number 1 to 16 are multiple choice type questions.
Each question carries 1 mark.
m
.co
(iv) Section B – questions number 17 to 21 are very short answer type
o m
questions. Each question carries 2 marks.
m
c
(v) Section C. – questions number 22 to 28 are short answer type questions. se
m carries 3 marks.
equestion l a
Eachs
la D – questions number 29 and 30 are case-based questions. Eachag
(vi) gSection
a question carries 4 marks. Each question has subparts with internal
choice in one of the subparts.
(vii) Section E – questions number 31 to 33 are long answer type questions.
Each question carries 5 marks.
(viii) There is no overall choice. However, internal choices have been provided
in some questions. A candidate has to write answer for only one of the
alternatives in such questions.
m
candidates. m .co
(ix) Kindly note that there is a separate question paper for Visually Impaired

s e
(x)
la
Wherever necessary, neat and properly labelled diagrams should be drawn.
g
a
SECTION – A
Question Nos. 1 to 16 are Multiple Choice Type Questions, carrying 1 mark
each. Choose the best option.
1. Identify the plant in which emasculation is not required for artificial
hybridization. 1

m(A) Rice (B) Wheat . com
.c o e m
em
(C) Pea s
(D) Papaya
l a
s
la 2. g
a ?
ag Which of the following is not a component of immune system 1
(A) Lymphocytes (B) Plasma Proteins
(C) Red Blood Cells (D) Bone Marrow

57/1/1 _________ Page 3 of 24 {} *P.T.O.

m .
.co s e m
s em l a
g la ag
a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 3 of 24

3.            : 1

(i)   ( )     
(ii)          (FSH)        
(iii)             
(iv)    - (  )  -    
 
(A)  (ii)     (B) (i)  (iii)   

(C)  (iv)     (D) (ii)  (iv)   

4.  )     :
  ( 1

(A)        – 12
(B)         () – 1000   
(C)   ()-       –    7
 
(D)  ()  –   

5.      ( )  ‘ ’     : 1

(A)    (B)   
(C)    (D) ,   

6.                
       – 1

(A) - (B)  ( )
(C)  (D) 
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m
m .co

m .co s e m
se g l a
a
3. Select the option that shows correct statements : 1

(i) Corpus luteum secretes progesterone.

(ii) Only FSH attains a peak level in middle of cycle.

(iii) LH surge induces rupture of graafian follicle.

(iv) Luteal phase of menstrual cycle is also called proliferative phase.
m
m .co
.co
Options :
e m
em
(A) Only (ii) is correct.
l as
s
laand (iii) are correct. ag
g
(B) (i)
a
(C) Only (iv) is correct.

(D) (ii) and (iv) are correct.

4. Select the mismatched pair : 1

(A) Mega diversity countries in the world – 12
m
.co
(B) Genetically different strains of rice in India – Less than 1000
m
s e
la
(C) Robert Mays estimation on global species diversity – 7 million
species worldwide
ag
(D) Zoological parks – Ex-situ conservation

5. Pomato was produced by fusing protoplasts of 1

(A) Tomato and Potato (B) Pomegranate and Tomato

(C) Pomegranate and Potato (D) Pomegranate, Potato and Tomato m
m .co
.co
m 6. s em
s e In an ecosystem, different species occupy different levels
g la and vertical
g la a
distribution of species is found. This is called _________. 1
a (A) Stratification (B) Layering

(C) Fragmentation (D) Population

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m .
.co s e m
s em l a
g la ag
a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 5 of 24

7.      ‘ ’      ? 1
(A)   (B) 
(C)  (D) 

8.                     
     ? 1

(A)    (B)    
(C)   (D)  

9. -I      -II            
   : 1
-I -II
a.   i.  
b.  ii.  
c. Ti iii.  
d. Ca ++ iv.  
v.  
 :
a b c d
(A) i ii iii iv
(B) ii v i iii
(C) v iv ii i
(D) v i iv ii

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m
m .co

m .co s e m
se g l a
a
7. Which of the following sacred groves is found in Meghalaya ? 1
(A) Jaintia hills (B) Bastar
(C) Chanda (D) Sarguja

8. In the following figure, two ways of pairing of two homologous pairs of
chromosomes are shown. Which of the following phenomena is expressed ? 1
m
m .co
m .co s e m
s e l a
g l a ag
a

o m
c
. Independent assortment of genes
(A) Linkage of genes m
(B)
e(D) Incomplete dominance
(C) Multiple alleles
la s
ag
9. Match Column-I with Column-II and choose the correct option : 1
Column-I Column-II
a. Biolistic gun i. Bacterial cell
b. Chitinase ii. Tumour inducing
c. Ti iii. Animal cell
d. Ca++ iv. Fungal cell
m
m
c. o Options :
v. Plant cell
m.co
m s e
s e a b c d
g l a
g la (A) i ii iii iv a
a (B) ii v i iii
(C) v iv ii i
(D) v i iv ii

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m .
.co s e m
s em l a
g la ag
a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 7 of 24

10.              ( ) 
    : 1

(A)   (B)  
(C)    (D) 

11.              ? 1

(A)            
(B)    ()      
(C)      ()    
(D)          

12.               ? 1

(A)  () (B)  ()
(C)  () (D) 

  13  16  ,      –     (A)   
 (R)                (A), (B), (C)  (D)
    :
(A)  (A)   (R)      (R),  (A)   
  
(B)  (A)   (R)   ,   (R),  (A)   
   
(C)  (A)  ,   (R)   
(D)  (A)  ,   (R)   
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m
m .co

m .co s e m
se g l a
a
10. The idea of use and disuse of organs for evolution of organism was proposed
by 1

(A) Charles Darwin

(B) Thomas Malthus

(C) Hugo De Vries
m
m .co
.co
(D) Lamarck
e m
em l as
s
a the following statements about plasmids is incorrect ?
11. Whichlof ag 1
ag
(A) Plasmids have the ability to replicate within the bacterial cell.

(B) Their replication is controlled by chromosomal DNA.

(C) They are autonomously replicating circular extra-chromosomal DNA.

(D) They often carry antibiotic resistant genes.

o m
c
12. Which connective tissue connects ovary .to pelvic wall and uterus ?
em
1

(A) Tendons
s
la (B) Ligaments
g
a (D) Bone
(C) Cartilage

For Questions number 13 to 16, two statements are given – one labelled as
Assertion (A) and the other labelled as Reason (R). Select the correct answer
to these questions from the codes (A), (B), (C) and (D) given below :

m
.co
(A) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct
m
.co
explanation for Assertion (A).
e m
e m l as
(B) Both Assertion (A) and Reason (R) are true, but Reason (R) is not the
las correct explanation for Assertion (A). ag
ag
(C) Assertion (A) is true, but Reason (R) is false.

(D) Assertion (A) is false, but Reason (R) is true.

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m .
.co s e m
s em l a
g la ag
a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 9 of 24

13.  (A) :               
  
 (R) :             
           1

14.  (A) :   ‘’            
       
 (R) :    -    1

15.  (A) :   
            
         
 (R) :             1

16.  (A) :              
( )    
 (R) :                1

 – 
17. (a)    (  )     1

(b)            ()    
    1

18. (a) (i)                ? 1

(ii)            1


(b)           ( )  
    
         2

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m
m .co

m .co s e m
se g l a
a
13. Assertion (A) : The population of melanized moths increased in industrial
areas after Industrial Revolution.
Reason (R) : In Industrial environment lichen covered trees were
replaced by soot-covered trees offering better camouflage to
dark coloured moths. 1

m
.co
14. Assertion (A) : The milk produced by transgenic cow ‘Rosie’ was
m
.co m
nutritionally more balanced product for human babies than
m natural cow milk. s e
s e
Reasona (R) g l a
l a
: It was human protein enriched milk containing human
ag alpha lactaglobulin. 1

15. Assertion (A) : Flocs are masses of bacteria associated with fungal
filaments in secondary treatment of sewage.
Reason (R) : Flocs help in digestion of solid waste by anaerobic
respiration. 1

m
.co
16. Assertion (A) : In terrestrial ecosystem much larger fraction of energy
flows through grazing food chain.
e m
Reason (R)
las
: Grazing food chain may be connected to Detritus food chain
at some levels.
ag 1

SECTION – B
17. (a) Define Humoral immune response. 1
(b) Name any two types of antibodies found to give humoral immune
response in humans. 1

m
c. o
m
18. (a) (i) How does a farmer use dormancy of seed to his advantage ?
.co 1
(ii) em
Differentiate between pea seed and castor seed.
s 1

s em OR
g la
l a a
ag (b) Identify the stage of follicle where primary oocyte undergoes first
meiotic division.
Also mention the products of this division. 2

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m .
.co s e m
s em l a
g la ag
a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 11 of 24

19.                   
  :
5' – GAATTC – 3'
3' – CTTAAG – 5'
(a)        ?         
       1
(b)         ? 1

20. (a)          ()    :
 ()-I :   (XO)             
     (XX)   
 ()-II :        (ZW)       
       (ZZ)   
  ()         -  
  1+1

(b) (i)          1
(ii)              1

21. (a)                  
  ()       ( )     

(i)              
             1
(ii)          1

(b)        () /   -    
(i)  -     ? (  ) 1
(ii) -           1

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m
m .co

m .co s e m
se g l a
a
19. Study the sequence of bases in a DNA molecule that is shown below and
answer the questions.
5' – GAATTC – 3'
3' – CTTAAG – 5'
(a) What are such sequences called ? Name the enzyme used that
recognises such nucleotide sequences. 1
(b) How do these enzymes function ? m
.co
1

o m m
c
20. (a) Analyse .the following two cases of sex determination in different s e
s em :
organisms
g l a
l a a
ag copies of same sex chromosome (XX).
Case I : Males have (XO) sex chromosomes and females have two

Case II : Females have two different sex chromosomes (ZW) and
males have two copies of same sex chromosome (ZZ).
Identify the type of heterogamety in each case, giving one example of
each. 1+1
OR
(b) (i)
m
Differentiate between a DNA and RNA nucleotide. 1
co within a single nucleotide.
(ii) Name the two types of bonds .present 1

s em
21. (a) Given below is a pyramidlafound in an ecosystem, where each bar
g
represents the standingacrop available in the trophic level.

(i) Identify the kind of pyramid and with the help of an example
explain the conditions where this kind of pyramid is possible in
m
.co
nature. 1

. c om (ii)
em
Write any two limitations of ecological pyramids. 1

e m OR
la s
las (b) In an ecosystem there was loss of biodiversity duegto some project in
a
ag that area.
(i) How will biodiversity be affected ? (2 points) 1
(ii) List two major causes of loss of biodiversity. 1

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m .
.co s e m
s em l a
g la ag
a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 13 of 24

 – 
22. (a)          ?    
        2½
(b)   ()         ? ½

23. (a)     ?             1 + 1
(b)         
(i)    ()   ½
(ii)      ()        () 
  ½

24. (a)  –   (p2 + 2pq + q2) = 1       ? 2
(b)           
       1

25.   ()          (6) 
    ½6=3

26. (a)                  1
(b)    -      ?        
      2

27.    -A  -B          -A   
   -B        (GM)   
       -A      ,    
 -A  Bt       
(a)                 ½
(b)    Bt      ? 1½
(c) -B            ()   
  ?    1

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m
m .co

m .co s e m
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a
SECTION – C
22. (a) Do all pollen grains remain viable for the same length of time ?
Support your answer with two suitable examples. 2½
(b) How are pollen grains stored in pollen banks ? ½

23. (a) What is pedigree analysis ? Mention its importance in human
genetics. (2 pts.) m
.co
1+1
m
.co
(b) Analyse the following pedigree and write the
e m
(i) Pattern of inheritance.
em ½
l as
l as
(ii) Give one example of disease showing such an inheritance
pattern. ½ ag
ag

o m
c
24. (a) How is Hardy-Weinberg expression. (p + 2pq + q2) = 1 derived ?
2 2
s emthe genetic equilibrium.
(b) List any two factors that disturb 1

g la
a
25. Draw a neat diagram of megasporangium of an angiosperm and label any
six parts. ½6=3

26. (a) Mention the scientific name of the source plant and the part from
which opioids are extracted. 1
(b) How are morphine and heroin related ? Mention the effect each one
of them has on human body. 2
m
27. A farmer grew two varieties of corn crop in field A and B. He grew normal
m .co
m .co corn crops in field A and GM corn crops in field B.
s e m
s e He observed that corn borers attacked only in field A. To control it, spores
of Bt were sprayed on field A. g l a
g la (a) Name the gene in the spores responsible for control of pest. ½ a
a (b) What effect will the spores of Bt have on insect pest ? 1½
(c) How has corn plants of field B developed resistance against this
pest ? Explain. 1

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m .
.co s e m
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g la ag
a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 15 of 24

28.              100    1800 
   ()          ()
            :

(a)           ?   
  1
(b)             ‘X’  100
      

‘X’                ? 
‘X’       ? 2

 – 
  29  30 -       -     - 
     
29.               
      
    
               
    
      

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m
m .co

m .co s e m
se g l a
a
28. Observe the given picture carefully. A mixture of DNA with fragments
ranging from 100 base pairs to 1800 base pairs were separated by
electrophoresis on agarose gel with the following arrangement :

m
m .co
.co s e m
s em l a
g la ag
a
(a) What result will be obtained in staining with ethidium bromide ?
Explain with reasons. 1
(b) The above setup was modified as shown below and a band with 100
base pairs was obtained at X.

m
m .co
s e
g la
a
What changes were made to the previous design to get a band at ‘X’.
Why did the band appear at ‘X’ ? 2

SECTION – D
o m
m c
. has sub-
c. o Question Nos. 29 and 30 are case-based questions. Each question
s e m
e m sections with internal choice in one sub-section. l a
l as 29. The diagram below shows the distribution of two gbarnacle
a species,

ag Chthamalus and Balanus on a rocky sea shore.
When Balanus is experimentally removed, Chthamalus expands its range
in lower intertidal zone.

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.co s e m
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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 17 of 24

(a)     ()          
     1


(a)                1
(b)                 
  1
(c)          ?         2
30.        ()       ()   
                  
       :

(a)  -I  II       - ()   
  ? 1

(a)   ()           ? 1

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(a) Identify and define the ecological phenomenon demonstrated by this
observation. 1

m
m .co
m .co s e m
s e l a
g l a ag
a

OR
(a) State the principle that explains the elimination of one species. 1
(b) Two different species can compete for the same resource. Give
another example of it. 1
(c) m
How do species avoid competition in nature ? Explain with an example.
o
2
c
. and represented the result in
30. A student performed some crosses in plants
the form of bar graphs as shown m
e below. Each graph displays the
l as
phenotypic proportion of the progeny. Study the graphs and answer the
questions : a g

m
m .co
m .co s e m
s e g l a
g la a
a (a) What can you infer about the genotype of parents in crosses I and II ? 1
OR
(a) Which genetic cross is represented by these crosses ? 1

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a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 19 of 24

(b) -III       ()        
       2

(c)  I  II                ?
         1

 – 
31. (a)   ()            
               5


(b) (i)      ()             
    ()             
                
             
    
-I –  –   
 –   ,   ()  
( )       1

-II –  –        
 –            1

-III –  –  
 –            1

(ii)      (  )    
                
         2

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m
m .co

m .co s e m
se g l a
a
(b) Looking at bar graph of cross III, identify the type of cross performed
and its importance in genetics. 2

(c) What conclusion can you draw from the results of bar graphs of
crosses I and II ? Name the genetic principle illustrated. 1

m
m .co
.co SECTION – E
s e m
31. (a) Traceemthe events from fertilization till implantation of blastocyst in la
l as ag
aghuman female. Also mention the site where fertilization takes place. 5
OR

(b) (i) Case studies of some couples are given below. They were not
able to have kids even though the parents were not taking any
precautions. They also do not wish to adopt a child or take the

m
help of donors. Study these cases and suggest an appropriate
o
c
. that could help them.
m
Assisted Reproductive Technology
e
s
la Reports
Case I – Female – Normal
a g
Male – Normal sperms but no connection between
epididymis and vas deferens. 1

Case II – Female – Normal eggs but Fallopian tube blocked.

Male – Normal sperms. Male reports are normal. 1

Case III – Female – Normal Reports.
o m
m Male – Low sperm count with less motility.m.
c
m .co s e 1

s e l a
la (ii) Copper releasing intrauterine devices areag
very effective and
ag popular contraceptive devices. Name any two copper releasing
IUDs. Write two reasons that make them effective contraceptives. 2

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m .
.co s e m
s em l a
g la ag
a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 21 of 24

32. (a) (i)              
 ?       ,       2
(ii)             3

(b)  DNA               
   
5' - ATG ACC GTA TTT TCT GTA GTG CCC GTA CTT CAG GCA TAA 3'
(i)         mRNA    
    2
(ii)   mRNA  GUA     mRNA   / 
 hnRNA       
(1)    1
(2)    1
(iii)    ()        
      ? 1

33. (a) (i)              
       ½
(ii)             
          2
(iii)  ()              
  ? 1½
(iv)               
()     1

(b) (i) -   ? 1
(ii)    -           -
               
    3
(iii)     -        1
_________

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m
m .co

m .co s e m
se g l a
a
32. (a) (i) Watson and Crick’s discovery of double helical structure was
based on which two findings. Also mention the name of the
scientists associated with these findings. 2
(ii) Write down the salient features of double helix structure of
DNA (any three points). 3
OR
m
.co
(b) Given below is a stretch of DNA showing the coding strand of
o m
structural gene of transcription unit.
m
. c GTA TTT TCT GTA GTG CCC GTA CTT CAG GCA TTA 3' se
(i) se
m
5' - ATG ACC
Write the corresponding template strand and m-RNA strand gl
a
g la that will be transcribed along with its polarity. a 2
a (ii) If GUA of transcribed mRNA is an intron, then depict the
sequence involved in formation of mRNA / mature / processed
hnRNA strand :
(1) In a bacterium 1
(2) In humans 1
(iii) How many amino acids the resulting polypeptide will have after
the process of translation in humans ? m 1
c. o
em
33. (a) (i) Name the protozoan species that is responsible for causing the

as
most serious and even fatal malarial disease.
l the parasite completes its sexual stages
½

ag
(ii) Name the host in which
and explain the changes taking place. 2
(iii) How does the parasite damage the human body after entering
the blood stream ? 1½
(iv) Suggest two effective preventive measures to control the spread
of this disease in endemic regions. 1
OR
(b) (i) What are bio-fertilizers ?
o m 1
m (ii) Name the different types of microorganisms used. as bio- c
m .co fertilizers in organic farming and explain how each
s emcontributes
s e to soil fertility.
g la 3

g la a over chemical
(iii) Write two advantages of using bio-fertilizers
a fertilizers. 1
____________

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m .
.co s e m
s em l a
g la ag
a For more Question Papers, Sample Papers, Notes & Syllabus visit Page 23 of 24

2401-1
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