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About ASSEB (Formerly AHSEC)
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HS 2nd Year Biology Solved Question Paper 2025
Assam Board Class 12 Biology Solved Question Paper 2025
AHSEC Class 12 Biology Question Paper with Answers 2025
Class 12 Biology Solved Question Paper 2025 (ASSEB / AHSEC)
2025
BIOLOGY (THEORY)
Full Marks: 70
Pass Marks: 21, Time: Three hours
The figures in the margin indicate full marks for the questions.
PART-I (BOTANY) MARKS - 35
1. What is the palindrome of TATA? 1
Answer:- ATAT.
2. Name an example of a plant where both cleistogamous and chasmogamous flowers are present. 1
Answer:- Commelina.
3. Name one microbe used in biofertilizers.1
Answer:- Rhizobium.
4. What is meant by speciation? 1
Answer:- Formation of new species from existing species due to evolutionary processes.
5. Write on adaptation of either hydrophytes or xerophytes. 2
Answer:- Adaptations of Xerophytes:- Xerophytes are plants that have adapted to survive in arid environments with very little water. These adaptations include thick cuticles to reduce water loss, leaves modified into spines that reduce transpiration, sunken stomata that reduce evaporation, and succulent stems or leaves to store water. Many xerophytes also use CAM (crassulacean acid metabolism) photosynthesis, opening their stomata at night instead of during the day, further conserving water.
6. How plant tissue culture has helped in the improvement of crops? 2
Answer:- Plant tissue culture enables the rapid, large-scale production of disease-free and genetically uniform plants. It also allows for the propagation of new, improved varieties with desirable traits such as higher yields, better resistance to diseases, and greater adaptability, helping in the conservation of rare species and the prompt development of crops with improved characteristics.
7. Write briefly about application of electrophoresis. 2
Answer:- Application of Electrophoresis:- Electrophoresis is widely used for DNA analysis and fragmentation, allowing scientists to separate and identify DNA segments for genetic studies and forensic analysis. It is also important in protein detection, where it helps to analyze specific proteins, study their behavior in diseases, and confirm purity or molecular weight in biochemical research.
Or
Write a brief account on ethical issues on biotechnology. 2
Answer:- Ethical Issues in Biotechnology:- Biotechnology faces ethical concerns such as biosafety, environmental impact, genetic privacy, and tampering with natural genetic structure. There is an ongoing debate over the use of genetically modified organisms (GMOs), potential long-term effects on ecosystems, food safety, and unintended consequences of cloning or gene editing. Social consensus and regulatory oversight are critical to address these issues.
8. What is meant by double fertilization in angiosperms? 2
Answer:- Double Fertilization in Angiosperms:- Double fertilization in angiosperms is a unique process in which one male gamete fuses with the egg cell to form a zygote (diploid embryo), and the other male gamete fuses with the two polar nuclei to form a triploid endosperm. This ensures the simultaneous development of the embryo and its nutrition.
Or
Write briefly on artificial vegetative reproduction in plants. 2
Answer:- Artificial Vegetative Propagation in Plants:- Artificial vegetative propagation involves the production of new plants from vegetative parts such as stems, roots or leaves using methods such as cuttings, layering, grafting or tissue culture. This technique allows rapid propagation of plants with desired traits, ensures uniformity, and bypasses the long sexual reproduction cycle.
9. What is cellular totipotency? What is the importance in plant science of it? 2
Answer:- Cellular Totipotency and Its Importance in Plant Science:-
Cellular totipotency refers to the ability of a single plant cell to develop into a complete plant under suitable conditions. This property is fundamental in plant tissue culture, genetic engineering, and plant breeding, as it enables the regeneration of entire plants from single cells, thereby allowing clonal propagation and crop improvement.
10. Explain briefly: (any two) 2x2=4
(i) Genetic therapy
Answer:- Genetic therapy is the technique of correcting defective genes responsible for the development of disease, by inserting healthy genes into the patient's cells to treat genetic disorders.
(ii) Bioreactor
Answer:- Bioreactor is a vessel or device designed to provide an optimal controlled environment for the growth of microorganisms, cells or tissues, supporting biochemical processes for the large-scale production of biological products such as proteins and antibiotics.
(iii) Transgenesis
Answer:- Transgenesis is the process of incorporating a foreign gene (transgene) into the genome of an organism to create genetically modified organisms (GMOs) that express new traits not originally present.
(iv) Endonuclease
Answer:- Endonuclease is an enzyme that cuts DNA at specific nucleotide sequences from within the molecule, often used in genetic engineering as molecular scissors to cut DNA at precise locations.
11. Write the scientific name with their utility of the following plants: (any three) (0.5+0.5)x3=3
(i).Teak
(ii). Jute
(iii) Rauwolfia
(iv) Coffee
Answer:-
(i). Teak
Scientific Name: Tectona grandis
Utility: Teak wood is used for making furniture, doors, and windows because it is strong and long-lasting.
(ii). Jute
Scientific Name: Corchorus capsularis
Utility: Jute is used for making bags, ropes, mats, and sacks. It is also called the “golden fiber.”
(iii). Rauwolfia
Scientific Name: Rauwolfia serpentina
Utility: It is used in making medicines for high blood pressure and mental illnesses.
(iv). Coffee
Scientific Name: Coffea arabica
Utility: Coffee seeds are used to make the popular beverage called coffee. It helps to refresh and energize.
12. Write the applications of mychorrhiza.
Answer:- Mycorrhiza helps plants by:
Increasing absorption of water and minerals from soil.
Protecting roots from disease-causing organisms.
Helping plants grow better in poor soil conditions.
Sometimes helping in nitrogen fixation.
13. What are the cells present in a typical matured embryo sac of angiosperms?
Answer:- A typical matured embryo sac of angiosperms has seven cells and eight nuclei. These cells are:
One egg cell
Two synergid cells (on either side of the egg cell)
Three antipodal cells (at the opposite end of the egg)
One central cell with two polar nuclei
Or
What is parthenocarpic fruit? How can induce the formation of such fruits?
Answer:- Parthenocarpic fruit is a fruit that develops without fertilization and does not have seeds. Such fruits can be induced artificially by applying plant hormones like auxins or gibberellins.
14. Write briefly on modern synthetic theory of evolution.
Answer:- Modern synthetic theory of evolution explains how evolution happens using the ideas of Darwin and modern genetics. It includes:
Genetic variation in a population
Natural selection
Mutation
Genetic drift
Reproductive isolation
These factors together explain how new species are formed over time.
Or
What is Organic evolution? Write briefly about any one evidence of Organic evolution.
Answer:- Organic evolution means the slow and continuous change in living organisms over time, leading to the development of new species.
One evidence: Fossil evidence – Fossils show the remains of old organisms. They help us understand how present-day animals and plants evolved from earlier forms.
15. Define biotechnology. Write the applications of biotechnology in agriculture.
(1+4=5)
Answer:- Biotechnology is the use of living organisms, cells, or biological systems to develop products and improve life.
Applications of biotechnology in agriculture:
Improved crop varieties – Crops with higher yield and better quality.
Pest-resistant crops – Genetically modified (GM) crops like Bt cotton protect plants from pests.
Drought and disease resistance – Crops that can grow in poor conditions or resist diseases.
Bio-fertilizers and bio-pesticides – Natural ways to increase soil fertility and control pests.
Tissue culture – Growing plants quickly in labs using plant cells.
Or
What is plasmid? Write briefly on the main aims of biotechnology.
Answer:- A plasmid is a small circular piece of DNA found in bacteria that can replicate independently of the main chromosome.
Main aims of biotechnology:
To improve human health through medicines and vaccines.
To increase agricultural production using better crops.
To protect the environment using eco-friendly methods.
To reduce the use of chemicals by using natural alternatives.
To create useful products like enzymes, hormones, and antibiotics.
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