2nd PUC Biology Model Question Paper 4 with Answers

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Karnataka 2nd PUC Biology Model Question Paper 4 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 is polyembryony?
Answer:
Occurrence of more than one embryo in a seed is referred as Polyembryony.

Question 2.
Define saltation.
Answer:
Single step mutation that results in speciation is the saltation.

Question 3.
Name the disease diagnosed by Widal test
Answer:
Typhoid.

Question 4.
Mention the chemical present in Heroin.
Answer:
Diacetylmorphine.

Question 5.
What are somaclones?
Answer:
Genetically identical plants produced through plant tissue culture.

Question 6.
What are microbial floes?
Answer:
The mass of bacterial and filamentous fungi that form a network of mesh during aerobic digestion.

Question 7.
What is insertional inactivation?
Answer:
The process of inactivation of the expression of selectable marker gene by inserting a gene of interest into it.

Question 8.
Define Natality.
Answer:
It is the number of organisms that are added to a population by birth, germination, multiplication of microbes.

Question 9.
What is in – situ conservation?
Answer:
The conservation of plants and animals in their natural habitats.

Question 10.
Define solid wastes.
Answer:
All the waste goes as thrash is called solid waste.

Part – B

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

Question 11.
What are vegetative propagules? Mention the vegetative propagules of i) Agave ii) Ginger
Answer:
Any vegetative parts of a plant that have the ability to give rise to new plants are called as vegetative propagules.
The vegetative propagules of
i) Agave – Bulbil
ii) Ginger – Rhizome

Question 12.
Define syngamy and triple fusion.
Answer:
Syngamy is the fusion of one of the haploid male gamete with female gamete or egg to form a diploid zygote.
Triple fusion is the fusion of diploid secondary cell or polar nuclei with second male gamete to form triploid primary endosperm nucleus.

Question 13.
Name the. hormones secreted by Leydig cells and corpus.
Answer:
Leydig cells – Testosterone or Androgens.
Corpus luteum – Progrestserone.

Question 14.
How do hormonal IUDs differ from non – medicated IUDs as contraceptives?
Answer:
The hormone releasing IUDs, make the uterus unsuitable for implantation and the cervix hostile to the sperms.

Question 15.
Define the terms linkage and recombination.
Answer:
The physical association of two genes is called linkage.
The generation of non – parental gene combinations is called recombination.

Question 16.
Explain any two properties of genetic code.
Answer:

1. Genetic code is triplet
2. Genetic code is universal
3. Genetic code in non – overlapping
4. Genetic code is unambiguous
5. Genetic code is without punctuation or comma less
6. Genetic code has initial and terminator codons
7. Genetic code is degenerative

Question 17.
Distinguish between Benign and malignant tumor.
Answer:
Benign tumor is confined to the region of its origin and do not spread to other parts of the body whereas the malignant tumor spreads to other region of the body from their origin site.

Question 18.
Differentiate between out – breeding and out – crossing.
Answer:
Out – breeding is the breeding of the unrelated animals, which may be between individuals of the same breed but having no common ancestors.

Out crossing is the mating of animals within the same breed, but having no common ancestors on either side of their pedigree up to 4 – 6 generations.

Part – C

III. Answer any FIVE of the following Questions in 100-150 words each, wherever applicable. ( 5 × 3 = 15 )

Question 19.
Explain the phases of life span in organisms.
Answer:

• Juvenile or vetetative phase – The period from birth to reproductive maturity in animal or germination to flowering in plants respectively.
• Reproductive phase – The phase at which an organism attain reproductive maturity and starts producing gametes.
• Senescent phase – The terminal irreversible ageing that ultimately results in death of an organisms.

Question 20.
Mention any three strategies of reproductive health.
Answer:

1. Reproductive health requires strong infrastructural facilities
2. Professional expertise
3. Material support

Question 21.
What are Mendelian disorders? Mention any two of them.
Answer:
The genetic disorders that follow Mendelian laws of inheritance are called Mendelian disorders.
Pheyketonuria, Sickle cell anemia, Thalassemia, Colorblindness, Hemophilia.

Question 22.
Explain the stages of post – transcriptional modification.
Answer:

• Capping – It is the process of addition of 5 – methylguanosine to the 5’ region of Pre – mRNA.
• Splicing – It is the process of cutting of introns and ligation of exoms by spliceosome complex.
• Poly – A – tailing – It is the process of addition of approximately 200 adenosine residues to the 3’ end of Pre – mRNA.

Question 23.
Name the pathogen, vector and a sympton of filariasis.
Answer:

• Pathogen – Waucheria bancrofti.
• Vector – Female mosquito.+
• Symptom – Swelling of legs, scrotum and lymphatic vessels.

Question 24.
What is ecological succession? Mention the types with an example.
Answer:
It is the fairly and gradual replacement of species composition in an area.

• Xerosere
• Hydrosere

Question 25.
Mention any three ecosystem services to humans
Answer:

1. Healthy forest ecosystems purify air and water, mitigate droughts and floods, cycle nutrients, generate fertile soils, provide wildlife habitat.
2. Maintain biodiversity, pollinate crops, provide storage site for carbon.
3. Provide aesthetic, cultural and spiritual values.

Question 26.
Mention any three reasons of loss of biodiversity.
Answer:

1. Habitat loss and Fragmentation
2. Over exploitation
3. Introduction of Alien species
4. Co – extinction

Part – D

Section – I

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

Question 27.
Mention any five difference between microsporogenesis and megasporogenesis.
Answer:
Microsporogenesis:

• Process of formation of microspores
• Occurs in the pollen chambers
• All the sporogenous cells differentiate into microspore mother cells
• Gamete mother cell or meiocytes are the microspore mother cells
• Each microspore mother cell give rise to four functional microspores.

Megasporogenesis:

• Process of formation of megaspore.
• Occur in the ovule.
• Only one sporogenous cell differentiate into megaspore mother cell.
• Gamete mother cell or meiocytes are the megaspore mother cell.
• Each magaspore mother cell give rise to 1 – 4 functional megaspore.

Question 28.
Draw a labelled diagram of Human male reproductive system
Answer:

Question 29.
Give the schematic representation of one gene inheritance with respect to law of Dominance.
Answer:

Question 30.
Explain the structure of Nucleosome.
Answer:

• The negative charged DNA is wrapped around the positively charged histone octamer to form a structure called nucleosome.
• Histones are organised to form a unit of eight molecules called as histone octamer.
• A typical nucleosome contains 200 bp of DNA helix.
• Nucleo somes constitue the repeating unit of a structure in nucleus called chromatin, thread like stained (coloured) bodies seen in nucleus
• The nucleosomes in chromatin are seen as “beads – on – string” structure when viewed under electron microscope.

Question 31.
Give the diagrammatic representation of Stanley Miller’s experiment.
Answer:

Stanly miller and H.C. Urey experimentally proved chemical evolution with their simulation experiments (creating conditions similar to that of conditions of primordial earth). They designed an apparatus. A mixture of methane (CH₄), ammonia (NH₃), hydrogen (H₂) and water vapour was pumped into the apparatus. Vacuum conditions were maintained (simulation of primordial atmosphere).

The mixture was treated with electrical discharges produced with the help of spark discharging chamber (simulation of lighting), mean (-) while water was boiled to produce water vapour. (Simulation of evaporation) in the water boiler; The gas mixture with water vapour is made to circulate constantly through spark discharging chamber, condenser and water boiler, for about a week.

The reaction sample was drawn through sample outlet and it was analyzed for chemical composition; they noticed simple amino acids like glycine, alanine and aspartic acid concluding that primordial conditions of the earth lead to the formation of organic compounds which in turn form the building materials of life.

Question 32.
Mention any five microbes and their commercial or industrial products.
Answer:

1. Aspergillus niger – citric acid
2. Acetobacter aceti – acetic acid
3. Clostridium butylicum – butyric acid
4. Lactobacillus – lactic acid.
5. Yeast (Saccharomyces cerevisiae) – ethanol.
6. Penicillium hotatum (a fungus) – Penicillin antibiotic
7. Streptococcus sp. (bacterium) – Streptokinase

Section – II

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

Question 33.
Describe the major steps involved in plant breeding programmes.
Answer:
Collection of variability : The entire collection (of plants / seeds) having all the diverse alleles for all genes in a given crop is called germplasm collection.

Evaluation and selection of parents : The germplasm is evaluated so as to identify plants with desirable combination of characters to be used as parents.

Cross hybridization among the selected parents : This is possible by cross hybridizing the two parents to produce hybrids that genetically combine the desired characters in one plant. Usually only one in few hundred to a thousand crosses shows the desirable combination.

Selection and testing of superior recombinatns : This step consists of sleeting, among the progeny of the hybrids, those plants that have the desired character combination.

Testing, release and commercialization of new cultivars: The newly selected lines are evaluated in research fields is followed by testing the materials in farmers’ fields, for at least three growing seasons at several locations in the country, representing all the agro climatic zones where the crop is usually grown.

Question 34.
Draw a labelled diagram of simple stirred tank bioreactor.
Answer:

Question 35.
How are genetically modified plants useful to mankind.
Answer:

• Made crops more tolerant to abiotic stresses (cold, drought, salt, heat).
• Reduced reliance on chemical pesticides (pest – resistant crops).
• Helped to reduce post harvest losses.
• Increased efficiency of mineral usage by plants (this prevents early exhaustion of fertility.of soil).
• Enhanced nutritional value of food, e.g., Vitamin ‘A’ enriched rice.

Question 36.
a) Mention any four major abiotic factors
b) Name the type of interaction in the following organisms
i) Fungi – Roots of higher plants
ii) Cattle – Egret
iii) Cuckoo – Crow
Answer:
The four abiotic factors includes : Light, temperature, soil, water
i) Fungi – Roots of higher plants – Mutualism
ii) Cattle – Egret – Commensalism
iii) Cuckoo – Crow – Brood parasitism

Question 37.
Discuss the consequences of
a) Global warming
b) Ozone depletion
Answer:

• Causes deleterious changes in the environment and resulting in odd climatic changes (e.g. El Nino effect).
• Leads to increased melting of polar ice caps as well as of other places like the Himalayan snow caps.
• Over many years, this will result in a rise in sea level that can submerge many coastal areas.
• It causes aging of skin, damage to . skin cells and various types of skin cancers.
• In human eye, cornea absorbs UV – B radiation, and a high dose of UV – B causes inflammation of cornea, called snow – blindness cataract, etc. Such exposure may permanently damage the cornea.