CBSE Class 12 Biology Sample Paper Set-10


CBSE Class 12 Biology
Sample Paper
Set-10


CBSE Sample Papers for Class 12 Biology Solved 2016 Set 10

Section A

1.Opuntia is often termed as Xerophytic plants. Comment.

2. Name the two components of an ecosystem with examples.

3.Zygote begin to divide only after the division of primary endosperm cell (PEC).Justify.

4. Why bottled fruit juices appear clearer?

5. Which is the most commonly used as a medium/matrix in gel electrophoresis?

Section B

6.In what way you can determine the age of any rock? Discuss.

7.Why emasculation is not required in unisexual flowers?

8.Rachit suggested his friends father that the chemicals that they uses for agriculture often harm our environment. In such way they can use microbes in place of them. Discuss the role of microbes in reducing environmental degradation.

9.Draw a diagrammatic sketch of a biogas plant labelling its various components such as sludge chamber, digester, gas holder, dung water chamber.

10.Fertilisation does not acts as a compulsory event in all plants for the fruit production. Comment.

Section C

11.Given below are the events that are observe in an artificial hybridisation programme.Arrange them in the correct sequential order in which they are followed in the hybridisation programme.Rebagging, Bagging, selection of parents, Dusting the pollen on stigma, emasculation, collection of pollen from male parent.

12.Recombinant DNA vaccine has been confirmed as an important tool for the research and in the treatment of many diseases. Justify its role, method of production, utility. Also give two common examples.

13.Reproductive and child health care programme is under action. It helds a seminar in your locality for creating awareness. Explain the roles played by the following in controlling reproduction and its related issues.
(i)Role of government and NGOs.
(ii)Role of local people.

14.(i) Identity the type of RNA out of three having the shape of the clover leaf in two
dimensional structure.
(ii)Draw the diagram of the process of transcription in eukaryotes.

15.LAB plays an important part in the life of human beings. Discuss its role in detail.
Or
Microbes are able to survive in extremely harsh conditions when compared to other organism. Justify with the help of examples.

16.Discuss the latest methods of detection of cancer.

17.Give three differences between plasmid DNA and chromosomal DNA.

18.Bacterium Thermus aquaticus has been employed in recombinant DNA technology and has lead to many benefits. How can you prove this statement?

19.In what way co-extinction acts as the one of the cause of biodiversity loss? Explain giving one example, List the other three causes also.

20.Name the pathogen which causes chikungunya. How it is transmitted to a healthy person? Also give some of its preventive measures.

21.The traits are known to get inherited through generations. This fact was proved by principles of law of inheritance been proposed by Gregor Mendel in 1865. However, Mendel did not discovered these principles of inheritance by studying human beings, then how his principles are applied in case of humans?

22.(i) How does analogous organs support the theory of organic evolution? Explain.
(ii)Elucidate the phenomenon of homologous organs with one example of an organ homologous to the hand of man.

Section D

23.While explaining the global warming, teacher make a remark that “It is the serious most threat to civilisation now” Kalpana gets curious about the various aspects of global warming and asks some question to her teacher.
(i)What is global warming?
(ii)What are various cause of global warming?
(iii)What values are shown by Kalpana as environmentalist?

Section E

24.(i) Write the differences between spermatogenesis and oogensis.
(ii) Give schematic representation of spermatogenesis and oogenesis.
Or
Describe the functions of the following
(i)Epididymis
(ii)Vas deferens
(iii)Seminiferous tubules
(iv)Vagina
(v)Trophoblast
CBSE Sample Papers for Class 12 Biology Solved 2016 Set 10

25.(i) How does a chromosomal disorder differ from a Mendelian disorder?
(ii)Name two chromosomal aberrations-associated disorders.
(iii)List the characteristics of the disorders mentioned above that help in their diagnosis.
Or
Explain the causes, inheritance pattern, symptoms of two Mendelian genetic disorders.

26.What measures as an individual would you take to reduce environmental pollution?
Or
(i)What do you understand by the terms slash and burn cultivation?q
(ii)What was Montreal protocol?

Answers

Section A

1.Opuntia is often termed as Xerophytic plants. Comment.
Ans.Opuntiais termed as xerophytic plant a desert plant because roots of this type plants grows very deep to explore any possibility of available underground water. It has no leaves and often reduced to spines. The process of photosynthesis occurs in flattened stems in this.

2. Name the two components of an ecosystem with examples.
Ans.Two components of ecosystems are biotic components (flora and fauna) and abioticq
components (light, wind, water, temperature and soil).

3.Zygote begin to divide only after the division of primary endosperm cell (PEC).Justify.
Ans.It happens in a way because a zygote often needs a nourishment during its development.As the cell matures, fertilised embryosac offers little nourishment to the zygote. So, the primary endosperm cell divides and generates the endosperm tissue which nourishes zygote.

4. Why bottled fruit juices appear clearer?
Ans.Bottled fruit juices contain pectinase and protease. Thus, due to the action of these enzymes,bottled juices appear clearer.

5. Which is the most commonly used as a medium/matrix in gel electrophoresis?
Ans.Agarose is the most commonly used matrix. It is a natural linear polymer of D-galactose and3, 6 – anhydro – L- galactose which is extracted from sea weeds.

Section B

6.In what way you can determine the age of any rock? Discuss.
Ans.Age of rocks and fossils in number of years can be easily determined by the scientists through radiometric age dating, a technique used to date materials such as rocks or carbon, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products.

7.Why emasculation is not required in unisexual flowers?
Ans.Emasculation is not needed in unisexual flowers because the female flowers are bagged before the flowers open. When the stigma becomes receptive, pollination is carried out using the desired pollen and the flowers are rebagged.

8.Rachit suggested his friends father that the chemicals that they uses for agriculture often harm our environment. In such way they can use microbes in place of them. Discuss the role of microbes in reducing environmental degradation.
Ans.Synthetic and unnatural chemicals such as pesticides, herbicides and other organic compounds when used remains as such in the atmoshphere for number of years, thus, causing the environmental degradation. In place of this if microbes transform the complex organic substances into relatively simpler, non-toxic substances by the process of bioremediation the microbes also removes the environmental pollutants found in water, soil and air.

9.Draw a diagrammatic sketch of a biogas plant labelling its various components such as sludge chamber, digester, gas holder, dung water chamber.
Ans.
CBSE Sample Papers for Class 12 Biology Solved 2016 Set 10

10.Fertilisation does not acts as a compulsory event in all plants for the fruit production. Comment.
Ans.Fertilisation does not acts as a compulsory process for all plants for the production of fruit.Fruits that are formed without fertilisation are called parthenocarpic fruits. These do not have seeds, e.g. banana.

Section C

11.Given below are the events that are observe in an artificial hybridisation programme.Arrange them in the correct sequential order in which they are followed in the hybridisation programme.Rebagging, Bagging, selection of parents, Dusting the pollen on stigma, emasculation, collection of pollen from male parent.
Ans.The correct sequential order of the events shown in artificial hybridisation are Selection of parents —> Emasculation (i.e. removal of anthers from the flower bud before anther dehisces)—> Bagging (i.e. process of covering the emasculated flower with a bag made up of butter paper)—> Collection of pollen from the male parent— Dusting of pollen on stigma —> Rebagging.

12.Recombinant DNA vaccine has been confirmed as an important tool for the research and in the treatment of many diseases. Justify its role, method of production, utility. Also give two common examples.
Ans.Like all other techniques of biotechnology this recombinant DNA vaccine has also influenced the life of human beings. It is either produced by using genetically engineered plasmids. They have gene inserts for the surface proteins of a pathogen that elicit immunity but do not result in infection. These plasmids are inserted in bacteria or yeast cells that express the viral proteins which are then injected into the human host as vaccine. There they are recognised as foreign and an immune response is elicited. Recombinant DNA vaccine is used for treating diseases such as vaccinia virus, hepatitis B, polio etc. Example Recombinant hepatitis-B vaccine and polio vaccine are the examples of recombinant DNA vaccine.

13.Reproductive and child health care programme is under action. It helds a seminar in your locality for creating awareness. Explain the roles played by the following in controlling reproduction and its related issues.
(i)Role of government and NGOs.
(ii)Role of local people.
Ans.(i) Role of Government and NGOs
(a)Effective implementation of different programmes.
(b)Population controlling measures to be implemented effectively.
(c)With the help of audio visual and the print media, governmental and non- governmental agencies can take various steps to create awareness.
(ii) Role of Local People
(a)Parents, teachers and friends play a very important role in the dissemination of information about reproduction related information.
(b)Introduction of sex education in schools in the adolescent age group should be encouraged.
(c)Educating people, especially fertile couples those in marriageable age group about available birth control options, care of pregnant mothers, post-natal care of the mother and child.

14.(i) Identity the type of RNA out of three having the shape of the clover leaf in two
dimensional structure.
(ii)Draw the diagram of the process of transcription in eukaryotes.
Ans.(i) ?RNA has the shape of clover leaf.
(ii) Process of transcription in eukaryotes is as follows
CBSE Sample Papers for Class 12 Biology Solved 2016 Set 10

15.LAB plays an important part in the life of human beings. Discuss its role in detail.
Or
Microbes are able to survive in extremely harsh conditions when compared to other organism. Justify with the help of examples.
Ans.Function of LABq Lactobacillus bacteria (Lactic acid bacteria) are
(i)During growth, the LAB produce acids that coagulate and partially digestthe milk proteins.
(ii)Helps in conversion of curd.
(iii)It also improves its nutritional quality by increasing vitamin-B12.
(iv)In our stomach, LAB play beneficial role in checking disease causing microbes.
Or
Microbes adapt to extreme and harsh conditions by some adaptation given below e.g.
(i)The bacteria forms an endospore, which is a very tough structure. Therefore, they keep themselves safe in harsh conditions.
(ii)Some bacteria form spores which spores are extremely resistant to harsh chemical conditions and heat. They are dormant, so they do not require any food.
(iii)Microbes adapt themselves to extreme cold and high pressure by accumulating the polymers called polyphosphates. They may also adapt by forming symbiotic relationship with other organisms.

16.Discuss the latest methods of detection of cancer.
Ans.Latest methods for cancer detection are
(i)Biopsy A piece of suspected tissue cut into thin sections is stained and examined under microscope (histopathological studies) by a pathologist.q
(ii)Computed Tomography Uses X-rays to generate a 3-dimensional image inside the tissue to be detected.
(iii)Monoclonal antibodies against cancer-specific antigens are also used for cancer detection.q

17.Give three differences between plasmid DNA and chromosomal DNA.
Ans.Differences between plasmid DNA and chromosomal DNA
CBSE Sample Papers for Class 12 Biology Solved 2016 Set 10

18.Bacterium Thermus aquaticus has been employed in recombinant DNA technology and has lead to many benefits. How can you prove this statement?
Ans.Therm us aquaticus, a bacterium yields that DNA polymerase as employed in recombinant DNA technology in the following ways
(i)This enzyme remains active during the high temperature applied during denaturation of double-stranded DNA.
(ii)It extends the primers using the nucleotides provided in the reaction and the genomic DNA as template.
(iii)Repeated amplification is achieved by this enzyme. The fragments thus amplified if desired can be used to ligate with a vector for further cloning.

19.In what way co-extinction acts as the one of the cause of biodiversity loss? Explain giving one example, List the other three causes also.
Ans.Co-extinction refers to the indirect extinction of a species as a result of the extinction of another species on which the first one was dependent. Co-extinctions occur due to inter-connectedness of organisms.
For example, extinction of a type of Hibiscus due to extinction of its pollinator species, like honey creeper bird. Other causes of biodiversity loss are over exploitation, alien species invasion, loss and fragmentation of habitat etc.

20.Name the pathogen which causes chikungunya. How it is transmitted to a healthy person? Also give some of its preventive measures.
Ans.Chikungunya is caused by the chikungunya virus. It is transmitted to a healthy person by the bite of Aedes aegypti mosquito.
Chikungunya can be prevented by the following measures.
(i)By elimination of mosquitoes and their eggs.
(ii)By taking bed rest and taking adequate amount of fluid.

21.The traits are known to get inherited through generations. This fact was proved by principles of law of inheritance been proposed by Gregor Mendel in 1865. However, Mendel did not discovered these principles of inheritance by studying human beings, then how his principles are applied in case of humans?
Ans.Mendel performed his experiments on pea plant, e., Pisum sativum.After eight years of tedious experiments with pea plants, he proposed three fundamental principles of inheritance. These principles eventually assisted clinicians in human disease research. For example, after a few years of the discovery of Mendel’s work Archibald Garrod applied Mendel’s principles to his study of alkeptonuria. Today, whether we talk about pea plants or humans, genetic traits that follow the rules of inheritance that Mendel proposed are called Mendelian principles.

22.(i) How does analogous organs support the theory of organic evolution? Explain.
(ii)Elucidate the phenomenon of homologous organs with one example of an organ homologous to the hand of man.
Ans.(i) Analogous organs have different developmental origin and structural design but perform similar function. For example, the wings of birds and insects are analogous organs indicating that they have different ancestors but have a convergent evolution.
(ii) Flomologous organs are with same structural designs and developmental origin but differ in their functions. Forelimb of human being is homologous to the forelimbs of whales and bats.

Section D

23.While explaining the global warming, teacher make a remark that “It is the serious most threat to civilisation now” Kalpana gets curious about the various aspects of global warming and asks some question to her teacher.
(i)What is global warming?
(ii)What are various cause of global warming?
(iii)What values are shown by Kalpana as environmentalist?
Ans.(i) The gradual continuous increase in average temperature of surface of the earth, is called global warming.
(ii)Various causes of global warming are
(iii)FHigh level of green house gases in the atmosphere.
(iv)Rise in atmospheric temperature.
(v)Kalpana was curious to know about her nature. She also wants to spread awareness among the people.

Section E

24.(i) Write the differences between spermatogenesis and oogensis.
(ii) Give schematic representation of spermatogenesis and oogenesis.
Or
Describe the functions of the following
(i)Epididymis
(ii)Vas deferens
(iii)Seminiferous tubules
(iv)Vagina
(v)Trophoblast
Ans.Differences between Spermatogenesis and Oogenesis are as follows
CBSE Sample Papers for Class 12 Biology Solved 2016 Set 10
CBSE Sample Papers for Class 12 Biology Solved 2016 Set 10
CBSE Sample Papers for Class 12 Biology Solved 2016 Set 10
Or
(i)Epididymis Maturation of spermatids to functional spermatozoa takes place here and the sperms are stored temporarily till ejaculation.q
(ii)Vas Deferens It stores and transports the sperms from the tests to the outside through urethra.
(iii)Seminiferous Tubules Sperms are produced here by the process of spermatogenesis.
(iv)Vagina It receives the semen from the male penis. It serves as the birth canal during parturation.
(v)Trophoblast It is the inner layer of blastocyst, which sends finger-like projections calledq chorionic villi into uterine stroma. Chorionic villi and uterine tissues jointly form the placenta.

25.(i) How does a chromosomal disorder differ from a Mendelian disorder?
(ii)Name two chromosomal aberrations-associated disorders.
(iii)List the characteristics of the disorders mentioned above that help in their diagnosis.
Or
Explain the causes, inheritance pattern, symptoms of two Mendelian genetic disorders.
Ans.(i)Differences between Mendelian and Chromosomal disorders are
CBSE Sample Papers for Class 12 Biology Solved 2016 Set 10
(ii)Two chromosmal aberration associated disorders are Turner’s syndrome and Down’s syndrome.
(a) Tunner’s Syndrome -The female are sterile with rudimentary ovaries, webbed neck, shield shaped thorax and poor development of breasts.
(b) Down’s Syndrome -Individual is short statured with small, round head, partially open mouth with protuding furrowed tongue and show mental development.
Or
Mendelian genetic disorders are deternined by alteration or mutation in the single gene. These are transmitted into next generation according to the principle of inheritance and can be studied by pedigree analysis.
Causes, inheritance pattern and symptoms of two Mendelian disorders are given below
(i) Haemophillia It is a sex-linked recessive disease, which transmits from an unaffected Carrier female to some of the male offspring. It is caused by the defect in one of the genes (located on X-chromosome) that determine how the body makes blood clotting factor VIII or IX.
CBSE Sample Papers for Class 12 Biology Solved 2016 Set 10
Symptoms Prolonged bleeding after even a minor cut are the major diagnostic symptoms of haemophillia due to which person may die of blood loss.
(ii) Sickle-cell anaemia It is an autosomal linked recessive trait that can be transmitted when both parents are carriers of the gene. It is caused by the substitution of amino acid glutamic acid by valine at the sixth positions of the beta globin chain of the haemoglobin molecule.
CBSE Sample Papers for Class 12 Biology Solved 2016 Set 10
Symptoms Most common symptoms is fatigue (feeling of tiredness and weakness). Other symptoms include shortness of breath, headache, coldness in hands and feet. Jaundice, paler than normal skin or mucous membrane, it is to be noted that the signs of symptoms of sickle cell anaemia may vary form mild to severe ones.

26.What measures as an individual would you take to reduce environmental pollution?
Or
(i)What do you understand by the terms slash and burn cultivation?q
(ii)What was Montreal protocol?
Ans.To reduce environmental pollution, I will change my habits and lifestyle so, as to reduce the use of disposable materials. I will also use preferably those items, which can easily be recycled and also will minimise the use of fossil fuels.
Following steps may be taken to reduce pollution

  • Prevention of noise pollution by using fire crackers/TV/loudspeakers at permissible limits.
  • Reduction in air pollution from automobile exhausts by using proper speed and regular servicing and using catalyst converters in vehicles.
  • No use of polythene bags.
  • Tree plantation around my residential area.
  • Minimum use of fossil fuels. (4)

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