2nd PUC Biology Model Question Paper 2 with Answers

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Karnataka 2nd PUC Biology Model Question Paper 2 with Answers

Time: 3.15 Hours
Max Marks: 70

General Instructions:

This question paper consists of four parts A, B, C and D. Part D consists of two parts, Section – I and Section – II.
All the parts are Compulsory.
Draw diagrams wherever necessary. Unlabelled diagrams or illustrations do not attract any marks.

Part – A

I. Answer the following questions in One Word or One Sentence each : ( 10 × 1 = 10 )

Question 1.
What is life span?
Answer:
The period from birth to natural death of an organisms

Question 2.
What is Apomixis?
Answer:
The production of seeds without fertilization.

Question 3.
Name the foetal sex determination text.
Answer:
Amniocentesis.

Question 4.
Define alleles.
Answer:
Genes which code for a pair of contrasting traits are known as, alleles.

Question 5.
Expand VNTR.
Answer:
Variable number of tandem repeats.

Question 6.
What is totipotency.
Answer:
The capacity to generate a whole plant from any cell / explant.

Question 7.
What are biofertilizers?
Answer:
Biofertilizer are organisms that enrich the nutrient quality of the soil.

Question 8.
Define biotechnology
Answer:
Biotechnology deals with techniques of using live organisms or enzymes to produce products and processes useful to humans.
OR
The integration of natural science and organisms, cells, parts there of and molecular analogs for products and services.

Question 9.
Give example for ex – situ conservation.
Answer:
Zoological parks, Botanical gardens, wild life safari parks.

Question 10.
Water hyacinth is called terror of Bengal why?
Answer:
They grow abundantly in eutrophic water body leading to misbalancing ecosystem dynamics.

Part – B

II. Answer any FIVE of the following questions in 3 – 5 sentences each, wherever applicable : ( 5 × 2 = 10 )

Question 11.
Distinguish between geitenogamy and xenogamy.
Answer:
Geitenogamy:
Transfer of pollengrains from anther to stigma of another flower of the same plant is called geitenogamy.
Xenogamy:
Transfer of pollengrains from anther to stigma of a flower of the different plant is called Xenogamy.

Question 12.
Mention the functions of placenta.
Answer:

Supply oxygen to the foetus
Supply nutrients to foetus
Removes carbon dioxide and excretory waste material produced by the foetus. Produces harmones like hCG, hPL

Question 13.
Name any two assisted reproductive technique.
Answer:

In – vitro fertilization and embryo transfer – IVF – ET.
Zygote intra fallopian transfer – ZIFT
Intra uterine transfer – IUT
Gamete intra fallopian transfer – GIFT
Intra cytoplasmic sperm injection – ICSI
Artificial insemination – AI
Intra uterine insemination – IUI

Question 14.
List the characteristics features of genetic code.
Answer:

Genetic code is triplet: Each codon consists of sequence of three nitrogen bases.
Genetic code is universal: A particular codon codes for the same amino acid in all organisms.
Genetic code is non overlapping: The successive triplet codons are read in order without overlapping and they do not share any base.
Genetic code is degenerate: A single amino acid is coded by more than one codon.
Eg: valine is coded by 4 different codons GUA, GUC, GUU and GUG
Genetic code is commaless: Codons are without punctuation and written in linear form. There is no signal to indicate the end of one codon or beginning of the next codon.
Genetic code is non-ambiguous:
Each codon specifies a particular amino acid in all organisms.
Eg: AUG codes for methionine
Initiator codons: Protein synthesis is always initiated by particular codons called initiator codons.
Eg : AUG in eukaryotes, GUG in prokaryotes
Terminator codons: Three codons that act as stop signals to terminate protein synthesis are called terminator codons or nonsense codons.
E.g..UAA (Ochre), UGA (Amber) and UGA (Opal).

Question 15.
What are analogous organs? Give two examples.
Answer:
Structures that differ in anatomical plane and origin but perform similar functions are called analogous organs.
Examples :

Wings of birds and insects.
Eyes of octopus and mammals.
Flippers of penguins and dolphins.
Tuber of potato and sweet potato.

Question 16.
What is interbreeding depression? How is it controlled?
Answer:
Continue inbreeding usually reduces fertility and productivity called inbreeding depression.
Controlled by

Out breeding
Out crossing
Cross breeding Inter specific hybridization.

Question 17.
Write a short note on Biopiracy?
Answer:

Biopiracy is the term used to refer to the use of bioresource by the multinational companies and other organizations without proper authorization from the countries and people concerned without compensatory payment.
Most of the industrialized and developed countries are financially rich but poor in the traditional knowledge and biodiversity.
Traditional knowledge related to the bio resources can be exploited to develop modem application and can also be used to save time effort and expenditure during commercialization.
Some nations are developing law to prevent bio piracy.

Question 18.
Draw a neat diagram of pyramid of number in a grassland ecosystem
Answer:

Part – C

III. Answer any FIVE of the following Questions in 40-80 words each, wherever applicable. ( 5 × 3 = 15 )

Question 19.
Write short notes on fertilization?
Answer:

The process of fusion of gametes results in the formation of zygote.
External fertilization the gamatic fusion that occurs in the external medium of water outside the body.
Internal fertilisation : syngamy occurs in the body of the organism.

Question 20.
How do intra uterine devices prevent conception in humans?
Answer:

Increase phagocytosis of sperms within the uterus.
Cu ions released by them suppress sperm motility and the fertilizing capacity of sperms.
Hormones releasing IUDS make the uterus unsuitable for implanatation.

Question 21.
Mention the causes of Down syndrome and add a note on symptoms.
Answer:
Cause : The presence of an additional copy of the chromosome number 21 (trisomy of 21)

Short statured with small round head
Furrowed tongue
Partially open mouth.
Palm is broad with Characteristic palm crease.
Physical, psychomotor and mental development is retarded.

Question 22.
List any three criteria that molecule can acts as a genetic material.
Answer:

It should be able to generate its replica (replication)
It should chemically and structurally be stable.
It should provide the scope for slow changes (mutation)
It Should be able to express itself in the form of Mendalian characters.

Question 23.
Draw a labeled diagrammatic representation of Miller’s experiment
Answer:

Question 24.
Name the causative organism of the following diseases
a) Typhoid:
Answer:
Streptococcus pneumonia

b) Malaria
Answer:
Plasmodium vivax, P.Malaria, P.falciparum

c) Elephantiasis:
Answer:
Wucharia bancrofti, Waucheria malyi

Question 25.
What are genetically modified organisms? Mention their significance.
Answer:
Plants, bacteria, fungi and animals whose genes have been altered by gene manuplation are called genetically modified organisms.
Made plants more tolerant to a biotic stress like cold, drought, salt, and heat.

Reduced reliance on chemical pesticide – pest resistant crops.
Helped to reduce post harvest losses.
Increase the efficiency of mineral nutrition usage by plants.
Enhance the nutritional value of the Food.

Question 26.
Mention the types of biodiversity.
Answer:

Genetic diversity
Species diversity
Ecological diversity.

Part – D

Section – I

IV. Answer any FOUR of the following questions on 200 – 250 words each, wherever applicable. ( 4 × 5 = 20 )

Question 27.
Describe the structure of mature embryo sac
Answer:
Embryo sac is the mature female gametophyte in angiosperms which is a 7 celled and 8 nucleated structure called polygonium type; it consists of a central vacuole and three types of cells namely, egg apparatus, antipodal cells and a central cell.

1) Egg apparatus: It is present towards the micropylar end of the embryo sac and consists of three cells, a centrally placed egg cell and two cells on either side called synergids. Synergids help in the conduction of food materials from the nucellus into the embryo sac and also direct the movement of pollen tube towards micropylar end during fertilization.

2) Antipodal cells: The three smaller cells present towards the chalazal end of the embryo sac are called antipodal cells. These are vegetative cells and degenerate before or after fertilization.

3) Central cell: It is the largest cell lies in the center of the embryo sac. It consists of large central vacuole and two haploid polar nuclei. The two polar nuclei at the time of fertilization fuse to form polar secondary nucleus which is diploid (2n) in nature.

Question 28.
Explain the law of Segregation using monohybrid cross.
Answer:
Statement : The alleles do not show any blending and two alleles during gamete formation segregate each other such that every gamete receives only one of the two factors.

Mendel crossed tall and dwarf pea plants to study inheritance of one gene.
Only one of the parental trait tall appeared in F1 generation.
F1 tall plant was allowed to undergo self pollination.
In F2 both traits appeared in 3 tall and 1 dwarf ratio.

Question 29.
Explain the structure of antibody.
Answer:

Antibody molecule has four polypeptide chain
Two small chains called light chain and two longer chains called heavy chains.
Antibody molecule is H2L2
The light chain an d heavy chain are attached with di-sulphide bridges
Antibody molecule consist of antigen blinding site.

Question 30.
Explain the role of microbes in production of any five industrial products.
Answer:

Fermented beverages : wine beer, whisky, brandy have been produced by yeast.
Antibiotics : Antibiotics like penicillin produced from Penicillium notatum.
Chemicals : Organic acids are produced in the following way : Citric acid Aspergillus niger (afungus) of citric acid
Acetic acid; Acetobacter acetic (abacterium) of acetic acid, butyric acid – Clostridium butylicum, lactic acid – Lactobacillus
Enzymes – Lipases used in laundry Pectinases use to purify the bottled fruit juices
Bio active molecules – cyclosporine A – Trichoderma polysporum immunosupressent agent.
Statins – Monascus purpureus used to reduce cholesterol level in the body.

Question 31.
Exnlain the structure of nBR322.
Answer:

pBR322 consist of a strong origin called ori
Consist of rop gene that code for the protein involved in replication of the plasmid.
It consist of ampicilin and tetracycline resistence gene.
Ampiciline resistant gene consist of retriction site for REN – PstI and Pvul.
Tetracycline resistant gene consist of retriction site for REN – BamHI, Sail.
pBR322 also consists of restriction sites for REN EcoRI, Clal, Hindlll.

Question 32.
What is ecology? Explain major abiotic factor in any ecosystem.
Answer:
The branch of biology that deals with the study of the interrelationships between living organisms and their environment is called ecology or environmental biology.
Abiotic components

Abiotic or physico-chemical components of the ecosystem comprise both climatic and edaphic factors.
They include temperature, light, water, soil, humidity, wind currents, etc.

1. Temperature

It is the major ecological factor; it affects metabolic activities of living organisms by controlling the activity of enzymes.
The levels of thermal tolerance of different species determine to a large extent their geographical distribution.
Based on thermal tolerance animals are grouped into eurythermal and stenothermal.
Animals which can tolerate wide range of temperatures are called euiythermal.
Stenothermal animals cannot withstand higher temperatures and are restricted to narrow range of temperatures.

2. Water

Water is an essential requirement of life.
It is the major component of all living organisms.
The availability of water determines the distribution of plants and animals on earth.
The quality of water, chemical composition, pH, etc., greatly influences the life of aquatic organisms.
Sea water has very high salt concentration (3.5%).
The organisms which can tolerate wide range of salinity are called euryhaline. While those restricted to narrow range of salinity are called stenohaline.

3. Light

It is essential for photosynthetic activity of autotrophs for the preparation of food.
It is necessary for inducing flowering phenomenon (photoperiodism) in plants.
Many plants dependent on sunlight to meet their photoperiodic requirements for flowering.
It is necessary for vision and it controls daily activities in diurnal and nocturnal animals.
It influences biological rhythms (circadian rhythms or daily rhythms) in organisms.
It controls wide range of biological activities in animals such as foraging, reproduction and migration etc., in animals such as fishes, birds and mammals.

4. Soil

It is an edaphic factor.
The type of vegetation that soil supports depends on its chemical composition, grain size, pH, water holding capacity and topography.
In the aquatic environment the sediment characteristics determine the type of benthic animals.

Section – II

Answer any THREE of the following questions in 200 – 250 words each, wherever applicable. ( 3 × 5 = 15 )

Question 33.
Draw a labelled diagram of sectional view of female reproductive system.
Answer:

Question 34.
Explain lac operon concept.
Answer:
In 1961 F. Jacob and J. Monad proposed lac operon concept to explain the regulation of gene expression at transcriptional level in Escherichia coli (E .coli) for this work they awarded NobelPrize in 1965.
a) An operon is a unit of transcription.
b) It consists of three control genes and three structural genes.

Control genes:
1. Regulator or inductor gene (I): It directs the synthesis of a repressor protein to block the activity of operator, thus, inactivates or switch off the structural – genes. It is also called T gene as it produces inhibitor or repressor.

2. Promoter gene (P): It is present between the regulator gene and operator gene. It is the site for attachment of RNA polymerase required for transcription of structural genes.

3. Operator gene (O): It is present between the promoter gene and the first structural gene (lac z). When operator gene receives repressor protein it extends towards promoter gene and transcription does not take place as RNA polymerase cannot bind to promoter due to lack of space. Thus, promoter is functional only when operator is free from repressor proteins.

Structural genes:
These are used to transcribe a polycistronic rnRNA molecule that directs the synthesis of enzymes required for the utilization of lactose in the cell.

lac z : It transcribes mRNA for the synthesis of β galactosidase required for hydrolysis of lactose into glucose and galactose.
lac y : It synthesizes β galactosidase permiase enzymes required for uptake of lactose from external medium.
lac a : It synthesizes transacetylase enzyme that travelers acetyl group from acetyl Co-A to β galactosidase.

Question 35.
Explain the carbon cycle.
Answer:
The cyclic movement of carbon between the living and non living systems of the environment is called carbon cycle. It is a perfect gaseous cycle. Its reservoir pool is atmosphere, which is used and replenished continuously by living organisms through activities like photosynthesis, respiration and decomposition.

Sources : Carbon is present in the air in the form of carbon dioxide, its concentration is very low (0.0032%), burning of fossils fuels like petrol, diesel, peat, coal adds large amounts of CO, into the atmosphere. The decomposition of dead bodies atmosphere. Atmosphere and hydrosphere are the cycling pool ,where as lithosphere is the reservoir pool, therefore, a large amount of fixed carbon is used by marine zooplanktons to make calcium carbonate shells, these are not eaten or decomposed easily, they sink to the bottom and form carboniferous rocks (chalk, limestone), about 99% of carbon is stored in this form, therefore, ocean acts as global sink of COa.

Circulation: The CO₂ present in the atmosphere is used by plants for photosynthesis, during this process CO₂ is converted into carbohydrates. Some amount of glucose is used by plants during their respiration and the rest is converted into biomass (starch and fats) and stored as reserved food materials. These organic compounds containing carbon enter animals as food which are digested and absorbed. The absorbed organic nutrients are used to build their body mass.

Some amount of organic matter is also used by animals in respiration and CO₂ is released to the atmosphere after the death of plants and animals, the bodies are decomposed by decomposers like bacteria and helps in releasing back CO₂ to the atmosphere. This cyclic movement of carbon dioxide between plants, animals and back to atmosphere is called carbon cycle.

Question 36.
a) Explain the role of dairy farm management in human welfare.
Answer:

Select good breeds of high yield, high resistance to diseases.
Look after the cattle properly with well house.
Provide adequate water of good quality.
Feed scientifically with good quality food.
Keep the dairy farm clean
Maintain hygine of cattle and handler
As far as possible mechanized the practices

b) Write a note on single cell protein.
Answer:
Protein produced by metabolism of single cells like Methylophilus methalotrophus or spirulina is called single cell protein.

250 grm of microbe is known to produce 25 tons of proteins in a day.
It can be easily grown on waste water coming out of potato
processing unit or sewage. It is a rich source of protein for human and animal consumption.

Question 37.
What is global warming? Explain causes and effects of global warming.
Answer:
The enhanced green house effect due to atmospheric pollution which is responsible for increase in the average temperature all over the world is known as global warming.

Causes:

Increase in the concentration of green house gases like CO₂, CH₄, ClFCs and N₂O due to burning of fossil fuels like petrol, diesel, coal etc in automobiles and thermal power stations.
Human activities like urbanization and expansion of agriculture leading to deforestation is the major cause of global warming, because forest act as sink of CO₂ as the same for photosynthesis.
Natural decomposition of organic wastes, marshy areas, paddy cultivation, rearing of dairy animals (enteric fermentation in cattle produces large quantities of methane) are the major sources of methane.
Excessive use of refrigerators, air conditioners, aerosol propellants in jet engines, fire extinguishers, insulators, etc are the sources of aerosols like chlorofluorocarbons (CFCs).
Use of nitrogen and phosphorous fertilizers in agricultural practices, degradation and desertification in waterlogged soils, biomass burning and industrial processes, resulted in increased concentration of nitrous oxides (N₂O).

Effects:

A rise in global temperature leads to melting of polar ice caps and glaciers that increases sea level which in turn causes floods and submersion of many coastal areas, islands, etc.

Control measures:

Minimizing the use of fossil fuels to reduce the emission of green house gases into atmosphere.
Use of alternative sources or renewable energy sources such as solar energy, wind energy and tidal energy, electrical energy, etc.
Implementation of aforestation and reforestation programmes like vanamahotsava, reducing deforestation will help in increasing the vegetation cover to increase utilization of CO₂ by plants for photosynthesis.
Slowing down the growth of population, limits indiscriminate use of natural resources. International initiatives are also being taken to mitigate the emission of green house gases.