2nd PUC Biology Model Question Paper 3 with Answers

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Karnataka 2nd PUC Biology Model Question Paper 3 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 x 1 = 10 )

Question 1.
What is a staminate flower?
Answer:
Unisexual male flower.

Question 2.
What is amniocentesis?
Answer:
A foetal sex determination test based on chromosomal pattern in the amniotic fluid.

Question 3.
Who provided an experimental proof for chemical evolution of life?
Answer:
S.L. Miller

Question 4.
Name the causative organism of ringworm.
Answer:
Trichophyton / Epidermophyton / Microsporum

Question 5.
What are oncogenic viruses?
Answer:
Cancer causing viruses.

Question 6.
Name the bioactive molecule used in organ transplanation
Answer:
Cyclosporin – A.

Question 7.
Write the function of DNA ligase.
Answer:
It is an enzyme used to join any two segments of DNA.

Question 8.
What are eurythermal organisms?
Answer:
The organisms can tolerate and thrive in a wide range of temperatures.

Question 9.
What is an ecological succession?
Answer:
The gradual and fairly predictable change in the species composition of a given area.

Question 10.
Define Endemism.
Answer:
Species confined to that region and not found anywhere else.

Part – B

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

Question 11.
Mention any two vegetative propagules of angiosperms.
Answer:
Runner, Rhizome, Sucker, Tuber, Offset, Bulb.

Question 12.
Differentiate between chasmog- amous and cleistogamous flowers.
Answer:
Flower with exposed anthers and stigma
Flowers with unexposed anthers and stigma.

Question 13.
Mention any two hormones secreted by ovary.
Answer:
Estrogen and progesterone.

Question 14.
Expand GIFT and ICSI.
Answer:
GIFT : Gamete Intra Fallopian Transfer
ICSI : Intra Cytoplasmic Sperm Injection

Question 15.
Write any two preventive measures to control STD’s
Answer:

1. Avoid sex with unknown partners / multiple partners.
2. Always use condoms during coitus.
3. Incase of doubts one should go to a qualified doctor for early detection and complete treatment if diagnosed with disease.

Question 16.
What is male heterogamety? Give an example.
Answer:
It is a mechanism of sex determination in which males produce two different types of gametes.
Example : XO type, XY type of sex determination.

Question 17.
Name the technique involved in separation and isolation of DNA fragment, which dye is used to stain gel to make the DNA visible under UV light.
Answer:

• Gel Electrophoresis
• Ethidium bromide.

Question 18.
With reference to transcription, define
a) splicing
b) capping.
Answer:
a) The removal of introns and joining of exons
b) Addition of adenylate residues at 3 prime end of RNA

Part – C

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

Question 19.
What is asexual reproduction? Mention any two types.
Answer:
Process of formation of offsprings by a single parent without the formation and fusion of gametes.
Two types : Budding, conidia, gemmule, sporulation.

Question 20.
Write karyotype of Klinefelter syndrome. Mention any two symptoms.
Answer:
47, XXY / 44 + XXY-01 Masculine development, development of breast, sterile individuals are sterile.

Question 21.
List out any Three important goals of Human Genome Project.
Answer:

1. To identify all the approximately 25,000 – 30,000 genes in human DNA.
2. To determine the sequence of 3 billion chemical base pairs (3 x 10⁹ bp) that make up of human DNA.
3. To store this information in data bases.
4. To improve tools for data analysis.
5. To analyze the genomes of several organisms used in research laboratories.
6. To address ethical, legal and social issues (ELSI) that may arise from the project.

Question 22.
Define the terms
a) Explant
b) Toti potency
c) Somatic hybrids.
Answer:
a) Explant:
Any part of a plant taken out and grown in test tube under sterile conditions in a special nutrient media.

b) Toti potency:
The capacity to generate the whole plant from any cell / explants.

c) Somatic hybrids:
The plants produced by the process of somatic hybridization

Question 23.
What is plasmid? Mention two sites of plasmid.
Answer:
Autonomously, replicating circular extrachromosomal.

• Ori site (Origin of replication)
• Cloning site (recognition site)

Question 24.
Write any three effects of Global warming.
Answer:
Effects of Global warming :

1. Rise in temperature is leading to deleterious changes in the environment and resulting in odd climatic changes.
2. The capacity to generate the whole plant from any cell / explants.
3. Rise in sea level that can submerge many coastal areas.

Question 25.
List out any three causes of Biodiversity losses.
Answer:

1. Habitat loss and fragmentation.
2. Over exploitation
3. Alien species invasion
4. Coextinctions

Question 26.
Define the following :
a) Eutrophication:
Answer:
It is a natural aging of a lake by nutrient enrichment of its water.

b) Biological magnification:
Answer:
Increase concentration of the toxicant at successive trophic levels

c) Biochemical oxygen demand:
Answer:
It is the amount of oxygen that would be consumed if all the organic matter in one liter of water were oxidized by bacteria.

Part – D

Section – I

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

Question 27.
Give a schematic representation of Mendelian Dihybrid Cross.
Answer:

Question 28.
Enumerate salient features of Genetic Code.
Answer:

1. Genetic code is triplet: Each codon consists of sequence of three nitrogen bases.
2. Genetic code is universal: A particular codon codes for the same amino acid in all organisms.
3. Genetic code is non overlapping: The successive triplet codons are read in order without overlapping and they do not share any base.
4. 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
5. 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.
6. Genetic code is non-ambiguous: Each codon specifies a particular amino acid in all organisms.
   Eg: AUG codes for methionine
7. Initiator codons: Protein synthesis is always initiated by particular codons called initiator codons.
   Eg : AUG in eukaryotes, GUG in prokaryotes
8. 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 29.
Explain the following terms
a) Adaptive radiation
b) Founder’s effect
c) Homologous organs
d) Analogous organs
e) Saltation
Answer:
a) Adaptive radiation:
The process of evolution of different species in a given geographical area starting from a point and radiating to other areas of geography.

b) Founder’s effect:
Sometimes the change in allele frequency is so different in the new sample of population that they become a different species. The original drifted population becomes founders and the effect is called founder effect.

c) Homologous organs:
The organs having similar structure but perform different functions.

d) Analogous organs:
The organs having different structures and perform similar functions.

e) Saltation:
Single step large mutations is called Saltation.

Question 30.
List out the harmful effects caused by Alcohol / Drug abuses.
Answer:
The harmful effects of alcohol or drug abuse are as follows:

• The immediate adverse effects of drugs and alcohol abuse are manifested in the form of reckless behavior, vandalism and violence,
• In case of excessive doses of drugs coma and death may results due to respiratory failure, heart failure or cerebral hemorrhage.
• Drop in academic performance, lack of interest in personal hygiene, withdrawal, isolation, depression, fatigue, aggressive and rebellious behavior, deteriorating relationship with family and friends, lack of interest in hobbies, change in sleeping and eating habits, fluctuations in weight, appetite etc.
• If an abuser is unable to get money to buy drugs or alcohol he or she may turn to stealing, alcohol and drug addiction becomes the cause of mental and financial distress to his or her family or friends. .
• Sharing of infected needles and syringes during intravenous administration of drugs is responsible for spread of infections like AIDS, Hepatitis B from person to person.
• The chronic use of drugs and alcohol damages nervous system and causes liver cirrhosis, use of drugs or alcohol during pregnancy adversely affect the foetus.
• The misuse of an abolic steroids, narcotics, analgesics, diuretics and certain hormones used by sports persons to enhance their performance results in serious ill effects. In females, it leads to masculinisation (features like males) increased aggressiveness, mood swings, depression, abnormal menstrual cycles, excessive hair growth on the face and body, enlargement of clitoris, deepening of voice etc.

In males it causes acne increased aggressiveness, mood swings, depression, reduction in the size of testicles, decreased sperm production, kidney and liver dysfunction, breast enlargement, premature baldness , enlargement of prostate gland, etc.

Question 31.
a) How do Multiple Ovulation and Embryo Transfer (MOET) technology helps in increasing the herd size?
Answer:

• In this method, a cow is administered hormones, with FSH – like activity, to induce follicular maturation and super ovulation – instead of one egg, which they normally yield per cycle, they produce 6-8 eggs.
• The animal is either mated with an elite bull or aritificially inseminated.
• The fertilised eggs at 8 – 32 cells stages, are recovered non surgically and transferred to surrogate mothers.
• The genetic mother is available for another round of super ovulation.

b) Mention any two microbes as a source of single cell protein.
Answer:

1. Spirulina
2. Methyl philous methylotrophus.

Question 32.
Give an account of microbes used as Biofertilizers.
Answer:

• Biofertilisers are organisms that enrich the nutrient quality of the soil.
• The main sources of the biofertilisers are bacteria, fungi, cyanobacteria.
• The Rhizobium bacteria form nodules on the roots of legume plants and they fix atmospheric Nitrogen into organic forms, which is used by the plant as nutrient.
• Fungi are known to form symbiotic associations with plants. The fungal symbiont.

Section – II

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

Question 33.
Draw a labelled diagram of anatropous OVULE of angiosperm
Answer:

Question 34.
Give a schematic representation of Spermatogenesis
Answer:

Question 35.
List out the uses of Genetically Modified Plants.
Answer:

• Made crops more tot- ant 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, eg., Vitamin, ‘A’ enriched rice.

Question 36.
Mention five population interaction with an example each Population Interaction Example
Answer:
1. Mutualism
Example: Mycyorrhiza / lichens / Ophyris and wasp Orchid grown o eipiphyt / Barnacles growing

2. Commensalism
Example: on back of whales / cattle egret and grazing cattle

3. Parasitism
Example: Lice on humans / Ticks on dogs / Cuscuta on plants

4. Predation
Example: Herbivores feed on plants / Sparrow eating any seed / starfish pisaster

5. Competition
Example: South American lakes visiting flamingoes and resident fishes / Superior Barancle and small Branancle

Question 37.
Give a schematic representation of Nitrogen Cycle.
Answer: