AHSEC| CLASS 12| BIOLOGY| SOLVED PAPER - 2016| H.S. 2ND YEAR
2016
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 |
Use separate Answer scripts for
Part-I (Botany) and Part-II (Zoology)
Part-I (Botany)
1. Why grafting is not possible in Monocotyledonous plants? 1
Ans:- Grafting is not possible in
monocotyledonous plants, also known as monocots, because they lack cambium
tissue.
2. Name the unicellular fungi which reproduces asexually
by budding. 1
Ans:- Yeast is a unicellular fungus that
reproduces asexually by budding.
3. What were the raw materials used in Miller’s
experiment? 1
Ans:- The Miller-Urey experiment used the
following raw materials: Methane, Ammonia, Hydrogen, Water.
4. What is hidden hunger? 1
Ans:- Hidden hunger is a deficiency of
nutrients such as micronutrients, proteins and vitamins, which occurs when food
eaten as part of a regular diet does not meet the nutrient requirements of the
organism. People in developing countries often suffer from hidden hunger
because most people cannot afford nutrient-rich food.
5. Define antigen and antibody. 1+1=2
Ans:- Antigens are substances that
stimulate the immune system to produce antibodies. Each antigen has a different
surface characteristic or epitope. Thus, a specific reaction has a resultant
effect. Antigens can be anything such as pathogens or bacteria or fungi or even
viruses. They cause diseases or allergic reactions.
An antibody is an immunoglobulin. It
is a Y-shaped molecule that is basically a protein produced by the B cells of
the immune system. Antibodies are produced in response to exposure to antigen.
Or
How DNA is
isolated in purified from a bacterial cell? 2
Ans:- Here is how DNA is isolated in
pure form from a bacterial cell:-
(i) Treat bacterial cells with the
enzyme lysozyme to break down the cell wall.
(ii) Remove the RNA by treating it
with the enzyme ribonuclease.
(iii) Extract the protein by
treating it with the enzyme protease, which converts the protein into amino
acids.
(iv) Remove other impurities by
suitable treatment.
(v) Precipitate the purified DNA by
adding cold ethanol.
6. Draw the L.S. of a pistil of angiosperms which is
ready to take part in the process of fertilization. 2
Ans:-
Or
What are the
cells present in a developed embryo sac of angiosperms? 2
Ans:- There are seven cells; One egg cell, two
synergistic cells, three replicating cells and a secondary nucleus. The
secondary nucleus has two nuclei; Whereas other cells have one nucleus each.
7. What is polyploidy? Name the chemical used for
induction of polyploidy in plants. 1+1=2
Ans:- Polyploidy is a condition where a
cell or organism has more than two pairs of homologous chromosomes.
Colchicine is a chemical that can be
used to induce polyploidy in plants. Colchicine is a toxic alkaloid that
prevents the formation of microtubules during cell division. It prevents
chromosomes from separating during cell division, resulting in the plant having
more than one homologous pair of chromosomes.
Or
What are the
merits of interspecific hybridization? 2
Ans:- Interspecific hybridization is a type of
outbreeding where males and females of different, but related, species mate.
The main advantage of this type of breeding is that the offspring produced have
desirable characteristics of both species.
Here are some properties of
interspecific hybridization:-
(i) Superior progeny: The progeny produced is superior to
the existing progeny and has the desirable qualities of both the parents.
(ii) Economically beneficial
organisms:
Economically beneficial organisms can be obtained by interspecific
hybridization.
(iii) Disease resistant and high
yielding varieties: Disease
resistant and high yielding varieties can be obtained by selecting desirable
genes.
(iv) New plant varieties: Interspecific and intergeneric
hybridization contributes to the development of new plant varieties with unique
characteristics.
(v) Origin of new species: In plants, interspecific
hybridization followed by polyploidy can lead to the origin of new species.
8. Name two antibiotics that are produced from bacteria
along with names of concerned bacteria. 1+1=2
Ans:-
Here are some antibiotics and the bacteria they contain:-
(i) Penicillin: Comes from Penicillium notatum or
Penicillium chrysogenum.
(ii) Streptomycin: Comes from Streptomyces griseus
(iii) Chloratetracycline: Comes from Streptomyces
aureofaciens
(iv) Chloramphenicol: Streptomyces comes from Venezuela.
(v) Bacitracin: Comes from Racus subtis
(vi) Polymyxio-B: Comes from Aerobacillus polymyxa
Or
Name the
microbes used for production of Acetic acid and Lactic acid. 1+1=2
Ans:- Acetic acid is produced by the bacterium
Acetobacter acetic and lactic acid is produced by the bacterium Streptococcus
lactis.
Acetobacter Aceti is a bacterium
that can be unicellular or multicellular. Lactobacillus is also a bacterium,
and it helps prevent disease-causing germs in the stomach. Lactobacillus
ferments the milk sugar lactose to produce lactic acid, and is used to prepare
yogurt from milk.
9. How light influences the growth and development in
plants? 2
Ans:-
Light is an important factor in the growth and development of plants. It is
important for: -
(i) Photosynthesis: Light is required to produce
carbohydrates, which plants use for growth, movement and respiration.
(ii) Flowering: Light induces flowering and seed germination.
(iii) Plant hormone: Light regulates the biosynthesis and
signaling of auxin, a plant hormone that is highly sensitive to light.
(iv) Plant growth: Light regulates the growth of
plants through a process called photomorphogenesis.
(v) Stem elongation: Light slows down the stem
elongation by sending hormones down the stem from the tip.
Or
What are the
special characteristics of parasitic plant? 2
Ans:- Parasitic plants have the
following characteristics:-
(i) Modified roots: Parasitic plants have modified
roots called haustoria that penetrate other plants to steal nutrients. The
haustoria attach to the vascular system of the host plant, allowing the
parasite plant to extract water and nutrients.
(ii) Underdeveloped structures: The roots, stem and leaves of
parasitic plants are underdeveloped because they use other plants for support.
10. Write note on: (any one) 2
(a) Food
Chain
Ans:- Food chain is a linear network of links in a
food web, starting from a producer organism and ending with an apex predator.
It describes how energy and nutrients move through an ecosystem. Each organism
in the food chain gets its energy from the organism below it, and is eaten by
the organism above it.
(b) Tropic
level
Ans:- The trophic level of an organism is its
position in the food chain or food web. Trophic level is determined by the
organism's position in the food chain, with primary producers (such as plants)
at the first trophic level and apex predators (such as lions) at the highest
trophic level.
The trophic level of an organism is
important because it determines how much energy the organism receives. Primary
producers receive the most energy from the Sun, and apex predators receive the
least energy. This is because energy is lost at each trophic level as it is
passed up the food chain.
11. Write the scientific names with their utility of the
following plants. (0.5+0.5)x3=3
(Buy E-Books to read complete solutions)
DOWNLOAD [PAGE LINK:-CLICK HERE]
***
BIOLOGY SOLVED PAPERS PAGE LINK - Click here
BUY E-BOOK (PDF FILE)
[TO SEE FULL SOLUTION]
(Chapter wise Notes, Exam Question Papers solved, MCQ solved) [ARTS, COMMERCE, SCIENCE]
|
DOWNLOAD PAGE LINK:-CLICK HERE |
AHSEC PAGE LINK - CLICK HERE