AHSEC| CLASS 12| BIOLOGY| SOLVED PAPER - 2018| H.S. 2ND YEAR
2018
BIOLOGY
(Theory)
Full Marks: 70
Pass Marks: 21
Time: Three hours
The figures in the margin indicate full marks for the questions
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PART-I (BOTANY) MARKS – 35 Page No. 1 - 8 PART-II (ZOOLOGY) MARKS - 35 Page No. 9 – 15 |
Use separate Answer scripts for
Part-I (Botany) and Part-II (Zoology)
Part-I (Botany)
1. What is meant by Clone? 1
Ans:- Clone is defined as an exact carbon copy or
copies of a single genetic parent. The term 'clone' refers only to the living
species. If cloning technology is applied to veterinary science, valuable
animals can be cloned from desirable adult cells.
2. Define the term Apomixis. 1
Ans:- Apomixis is the process of asexual seed
production without fertilization. The plants growing from these seeds are
similar to the mother plant.
3. How the ages of fossils are calculated? 1
Ans:- The age of a fossil can be calculated using
radioactive dating, also known as radiometric dating. This technique compares
the abundance of a radioactive isotope with its decay products using known
decay rates.
Radiometric
dating is the most accurate method of determining the age of a fossil. It
depends directly on the decay rates, or half-lives, of radioactive elements to
determine the date of rocks.
There
are two methods of determining the age of fossils:-
(i) Relative
dating: compares the fossil with similar rocks and fossils of known age
(ii) Absolute
dating: Uses radiometric dating to measure the decay of isotopes to
determine the exact age of the fossil
Some techniques
work best with materials millions or billions of years old, while others work
only for very young materials. Each method only works for certain materials,
ranging from volcanic rock to charcoal and bone.
4. Write the scientific name of the microorganism used to
produce ethanol. 1
Ans:- In the wine industry, baker's yeast or
Saccharomyces cerevisiae is used to produce alcohol. This releases carbon
dioxide in the form of gas from the sugar.
5. What is Triple Fusion? Name the nuclei involved in
triple fusion. 2
Ans:- Triple fusion is a process that occurs during
double fertilization in seed plants.
It involves the
fusion of two polar nuclei and one sperm nucleus.
This fusion
results in the formation of a triploid nucleus called the primary endosperm
nucleus (PEN). The PEN eventually becomes an endosperm.
The nuclei
involved in triple fusion are:-
(i) a male
gamete nucleus
(ii) two polar
nuclei
The endosperm
produced is triploid and provides nutrition to the developing zygote.
Or
Explain any
two outbreeding devices that flowering plants have developed to encourage Cross
Pollination.
Ans:-
Flowering plants have evolved various mechanisms to encourage cross-pollination
and discourage self-pollination. These mechanisms are known as outbreeding
devices and are important for the survival of plant species and genetic
diversity.
Here are
two outbreeding devices that flowering plants have developed to encourage
cross-pollination:-
(i)
Dicliny: This occurs when flowers are unisexual, so self-pollination is not
possible. In some plants, male and female flowers occur on separate
individuals, while in others, they occur on the same individual but in separate
inflorescences.
(ii)
Prepotency: This occurs when pollen grains from another flower germinate
more quickly than pollen grains from the same flower. For example, pollen from
apples and grapes germinate more quickly than pollen from the same flower.
6. Mention four objectives for improving the nutritional
quality of crops by the process of biofortification. 2
Ans:- Biofortification is the process of breeding
crops to improve their nutritional value.
Biofortification
has four objectives:-
(i) Protein
content and quality
(ii) Quantity
and quality of oil
(iii) Vitamin
content
(iv)
Micronutrient and mineral content
Biofortification
aims to reduce mortality and morbidity rates related to micronutrient malnutrition.
It also aims to increase food security, productivity and quality of life for
poor populations in developing countries.
Some examples
of biofortified plants include golden rice and iron-rich beans.
Or
What is
totipotency of the cell? What is the importance of totipotency in Plant
Science?
Ans:-
Totipotency is the ability of a cell to divide and generate all the
differentiated cells in an organism. In other words, it is the ability of a
cell to produce an entirely new individual.
Totipotency is
the ability of a plant cell to form a new plant. This ability allows plant
cells to be used for plant propagation and improvement.
Totipotency
is important in plant science because:-
(i) Allows
plants to adapt to environmental changes: A single plant cell can form an
entire plant without fertilization.
(ii) Reflects
the plasticity of plant genome: Totipotency allows plants to withstand
biotic, abiotic and biotic stresses.
7. Write a brief note on Biochemical Oxygen Demand. 2
Ans:- Biochemical oxygen demand (BOD) is a measure of
the amount of dissolved oxygen (DO) required by aerobic biological organisms to
break down organic matter present in a given water sample at a given
temperature over a specific time period. BOD values are usually expressed in
milligrams of oxygen consumed per liter of sample during 5 days of incubation
at 20 °C.
BOD is used as a
surrogate of the degree of biological water pollution. It is also used to
assess the relative strength of a waste. The BOD test is used to measure the
amount of oxygen consumed by these organisms during a specified period of time.
The rate of
oxygen consumption in a stream is affected by several factors: temperature, pH,
the presence of certain types of microorganisms, and the type of organic and
inorganic material in the water.
Or
What are
Antibiotics? Name two microorganisms used to produce antibiotics.
Ans:-
Antibiotics are chemical substances produced by certain microorganisms that can
kill other microbes or slow their growth. The word antibiotic means
"against life".
Here are
some examples of microorganisms used to produce antibiotics:-
(i)
Penicillium notatum: A fungus that produces penicillin
(ii)
Streptomyces griseus: A bacteria that produces streptomycin.
Antibiotics
can be taken orally in the form of tablets, capsules or liquids.
8. How the insecticidal proteins act on Pest? 2
Ans:- Insecticidal proteins, also known as BT toxins,
are stomach poisons that kill insects by causing holes in their intestines.
Here's how
pesticide proteins work:-
(i) Insects
swallow proteins.
(ii) Proteins in
the digestive system of insects are activated by proteases.
(iii) The
proteins become active due to the alkaline environment in the insect's
intestine.
(iv) Proteins
bind to receptors in the intestine.
To activate the
poison, the pH of the insect's intestine must be 9.0 to 10.5. This is different
from the human intestine, which has a lower pH and is more acidic.
Insecticidal
proteins are present in Bt crops. They work well for transgenic BT crop
applications but not so well for sprayable products.
Or
Describe
briefly about Bioreactors.
Ans:- A
bioreactor is a device or system that supports a biologically active
environment. It is a vessel in which a chemical process is carried out
involving an organism or biochemically active substances derived from such
organisms. This process can be either aerobic or anaerobic. These bioreactors
are usually cylindrical, ranging in size from liters to cubic meters, and are
often made of stainless steel.
Bioreactors
are used in various industries including pharmaceutical, food and beverage
industries. They are used to produce a wide variety of products including
antibiotics, vaccines, enzymes and biofuels.
Bioreactors
are designed to provide optimal conditions for the growth of microorganisms or
cells. These conditions include temperature, pH, dissolved oxygen, and
nutrients. The bioreactor also has a system for removing waste products.
9. What is Single Cell Protein (SCP)? Name two algae used
to produce SCP. 2
Ans:- Single cell proteins (SCPs) are edible
microorganisms that are unicellular. Algae like Chlorella and Spirulina are
examples of SCP.
Here are some
other algae that can be used to produce SCP: Spirulina maxima, Cneidemus
acutus, Chondrus crispus.
SCP is used in
food as a vitamin and flavor carrier, emulsifying agent, and to improve the
nutritional value of soups, baked goods, and ready-to-serve meals. They are
also used in technical fields such as paper and leather processing and as foam
stabilizers.
Or
Write an
account on the role of microbes in biogas production,
Ans:-
Microorganisms play an important role in biogas production. In an artificial
system called a biogas plant, microbes convert waste materials from sewage or
cattle waste slurry into environmentally functional by-products such as natural
manure, fertilizer, and biogas. Biogas is a clean fuel option.
Biogas is
produced by microbial decomposition of organic matter under anaerobic
conditions. It is a mixture of gases, mainly methane (63%), with carbon dioxide
and hydrogen. The microorganisms that produce these gases are collectively
called methanogens. They are found in sludge produced during sewage treatment
and in the rumen of cattle.
10. Explain briefly: (any one) 2
(a) Molecular
diagnosis.
Ans:-
Molecular diagnostics is a collection of techniques that analyze biological
markers in the genome and proteome. It involves analyzing DNA or RNA sequences
to identify genetic mutations or variations that may contribute to the
development of the disease.
Molecular
diagnosis is also known as molecular pathology. It can be used to diagnose and
monitor disease, find out risk, and decide which therapy will work best for
individual patients.
(b) Molecular
Scissors
Ans:-
Molecular scissors are also known as restriction enzymes. They are called
molecular scissors because they cut genetic material at specific ends and use
ligases to cleave the ends to the second or foreign strand.
Restriction
enzymes are enzymes that have a specific restriction factor. He cut the DNA
double helix very precisely. They cleave DNA into fragments at or near specific
recognition sites within the molecule called restriction sites.
11. What is Mutualism? Explain mutualism with suitable
examples. 3
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