Kerala Plus Two Question Paper 2025 Biology

KERALA BOARD

QUESTION
PAPER
2025
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Kerala Board of Public
Examinations

SY-426
Reg. No. : ......................................

Name : ...........................................

SECOND YEAR HIGHER SECONDARY EXAMINATION, MARCH 2025
Part – III Time : 2 Hours
BIOLOGY Cool-off time : 15 Minutes
(Botany & Zoology) Preparatory Time : 10 Minutes
Maximum : 60 Scores
General Instructions to Candidates :
 There is a ‘Cool-off time’ of 15 minutes in addition to the writing time. Further there
is a ‘10 minutes’ ‘Preparatory Time’ at the end of the Botany Examination and before
the commencement of Zoology Examination.
 Use the ‘Cool-off time’ to get familiar with questions and to plan your answers.
 Read questions carefully before answering.
 Read the instructions carefully.
 Calculations, figures and graphs should be shown in the answer sheet itself.
 Malayalam version of the questions is also provided.
 Give equations wherever necessary.
 Electronic devices except non-programmable calculators are not allowed in the
Examination Hall.
 
    15  ‘  ’ .
     
‘10  ’   .  
  ,   
 .
 ‘  ’    
 .
      .
    .
  , , ,   
.
   .
    .
     
    .

SY-426 1

PART – A

BOTANY

(Maximum : 30 Scores) Time : 1 Hour

I. Answer any 3 questions from 1 to 5. Each carries 1 score. (3  1 = 3)

1. Decomposition would be fast if the detritus contains _____ .

(a) Cellulose

(b) Lignin and chitin

(c) Nitrogen and water soluble sugars

(d) Cellulose and pectin

2. Name the method in which the alien DNA is directly injected into the nucleus of an

animal cell.

3. Observe the first pair and fill in the blanks.

Population interaction in which one species benefits and other is neither harmed nor

benefited : Commensalism

Population interaction where one species is harmed and other is unaffected : _____ .

4. If any protein coding gene is expressed in a heterologous host, the protein formed is

called _____ .

SY-426 2

PART – A

BOTANY

(Maximum : 30 Scores) Time : 1 Hour

I. 1  5    3  .

1  . (3  1 = 3)

1. _____     .

(a) 

(b) , 

(c) ,   

(d) , 

2.      
  .

3.     .

       
 : .

      
 : _____.

4.      
      _____ .

SY-426 3 P.T.O.

5. Which among the following is a non-albuminous seed ?

(Wheat, Groundnut, Maize, Barley)

II. Answer any 9 questions from 6 to 16. Each carries 2 scores. (9  2 = 18)

6. (a) Tapetum play an important role in the development of male gametophyte. Give

reason.

(b) Write any one peculiarity of tapetal cell.

7. Write the steps in making the bacterial cell competent to take up the recombinant

DNA.

8. (a) Define Gross primary productivity.

(b) What are the factors affecting primary productivity ?

9. Apomixis is a blessing to agriculture. Justify the statement with reasons.

10. (a) What is population density ?

(b) List any two ways of measuring population density of a habitat.

SY-426 4

5.     .

(, , , )

II. 6  16    9  .

2  . (9  2 = 18)

6. (a)      

.

(b)      .

7.   DNA    

   .

8. (a)    .

(b)     .

9.    .  

 .

10. (a)    ?

(b)      ?

SY-426 5 P.T.O.

11. Match the following :

1. ADA deficiency – AIDS

2. Humen -lactalbumin – Emphysema

3. ELISA – Genetherapy

4. -1 Antitrypsin – Rosie

12. The most spectacular and evolutionarily fascinating examples of mutualism are found

in plant – animal relationship. Elucidate with examples.

13. Give suitable terms for the following :

(a) A technique in plant biotechnology in which two different plant protoplasts are

fused to create a hybrid with desirable traits from different varieties of plants.

(b) Genetically identical plants obtained by micropropagation.

14. The species facing competition might evolve mechanism that promote co-existence

rather than exclusion. Evaluate the statement.

15. (a) Write the first trophic level of Grazing food chain and detritus food chain.

(b) In aquatic ecosystem, which food chain is the major conduit for energy flow ?

SY-426 6

11.  .

1.   – 

2.    – 

3. ELISA –  

4. -1  – 

12.       
 .  .

13.     .

(a)       
      
  

(b)      .

14.      
    
.   .

15. (a)    
  .

(b)       
   ?

SY-426 7 P.T.O.

16. Pathogens are used very effectively in biotechnology to transfer the DNA into host

cells (plant and animal cell). Substantiate with suitable example.

III. Answer any 3 questions from 17 to 20. Each carries 3 scores. (3  3 = 9)

17. (a) What are the adaptations of water pollinated flowers ?

(b) Give examples for the following :

(i) A water pollinated plant where pollen released on the surface of water

(ii) Water pollinated plant where pollen released inside the water

18. For effective treatment of a disease, early diagnosis and understanding its

pathophysiology is very important. Early detection is possible through molecular

diagnosis. Explain three molecular diagnostic tools for the early detection of disease.

19. Given below the diagram of two bioreactors.

(a) Identify (i) and (ii).

(b) Compare the functioning mechanism of the two reactors.

(i) (ii)

SY-426 8

16.      
   . 
 .

III. 17  20    3  .
3  . (3  3 = 9)

17. (a)        ?
(b)    .
(i)     
  .
(ii)    .

18.      
 .     
   .  
    .

19.     .
(a) (i), (ii) 
(b)     
 .

(i) (ii)

SY-426 9 P.T.O.

20. Given below the organisms of a Grassland eco-system.

Grasshopper, Grass, Snake, Frog

(a) Draw the pyramid of numbers.

(b) Pyramid of biomass in a marine eco-system is inverted. Give reason.

(c) Write any one limitation of ecological pyramids.

SY-426 10

20.      

, , , 

(a)   .

(b)      

.  .

(c)     .

SY-426 11 P.T.O.

PART – B

ZOOLOGY

(Maximum : 30 Scores) Time : 1 Hour

I. Answer any 3 questions from 1 to 5. Each carries 1 score. (3  1 = 3)

1. Name the oral contraceptive for female developed by CDRI.

2. Exaggerated response of the immune system to certain antigens present in the
environment is called _____ .

3. Note the relationship between the first two words and fill the missing word.

(a) Primary sex organ in male : Testes;

Primary sex organ in female : _____.

(b) Leydig cells : Androgen;

Corpus luteum : _____ .

4. How many Thymine bases will a double stranded DNA have, if it has 30 Adenine
bases ?

5. Select the genetic disorder in which a blood clotting protein is affected leading to a
non-stop bleeding even through a simple wound.

(Phenylketonuria, Haemophilia, Thalassemia, Sickle-cell Anaemia)

SY-426 12

PART – B

ZOOLOGY

(Maximum : 30 Scores) Time : 1 Hour

I. 1  5    3  .
1  . (3  1 = 3)

1.  CDRI    .

2.      
   _____ .

3.      ,  
.

(a)    : ;

   : _________

(b)   : ;

 : _____.

4.    ,   30  
   ?

5.        
 ,      
   .

(Phenylketonuria, Haemophilia, Thalassemia, Sickle cell Anaemia)

SY-426 13 P.T.O.

II. Answer any 9 questions from 6 to 16. Each carries 2 scores. (9  2 = 18)
6. In a debate conducted in school, a student argued that, ‘AIDS can be transmitted
through touch or physical contact’.
(a) Do you agree with this statement ? Substantiate.
(b) Name the clinical test used to diagnose AIDS.
(c) Write any one measure to prevent AIDS.

7. Complete the table.
Hints : Biocontrol, Clostridium butylicum, Citric Acid, Lactic Acid-Bacteria

Microorganism Uses of Microorganism

__________
a Curdling of milk

Bacillus thuringiensis __________
b

Aspergillus niger __________
c

__________
d Production of butyric acid

8. Observe the diagram showing lac operon in E. coli.

(a) Name the inducer.
(b) What do the letters ‘o’ and ‘p’ in lac operon stand for ?

SY-426 14

II. 6  16    9  .
2  . (9  2 = 18)
6.       .
   AIDS .
(a)     ? .
(b) AIDS     ?
(c) AIDS-     .

7.  .
Hints : Biocontrol, Clostridium butylicum, Citric Acid, Lactic Acid-Bacteria.
Microorganism Uses of Microorganism
__________
a Curdling of milk
Bacillus thuringiensis __________
b
Aspergillus niger __________
c
__________
d Production of butyric acid

8. E.coli  lac operon-  .

(a)    ?
(b) lac operon-  ‘o’, ‘p’   
 ?
SY-426 15 P.T.O.

9. Complete the flow-chart.

10. Given below is a table showing codons of various amino acids. Observe it and write
the name of :
(a) Stop codons
(b) Initiator codon

11. Expand :
(a) ZIFT
(b) ICSI

SY-426 16

9.  .

10.        
 .  ,   .
(a)  
(b)  

11. 
(b) ICSI
(b) ICSI
SY-426 17 P.T.O.

12. Match the following :

Column A Column B

Physical Barrier Neutrophil

Physiological Barrier Skin

Cellular Barrier Interferon

Saliva in mouth
Cytokine Barrier
Antibody

13. First child of a couple was affected with sickle-cell anaemia. During the second
pregnancy, they visited a genetic counsellor and he prepared a pedigree chart of their
family. Identify these symbols used in a pedigree chart.

(a) (b)

(c) (d)

14. Observe the diagram and answer the questions about oviduct.

SY-426 18

12.  .

Column A Column B

Physical Barrier Neutrophil

Physiological Barrier Skin

Cellular Barrier Interferon

Saliva in mouth
Cytokine Barrier
Antibody

13.      . 
        
       .
     .

(a) (b)

(c) (d)

14.       
.

SY-426 19 P.T.O.

(a) Finger like projections that help in collection of ovum.

(b) Part of oviduct with narrow lumen that joins the uterus.

(c) Funnel shaped part of oviduct that is seen near the ovary.

(d) Site of fertilisation.

15. Snapdragon plants have red flowers and white flowers. If red flowered plants are
crossed with white flowered ones, F1 generation produce pink flowers.

(a) Name this pattern of inheritance.

(b) Write the genotypic and phenotypic ratio of F2.

16. In a population, the allele frequency of a species is p 2 + 2pq + q2 = 1.

(a) Name the principle.

(b) Mention any 3 factors that may affect it.

III. Answer any 3 questions from 17 to 20. Each carries 3 scores. (3  3 = 9)

17. (a) Identify pictures ‘A’ and ‘B’.

Hint : A – IuD, B – Sterilisation procedure in male

(b) Amniocentesis for sex-determination is banned in our country. Is this ban
necessary ? Comment.

SY-426 20

(a)      
(b)   
 .
(c)   
 .
(d)   .

15.       .
      
, F1     .
(a)     ?
(b) F2     
.

16.     p2 + 2pq + q2 = 1 .
(a)    ?
(b)     3 .

III. 17  20    3  .
3  . (3  3 = 9)
17. (a) ‘A’, ‘B’    .
Hint : A – IuD, B – Sterilisation procedure in male.

(b)     ,
   .  
 ?   .
SY-426 21 P.T.O.

18. (a) Identify and write the name of the experiment shown in figure.
(b) What was the aim of this experiment ?

(c) Name the processes marked as ‘A’, ‘B’ and ‘C’/(3 steps).

19. The accelerated rates of species extinction that the world is facing now are largely due
to human activities.
‘Evil Quartet’ is the sobriquet used to describe biodiversity loss.
(a) List out the 4 major causes of biodiversity loss.
(b) Mention 2 major approaches to biodiversity conservation.

20. Male heterogamety is seen in humans and Drosophila.
(a) What is male heterogamety ?
(b) How is sex determined in man ?
(c) Is sperm or egg responsible for sex determination in chicks ? Explain.
___________

SY-426 22

18. (a)      .
(b)     ?

(c) ‘A’, ‘B’, ‘C’     / (3 ) ?

19.     
  .  
    ‘
’.
(a)    4  
.
(b)    2  
 ?

20.     .
(a)     ?
(b)     ?
(c)     
 ? .
_____________

SY-426 23 P.T.O.

SY-426 24