SECOND YEAR HIGHER SECONDARY
EXAMINATION, MARCH 2025
๐ฅ Download PDF of this Question Paper
PART A: BOTANY
I. Answer any 3 questions from 1 to 5. Each carries 1 score. (3 x 1=3)
(a) Cellulose
(b) Lignin and chitin
(c) Nitrogen and water soluble sugars
(d) Cellulose and pectin
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: ________
(Wheat, Groundnut, Maize, Barley)
II. Answer any 9 questions from 6 to 16. Each carries 2 scores. (9 X 2 = 18)
(b) Write any one peculiarity of tapetal cell.
(a) Tapetum nourishes the developing pollen grains (male gametophytes).
(b) Tapetal cells possess dense cytoplasm and generally multinucleate.
● Treating the bacterial cells with a specific concentration of a divalent cation, such as calcium.
● Incubating the cells with recombinant DNA on ice.
● Placing them briefly at 42°C (heat shock).
● Putting them back on ice.
(b) What are the factors affecting primary productivity?
(a) Gross primary productivity (GPP) is the rate of production of organic matter during photosynthesis in an ecosystem.
(b) Sunlight, temperature, moisture, photosynthetic capacity, plants in that area, availability of nutrients etc.
Apomixis is the production of seeds without fertilization.
• It allows farmers to keep using hybrid seeds year after year because the desirable characters do not segregate in the progeny.
• It reduces the cost of seeds for farmers as they don't need to buy expensive hybrid seeds every season.
(b) List any two ways of measuring population density of a habitat.
(a) Population density refers to the number of individuals of a species per unit area or volume at a given time.
(b) (i) Percent cover or biomass.
(ii) Relative density (e.g., number of fish caught per trap). (iii) Indirect estimation (e.g., tiger census based on pug marks and faecal pellets).
| 1. ADA deficiency | AIDS |
| 2. Human alpha-lactalbumin | Emphysema |
| 3. ELISA | Gene therapy |
| 4. alpha-1 Antitrypsin | Rosie |
| 1. ADA deficiency | Gene therapy |
| 2. Human alpha-lactalbumin | Rosie |
| 3. ELISA | AIDS |
| 4. alpha-1 Antitrypsin | Emphysema |
Plants need animals for pollinating their flowers and dispersing their seeds, and animals are rewarded with pollen/nectar or juicy fruits.
• Example 1: The Mediterranean orchid Ophrys employs 'sexual deceit' to get pollination done by a species of bee.
• Example 2: Fig trees and wasps. The wasp pollinates the fig inflorescence while looking for egg-laying sites, and the fig provides developing seeds as food for the wasp larvae.
(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.
(a) Somatic hybridization.
(b) Somaclones.
This refers to Resource Partitioning. If two species compete for the same resource, they could avoid competition by choosing different times for feeding or different foraging patterns.
• Example: MacArthur showed that five closely related species of warblers living on the same tree were able to avoid competition and co-exist due to behavioral differences in their foraging activities.
(b) In aquatic ecosystem, which food chain is the major conduit for energy flow?
(a) Grazing Food Chain (GFC): Producers (Living plants).
Detritus Food Chain (DFC): Dead organic matter (Detritus).
(b) Grazing Food Chain (GFC).
Pathogens are "disarmed" to serve as vectors.
• Plant cells: Agrobacterium tumefaciens uses its Ti-plasmid to deliver genes into plants. The T-DNA is replaced with the gene of interest.
• Animal cells: Retroviruses are disarmed and used to deliver desirable genes into animal cells.
III. Answer any 3 questions from 17 to 20. Each carries 3 scores. (3 X 3 = 9)
(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
(a) Adaptations: Pollen grains are protected from wetting by a mucilaginous covering. Flowers are often small and inconspicuous. They do not produce nectar or fragrance.
(b) (i) Vallisneria. (ii) Zostera (Sea grasses).
● Recombinant DNA technology: Allows for the detection of specific gene sequences.
● Polymerase Chain Reaction (PCR): Can detect pathogens (like HIV) even at very low concentrations by amplifying their nucleic acids.
● Enzyme Linked Immuno-sorbent Assay (ELISA): Based on the principle of antigen-antibody interaction to detect infections.
(a) Identify (i) and (ii).
(b) Compare the functioning mechanism of the two reactors.
(a) (i) Simple stirred-tank bioreactor.
(ii) Sparged stirred-tank bioreactor.
(b) Simple stirred-tank: Has a stirrer that facilitates even mixing and oxygen availability throughout the bioreactor.
Sparged stirred-tank: Sterile air is bubbled through the reactor (sparging). These bubbles dramatically increase the surface area for oxygen transfer.
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.
(a) Pyramid of Numbers:
(b) This is because the biomass of fishes (consumers) far exceeds the biomass of phytoplankton (producers) at any given time.
(c) Limitations: 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.
PART B: ZOOLOGY
I. Answer any 3 questions from 1 to 5. Each carries 1 score. (3 x 1=3)
(a) Primary sex organ in male: Testes
Primary sex organ in female: ________
(b) Leydig cells: Androgen
Corpus luteum: ________
(Phenylketonuria, Haemophilia, Thalassemia, Sickle-cell Anaemia)
II. Answer any 9 questions from 6 to 16. Each carries 2 scores. (9 X 2 = 18)
(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.
(a) No, I do not agree. AIDS is not spread by mere touch or physical contact; it spreads only through body fluids (blood, semen, etc.).
(b) ELISA (Enzyme-Linked Immuno-Sorbent Assay).
(c) Use of disposable needles and syringes / Using condoms during intercourse.
| Microorganism | Uses of Microorganism |
|---|---|
| ____(a)____ | Curdling of milk |
| Bacillus thuringiensis | ____(b)____ |
| Aspergillus niger | ____(c)____ |
| ____(d)____ | Production of butyric acid |
(a) Lactic Acid Bacteria (LAB).
(b) Biocontrol (agent).
(c) Citric Acid.
(d) Clostridium butylicum.
(a) Name the inducer.
(b) What do the letters 'o' and 'p' in lac operon stand for?
Dryopithecus → A → Australopithecines → B → C → Neanderthal Man → D
A: Ramapithecus
B: Homo habilis
C: Homo erectus
D: Homo sapiens
(a) Stop codons
(b) Initiator codon
(a) UAA, UAG, UGA.
(b) AUG.
(b) Intra Cytoplasmic Sperm Injection.
| Column A | Column B |
|---|---|
| Physical Barrier | Neutrophil |
| Physiological Barrier | Skin |
| Cellular Barrier | Interferon |
| Cytokine Barrier | Saliva in mouth |
| Column A | Column B |
|---|---|
| Physical Barrier | Skin |
| Physiological Barrier | Saliva in mouth |
| Cellular Barrier | Neutrophil |
| Cytokine Barrier | Interferon |
(a) Mating.
(b) Mating between relatives (Consangineous mating)
.
(c) Affected female.
(d) Unaffected male.
(a) Projections for ovum collection.
(b) Part joins uterus.
(c) Part near ovary.
(d) Site of fertilisation.
(a) Fimbriae.
(b) Isthmus.
(c) Infundibulum.
(d) Ampullary region.
(a) Name this pattern of inheritance.
(b) Write the genotypic and phenotypic ratio of F2.
(a) Incomplete dominance.
(b) Phenotypic ratio: 1:2:1.
Genotypic ratio: 1:2:1.
(a) Name the principle.
(b) Mention any 3 factors that may affect it.
(a) Hardy-Weinberg Principle.
(b) Gene migration (Gene flow), Genetic drift, Mutation, Genetic recombination, Natural selection (Any three).
III. Answer any 3 questions from 17 to 20. Each carries 3 scores. (3 X 3 = 9)
Hint: A - IUD, B - Sterilisation procedure in male
(b) Amniocentesis for sex-determination is banned in our country. Is this ban necessary? Comment.
(a) A: CuT (Copper T). B: Vasectomy.
(b) Yes, the ban is necessary to prevent female foeticide, which is essential to maintain a healthy sex ratio in society.
(b) What was the aim of this experiment?
(c) Name the processes marked as 'A', 'B' and 'C' (3 steps).
(a) Hershey-Chase Experiment (Blender Experiment).
(b) To prove that DNA is the genetic material.
(c) A: Infection, B: Blending, C: Centrifugation.
'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.
(a) 1. Habitat loss and fragmentation
2. Over-exploitation
3. Alien species invasions
4. Co-extinctions.
(b) 1. In-situ conservation (e.g., National parks)
2. Ex-situ conservation (e.g., Zoological parks).
(a) What is male heterogamety?
(b) How is sex determined in man?
(c) Is sperm or egg responsible for sex determination in chicks? Explain.
(a) Male heterogamety is the production of two different types of gametes (sperms) by the male (e.g., 50% with X chromosome and 50% with Y chromosome).
(b) Sex is determined by the type of sperm fertilizing the egg. If a sperm with an X chromosome fertilizes the egg, the child is female (XX). If a sperm with a Y chromosome fertilizes the egg, the child is male (XY).
(c) Egg (Female heterogamety). In chicks, the female (ZW) produces two types of eggs, while the male (ZZ) is homogametic. Therefore, the egg determines the sex.