Solved question paper for Biology Mar-2018 (PSEB 12th)

Biology

Previous year question paper with solutions for Biology Mar-2018

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Question paper 1

1. Gentic disorder due to trisomy of chromosome 21 in humans is

(a) Down's Syndrome

(b) Turner's Syndrome

(b) Klinfelter's Syndrome

(d) None of the above

Answer:
(a) Down's Syndrome
2. Photochemical smog contains

(a) PAN

(b) Nitrogen Dioxide

(c) Ozone

(d) All of the above

Answer:
(d) All of the above
3. What is Menarche ?

Answer:
The first menstruation begins at puberty and is called menarche.
4. Name the Bacteria which acts as Natural Genetic Engineer.

Answer:
Agrobacterium tumefaciens.
5. HIV decreases natural immunity of the body by destroying

(a) Erythrocytes

(b) T-Lymphocytes

(c) Antibodies

(d) B-Lymphocyres

Answer:
(b) T-Lymphocytes
6. What are Sciophyres ?

Answer:
Sciophytes are the shade loving trees or plants. These plants have larger photosynthetic units than sun plants. They reach their saturation level in only 20% sunlight
7. Vegitative propation in onion occurs by

(a) Offset

(b) Bulb

(c) sucker

(d)Rhizome

Answer:
(b)Bulb.
8. Define pleiotropy

Answer:
The multiple effect of a gene is called pleiotropy
9. What is the role of Ori for cloning vector

Answer:
- Ori stands for origin of replications.
- It is a sequence from where replication starts.
- It is a specific position of plasmid genome that serves as a start signal for self-replication.
- It is desirable that cloning of target DNA should be carried out in such a vector where origin facilitates a high copy number.
10. Briefly explain the ecologicar pyramid which is always upright

Answer:
The pyramid of energy is always upright. Pyramid of energy is a graphical representation amount of accumulated energy per unit area at different trophic levels in a food chain.
11. What is meant by emasculation ? How is it useful in plant breeding programme?

Answer:
Emasculation:Removal of stamens or anthers or killing the pollen grains of a flower without affecting the female reproductive organs is called emasculation.

Uses:
- It is essential in bisexual flowers to prevent self-pollination.
- By practicing emasculation, the plant breeder makes a female flower which can be artificially pollinated by the desired pollen grains.
12. what do you mean by incomplete dominance ? Give example.

Answer:
The expression of the traits of two pure parents as an intermediate condition or fine mixture in the F1 hybrids is known as incomplete or partial dominance. It is also called blended or intermediate or mosaic inheritance.

FOR EXAMPLE:-

Parents.

Phenotype:   pure red flower      *      pure white flower

Genotype:      RR                                        WW

Gametes: R R                                         W W

F1 gen:-

R R

RW

RW

RW

RW

W

W

Genotypic ratio:   RW : RW : RW : RW

1   :   1   : 1    : 1

Phenotype =>All hybrids pink.

F2 gen:- (self-cross)

R W

RR

RW

RW

WW

R

W

Genotypic ratio:- RR : RW : RW : WW.

1 :      2          : 1

Phenotype:- pure red : hybrid pink : pure white.
13. Briefly write about Biopiracy.

Answer:
Bio piracy is the robbery or stealing of biological and genetic resources which are indigenous to a particular country.

Its main impacts are:-
- Bio piracy by western corporations robs intellectual contributions of another country and wealth, hence creating intellectual poverty.
- Bio pirates steal certain useful biological material for their enrichment.
14. Name any one symbiotic nitrogen fixing bacteria. How does it help in nitrogen fixation ?

Answer:
Rhizobium bacteria show symbiotic association with the roots of leguminous plants.
- This bacteria fails to fix atmospheric nitrogen in its free state. It is present inside soil in free state. It multiplies when multiplies when it enters the roots of surrounding areas ie rhizosphere.
- When the plant dies, the fixed nitrogen is released, making it available to other plants. This helps to fertilize the soil.
15. "Liver suffers most from excessive drinking". Discuss on the statement.

Answer:
The effects of alcohol on the liver :-
- In the liver alcohol is converted into a more toxic substance, acetaldehyde.
- Liver synthesizes fats from alcohol. The excess fats reduce formation of glycogen enzymes and structural proteins.
- Thus the liver changes from being an important centre of carbohydrate, fat and protein metabolism to a mere store house of fat. This causes fatty liver syndrome.
16. A man with blood group A marries a woman with blood group B. What will be the genotype of man and woman if one of their child is born with blood group O ? Show the type of progeny formed with help of Punnett square.

Answer:
17. Define phenotypic adaptation.Also give one example

Answer:
Phenotypic adaptation:- Non genetic change in an individual is called phenotypic adaptation. Phenotypic adaptation involves changes in the body of an organism in response to a genetic mutation or certain environmental changes. These responsive adjustments occur in order to cope with environmental conditions present in their natural habitats.

For example:-
- Morphological and physiological adaptations.
Animals with constant body temperature called homeotherms have an insulation layer to prevent loss of body heat. This layer consists of hair in most mammals, blubber in whales and seals and feathers in birds.

Shivering warms up the body and perspiration or panting cools down the body of these animals when required. These are also called endotherms.
- Behavioural adaptations:-
The animals with variable temperature called poikilotherms are affected by temperature variations more than homeotherms.

They are also called ectotherms (cold-blooded animals). Their body temperature varies with environmental temperature in which they live. They fight temperature variation in the following manner.
1. Hibernation:- insects, molluscs, amphibians, reptiles and even some mammals escape cold by hiding in frost free shelters such caves, burrows, crevices, hollow tree trunks and mud. It is also known as winter sleep.
2. Aestivation:- several insects, certain spiders, molluscs, fish, reptiles and mammals living in hot and dry regions undergo aestivation. It is also known as summer sleep.
3. Winter eggs:- in some animals, adults die as winter approaches race is maintained by means of “winter eggs” which can withstand the coldweather.
18. Explain any two methods for introduction of recombinant DNA into host cell.

Answer:
1. Particle bombardment gun method:-
This method was first developed by prof. Stanford and co-workers at Cornell University, USA in 1987. The technique involves shooting foreign DNA into plant cells at a very high velocity. This method is also known as biolistic technique.

In this method, a 1-2μm gold or tungsten particles coated with DNA are shot into plant cells using a helium pressure particle gun device.

Important crops and plants like wheat, rice and maize have now been transformed by this method.
1. Micro injection:- in this method, the DNA solution is injected directly inside the cell using capillary glass micropipettes or a micro syringe. This technique was originally used in animal cells but is now applied to plant cells also. However, the method of injection requires great technical skill because many cells die during the process.
19. What is Human genome project ? Briefly write about the salient features of Human Genome project

Answer:
Human genome project is a comprehensive international effort that started in the year 1990 by molecular biologists to develop ways of mapping human genome to a finer level.
- It was developed to store this information on a database and tools for development and for data analysis.
- To note the ethical, social and legal issues of this project.
- HGP consists of approximately three billion base pairs(3*10bp), and if the cost of sequencing a single base pair required about US $3, then the overall expenditure was estimated to be approximately 9 billion US dollars to complete this project.
- If the data is to be stored in books with each book having 1000 pages and each page having 1000 letters, 3300 books would be required. Therefore, this project is also known as human mega project.
SALIENT FEATURES OF HUMAN GENOME:-
- The total number of nucleotide bases present in the human genome is 3164.7 million.
- The average gene has 3000 bases, but their sizes vary greatly. The largest human gene is dystrophin, which contains 2.4 million bases.
- The total number of genes contained in a human genome is about 30,000. Earlier this number was thought to be 80,000 to 1,40,000 genes.
- The maximum number of genes 2968 are found in chromosome I whereas minimum number 231 are found in Y-chromosome of human genome.
- Almost all nucleotide bases are exactly the same in all human beings.
- Functions of more than 50% of the discovered genes are not known.
20. In case of an infertile couple male has abnormally low sperm count in ejaculation' Also female has blocked oviducts and has spermicidal secretions in vagina but can provide suitable environment for development of embryo. Suggest and explain the assisted reproductvie technology (ART) useful to this couple

Answer:
Test tube baby programme:- This method involves in vitro fertilisation (IVF) ie fertilisation of male gamete (spermatozoa) and female gamete (ovum) outside the body in almost similar conditions as that in the body followed by zygote or embryo transfer (ET).
1. Test tube baby:-in some women, normal conception is not possible because of blocked oviducts or spermicidal secretions in the vagina or low sperm count of the husband. There are also cases where women can’t produce ova or men can’t produce sperms.
In all such cases, ovum from the wife/donor female is removed surgically after hormonal stimulation of the follicles.

It is then fertilized by her husband’s/male donor’s sperm in a laboratory dish containing a nutrient bath.
1. ZIFT:- Hear the zygote or early embryo(up to 8 blastomeres stage) is transformed or transferred to the fallopian tube in a process called zygote intra fallopian transfer or embryo with more than 8 blastomeres is transferred to the uterus in a process called inter uterine transfer or IUT to complete further development of zygote or embryo.
With proper medical care, the mother will give birth to a normal child upon completion of gestation period.

Success rate of test tube babies:-

The success rate of the technique of producing test tube babies is less than 20%. To increase chances of success, the prospective mother is given fertility drugs which cause many ovarian follicles to mature at the same time. This releases many eggs simultaneously thereby increasing chances of success.
21. Briefly discuss

(a) Biofortification

(b)Role of microbes in household food processing

Answer:
1. Biofortification:- is a plant breeding program designed to increase vitamins, minerals, higher protein and healthier fat content in crop production.
Many crop varieties such as
- vitamin A enriched carrots, spinach, pumpkin;
- Vitamin C enriched tomato;
- Iron and Calcium enriched spinach and bathua have been released by the Indian Agricultural Research institute, New Delhi.
1. Role of microbes in household food processing
1. Curd – lactobacillus bulgaricus.
2. Dough – streptococcus faecalis.
3. Cheese (Types).
Cottage cheese.

– Streptococcus lactis.

- Propionibacterium shermanii.

Roquefort cheese.

- Penicillium roqueforti.
1. Baker’s yeast – Saccharomyces cerevisiae.
2. Sausage – Lactic acid bacteria.
22. Write about cause, symptoms and modes of transmission of Amoebiasis.

Answer:
Causing agent:- Entamoeba histolytica.
- Symptoms:- Severe griping pain in the abdomen.
- Fever
- Nausea and exhaustion
- Nervousness
Mode of transmission:-

Infection is caused by injecting cysts which may occur in food and drinks prepared in unhygienic conditions.

OR

(a) Write any two points of difference between B-Lymphocytes and T: Lymphocytes.

Answer:

B-lymphocytes	T-lymphocytes
B-cells form humoral or antibody – mediated immune system (AMIS).	T-cells form cell mediated immune system (CMIS).
They are differentiated in gut-associated bursal lymphoid tissues.	They are differentiated in the thymus gland.
They are formed by division of plasma cells.	They are formed by division of lymphoblast of three types: killer, helper and suppressor cells
Plasma cells do not move to the site of infection.	Lymphoblasts move to the site of infection.
Plasma cells have no inhibitory role on the immune system.	Suppressor cells inhibit the immune system.

(b) What are the different causes of cancer?

Answer:
Cancer is the uncontrolled division and growth of cells.

Causes:-
- Exposure to radiation like X-rays, gamma rays etc.
- Chemical agents like caffeine, heavy metallic ions etc.
- Cigarette and cigar tobacco smoking causes lip, mouth and lung cancer.
- Jagged teeth may cause tongue cancer.
23. Expand PCR. How it helps in the amplification of the gene of interest?

Answer:
or

What do you mean by GM organisms? Mention any three advantages of GM organisms'

Answer:
24. What is the ecosystem? Discuss its different components with a specific example of a pond as an ecosystem.?

Answer:
or

Describe various causes of loss of biodiversity'

Answer:
25. What is fertilization? In which part of the Human female reproductive system does it occur? Explain diagrammatically various physical and chemical events of fertilization in humans.

Answer:
or

Explain the development of female gametophyte in angiosperms. Illustrate the answer with suitable diagrams.

Answer:
26. Define DNA Replication. In which phase of the cell cycle does replication occur in Eukaryotes? "Describe briefly theme mechanism of DNA

Answer:
or

(a) Give an example of Connecting Link

(b) What is divergent evolution ? Give example

(c)State and explain Hardy Weinberg's Principle'

Answer:

Question paper 2

1. What are Sciophytes ?

Answer:

2. Genetic disorder due to trisomy of chromosome 21 in humans is

(a) Down's Syndrome (b) Klinfelter's Syndrome

(c) Turner's Syndrome (d) None of the above

Answer:
3. Photochemical smog contains

(a) PAN (c) Nitrogen dioxide

(b) Ozone (d) All of the above

Answer:
4. What is Menarche ?

Answer:

5. Name the Bacteria which acts as Natural Genetic Engineer.

Answer:

6. Vegetative propagation in onion occurs by

(a) Offset (b) Bulb

(c) Sucker (d) Rhizome

Answer:
7. Define Pleiotropy.

Answer:

8. HIV decreases natural immunity of the body by destroying

(a) Erythrocytes (b) Antibodies

(c) T-Lymphocytes (d) B-Lymphocytes

Answer:
9. Name any one symbiotic nitrogen fixing bacteria. How does it help in nitrogen fixation ?

Answer:

10. What is the role of Ori for cloning vector?

Answer:

11. Briefly explain the ecological pyramid which is always upright.

Answer:

12. What is meant by emasculation ? How is it useful in plant breeding programme?

Answer:

14. “Liver suffers most from excessive drinking”. Discuss on the statement

Answer:
16. Briefly write about Biopiracy

Answer:

17. Briefly discuss

(a) Biofortification

(b) Role of microbes in household food processing.

Answer:
18. Define phenotypic adaptation. Also give one example

Answer:

19. In case of an infertile couple male has abnormally low sperm count in ejaculation. Also female has blocked oviducts and has spermicidal secretions in vagina but can provide suitable environment for development of embryo. Suggest and explain the assisted reproductvie technology (ART) useful to this couple

Answer:
20. What is Human genome project? Briefly write about the salient features of Human
Genome project.

Answer:

21. Explain any two methods for introduction of recombinant DNA into host cell.

Answer:
22. Expand PCR. How it helps in amplification of gene of interest?

OR

Answer:
What do you mean by GM organisms ? Mention any three advantages of GM organisms.

Answer:
23. Write about cause, symptoms and modes of transmission of Amoebiasis.

OR

Answer:

(a) Write any two points of difference between B-Lymphocytes and T-Lymphocytes.

Answer:
(b) What are different causes of cancer?

Answer:
24. Define DNA Replication. In which phase of cell cycle does replication occur in

Eukaryotes? Describe briefly the mechanism of DNA replication.

OR

Answer:

(a) Give an example of Connecting Link

(b) What is divergent evolution ? Give example.

(c) State and explain Hardy Weinberg's Principle

Answer:
25. What is ecosystem ? Discuss its different components with specific example of pond as An ecosystem
OR

Answer:
Describe various causes of loss of biodiversity.

Answer:

26. Explain the development of female gametophyte in angiosperms. Illustrate the answer with suitable diagrams

Answer:

OR

What is fertilization? In which part of Human female reproductive system does it occurs ?
Explain diagrammatically various physical and chemical events of fertilization in humans.

Answer:

1. What is Menarche ?

Answer:
2. Define Pleiotropy.

Answer:
3. Name the Bacteria which acts as Natural Genetic Engineer.

Answer:
4. What are Sciophytes ?

Answer:
6. Genetic disorder due to trisomy of chromosome 21 in humans is

(a) Down's Syndrome (b) Klinfelter's Syndrome

(c) Turner's Syndrome (d) None of the above

Answer:
7. HIV decreases natural immunity of the body by destroying

(a) Erythrocytes (b) Antibodies

(c)T-Lymphocytes (d) B-Lymphocytes

Answer:
8. Photochemical smog contains

(a) PAN (b) Ozone

(c) Nitrogen dioxide (d) All of the above

Answer:
10. Aman with blood group A marries a woman with blood group B. What will be the genotype of man and woman if one of their child is born with blood group O ? Show the type of progeny formed with help of Punnett square.

Answer:
11. What do you mean by incomplete dominance ? Give example.

Answer:
12. Name any one symbiotic nitrogen fixing bacteria. How does it help in nitrogen fixation ?

Answer:
13. “Liver suffers most from excessive drinking”. Discuss on the statement.

Answer:
14. What is the role of Ori for cloning vector ?

Answer:
15. Briefly write about Biopiracy

Answer:
16. Briefly explain the ecological pyramid which is always upright.

Answer:
17. In case of an infertile couple male has abnormally low sperm count in ejaculation. Also Female has blocked oviducts and has spermicidal secretions in vagina but can provide suitable environment for development of embryo. Suggest and explain the assisted reproductvie technology (ART) useful to this couple.

Answer:
18. What is Human genome project ? Briefly write about the salient features of Human
Genome project.

Answer:
19. Briefly discuss
(a) Biofortifications (b) Role of microbes in household food processing

Answer:
20. Explain any two methods for introduction of recombinant DNA into host cell.

Answer:
21. Define phenotypic adaptation. Also give one example.

Answer:
22. Write about cause, symptoms and modes of transmission of Amoebiasis. or

Answer:
(a) Write any two points of difference between B-Lymphocytes and T-Lymphocytes.

(b) What are different causes of cancer?

Answer:
23. Expand PCR. How it helps in amplification of gene of interest ?

or

Answer:
What do you mean by GM organisms ? Mention any three advantages of GM organisms

Answer:
24. Explain the development of female gametophyte in angiosperms. Illustrate the answer with suitable diagrams. or

Answer:
What is fertilization ? In which part of Human female reproductive system does it occurs
? Explain diagrammatically various physical and chemical events of fertilization in humans.

Answer:
25. Define DNA Replication. In which phase of cell cycle does replication occur in
Eukaryotes ? Describe briefly the mechanism of DNA replication.

Answer:
or
(a) Give an example of Connecting Link
(b) What is divergent evolution ? Give example.
(c) State and explain Hardy Weinberg's Principle.

Answer:
26. What is ecosystem ? Discuss its different components with specific example of pond as an ecosystem

Answer:
or
Describe various causes of loss of biodiversity.

Answer:

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Solved question paper for Biology Mar-2018 (PSEB 12th)

Biology

Previous year question paper with solutions for Biology Mar-2018

These Questions are downloaded from www.brpaper.com You can also download previous years question papers of 10th and 12th (PSEB & CBSE), B-Tech, Diploma, BBA, BCA, MBA, MCA, M-Tech, PGDCA, B-Com, BSc-IT, MSC-IT.

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