ASSEB Class 12 Biology Solved Paper - 2025| H.S. 2ND YEAR
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
PART-II
(ZOOLOGY)
MARKS
- 35
Part-I (Botany)
1. What is the palindrome of TATA? 1
Ans:- ATAT.
2. Name an example of a plant where both
cleistogamous and chasmogamous flowers are present. 1
Ans:- Commelina.
3. Name one microbe used in
biofertilizers. 1
Ans:- Rhizobium.
4. What is meant by speciation? 1
Ans:-
Formation of new species from existing species due to evolutionary processes.
5. Write on adaptation of either
hydrophytes or xerophytes. 2
Ans:- 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 improvement of crops? 2
Ans:- 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
Ans:-
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 brief account on ethical issues on biotechnology. 2
Ans:- 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
Ans:- 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
Ans:- 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
Ans:- 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
Ans:- 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
Ans:- 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
Ans:- 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
Ans:- 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
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