Bihar Board 12th Biology Model Question Paper 2 in English Medium

Time : 3 Hours 15 Min
Total Marks : 70

Instructions for the candidates:

Candidates are required to give answers in their own words as far as practicable.
Figures in the right-hand margin indicate full marks.
While answering the questions, the candidate should adhere to the word limit as for as practicable.
15 Minutes of extra time has been allotted for the candidates to read the questions carefully.
This question paper is divided into two sections: Section – A and Section – B
In Section – A, there are 35 objective type questions which are compulsory, each carrying 1 mark. Darken the circle with blue/black ball pen against the correct option on OMR Sheet provided to you. Do not use Whitener/Liquid/ Blade/Nail on OMR Sheet otherwise result will be treated as invalid.
In Section – B, there are Non-objective type questions. There are 18 Short answer type questions, out of which any 10 questions are to be answered. Each question carries 2 marks. Apart from this, there are 6 long answer type questions, out of which any 3 of them are to be answered. Each question carries 5 marks
Use of any electronic device is prohibited.

Objective Type Questions

There are 1 to 35 objective type questions with 4 options. Choose the correct option which is to be answered on OMR Sheet. (35 x 1 = 35)

Question 1.
All tissue can be formed from
(a) Ectoderm
(b) Endoderm
(c) Mesoderm
(d) Stem cell
Answer:
(d) Stem cell

Question 2.
Astrogen and Progesterone are secreted by
(a) Ovary
(b) Testis
(c) Placenta
(d) All of the above
Answer:
(c) Placenta

Question 3.
Which one is not a part of anther wall?
(a) Endothecium
(b) Endothelium
(c) Tapetum
(d) All of the above
Answer:
(b) Endothelium

Question 4.
Which of the following is true fruit?
(a) Coconut
(b) Apple
(c) Pear
(d) Cashew
Answer:
(a) Coconut

Question 5.
Haploid chromosome number in dog is
(a) 23
(b) 39
(c) 19
(d) 4
Answer:
(b) 39

Question 6.
Which one does not show Oestrus cycle?
(a) Cow
(b) Sheep
(c) Monkey
(d) Dog
Answer:
(c) Monkey

Question 7.
Which one of the following is a major source of air pollution?
(a) Industries
(b) Automobiles
(c) Burning coals
(d) All of the above
Answer:
(d) All of the above

Question 8.
Bt cotton is resistant to
(a) Insects
(b) Weeds
(c) Salts
(d) None of the above
Answer:
(a) Insects

Question 9.
Lamarck was from
(a) India
(b) England
(c) France
(d) None of the above
Answer:
(c) France

Question 10.
Which among the following is a hereditary disease
(a) Haemophilia
(b) Diabetes
(c) Cretenism
(d) All of the above
Answer:
(a) Haemophilia

Question 11.
Which bacteria is helpful in the formation of curd from milk?
(a) Anabena
(b) Streptococcus
(c) Lactobacillus
(d) All of the above
Answer:
(c) Lactobacillus

Question 12.
The example of retrovirus is
(a) Plasmodium
(b) TMV
(c) HIV
(d) None of the above
Answer:
(c) HIV

Question 13.
Spermatogenesis produces
(a) Sperm
(b) Ova
(c) Zygote
(d) None of the above
Answer:
(a) Sperm

Question 14.
Humulin term is used for
(a) Digestive enzyme
(b) Antibiotic
(c) Chitin
(d) Human insulin
Answer:
(d) Human insulin

Question 15.
Pomato is a hybrid of
(a) Tomato and Cabbage
(b) Carrot and Radish
(c) Potato and Tomato
(d) None of the above
Answer:
(c) Potato and Tomato

Question 16.
The substance which causes a definite change in gene is called
(a) Mutagen
(b) Alkaloid
(c) Cytotoxin
(d) None of the above
Answer:
(a) Mutagen

Question 17.
Linkage was discovered by
(a) Muller
(b) Punnet
(c) Mendel
(d) Morgan
Answer:
(d) Morgan

Question 18.
A child with mother of A group and father of AB group will not have the following blood group
(a) A
(b) B
(c) AB
(d) O
Answer:
(d) O

Question 19.
The ratio 9 : 7 is produced due to
(a) Complementary genes
(b) Lethal genes
(c) Epistatic genes
(d) None of the above
Answer:
(a) Complementary genes

Question 20.
The exposure of X-ray enhances the frequency of
(a) Linkage
(b) Segregation
(c) Crossing over
(d) None of the above
Answer:
(c) Crossing over

Question 21.
Part of DNA which switch their position are called
(a) Exon
(b) Cistrons
(c) Transposons
(d) None of the above
Answer:
(c) Transposons

Question 22.
Nucleic Acids are polymers of
(a) Amino acid
(b) Nucleosides
(c) Nucleotides
(d) None of the above
Answer:
(c) Nucleotides

Question 23.
The lac operon consists of
(a) One structural gene
(b) Three structural gene
(c) Four structural gene
(d) None of the above
Answer:
(b) Three structural gene

Question 24.
The technique of DNA fingerprinting was initially developed by
(a) Alec Jeffreys
(b) Griffith
(c) Mirsky
(d) None of the above
Answer:
(a) Alec Jeffreys

Question 25.
In split genes, the coding sequences are called
(a) Exons
(b) Introns
(c) Cistrons
(d) Operons
Answer:
(a) Exons

Question 26.
Vermiform appendix is a
(a) connecting link
(b) vestigial organ
(c) homologous organ
(d) None of the above
Answer:
(b) vestigial organ

Question 27.
Use and disuse was proposed by
(a) Darwin
(b) Haeckel
(c) Lamarck
(d) None of the above
Answer:
(c) Lamarck

Question 28.
Modern man is called
(a) Neanderthals
(b) Ramapithecus
(c) Homosapiens
(d) None of the above
Answer:
(c) Homosapiens

Question 29.
Nervous system is influenced by
(a) Cocaine
(b) Heroine
(c) Hashish
(d) All of the above
Answer:
(d) All of the above

Question 30.
Pathogen of malaria is
(a) Aedes
(b) Wuchereria
(c) Anopheles
(d) Plasmodium
Answer:
(d) Plasmodium

Question 31.
The term ecology was coined by
(a) Odum
(b) Linnaeus
(c) Haeckel
(d) None of the above
Answer:
(c) Haeckel

Question 32.
Organisms which can inbreed with each other come under the same
(a) Kingdom
(b) Family
(c) Species
(d) Genus
Answer:
(c) Species

Question 33.
In a food chain, herbivores are
(a) Primary producers
(b) Primary consumers
(c) Secondary consumers
(d) None of the above
Answer:
(b) Primary consumers

Question 34.
Ovulation is induced by a hormone called
(a) FSH
(b) LH
(c) Both
(d) None of the above
Answer:
(b) LH

Question 35.
Bamboo species flower
(a) Only one in lifetime
(b) Every year
(c) Once in 12 years
(d) None of the above
Answer:
(c) Once in 12 years

Non-Objective Type Questions

Short Answer Type Questions

In this section, there are 18 short answer type question (each carryies 2 marks) out of which answers any ten (10) questions. (10 x 2 = 20)

Question 1.
Describe briefly a Technique of gel elecrophoresis.
Answer:
Gel electrophoresis is a technique of separating DNA fragments, formed by the action restriction endonucleases. The fragments of DNA are placed in typical agarose gel under an electric field. The DNA fragments move towards the anode as these fragments are negatively charged molecules. The DNA fragments separate (resolve) according to their size through sieving effect provided by the agarose gel. The smaller the fragments size, the farther it moves.

The separated DNA fragments are stained with ethidium bromide followed by exposure to UV radiation. The DNA fragments are seen as orange coloured and are cut out from the agarose gel and extracted from the gel piece. This step is known as elocution. The DNA fragments purified in this way are used in construction recombinant of DNA by joining them with cloning vectors.

Question 2.
Where is Bee-keeping practiced ? What are the main points for successful bee-keeping ?
Answer:
The bee-keeping is practised in area where there are sufficient bee pastures of wild shrubs, fruit orchards and cultivated crops. Bee-hives can be kept in one’s courtyard, on the verandah of the house or even on the roof.
The main points for successful bee-keeping are :

Selection of suitable location for keeping bees.
Knowledge of the nature and habits of bees.
Catching and hiving of swarms.
Management of bee-hives during different seasons.
Handing and collection of honey and bees wax.

Question 3.
Write a short note on Haemophilia.
Answer:
It is sex linked recessive disease which is transmitted from unaffected carrier female to male progeny. In this disease a single protein is affected that is a part of the cascade of proteins involved in the clotting of blood. As a result of this a simple cut results into non stop bleeding. The heterozygous female (carrier) for haemophilia may transmit the disease to sons. The possibility of a female to become haemophilic is extremely rare because mother of such a female has to one atleast carrier and the father should be haemophilic. The family pedigree of Queen Victoria has a number of haemophilic descendents as she was a carrier of the disease.

Question 4.
Name one organ analogous to the wings of bird. Why are they both analogous ? Can you include the wing of bat also with them under the same category ? Give reasons.
Answer:
The wings of an insect are analogous to the wings of bird. They are analogous because both perform the same function but have the dissimilar structure and origin. The wings of an insect are modified outgrowth of the body without having bone where-as wings of birds are modified fore-limbs. The wings of a Vt cannot be put under the same category. The wings of a bat and birds are homologous organs as both are modified and perform the same function of flying.

Question 5.
How does sickle cell anaemia is caused ? What are its symptoms?
Answer:
Sickle cell anaemia is caused by the substitution of valine for glutamine at the sixth position in |3 chain of globin molecule of haemoglobin. The mutant haemoglobin molecule undergoes polymerization under low oxygen tension causing the change in the shape of the RBC from biconcave disc to elongated sickle like structure. In this disease, red blood cells become elongated sickle like structure. It is autosomal disease due to recessive genes.

Symptoms-In this disease, red blood cells become elongated and curved under low oxygen tension. Individuals with this disease suffer attacks due to aggregation of red blood cells. These erythrocytes are destroyed more rapidly than the normal red blood cells leading to anaemia.

Question 6.
Define the term Biotechnology. Why has it become important lately?
Answer:
Biotechnology : It is the branch of micro-biological science which is concerned with the utilization of micro-organisms, plants and animal cells and their components to generate useful products and services in industrial processes.

Biotechnology has become very important because it gives us wide variety of products in immense qualities. Most of the industries for preparing alcohol, enzyme, antibiotic and vaccines etc. at large scale are using microbes. Through these products earlier used to prepare at home in meager amounts but biotechnology thas opened a new way with greater potentialities.

Question 7.
What is Adaptation? What type of adaptation is found in organisms of water?
Answer:
Adaptation is an attribute of the organism (morphological, physiological, behavioural) that enables the organisms to survive and reproduce in its habitat. Many adaptations have evolved over a long evolutionary time and are genetically fixed. In the absence of an external source of water, the Kangaroo rat in North American deserts is capable of meeting all its water requirement through the internal fat oxidation. It also has the ability to concentrate it urine so that minimum volume of water is used to remove excretory products.

Many desert plants have a thick cuticle on their leaf surfaces and have their stomata arranged in deep pits to minimise water loss through transpiration. Mammals from colder climates generally have shorter ears and limbs to minimise heat loss. This is called Allen’s Rule.

Question 8.
Explain main steps in plant breeding.
Answer:
Plant breeding as a technology has helped to increase yields to a very large extent. It is the purposeful manipulation of plant species in order to create desired plant types that are better suited for cultivation, give better yields and are disease resistant. Classical plant breeding involves crossing or hybridisation of pure lines, followed by artificial selection to produce plants with desirable traits of higher yield, nutrition and resistance to diseases. With advancements in genetics, molecular biology and tissue culture, plant breeding is now increasingly being carried out by using molecular genetic tools. Plant breeding programmes are carried out in a systematic way worldwide in government institutions and commercial companies.

Question 9.
Describe three advantages and three disadvantages of cross pollination in plants.
Answer:
Following are the three advantages of cross-pollination in plants:

New hybrids of plants can be produced by this method.
It introduces variations due to genetic recombination.
The offsprings produce are better adapted to change in environment.

Three Disadvantages of Cross-pollination:

There is enormous loss of pollen grains.
Good characters can be diluted and undesirable characters will enter in the progeny.
There is always a chance factor for it.

Question 10.
Distinguish between structural gene, regulatory gene and operator gene.
Answer:
Structural gene: This is a gene which has the information to code for amino acid sequence. It produces m-RNA to synthesize a specific polypeptide (enzymes) and it is regulated as a unit,by a single switch (operator).

Regulatory gene: It is a gene that produces repressor to inhibit the action of an operator gene and thus, turns off the operon. It also controls the rate of synthesis of the produces of other gene.

Operator gene: It is a gene which switches on or off the adjacent structural genes. When this gene is on, then the expression of structural genes occur to initiate the transcription and translation but in the off condition, no synthesis of polypeptide chain takes place.

Question 11.
Write a short note on ‘Adaptive Immunity’?
Answer:
Every antigen is processed by antigen-presenting cells like macrophages, B lymphocytes etc. The processed antigen is presented on the surface of these cells. A subgroup of T cells, called T-help cells, specifically interacts with the presented antigen and becomes activated. The activated T help cells then activate B cells and a sub-group of T cells called T cytotoxic cells in a specific manner. The activated B and T cytotoxic cells proliferate to produce clones. All the cells of a clone recognise the same antigen and eliminate it.

Question 12.
What is Biogas? Name the biomass and bacteria involved in the production of Biogas.
Answer:
Biogas is the mixture of gases (predominantly methane) produced during decay of biomass in the absence of oxygen. The biomass used in the production of biogas is animal dung, sewage, crop residues, vegetable wastes, water hyacinth, poultry droppings and wastes from agro-based industries. Methanogens (Methanobacterium) which grow anaerobically on cellulosic material produce large amount of methane along with CO₂ and H₂.

Question 13.
Expand ELISA. On what principle ELISA test is based?
Answer:
ELISA: means Enzymes Linked ImmunoSorbent Assay. This is a simple and versatile technique which is used most widely for the screening HIV and is based on the principle of Ag- Ab reaction.

Question 14.
How is rabies caused ? Write about its symptoms and control measures in brief.
Answer:
Rabies is caused by Iyssavirus type-1 which RNA containing virus. In man it is caused by the bite of a rabid dog. The disease is transmitted from one organism to other through the saliva which enters wound made by the bite of the animal.
Symptom: The virus stimulates nervous system and damage the cells of spinal cord and brain.
It causes high fever, severe pain. The victim develops fear from water (Hydrophobia)
Control:

The patient should be isolated in a quiet room protected from external stimuli.
A series of injections are advised to be injected.

Question 15.
What is Gene gun ? Give its utility.
Answer:
Gene gun: It is the new technology where vectorless direct gene transfer occurs in organisms. DNA coated into microscopic pellets is directly shot into target cells.

Utility: This technique is used to insert genes that promote tissue repair into cells near wounds, leading to a reduction of healing time.

Question 16.
Write the important symptoms of Down’s Syndrome.
Answer:
Down syndrome is also known as Trisomy. It is a genetic disorder caused by the presence of all or part of a third copy of chromosome -21 symptom.

Developmental delays and physical and mental disabilities caused by genetic disorder.
Flat face and short neck is present in child.

Question 17.
Write short notes on Global Warming.
Answer:
Global Warming is the phenomenon of increase in the global mean temperature caused by greenhouse gases. Due to global warming, there is average increase in temperature in the atmosphere.

Question 18.
What is transcription?
Answer:
The first step of protein syntheris is known as Transcription. During transcription step the instruction encoded in the DNA of the genes are transcribed into the nucleotide sequence code of a RNA. Because this RNA molecule causes the Protein Synthesis instruction in the word a ‘message’ from the gene to the ribosome. So, it is called mRNA.

Long Answer Type Questions

There are 6 long answers type question (each carrying 05 marks) out of which answers any three questions. (5 x 3 = 15)

Question 19.
Give an account of Anemophily.
Answer:
Anemophily is a mode of pollination or transfer of pollen grains from anther to stigma through the agency of wind. The flowers which are wind pollinated are called anemophilous. The anemophilous flowers are characterized by the following adaptations
(a) Flowers are small, colourless, inconspicuous, odourless and nectarless.
(b) Calyx and corolla are either reduced or absent.
(c) Filament of stamens are usually long and versatile.
(d) Pollen grains are small, light, dry, dusty and some times winged (e.g. pine).
(e) Pollen grains are infinite in number.
(f) Stigmas are hairy and branched.
(g) When flowers are unisexual, male flowers are more abundant than female flowers.
In bisexual flowers the stamens are generally numerous.
Examples of wind pollinated flowers are grasses, sugarcane, bamboo, maize etc.

Question 20.
Give an account of Recombinant DNA technology.
Answer:
rDNA technology:

DNA sequence is obtained from tissue culture.
Specific restriction endonuclease is selected from the specific bacteria.
Restriction endonuclease cuts specific DNA at the two ends.
Some restriction endonuclease cuts a matching DNA sequence from a plasmid.
Ligase enzyme which acts as a molecular glue joins the restriction fragment in the place vacated by the cut DNA segment of the plasmid. The plasmid DNA now contains foreign DNA and its DNA is called recombinant DNA (r.DNA)
Recombinant plasmids containing recombinant DNA are now injected into a host cell.
This is done by electroporation.
Host bacterium divides to give multiple copies of recombinant DNA.

Question 21.
Define the following terms and give one example for each:
(a) Commensalism
(b) Parasitism
(c) Camouflage
(d) Mutualism
(e) Interspecific competition.
Answer:
(a) Commensalism: It is the type of interaction between two organisms where one is benefitted and the other is neither benefitted nor harmed.
Example: The sucker fish bears a sucker on the dorsal side of its head which helps it to attach itself to the body of the shark. It benefits the sucker fish to get free transportation as well as free food left behind by the Shark.

(b) Parasitism: It is a type of interaction between two organisms where one lives at the expense of other.
Here, one is benefitted (parasite) and the other is harmed (host).
Examples: Lice are parasite on humans and ticks on dogs.

(c) Camouflage: It is a type of protective mechanism in many animals where they assume different shapes and colours resembling to the background for deceiving the predators as well as for ensuring better survival.
Example: Stick insect (Carausins morosus) resemble like a dry stick and leaf insect (Phyllium) looks like a leaf. Similarly, Praying maints mimics the green foliage to protect themselves from the predators and prey.

(d) Mutualism: It is the relationship between two organisms where both are benefitted for food, shelter and substratum for attachment.
Example: The fungal symbiotic association with algae is called lichens. The algae manufacture the food and shares with fungi. On the other hand the fungus provides the structural converging the anchorage to the algae.

(e) Interspecific competition: It is the competition between the individuals of two different species occurring in a habitat. In shallow South American lakes, the visiting flamingoes and resident fishes have interspecific competition for their common food.

Question 22.
What are the various sources of water pollution? Name some important constituents of effluents.
Answer:
The water gets polluted by the following sources:
(a) Domestic Waste: The large quantities of municipal and household wastes are discharged into the water and cause water pollution.

(b) Industrial Wastes: The contamination of water occurs with the industrial wastes such as pulp mills, leather, tanneries, sugar and oil refinery, steel, textile and jute mills, petroleum and chemical fertilizer plants. These wastes contain very harmful substances like pesticides, bleaching powder etc. which largely affect the flora and fauna.

(c) Sewage: Disposal of sewage into rivers and lakes cause several undesirable effects. The sewage water contains several organic substances, human and animal excreta, food residues, cleaning agents, detergents and other wastes which provide nutrition to bacteria and fungi and consequently cause deoxygenation of water with the formation of algae blooms.

(d) Thermal Pollution: Release of large volumes of hot water into a stream can cause serious thermal pollution. This thermal pollution can upset the life-cycle and metabolic activities of many aquatic plants and fishes. Not only fish, but entire aquatic ecosystem is also affected by the thermal pollution and its toxic effect increases with further rise in temperature.

(e) Oils, Grease and Petroleum Products: These when discharged into water by accident or by design are extremely toxic and immediately affect the living organisms of the oceans.

(f) Radio Active Wastes: These wastes from atomic reactors and plants into rivers or streams can affect the aquatic plants and animals to a very great extent. They cause ionizations.

(g) Industrial Effluents: The increased quantity of dissolved salts in water like fluorine, alkalis, phenols, cyanides, mercury compounds, various metals, insecticides, pesticides and excess of fertilizers may produce harmful effect on living organisms. The consumption of mercury leads to crippling deformity called minamata disease.

Question 23.
What is pollution? Write an essay on air pollution.
Answer:
Pollution is an undesirable change in the physical, or biological characteristics of air, water and soil that may affect human life or any other organism. The World Health Organization defines air pollution as the presence of materials in the air in such concentration which are harmful to man and his environment. A number of ingradients find these are mostly gases, which rapidly spread over wide areas.

Sources of air pollution: The sources of air pollutions are very large and varied. These are:

(i) Industrial pollutants: The common air pollutants which are discharged by the industrial chimneys and power houses are S02, C02, H2S and hydrocarbon together with dust, smoke and girt.

(ii) Automobile exhausts: Automobiles run by petro and diesel produce carbon monoxide, nitrogen oxide and hydro-carbons. Hundred and thousands of tonnes of hydrocarbons and CO are emitted into air daily.

(iii) Ionizing radiations from radioactive substances: Ionizing radiations include ex, (3 particles and the gamma rays etc. These are produced by the atomic explosions and the testing of atomic weapons.

Air pollutants: The air pollutants have been separated into two categories directly from some identifiable sources.
These include: Sulphur compounds are SO₇, SO₃, H₂S etc.
Carbon compounds include oxides of carbon (CO + CO₂) and hydrocarbons.
Nitrogen compounds are NO₂ and NH₃
Halogen compounds are hydrogen fluoride (HF) and HC₁.

(ii) Secondary pollutants: The secondary pollutants are produced by the combination of primary emitted pollutants in the atmosphere.

Effects of Pollutants on Animals and Man: Only some of the direct or indirect effects of airborne pollutants on animal life have been studied so far. The general effect of air pollutants is on the respiratory tract and lung causing pulmonary Oedema and lung cancer. In addition to irritation in eyes, mucous membrane and pulmonary congestion, chronic bronchitis, lung carcinoma and other effects.

Flourosis in cattle is caused if exposed to fluoride-containing dusts. More subtle physiological effects of ciliary action, alternation in pulmonary physiology, specific enzyme inhibition and changes in blood chemistry. Inhaling of ozone causes dryness of membrane of mouth, nose and throat changes, visual activity causes headache, pulmonary congestion and oedema. Radio-active elements which enter the air through nuclear explosions come by earth as nuclear follents. These enter the biological system the absorption through the leaves or roots of plants and often result in the formation of cancer.

Control of Air pollution: Air pollution is caused mostly by human agencies. The use of cheap fuels with higher sulphur contents should be avoided. Use of expensive fuels of high quality should be recommended. Strict check on car exhaust should be maintained for contents. The poisonous gases going out in the atmosphere should be treated chemically. The persons working in chemical factories, polishing and spray industries should be provided with suitable gas dust masks.

Question 24.
What is radiation pollution? What are the effects of it?
Answer:
When in atmosphere harmful changes happen due to different types of radiations and radio-active materials then it is called radiation pollution. It is the physical pollution of air, water and soil with radioactive materials. It is natural as well as man-made. The effect of radioactive pollutants depends on (i) strength of radiation, (ii) rate of diffusion and deposition of the pollutants, (iii) the length of time for which the tissue is exposed to radiation, and (iv) half-life of pollutants. Environmental factors also influence their effects.

Effects of radiation pollution :

Due to radiation pollution, body becomes weak and life becomes short.
Radiation pollution is harmful for DNA, RNA, Protein, Spleen, etc.
Radio-active radiations cause sterility, defect vision, tumour of lungs, loss of tissues, etc.
Long time exposure in ultraviolet radiations causes skin related diseases.
For long time or time-to-time radiation of radio active materials may cause blood cancer or Leuckaemia.
Cells vary in their sensitivity to injury by radiation.
Chances of depletion of ozone layer in stratosphere by nuclear explosions.