SECOND YEAR HIGHER SECONDARY
EXAMINATION, 2025 SAY
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PART A: BOTANY
I. Answer any 3 questions from 1 to 4. Each carries 1 score. (3 x 1 = 3)
Choose the correct answer.
Which of these is the first isolated restriction endonuclease?
(a) Hind II
(b) EcoR I
(c) Bam HI
(d) Sal I
The natural interconnection of many food chains is called ________.
Formation of seeds without fertilisation is called
(a) Polyembryony
(b) Parthenocarpy
(c) Dormancy
(d) Apomixis
The capacity to generate a whole plant from any cell or explant is called ________.
II. Answer any 9 questions from 5 to 15. Each carries 2 scores. (9 X 2 = 18)
• Syngamy: One of the male gametes moves towards the egg cell and fuses with its nucleus to form a diploid zygote.
• Triple fusion: The other male gamete moves towards the two polar nuclei in the central cell and fuses with them to produce a triploid Primary Endosperm Nucleus (PEN).
| Species A | Species B | Name of Interaction |
|---|---|---|
| + | 0 | A |
| - | 0 | B |
| + | + | C |
| - | - | D |
A: Commensalism
B: Amensalism
C: Mutualism
D: Competition
(a) Write the name of this process.
(b) How can we visualise DNA in this process?
(a) Gel Electrophoresis.
(b) By staining the DNA with a compound known as ethidium bromide followed by exposure to UV radiation.
(b) What is the principle of ELISA?
(a) Enzyme-Linked Immuno-Sorbent Assay.
(b) It is based on the principle of antigen-antibody interaction.
B: Natality (Birth rate).
D: Mortality (Death rate).
I: Immigration.
E: Emigration.
A: Scutellum.
B: Shoot apex.
C: Radicle.
D: Coleorhiza.
(b) How scientists have developed this plant?
(a) It is a somatic hybrid plant produced by fusing the protoplasts of tomato and potato.
(b) Through somatic hybridization, where protoplasts from two different species are fused to get a hybrid protoplast, which is then grown to form a new plant.
• It does not take into account the same species belonging to two or more trophic levels.
• It assumes a simple food chain and does not accommodate a food web.
• Saprophytes are not given any place in ecological pyramids.
• Biolistics (Gene gun): Host cells (mainly plants) are bombarded with high-velocity micro-particles of gold or tungsten coated with DNA.
• Micro-injection: Recombinant DNA is directly injected into the nucleus of an animal cell using a micro-needle.
| Column A | Column B |
|---|---|
| (a) Fragmentation | (i) Humus is degraded into inorganic nutrients |
| (b) Leaching | (ii) Bacterial and Fungal enzymes degrade detritus |
| (c) Catabolism | (iii) Water soluble inorganic substances go down |
| (d) Mineralisation | (iv) Detritivores break down detritus |
| (a) Fragmentation | (iv) Detritivores break down detritus |
| (b) Leaching | (iii) Water soluble inorganic substances go down |
| (c) Catabolism | (ii) Bacterial and Fungal enzymes degrade detritus |
| (d) Mineralisation | (i) Humus is degraded into inorganic nutrients |
(b) Which are other two types of ecological pyramids?
(a) Because when energy flows from one trophic level to the next, some energy is always lost as heat at each step.
(b) Pyramid of Number and Pyramid of Biomass.
III. Answer any 3 questions from 16 to 19. Each carries 3 scores. (3 X 3 = 9)
(a) What is the role of 'ori'?
(b) Which are the selectable markers present?
(c) What is the role of selectable markers?
(a) Sequence where replication starts and controls the copy number of linked DNA.
(b) ampR and tetR.
(c) Identifying and eliminating non-transformants and permitting the growth of transformants.
• Conduits for energy transfer across trophic levels.
• Keep prey populations under control.
• Help maintain species diversity by reducing competition among prey species.
(a) What is the function of ADA?
(b) Write two treatment methods to cure ADA deficiency.
(a) Crucial for the immune system to function.
(b) Bone marrow transplantation and Enzyme replacement therapy.
• Pollen release and stigma receptivity are not synchronized.
• Anther and stigma are placed at different positions.
• Self-incompatibility (genetic mechanism).
• Production of unisexual flowers.
PART B: ZOOLOGY
I. Answer any 3 questions from 1 to 5. Each carries 1 score. (3 x 1 = 3)
II. Answer any 9 questions from 6 to 16. Each carries 2 scores. (9 X 2 = 18)
• Menstrual phase.
• Follicular (Proliferative) phase.
• Ovulatory phase.
• Luteal (Secretory) phase.
(i) Fertilisation (ii) Implantation
(b) Diagram of human blastocyst is given below. Identify A and B.
(a) (i) Ampullary region of the Fallopian tube.
(ii) Uterus (Endometrium).
(b) A: Trophoblast. B: Inner cell mass.
(a) What do you think is the disease he is suffering from?
(b) What measures are to be taken to prevent such diseases?
(a) Sexually Transmitted Infection (STI).
(b) (i) Avoid sex with unknown or multiple partners.
(ii) Always use condoms during coitus.
(iii) In case of doubt, go to a qualified doctor for early detection and get complete treatment.
1 Red : 2 Pink : 1 White.
Does it follow Mendelian inheritance ratio? Give reason.
No, it does not follow the Mendelian monohybrid phenotypic ratio (3:1).
Reason: It is an example of Incomplete Dominance, where the dominant allele is not completely dominant over the recessive allele, resulting in an intermediate phenotype (Pink) in the heterozygote.
1 → Val – His – Leu – Thr – Pro – Glu
2 → Val – His – Leu – Thr – Pro – Val
(a) Which one is the haemoglobin of sickle cell anaemic patient?
(b) Give reason for it.
(a) Individual 2.
(b) Reason: In sickle-cell anaemia, Glutamic acid (Glu) is replaced by Valine (Val) at the sixth position of the beta-globin chain of haemoglobin.
(ii) Who proposed Central Dogma of molecular biology?
(i) a: Transcription. b: Translation.
(ii) Francis Crick.
(a) Identify the bird and name the island.
(b) Which phenomenon is depicted in it?
(a) Bird: Darwin's Finches. Island: Galapagos Islands.
(b) Adaptive Radiation.
| Column A | Column B |
|---|---|
| (a) Natural selection | (i) Convergent Evolution |
| (b) Use and Disuse theory | (ii) Genetic Drift |
| (c) Analogous structures | (iii) Charles Darwin |
| (d) Gene flow by chance | (iv) Lamarckism |
| Column A | Column B |
|---|---|
| (a) Natural selection | (iii) Charles Darwin |
| (b) Use and Disuse theory | (iv) Lamarckism |
| (c) Analogous structures | (i) Convergent Evolution |
| (d) Gene flow by chance | (ii) Genetic Drift |
| Causative Organism | Disease | Symptoms |
|---|---|---|
| Salmonella typhi | (a) | High fever, Constipation |
| Rhino Virus | (b) | Running nose, Sore throat |
| (c) | Ring worm disease | (d) |
(a) Typhoid.
(b) Common cold.
(c) Microsporum / Trichophyton / Epidermophyton.
(d) Dry, scaly lesions on skin/nails.
(a) Identify the protein.
(b) Label a and b.
(a) Antibody (Immunoglobulin).
(b) a: Heavy chain. b: Light chain.
(a) Do you agree? Give reason.
(b) Expand BOD.
(a) Yes.
Reason: High BOD indicates that the water is highly polluted with organic matter, as more oxygen is required by microbes to decompose the waste.
(b) Biochemical Oxygen Demand.
III. Answer any 3 questions from 17 to 20. Each carries 3 scores. (3 X 3 = 9)
(a) Do you agree with Raju's argument? (b) Give Reason.
(a) No, I do not agree.
(b) If both parents are heterozygous (IAi and IBi), they can also produce a child with blood group O (ii). Therefore, children can have A, B, AB, or O blood groups.
(a) Identify the figure.
(b) Label A and B.
(c) Name the protein associated.
(a) Nucleosome.
(b) A: Histone octamer. B: DNA.
(c) Histone proteins.
(a) What change is needed in the first codon to start translation?
(b) Till which codon can it be continuous? Give reason.
(a) The first codon AUA must be changed to AUG (the initiator codon).
(b) It will continue until the UGA codon.
Reason: UGA is a stop (terminator) codon, which signals the end of translation.
(a) Who proposed this?
(b) What do C and Z represent?
(c) Write two causes of loss of biodiversity.
(a) Alexander von Humboldt.
(b) C: Y-intercept. Z: Slope of the line (regression coefficient).
(c) (i) Habitat loss and fragmentation.
(ii) Over-exploitation.