JKBOSE Class 12 Biology (Botany Z Series) Solved Paper 2025 Year– Download PDF

JKBOSE Class 12 Biology (Botany Z Series) Solved Paper 2025 Year– Download PDF

In This Blog Article I Will Provide You Jkbose 12th Class Botany Solved Paper Pdf With Question Paper

🧪 SECTION-A (1 Mark Each)

1. Which of the following is wrongly matched?
   Answer: (C) AUG, GUA – Initiation Codons

2. Bt-toxin kills:
   Answer: (A) Insects

3. Biogas production is carried out by:
   Answer: (D) Methanogens

4. The flow of energy in an ecosystem is:
   Answer: (A) Unidirectional

5. Which one of the following is not a hotspot of biodiversity in India?
   Answer: (A) Eastern Ghats

🌱 SECTION-B (2 Marks Each)

6. Define Polyembryony. Differentiate between simple and adventive polyembryony.
   Answer: Polyembryony is the phenomenon where more than one embryo develops from a single fertilized egg. In simple polyembryony, multiple embryos arise from the same zygote due to cleavage. In adventive polyembryony, additional embryos are formed from surrounding tissues like the nucellus or integuments, not from the zygote. This process is common in citrus and mango plants and is useful for producing genetically identical plants.

7. What is Cellular Totipotency?
   Answer: Cellular totipotency refers to the ability of a single plant cell to regenerate into a complete plant under suitable conditions. This property is the basis of plant tissue culture, where cells from any part of the plant, like leaves or stems, can be cultured in a nutrient medium to form whole plants. It plays a vital role in cloning, genetic engineering, and conservation of rare species.

8. Differentiate between Mutualism and Competition.
   Answer: Mutualism is a type of interaction where both species benefit from each other, such as bees collecting nectar from flowers while helping in pollination. Competition, on the other hand, occurs when two organisms fight for the same resources like food, space, or light. For example, two plant species growing close together may compete for sunlight and nutrients, affecting each other's growth.

9. Define Pyramid of Energy. Why is it always upright?
   Answer: The pyramid of energy is a graphical representation showing the flow of energy at different trophic levels in an ecosystem. It is always upright because energy decreases as it moves from producers to consumers due to loss as heat and metabolic activities. This means the energy available to higher trophic levels is always less than that at the lower levels, ensuring the pyramid remains upright.

10. Name few outbreeding devices. Briefly describe any one.
    Answer: Outbreeding devices include dichogamy, herkogamy, self-incompatibility, and male sterility. Dichogamy is a mechanism where the male and female reproductive parts of a flower mature at different times, preventing self-pollination. This promotes cross-pollination and genetic diversity, which is essential for the survival and evolution of plant species.

🌿 SECTION-C (3 Marks Each)

11. How does a microspore develop into two male gametes in angiosperms?
    Answer: In angiosperms, the microspore undergoes mitotic division to form a pollen grain containing two cells: a vegetative cell and a generative cell. The generative cell further divides mitotically to produce two male gametes. During pollination, the pollen grain lands on the stigma, and the vegetative cell forms the pollen tube. The two male gametes travel through this tube to reach the ovule, where one fuses with the egg and the other with the polar nuclei, completing double fertilization.

12. Define Pleiotropic Gene. Give examples from plants and animals.
    Answer: A pleiotropic gene is a single gene that influences multiple traits or characteristics in an organism. In plants, a gene affecting kernel color in maize may also influence plant height. In animals, the sickle cell gene not only changes the shape of red blood cells but also affects oxygen transport and causes anemia. Pleiotropy shows how one gene can have widespread effects on an organism’s phenotype.

13. Describe various applications of Plant Tissue Culture.
    Answer: Plant tissue culture has several applications in agriculture and biotechnology. It allows rapid multiplication of plants through micropropagation, helping produce disease-free and uniform crops. It aids in conserving endangered plant species and developing genetically modified plants with desirable traits. Tissue culture is also used in producing secondary metabolites for pharmaceuticals and in research for studying plant development and genetics.

14. Briefly describe the following processes involved in decomposition: Fragmentation, Catabolism, and Leaching.
    Answer: Fragmentation is the breakdown of dead organic matter into smaller pieces by detritivores like earthworms. Catabolism involves enzymatic degradation of complex organic substances into simpler molecules by microbes. Leaching is the process where water-soluble nutrients are washed away from decomposing matter into the soil. Together, these processes help recycle nutrients and maintain soil fertility.

15. What are Ramsar Sites? Importance? Name some in India.
    Answer: Ramsar Sites are wetlands designated under the Ramsar Convention for their ecological importance. They support biodiversity, regulate water cycles, and act as carbon sinks. These sites are crucial for migratory birds and aquatic life. In India, notable Ramsar Sites include Wular Lake in Jammu & Kashmir, Chilika Lake in Odisha, and Keoladeo National Park in Rajasthan. Their conservation helps maintain ecological balance and supports livelihoods.

🧬 SECTION-D (5 Marks Each)

16. What is an Operon? Explain an Inducible Operon.
    Answer: An operon is a functional unit of DNA that contains a group of genes regulated together by a single promoter. These genes are usually involved in related functions. An inducible operon is one that remains inactive until a specific substrate is present. A classic example is the lac operon in E. coli, which controls the breakdown of lactose. When lactose is absent, a repressor binds to the operator region, preventing transcription. When lactose is present, it binds to the repressor, inactivating it and allowing the genes to be transcribed. This system ensures that the cell only produces enzymes when needed, conserving energy and resources. Inducible operons are vital for adapting to environmental changes and regulating metabolic pathways efficiently.

OR

State the principle of Independent Assortment. Explain with a dihybrid cross. Name one exception.
Answer: The principle of independent assortment states that genes for different traits are inherited independently of each other, provided they are located on different chromosomes. This was demonstrated by Mendel through a dihybrid cross between pea plants with round yellow seeds (RRYY) and wrinkled green seeds (rryy). The F1 generation (RrYy) produced an F2 generation with a phenotypic ratio of 9:3:3:1, showing combinations of traits that were not present in the parents. This proved that the alleles of one gene segregate independently of another. However, an exception to this principle occurs in the case of linked genes, which are located close together on the same chromosome and tend to be inherited together. This linkage reduces the chances of independent assortment and alters the expected genetic ratios.

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