2nd PUC Biology Model Question Paper 1 with Answers

Students can Download 2nd PUC Biology Model Question Paper 1 with Answers, Karnataka 2nd PUC Biology Model Question Papers with Answers helps you to revise the complete Karnataka State Board Syllabus and to clear all their doubts, score well in final exams.

Karnataka 2nd PUC Biology Model Question Paper 1 with Answers

Time: 3.15 Hours
Max Marks: 70

General Instructions:

1. This question paper consists of four parts A, B, C and D. Part D consists of two parts, Section – I and Section – II.
2. All the parts are Compulsory.
3. 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 are homogametes?
Answer:
These are the gametes similar in appearance.

Question 2.
Give an example for allosomal trisomy.
Answer:
Klinefelter-s syndrome.

Question 3.
What is saltation?
Answer:
Single step mutation leads to speciation is called saltation.

Question 4.
Name the microorganism which produces butyric acid.
Answer:
Clostridium butylicum.

Question 5.
What is biopiracy?
Answer:
The use of bioresources by multinational companies without proper authorization from the countries and people concerned without compensatory payment.

Question 6.
Define immigration.
Answer:
It is the number of individuals of the same species that have come into the habitat from elsewhere during the time period under consideration.

Question 7.
What are sacred grooves?
Answer:
These are the small forest patches have protected trees and wildlife.

Question 8.
Expand BOD.
Answer:
Biochemical oxygen demand.

Question 9.
What is food web?
Answer:
It is the natural interconnection of food chains.

Question 10.
What are meiocytes?
Answer:
These are specialized cells in diploid organisms undergo meiosis.

Part – B

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

Question 11.
What is placenta? Mention any one hormone secreted by placenta.
Answer:
It is the structual and function unit between developing embryo and maternal body.
Human chorionic gonadotrophin (hCG), Human placental lactogen (hPL), Estrogens and Progestogens.

Question 12.
Name any two reproductive health problems.
Answer:

1. Improper development and abnormal functions of reproductive organs.
2. Reduced knowledge about adolescence and related changes.
3. Lack of information about menstrual cycles.
4. Insufficient awareness of safe and hygienic sexual practice.
5. Believing in myths and misconception about sex related aspects.

Question 13.
What is test cross? Write its significance.
Answer:
The cross made between F₁ hybrids with the recessive parents. To know the genotypes of parents.

Question 14.
Mention the different types of RNAs.
Answer:

• rRNA
• tRNA
• snRNAs
• mRNA
• hnRNA

Question 15.
What is phenylketonurea? Write two symptoms.
Answer:
It is inborn errors of metabolism inherited due to autosomal recessive trait.
Symptoms:

1. Accumalation of phenyl pyruVic acid and phenyl alanine in brain. .
2. Excretion of phenyl alanine along with urine.

Question 16.
Write the chemical compounds of primordial earth.
Answer:
Methane, Ammonia, Hydrogen and water vapour

Question 17.
Name the causative organisms of
a) Typhoid
b) Malaria.
Answer:
a) Typhoid – Salmonella typhi
b) Malaria – Plasmodium vivax / P.malaria / P.flaciparum

Question 18.
Mention the names of cry genes of Bt – cotton.
Answer:
cryl Ac, cryllAb and cryLAb

Part – C

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

Question 19.
Differentiate asexual reproduction from sexual reproduction.
Answer:
Asexual reproduction:

• It is uniparental.
• Single parent is involved.
• No formation of male and female gametes.
• No fusion of gametes.
• Produces offspring that are identical to their parents.
• Offspring do not show variations.
• Offspring are not suitable for natural selection.
• Offspring have no better chances of survival.

Sexual reproduction:

• It is biparental.
• Two parents are involved.
• Male and female gametes are formed.
• Involves fusion of male and female gametes.
• Offspring are generally different from their parents.
• Offspring show variations due to genetic recombination^
• Offspring are suitable for natural selection since they show variations.
• Offspring have better chances of survival.

Question 20.
Explain the structure of pollen grain
Answer:

• Pollen grain represent male gametophyte.
• Pollengrains are generally spherical measuring about 25 – 50 micrometer in diameter.
• It has prominent two layered wall.
• The hard outer layer called as exine and is made up sporopollenin.
• Pollen grain exine has prominent aperture called as germ pore.
• The inner wall of pollen grain is – called as intine. It is thin made up of cellulose and pectin.
• When pollen grain is mature contain two cells called vegetative cell and generative cell.

Question 21.
What are IUDs? Give any two examples.
Answer:
These are birth control devices, inserted by doctor or nurse in uterus through vagina.
Examples :
Lippes loop, Copper – T.

Question 22.
Write any three salient features of human genome project.
Answer:

• The human genome contains 3164.7 million nucleotide bases.
• Less than 2% of the genome codes for proteins.
• Repeated sequences make up very large portion of the human genome.
• The functions of 50% genes discovered is unknown.
• The total genes is estimated is much lower than the previous estimates 80,000 – 1,40,000

Question 23.
Distinguish between homologous and analogous organs.
Homologous organs:

• These are structurally similar functionally dissimilar.
• These are developed by related animals.
• They show similar developmental pattern.
• They show divergent evolution.

Analogous organs:

• These are structurally dissimilar but functionally similar.
• These are developed by unrelated animals.
• Their developmental pattern is not similar.
• They show convergent evolution.

Question 24.
What are single cell proteins? Write their significance in nutrition.
Answer:
Alternative source of proteins for animals and human nutrition is single cell proteins.
Significances:

• To get more proteins micro organisms are cultured (Methylophilus methylotrophus) because of its high rate of biomass production and growth.
• Mushrooms are eaten by many people. So it is believable that , microbes would become accpeptable as food.

Question 25.
What is gene therapy? Write any two applications of gene therapy.
Answer:
The correction of genetic defect involves a delivery of normal gene into individual or an embryo to take over the function and compensate for the non functional gene.
Applications:

• The SCID disease is cured by insertion of ADA gene.
• Cystic fibrosis is cured by gene therapy.

Question 26.
Define biodiversity. Mention its types.
Answer:
The sum of total species richness is called biodiversity.
Types:

1. Species diversity
2. Genetic diversity
3. 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.
Draw a neat labeled diagram of TS of anther.
Answer:

Stamens are the male reproductive units of a flower. Each stamen is composed of an anther and filament; Anther consists of microsporangium, pollen grains which contribute male gametes are formed within microsporangium present in another.

A typical anther consists of column of sterile tissue called connective and anther lobes on either side. Each anther lobe bears two pollen chambers also called microsporangia. Thus, dithecous anther consists of 4 pollen sacs or microsporangia.

Anther at maturity consists of sporogenous tissue covered by anther wall which is made up of epidermis, endothelium, middle layer and tapetum.

Epidermis: It is the outmost covering of the anther wall, single layered and protective in function.

Endothelium: It lies below the epidermis. The cells of the endothelium are radially elongated with fibrous thickenings. These cells are hygroscopic and when they lose water they contract as a result anther dehisces which helps in the release of pollen grains.

Middle layers: Two to three layered cells present below the endothelium constitute middle layers. The cells of the middle layer store food materials.

Tapetum: It is the inner most layer of the anther wall and surrounds the sporogenous tissue. The cells have dense cytoplasm and prominent nuclei. Tapetum is nutritive in function which supplies nutritive materials to developing sporogenous tissue.

Question 28.
Explain incomplete dominance with example.
Answer:
Incomplete dominance is the partial expression of the dominant character, as it fails to suppress completely the recessive character as a result both the phenotypes are expressed in the F₁ hybrid in heterozygous condition (which is an intermediate between two homozygous parents). This phenomenon is called incomplete dominance Or partial dominance.

Incomplete dominance was first discovered by famous German Botanist- Carl Correns (1905) in the flowers of Mirabilis Jalapa Commonly called as 4 o clock plant. There are two varieties of Mirabilis Jalapa, red flowered plants (RR) and white flowered plants (rr).

When plants with red flowers (RR) are crossed with plants bearing white flowers (rr), plants with pink coloured (Rr) flowers are obtained in the F generation. When F₁ pink flowered plants are self crossed; Red, pink and white flower coloured plants were obtained in the ratio of 1: 2: 1 in the F₂ generation. This ratio is different from 3: 1 ratio observed for simple Mendelian inheritance. It is therefore, called deviated Mendelian ratio.

Question 29.
Describe the structure of double helix model of DNA.
Answer:
The duplex model of DNA was proposed by J.D Watson and F.H.C Crick based on the x- ray diffraction data obtained by Rosalind Franklin and Wilkins (1953). Watson and Crick along with Wilkins were awarded Noble Prize in 1962.
According to this model:

• The DNA is composed of two polynucleotide chains; which are complementary and anti-parallel. i.e., if one strand runs in 5’ – 3’ direction other strand runs in 3’ – 5’ direction.
• The two polynucleotide chains are spirally coiled ± around each other in a regular manner; so as to give the appearance of a twisted ladder or spiral staircase.
• The two chains are held together by hydrogen bonds between complementary purine and pyrimidine bases.
• The phosphate and deoxyribose sugar units connected with phosphodiester bonds are found on the periphery of the helix where as purine and pyrimidine nitrogen bases occur in the center.
• DNA nucleotide strand is formed by alternatively arranged phosphate and sugar groups.
• Base pairing is specific and complementary to each other.
• The purine adenine pairs with pyrimidine thymine by two hydrogen bonds (A = T).
• The purine guanine pairs with pyrimidine cytosine by three hydrogen bonds (C≡G).
• The diameter or distance or spacing between the nucleotide chains is 20A°.
• One complete turn of helix is called gyre. It has a length of 34A°.
• Each gyre accommodates 10 base pairs; therefore, the distance between two successive base pair is 3.4A°.
• Helix shows major groove with a diameter of 22A° and minor groove with a diameter of 12A° along the central axis,
• In a double stranded DNA; the number of purines is equal to the number of pyrimidines. This is called Chargaffs base equivalence rule.

Question 30.
Draw a neat labelled diagram of human sperm
Answer:

Question 31.
Explain the steps involved in rDNA technology.
Answer:
The steps involved in rDNA technology
1. Isolation of the genetic material:
The gene of interest is isolated from the nucleus of the donor organism. This involves digestion of cell wall or cell membrane of the donor organism by enzymatic action to obtain pure form of DNA.

2. Cutting of DNA at specific locations:

• The pure DNA obtained is cut into several fragments using restriction endonucleases.
• The fragments generated by restriction endonucleases are separated according to their size by gel electrophoresis.

3. Ampiflication of gene of interest using PCR:

• Polymerase chain reaction (PCR) is used to generate billions of copies of the desired DNA in vitro. This is called amplification.
• The desired gene is inserted into a suitable vector (Plasmid).
• The DNA ligases join the complementary ends of plasmid DNA with that of desired gene. The hybrid DNA is called recombinant DNA.

4. Insertion of recombinant DNA into host cell or organism:

• The recombinant DNA is transformed into a suitable bacterial host (E.coli) by transformation for the expression of the desired gene.
• The cells into which rDNA is inserted are called transformed cells.
• The transformed bacterial cells can be identified using suitable selectable markers.

5. Obtaining the foreign gene product:

• The transformed bacterial cells (recombinants) are grown in bioreactor having suitable nutrient medium.
• Bioreactors provide optimum conditions for achieving the desired product by providing optimum growth conditions such as temperature, pH, suitable salts, vitamins, oxygen etc.
• The desired protein is extracted from bacterial cells by separation and purification. These processes constitute downstream processing.

Question 32.
Draw a neat labelled diagram of retro virus (HIV) life cycle.
Answer:

Section – II

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

Question 33.
Discuss the steps involved in plant breeding technique.
Answer:
Steps in plant breeding:
1. Collection of variability:
In nature wild plants and their relatives’ exhibit great genetic diversity, collection of genetic diversity in the form of Seeds, planting material from improved crop varieties, old local or desi varieties amd wild species of crop plants is called germplasm collection.

2. Evaluation and selection of parents:
It is the oldest plant breeding method; the plants obtained from selected germplasm are valued for better phenotypes and genotypic characters. The selected plants with desirable characters are used in hybridization experiments to obtain pure lines. Selection is done through different methods like mass selection, pure line selection and clonal selection.

3. Cross hybridization among the selected parents:
Hybridization is crossing of two or more varieties of plants for bringing their traits together in the hybrid. It is necessary to create genetic variation in hybrid plants.

Process of hybridization involves the following steps:
a) Selection of parents
The most important step in hybridization is selection of homozygous plants with desirable characters, if desirable characters are observed in heterozygous plants. They are subjected to repeated selfing for several generations to bring homozygosity in the desired plants.

b) Emasculations
If the female plant bears bisexual flowers then anthers should be removed before the dehiscence of pollen grains, to prevent self pollination. This can be done through emasculation; It is the process of removal of anthers from bisexual flowers of female plants, when the flowers are still in bud condition. It prevents self pollination.

c) Bagging
Immediately after emasculation, the flower are enclosed in a polythene bag to prevent falling of pollen grains on the stigmatic surface. Bagging prevents undesirable cross pollination.

d) Artificial cross pollination
Pollen grains collected from the male plants are transferred to the surface of the stigma to bring artificial hybridization, seeds and fruits are formed after fertilization, which are collected and preserved.

4. Selection and testing of superior recombination:
The seeds collected from the above process are used to raise Fx generation. These ^plants are self pollinated for several generations till they reach state of uniformity (homozygosity). The characters will not segregate in the progeny. Plants possessing desirable characters are selected.

5. Testing release and commercialization of new pultivars:
The selected plants are tested for their yield and other agronomic traits of quality, disease resistance, by subjecting them to ideal conditions of irrigation and fertilizer, in the research fields. The seed collected from the desired plants is tested in the field at least for three generation, after evaluation seeds and plants are certified and released for commercial cultivation.

Question 34.
Write the role of microbe’s in house hold food products.
Answer:
Role of microbe’s in house hold food products:
1. Lactic acid bacteria (LAB), like Lactobacillus is used in the fermentation of milk for the preparation of various fermented daily products like curd, butter, butter milk, yoghurt and cheese, etc.

2. The curd added to milk as inoculum contains millions of LAB. It converts milk to curd; it also improves its nutritional quality by increasing vitamin B12.

3. The dough which is’used for making foods such a dosa and idli are also fermented products, the puffed up appearance of dough is due to production of COa gas by fermentation process. Similarly the dough used in the preparation of bread using Saccharomyces cererisae (baker’s yeast) is due to the production of C02 gas.

4. Toddy a traditional drink of some parts of south India is prepared from the sap or latex obtained from palm and coconut trees by fermentation process.

5. The Roquefort cheese are ripened by fungi is the best cheese made from sheep milk.

6. Different varieties of cheese known by their texture, flavor and taste are due to use of specific microbes for examples in “Swiss cheese” large holes are due to production of large amounts of C02 by bacterium Propionibacterium sharmanii.

7. Single cell proteins (SGP) which serves as protein supplement in human diet is obtained from microbial biomass such as Spirulina, Chlorella etc.

Question 35.
What is mutualism? Explain any four examples of mutualism.
Answer:
Interaction between two species in which both get benefited is known as mutualism.
Examples of Mutualism:

• Lichens – Fungus and algae.
• Mycorhiza – Fungi with higher plant root.
• Insects and pollinating plants.
• Wasps pollinate fig inflorescence.
• Pollination in ophrys.

Question 36.
Justify the phosphorus cycle is an incomplete cycle.
Answer:

• Phosphorus is a major constituent in biological membrane found in bones, teeth and shell of animals.
• The naturally phosphorus is available in phosphorus rocks, in the form of phosphates.
• By weathering phosphate dissolved in the form of solution and are absorbed by plants, is used. Then it is transferred to animals through food chain.
• The phosphate present in dead organism body is decomposed by bacteria in soil.
• The huge amount of phosphate is sediment in the water bodies and not exchanged between organisms and environment, hence is incomplete cycle.

Question 37.
a) Write a note on e – wastes.
Answer:

• These are irreparable computers and other electronic goods.
• They are buried in landfills or incinerated.
• Recycling and recovery of materials from solid wastes is a solution for reducing solid waste accumulation and disposal.
• Metals like copper, iron, silicon, nickel and gold etc can be recovered during recycling process.
• The solid waste generated is separated into biodegradable, recyclable and non biodegradable.
• Biodegradable wastes are subjected to natural decomposition; recyclable materials like paper, glass, metals, etc can be recovered.
• Non biodegradable solid wastes can be incinerated.

b) Write any two preventive measures of air pollution.
Answer:

1. Use of electro static precipitator.
2. Use of air pollution scrubbers.
3. Spraying water.
4. Wearing of mask.