Tamil Nadu 12th Std Model Question Paper 2026 Biology

Tamil Nadu Board Model Question Paper

No. of Printed Pages : 11
8327
£vÄ Gs
A Register Number

!8327Biology! PART - III
E°›¯À / BIOLOGY
( uªÌ ©ØÖ® B[Q» ÁÈ / Tamil & English Version )

Põ» AÍÄ : 3.00 ©o ÷|µ® ] [ ö©õzu ©v¨ö£sPÒ : 70
Time Allowed : 3.00 Hours ] [Maximum Marks : 70

AÔÄøµPÒ : (1) AøÚzx ÂÚõUPЮ \›¯õP £vÁõQ EÒÍuõ GߣuøÚ \›£õºzxU
öPõÒÍÄ®. Aa_¨£vÂÀ SøÓ°¸¨¤ß AøÓU PsPõo¨£õÍ›h®
EhÚi¯õPz öu›ÂUPÄ®.
(2) }»® AÀ»x P¸¨¦ ø©°øÚ ©mk÷© GÊxÁuØS®
AiU÷PõikÁuØS® £¯ß£kzu ÷Ásk®. £h[PÒ ÁøµÁuØS
ö£ß]À £¯ß£kzuÄ®.
Instructions : (1) Check the question paper for fairness of printing. If there is any lack of fairness,
inform the Hall Supervisor immediately.
(2) Use Blue or Black ink to write and underline and pencil to draw diagrams.

SÔ¨¦ : £Sv&I (E°›&uõÁµÂ¯À), £Sv&II (E°›&»[Q¯À) uÛzuÛ ÂøhzuõÎÀ
Âøh¯ÎUPÄ®.
Note : Candidate should answer Part-I (Bio-Botany) & Part-II (Bio-Zoology) in separate answer-
books.

£Sv - I (E°›&uõÁµÂ¯À) / PART - I (BIO-BOTANY)
(©v¨ö£sPÒ : 35) / (Marks : 35)
¤›Ä - 1/SECTION - 1
SÔ¨¦ : (i) AøÚzx ÂÚõUPÐUS® Âøh¯ÎUPÄ®. 8x1=8
(ii) öPõkUP¨£mkÒÍ |õßS ©õØÖ ÂøhPÎÀ ªPÄ® Hئøh¯
Âøhø¯z ÷uº¢öukzxU SÔ±mkhß Âøh°øÚ²® ÷\ºzx GÊuÄ®.
Note : (i) Answer all the questions.
(ii) Choose the most appropriate answer from the given four alternatives and write
the option code and the corresponding answer.

[ v¸¨¦P / Turn over

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1. CÛ¨¦ £mhõoz uõÁµzv¾ÒÍ ¤øn¨¦z öuõSvPÒ :
(A) 7 (B) 2 (C) 10 (D) 4
Linkage groups in Sweet pea :

(a) 7 (b) 2 (c) 10 (d) 4

2. uõÁµ[PÎß JÎa÷\ºUøPUS ©mk÷© £¯ß£kzu¨£k® `›¯ J롧 AÍÄ :
(A) 3 - 10% (B) 2 - 8% (C) 2 - 9% (D) 2 - 10%
Solar energy used by green plants for photosynthesis is only :

(a) 3 - 10% (b) 2 - 8% (c) 2 - 9% (d) 2 - 10%

3. P¸ÄÓõ PÛPÎÀ __________ Põn¨£kÁvÀø».
(A) «÷\õPõº¨ (B) Gs÷hõPõº¨ (C) Âøu (D) G¨¤Põº¨
Parthenocarpic fruits lack :

(a) Mesocarp (b) Endocarp (c) Seed (d) Epicarp

4. \uºß JØÔö¯k¨¦ öuõÈÀ~m£•øÓ GÁØøÓ¨ ¤›zöukUP £¯ß£kzu¨&
£kQÓx ?
(A) RNA (B) ¦µu® (C) ¼¨¤k (D) DNA
Southern blotting technique is used to separate __________.

(a) RNA (b) Protein (c) Lipid (d) DNA

5. øÁµì AØÓ uõÁµ[PÒ __________ À C¸¢x E¸ÁõUP¨£kQßÓÚ.
(A) ¦÷µõm÷hõ¤Íõ\ Áͺ¨¦ (B) EÖ¨¦ Áͺ¨¦
(C) ö\À ªuøÁ Áͺ¨¦ (D) BUSzv_ Áͺ¨¦
Virus-free plants are developed from :

(a) Protoplast culture (b) Organ culture

(c) Cell Suspension culture (d) Meristem culture

A

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6. Pº|õhPõÂß ]º] GßÝ® ChzvÀ `Çø»¨ £õxPõUS® ©UPÎß C¯UP® :
(A) A¨¤U÷Põ C¯UP® (B) ]¨÷Põ C¯UP®
(C) C¢v¯ ÁÚ ©Ûuß C¯UP® (D) Aªºuõ ÷u ¤èÁõì C¯UP®
People’s movement for the protection of environment in Sirsi of Karnataka is :

(a) Appiko movement (b) Chipko movement

(c) Forest Man of India movement (d) Amirtha Devi Bishwas movement

7. ö£hõöáÛêì (Pedogenesis) Gߣx __________ Ehß öuõhº¦øh¯x.
(A) E°›zöuõøP (B) öuõÀ¾°› £iÁ®
(C) ©s (D) }º
Pedogenesis refers to :

(a) Population (b) Fossil

(c) Soil (d) Water

8. ¤ßÁ¸ÁÚÁØÖÒ Gx £ÀTmk £õµ®£›¯zvØS Euõµn©õS® ?
(A) ÷uõmh¨£mhõo°ß PÛ°ß ÁiÁ®
(B) ªµõ¤»ì á»õ£õ ©»›ß {Ó®
(C) ©ÛuºPÎß ÷uõÀ {Ó®
(D) Bs ÷uÜ EØ£zv
Which one of the following is an example of polygenic inheritance ?

(a) Pod shape in garden pea

(b) Flower colour in Mirabilis jalapa

(c) Skin colour in humans

(d) Production of male honey bee

A [ v¸¨¦P / Turn over

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¤›Ä & 2 / SECTION - 2
SÔ¨¦ : RÌPõq® ÂÚõUPÎÀ H÷uÝ® |õßS ÂÚõUPÐUS Âøh¯ÎUPÄ®. 4x2=8
Note : Answer any four of the following questions.

9. ö©À¼m÷hõL¤À¼ GßÓõÀ GßÚ ?
What is Mellitophily ?

10. ÷£õ»ßQm £ØÔ ]Ö SÔ¨¦ ÁøµP.
Write short note on Pollenkitt.

11. ©i¯zvß •UQ¯zxÁ® H÷uÝ® CµsøhU SÔ¨¤kP.
Mention any two significance of Ploidy.

12. uõÁµ[PÎÀ ö\´¯¨£mkÒÍ ~sö£¸UPzvØS GkzxUPõmkPÒ u¸P.
Give the examples for micropropagation performed in plants.

13. £°º ö£¸UPzvß SÔU÷PõÒPÒ H÷uÝ® CµsiøÚ GÊxP.
Write any two objectives of Plant Breeding.

14. E°› ©¸¢x ©ØÖ® uõÁµ ©¸¢x ÷ÁÖ£kzxP.
Differentiate Bio-Medicines and Botanical Medicines.

¤›Ä & 3 / SECTION - 3
SÔ¨¦ : RÌUPõq® ÂÚõUPÎÀ H÷uÝ® ‰ßÖ ÂÚõUPÐUS Âøh¯ÎUPÄ®.
ÂÚõ Gs 19 &US Pmhõ¯©õP Âøh¯ÎUPÄ®. 3x3=9

Note : Answer any three of the following questions. Q. No. 19 is Compulsory.

15. ö©´°»õ©i¯zvß H÷uÝ® ‰ßÖ ÁøPPøÍ £h® ÁøµP.
Draw the diagram of any three different types of aneuploidy.

A

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16. ö\¯ØøP Âøu°ß |ßø©PÒ ‰ßÖ GÊxP.
Write any three advantages of Artificial Seeds.

17. ÁoP ÷ÁÍõs Põk Áͺ¨¦ ‰»® ÁͺUP¨£k® ‰ßÖ uõÁµ GkzxUPõmkPøÍz
u¸P.
Give three examples of plants cultivated in Commercial agroforestry.

18. "P»¨¤Ú Û¯®' – SÔ¨¦ ÁøµP.
Write a note on heterosis.

19. A›]°ß ö£õ¸Íõuõµ •UQ¯zxÁzøu GÊxP.
Write the economic importance of rice.

¤›Ä & 4 / SECTION - 4
SÔ¨¦ : AøÚzx ÂÚõUPÐUS® Âøh¯ÎUPÄ®. 2x5=10
Note : Answer all the questions.

20. (A) C¸£s¦ P»¨¦ ÷\õuøÚø¯ ÂÁ›.
AÀ»x
(B) Bt&£¸zv°ß |ßø©, wø©PøÍ GÊxP.
(a) Describe Dihybrid Cross.
OR
(b) Write the advantages and disadvantages of Bt-Cotton.

21. (A) EÁº \x¨¦ {»zuõÁµ[PÎß H÷uÝ® I¢x ¦Óz÷uõØÓ¨ £s¦PøÍ
Á›ø\¨£kzxP.
AÀ»x
(B) (i) EnÄ Áø» – Áøµ¯Ö.
(ii) EnÄ Áø»°ß •UQ¯zxÁzøu GÊxP.
(a) List out any five Morphological adaptations of halophytes.
OR
(b) (i) Define food web.
(ii) Write the significance of food web.

A [ v¸¨¦P / Turn over

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£Sv & II (E°›&»[Q¯À) / PART - II (BIO-ZOOLOGY)

(©v¨ö£sPÒ : 35) (Marks : 35)

¤›Ä & 1 / SECTION - 1

SÔ¨¦ : (i) AøÚzx ÂÚõUPÐUS® Âøh¯ÎUPÄ®. 8x1=8

(ii) öPõkUP¨£mkÒÍ |õßS ©õØÖ ÂøhPÎÀ ªPÄ® Hئøh¯
Âøhø¯z ÷uº¢öukzxU SÔ±mkhß Âøh°øÚ²® ÷\ºzx
GÊuÄ®.
Note : (i) Answer all the questions.

(ii) Choose the most appropriate answer from the given four alternatives and write
the option code and the corresponding answer.

1. £õ¼©÷µì \[Q¼ ÂøÚ, öÁ¨£{ø» ©õÖ£õmhõÀ ‰ßÖ uÛzuÛ {ø»PÎÀ
öuõhºQßÓx. Auß Á›ø\ :
(A) •ußø© Cøn¨¦ CøÇ £u¨£kzxuÀ, EØ£zv, C¯À¦ v›¦
(B) C¯À¦ v›¦, •ußø© Cøn¨¦ CøÇ £u¨£kzxuÀ, EØ£zv
(C) C¯À¦ v›¦, EØ£zv, •ußø© Cøn¨¦ CøÇ £u¨£kzxuÀ
(D) EØ£zv, •ußø© Cøn¨¦ CøÇ £u¨£kzxuÀ, C¯À¦ v›¦
PCR proceeds in three distinct steps governed by temperature, they are in order of :
(a) Primer Annealing, Synthesis, Denaturation
(b) Denaturation, Primer Annealing, Synthesis
(c) Denaturation, Synthesis, Primer Annealing
(d) Synthesis, Primer Annealing, Denaturation

2. GÆÁøP CÚ¨ö£¸UPzvÀ ÷ÁÖ£õkPÒ ÷uõßÖ® ?
(A) £õ¼¼ CÚ¨ö£¸UP® (B) PßÛ CÚ¨ö£¸UP®
(C) £õ¼Ú¨ö£¸UP® (D) (A) ©ØÖ® (B) Cµsk®
In which mode of reproduction, variations are seen ?
(a) Asexual (b) Parthenogenesis
(c) Sexual (d) Both (a) and (b)

A

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3. J¸ ö\À¼À EÒÍ £õº EÖ¨¦PÎß GsoUøPø¯ PnUQh £¯ß£k® Âv :
(A) N−1 Âv (B) Bö»Ûß Âv
(C) N+1 Âv (D) ÷áõºhõÛß Âv
Which of the following rule is used to calculate the number of Barr bodies in a cell ?

(a) N−1 Rule (b) Allen’s Rule

(c) N+1 Rule (d) Jordan’s Rule

4. öPõkUP¨£mkÒÍ TØÖPøͨ £izx \›¯õÚøu ÷uºÄ ö\´P.
TØÖ 1 : Cµ¨£µõÀ ö\´¯¨£mh vøµa \ÆÄPÒ P¸¨ø£ Áõ´ ‰iPÒ
©ØÖ® ©øÓ¨¦z vøµPÒ ÷£õßÓøÁ ö£s CÚ¨ö£¸UP¨
£õøu°À P¸¨ø£ Áõ°øÚ P»ÂUS •ß ‰h¨ £¯ß£kQßÓÚ.
TØÖ 2 : ÷©ØTÔ¯ AøÚzx® «sk® £¯ß£kzuUTi¯ ÷Áv¨ö£õ¸Ò
uk¨¦PÒ BS®.
(A) TØÖ 1 \› BÚõÀ TØÖ 2 uÁÖ.
(B) TØÖPÒ 1 ©ØÖ® 2 \›. ÷©¾® TØÖ 2 TØÖ 1 &ØPõÚ \›¯õÚ ÂÍUP©õS®.
(C) TØÖPÒ 1 ©ØÖ® 2 Cµsk÷© uÁÓõÚøÁ.
(D) TØÖPÒ 1 ©ØÖ® 2 \›. BÚõÀ TØÖ 2 TØÖ 1 &ØPõÚ \›¯õÚ ÂÍUPªÀø».
Read the given Statements and select the correct option.

Statement 1 : Diaphragms, cervical caps and vaults are made of rubber and are
inserted into the female reproductive tract to cover the cervix before
coitus.

Statement 2 : They are chemical barriers of conception and are reusable.

(a) Statement 1 is correct but Statement 2 is incorrect.

(b) Both Statements 1 and 2 are correct and Statement 2 is the correct explanation of
Statement 1.

(c) Both Statements 1 and 2 are incorrect.

(d) Both Statements 1 and 2 are correct but Statement 2 is not the correct explanation of
Statement 1.

A [ v¸¨¦P / Turn over

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5. \õuP©õÚ _ØÖa`ǼÀ J¸ E°›Úzvß AvP£m\ CÚ¨ö£¸UPzvÓß __________
GÚ AøÇUP¨£kQÓx.
(A) E°›Úz vÓß (B) uõ[S® vÓß
(C) vÓ÷ÚØÓ® (D) _ØÖa`ÇÀ uøhPÒ
The maximum reproductive capacity of an organism under optimum environmental conditions
is called __________.

(a) Biotic potential (b) Carrying capacity

(c) Capacitation (d) Environmental resistance

6. ö©\À\ß ©ØÖ® ìhõÀ ÷\õuøÚ {¹¤¨£x :
(A) i.Gß.H J¸ ©µ¦¨ö£õ¸Ò
(B) PhzxøP ©õØÓ®
(C) £õv £øÇ¯Ú PõzuÀ •øÓ DNA Cµmi¨£õuÀ
(D) ÷uõØÓ ©õØÓ®
Meselson and Stahl’s experiment proved __________.

(a) DNA is the genetic material

(b) Transduction

(c) Semi conservative nature of DNA replication

(d) Transformation

7. RÌUPshÁØÖÒ G¢u ~sq°› öuõÈØ\õø»PÎÀ ]m›U Aª» EØ£zvUS
£¯ß£kQÓx ?
(A) A죺âÀ»ì ø|Ạ(B) »õU÷hõ÷£]À»ì £ÀPõ›Pì
(C) øµ÷\õ£ì ø|U›Pßì (D) ö£Û]¼¯® ]ØÔÚ®
Which of the following micro-organism is used for production of citric acid in industries ?

(a) Aspergillus niger (b) Lactobacillus bulgaricus

(c) Rhizopus nigricans (d) Penicillium citrinum

A

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8. TØÖ :¢x ö\À¼ß uø»¨£Sv°À AU÷µõ÷\õ® ©ØÖ®
ø©m÷hõPõsm›¯õøÁU öPõsi¸UQÓx.
Põµn® : AU÷µõ÷\õ® v¸S Ái»ø©¢u ø©m÷hõPõsi›¯[PøÍU
öPõskÒÍx.
(A) TØÖ \›¯õÚx BÚõÀ, Põµn® uÁÓõÚx
(B) TØÖ ©ØÖ® Põµn® Cµsk® \› Põµn® TØÔß \›¯õÚ ÂÍUP® BS®
(C) TØÖ ©ØÖ® Põµn® Cµsk® uÁÓõÚøÁ
(D) TØÖ ©ØÖ® Põµn® Cµsk® \›¯õÚøÁ BÚõÀ Põµn® TØÔß \›¯õÚ
ÂÍUP® CÀø»
Assertion (A) : Head of the sperm consists of Acrosome and Mitochondria.
Reason (R) : Acrosome contains spiral rows of Mitochondria.
(a) (A) is true. (R) is false.
(b) (A) and (R) are true. (R) is the correct explanation of (A) .
(c) Both (A) and (R) are false.
(d) (A) and (R) are true. (R) is not the correct explanation of (A).

¤›Ä & 2 / SECTION - 2
SÔ¨¦ : RÌPõq® ÂÚõUPÎÀ H÷uÝ® |õßS ÂÚõUPÐUS Âøh¯ÎUPÄ®. 4x2=8
Note : Answer any four of the following questions.

9. ö£¸¢vµÒ ©µ£ØÖ¨÷£õuÀ GßÓõÀ GßÚ ?
What is mass extinction ?

10. •Êø©¯õÚ PßÛ CÚ¨ö£¸UPzøu •Êø©¯ØÓ PßÛ CÚ¨ö£¸UPzv¼¸¢x
÷ÁÖ£kzxP.
Differentiate Complete parthenogenesis from Incomplete parthenogenesis.

11. ›ÁõUP® u¸P :
(A) Z I F T (B) I C S I
Expand the following :
(a) ZIFT (b) ICSI

12. ©Ûu ©µ£q öuõSvz vmhzvß ]Ó¨¤¯À¦PÒ H÷uÝ® CµsiøÚU SÔ¨¤kP.
State any two salient features of Human Genome project.

13. Aø©¨ö£õzu EÖ¨¦PÒ GßÓõÀ GßÚ ? GkzxUPõmk u¸P.
What are homologous organs ? Give an example.

14. •ußø© •ß÷Úõi Cß_¼ß GßÓõÀ GßÚ ?
What is pre-pro insulin ?

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¤›Ä & 3 / SECTION - 3
SÔ¨¦ : GøÁ÷¯Ý® ‰ßÖ ÂÚõUPÐUS Âøh¯ÎUPÄ®. ÂÚõ Gs 19 &US
Pmhõ¯©õP Âøh¯ÎUPÄ®. 3x3=9
Note : Answer any three questions. Q. No. 19 is Compulsory.

15. Cßî¤ß GßÓõÀ GßÚ ? Auß £oPøÍU SÔ¨¤kP.
What is inhibin ? State its functions.

16. ¥øÚÀR÷hõ{³›¯õÂß AÔSÔPÒ ¯õøÁ ?
What are the symptoms of phenylketonuria ?

17. hõºÂÛ¯ ÷Põm£õkPÐUPõÚ Gvº P¸zxPÒ GøÁ÷¯Ý® ‰ßÔøÚU SÔ¨¤kP.
Mention any three main objections to Darwinism.

18. {»ÁõÌ E°›Ú[PÎÀ Põn¨£k® GøÁ÷¯Ý® ‰ßÖ uPÁø©¨¦PøÍ £mi¯¼k.
List any three adaptations seen in terrestrial animals.

19. ÷|÷ÚõQµõ® A;ÒÍ Gvº¨ö£õ¸Ò ysiPøÍU Th PshÔ¯ EuÄ®
Av EnºvÓß öPõsh ÷\õuøÚ Gx ? Auß uÛa ]Ó¨¤øÚU SÔ¨¤kP.
Which test is highly sensitive and can detect antigens in the range of nanogram ? Mention
the added advantages it possesses.

¤›Ä & 4 / SECTION - 4
SÔ¨¦ : AøÚzx ÂÚõUPÐUS® Âøh¯ÎUPÄ®. 2x5=10
Note : Answer all the questions.

20. (A) ©Ûu CÚaö\À E¸ÁõUP® {PÌÄPøÍ Áøµ£h® ‰»® ÂÍUSP.
AÀ»x
(B) ö\¯»õUP ÷|õ´zuøh Põ¨¤øÚ ©¢u©õÚ ÷|õ´z uøh Põ¨¤¼¸¢x
÷ÁÖ£kzxP.
(a) Give a schematic representation of gametogenesis in humans.
OR
(b) Differentiate active immunity from passive immunity.

A

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21. (A) ö£Ø÷Óõøµz wº©õÛUS® ¤µa]øÚPÐUSz wºÄ Põq® öuõÈÀ ~m£®
Gx ? AzöuõÈÀ ~m£zvß £i{ø»PÒ ¯õøÁ ?
AÀ»x
(B) ÃkPÒ, £ÒÎ AÀ»x _ØÖ»õz u»[PÎÀ EßÚõÀ E¸ÁõUP¨£k®
PÈÄPøͨ £mi¯¼kP. AÁØøÓ ªP GÎuõPU SøÓUP •i²©õ ? G¢u
ÁøPU PÈÄPøÍ SøÓ¨£x ªPU PiÚ® AÀ»x •i¯õx ?
(a) What is the technique used for settling parental dispute ? What are the steps involved
in this technique ?
OR
(b) List all the wastes that you generate, at home, school or during your trip to other
places. Could you very easily reduce the generation of these wastes ? Which would be
difficult or rather impossible to reduce ?

-oOo-

A [ v¸¨¦P / Turn over