Biology: CBSE Sample Question Paper- 3 Notes | Study Sample Papers for Class 12 Medical and Non-Medical - Class 12

Class 12: Biology: CBSE Sample Question Paper- 3 Notes | Study Sample Papers for Class 12 Medical and Non-Medical - Class 12

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 Page 1


d o n e Biology - Sample Paper-3
1) Write the central dogma of molecular biology.
Answer:
 It is unidirectional flow of information DNA to mRNA and then decoding the information
present in mRNA in the formation of polypeptide chain or protein.
2) What are the Okazaki fragments?
Answer:
The replication of lagging strand generates small polynucleotide fragments called' Okazaki fragments'. One strand may
synthesize a continuous strand and the other Okazaki fragments, both new strands are synthesized in the direction.
3) Why the disease filariasis is also called elephantiasis?
Answer:
Filarial worms (W. bancrofti and W. malayi) cause proliferation of endothelial cells of the wall of lymph vessels which causes
blockage of lymph vessels and swelling of certain body parts. When swelling occurs in the legs, then the legs become swollen
like those of elephants.
4) Write the two uses of PCR technique. H
Answer:
(a) PCR is now routinely used to detect HIV in suspected AIDS patients. (b) It is being used to detect mutations in gene in
suspected cancer patients.
5) HIV infection causes cellular immunodeficiency. Explain how.
Answer:
HTV attacks helper T-lymphocytes, so their number is greatly reduced. This causes severe cellular immuno deficiency because
helper T-cells stimulate the B-lymphocytes to produce antibodies.
6) Write the ratio of phenotype and genotype when a heterozygous is crossed with recessive parent?
Answer:
Phenotypic ratio: Tall       :     Dwarf
2          :           2          =1:1
Genotypic ratio: 2 Tt      :           2tt
1          :           1
7) What is immunity? Explain the types of imunity.
  
Page 2


d o n e Biology - Sample Paper-3
1) Write the central dogma of molecular biology.
Answer:
 It is unidirectional flow of information DNA to mRNA and then decoding the information
present in mRNA in the formation of polypeptide chain or protein.
2) What are the Okazaki fragments?
Answer:
The replication of lagging strand generates small polynucleotide fragments called' Okazaki fragments'. One strand may
synthesize a continuous strand and the other Okazaki fragments, both new strands are synthesized in the direction.
3) Why the disease filariasis is also called elephantiasis?
Answer:
Filarial worms (W. bancrofti and W. malayi) cause proliferation of endothelial cells of the wall of lymph vessels which causes
blockage of lymph vessels and swelling of certain body parts. When swelling occurs in the legs, then the legs become swollen
like those of elephants.
4) Write the two uses of PCR technique. H
Answer:
(a) PCR is now routinely used to detect HIV in suspected AIDS patients. (b) It is being used to detect mutations in gene in
suspected cancer patients.
5) HIV infection causes cellular immunodeficiency. Explain how.
Answer:
HTV attacks helper T-lymphocytes, so their number is greatly reduced. This causes severe cellular immuno deficiency because
helper T-cells stimulate the B-lymphocytes to produce antibodies.
6) Write the ratio of phenotype and genotype when a heterozygous is crossed with recessive parent?
Answer:
Phenotypic ratio: Tall       :     Dwarf
2          :           2          =1:1
Genotypic ratio: 2 Tt      :           2tt
1          :           1
7) What is immunity? Explain the types of imunity.
  
Animal body has the ability to resist almost all types of organisms or toxins that damage the tissues and
organs.
Immunity is of two types:
(a) Innate immunity (Inborn immunity): It is inherited from parents and protect us from birth throughout
life.
(b) Acquired immunity (Adaptive immunity): It is developed by our body in response to a disease caused by
infection of a pathogen.
8)
Describe the function of restriction enzymes. Give an example.
OR
Write any two uses of gene cloning.
Answer:
Restriction enzymes are used in genetic engineering for the construction of recombinant DNA molecules.
When cut by the same restriction enzyme, the formed DNA fragments have the same kind of 'sticky ends'
which can be joined together end to end by use of DNA-ligases.
Example: EcoRI is an endonuclease enzyme isolated from strains of E.coli and a part of restriction
modified system.
OR
Uses of gene cloning are:
(a) Genes of interest can be inserted into animals, so as to produce better farm animals.
(b) Specific proteins like insulin, hormones, interferons, vitamins can be manufactured in bacteria on an
industrial basis.
9) Why is secondary succession faster than the primary succesion?
Answer:
Secondary succession is faster than the primary sucession b:
(a) Since the soil is already there, the rate of secondary succession is much faster and takes less time for
the climax to reach.
(b) Availability of water, the environment and also the seeds or other propagules are present.
10) Describe the importance of species diversity to the ecosystem.
Answer:
Importance of species diversity to the ecosystem : Ecologists believe that communities with more species tend to be more
stable than those with less species. (ii) There is very little variation in yearly total biomass if ecosystem is rich in species
diversity. This was confirmed by David Tilman. He told that plots with increased diversity showed higher productivity.
11)
(i) Why asexual reproduction does not produce the genetic variability?
(ii) Banana is a parthenocarpic fruit whereas oranges show polyembryony. How are they different from
each other with respect to seeds?
Answer:
(i)  Asexual reproduction does not produce the genetic variability because only mitotic division occurs
during asexual reproduction.
(ii) Banana develops from an ovary without fertilization having non-viable seeds so it is called a
parthenocarpic fruit. An orange contains seeds with more than one embryo, thus it shows polyembryony.
12) What are the different types of fertilization?
Answer:
The phenomenon effusion of the male and female germ cells or gametes is called fertilization. If the fusion takes place outside
the body of the parents, as in fishes and amphibians, it is called external fertilization, on the other hand, if the fusion takes place
Page 3


d o n e Biology - Sample Paper-3
1) Write the central dogma of molecular biology.
Answer:
 It is unidirectional flow of information DNA to mRNA and then decoding the information
present in mRNA in the formation of polypeptide chain or protein.
2) What are the Okazaki fragments?
Answer:
The replication of lagging strand generates small polynucleotide fragments called' Okazaki fragments'. One strand may
synthesize a continuous strand and the other Okazaki fragments, both new strands are synthesized in the direction.
3) Why the disease filariasis is also called elephantiasis?
Answer:
Filarial worms (W. bancrofti and W. malayi) cause proliferation of endothelial cells of the wall of lymph vessels which causes
blockage of lymph vessels and swelling of certain body parts. When swelling occurs in the legs, then the legs become swollen
like those of elephants.
4) Write the two uses of PCR technique. H
Answer:
(a) PCR is now routinely used to detect HIV in suspected AIDS patients. (b) It is being used to detect mutations in gene in
suspected cancer patients.
5) HIV infection causes cellular immunodeficiency. Explain how.
Answer:
HTV attacks helper T-lymphocytes, so their number is greatly reduced. This causes severe cellular immuno deficiency because
helper T-cells stimulate the B-lymphocytes to produce antibodies.
6) Write the ratio of phenotype and genotype when a heterozygous is crossed with recessive parent?
Answer:
Phenotypic ratio: Tall       :     Dwarf
2          :           2          =1:1
Genotypic ratio: 2 Tt      :           2tt
1          :           1
7) What is immunity? Explain the types of imunity.
  
Animal body has the ability to resist almost all types of organisms or toxins that damage the tissues and
organs.
Immunity is of two types:
(a) Innate immunity (Inborn immunity): It is inherited from parents and protect us from birth throughout
life.
(b) Acquired immunity (Adaptive immunity): It is developed by our body in response to a disease caused by
infection of a pathogen.
8)
Describe the function of restriction enzymes. Give an example.
OR
Write any two uses of gene cloning.
Answer:
Restriction enzymes are used in genetic engineering for the construction of recombinant DNA molecules.
When cut by the same restriction enzyme, the formed DNA fragments have the same kind of 'sticky ends'
which can be joined together end to end by use of DNA-ligases.
Example: EcoRI is an endonuclease enzyme isolated from strains of E.coli and a part of restriction
modified system.
OR
Uses of gene cloning are:
(a) Genes of interest can be inserted into animals, so as to produce better farm animals.
(b) Specific proteins like insulin, hormones, interferons, vitamins can be manufactured in bacteria on an
industrial basis.
9) Why is secondary succession faster than the primary succesion?
Answer:
Secondary succession is faster than the primary sucession b:
(a) Since the soil is already there, the rate of secondary succession is much faster and takes less time for
the climax to reach.
(b) Availability of water, the environment and also the seeds or other propagules are present.
10) Describe the importance of species diversity to the ecosystem.
Answer:
Importance of species diversity to the ecosystem : Ecologists believe that communities with more species tend to be more
stable than those with less species. (ii) There is very little variation in yearly total biomass if ecosystem is rich in species
diversity. This was confirmed by David Tilman. He told that plots with increased diversity showed higher productivity.
11)
(i) Why asexual reproduction does not produce the genetic variability?
(ii) Banana is a parthenocarpic fruit whereas oranges show polyembryony. How are they different from
each other with respect to seeds?
Answer:
(i)  Asexual reproduction does not produce the genetic variability because only mitotic division occurs
during asexual reproduction.
(ii) Banana develops from an ovary without fertilization having non-viable seeds so it is called a
parthenocarpic fruit. An orange contains seeds with more than one embryo, thus it shows polyembryony.
12) What are the different types of fertilization?
Answer:
The phenomenon effusion of the male and female germ cells or gametes is called fertilization. If the fusion takes place outside
the body of the parents, as in fishes and amphibians, it is called external fertilization, on the other hand, if the fusion takes place
within the body of the mother, as in reptiles, birds and mammals, it is called internal fertilization. Fertilization ensures restoration
of the original diploid nature of the parent. It causes new combinations of characters.
13) Although sexual reproduction is a long drawn, energy intensive complex form of reproduction, many groups of organism in
kingdom Animalia and Plantae prefer this mode of reproduction. Give at least three reasons for this.
Answer:
Three reasons for mode of sexual reproduction:
(a) Sexual reproduction results in offspring that are not identical to the parents or to themselves and
create variation in them.
(b) Since gamete formation is proceeded by meiosis, genetic recombination occuring during crossing
over in meosis-I leads to a great deal of variation in the DNA of gametes.
(c) The organism has better chance of survival in a changing environment.
14) Draw a labelled diagram of the sectional view of a mature pollen grain of angiosperm. Explain the features of each of its
labelled parts.
Answer:
Sectional view of mature pollen grain.
Features:
(a) Exine: It is the hard outer layer made up of sporopollenin which is resistant to physical and biological
decomposition. It protects the pollens from environmental extremes.
(b) Inline: The inner wall of pollen grain is called intine. It is a thin and continuous layer made up of
cellulose and pectin.
(c) Vegetative cell: It is the bigger cell and has abundant food reserve.
(d) Generative cell: It is small and floats in cytoplasm of the vegetative cell. It divides mitotically to give
rise to two male gametes.
15) Draw a labelled schematic structure of a transcription unit. Explain in one line the function of each region.
Answer:
The process of copying genetic information from one strand of the DNA into RNA is termed as
transcription. The transcription unit of DNA is defined primarily by the three regions in the DNA.
(a) A promoter: where RNA polymerase binds.
(b) A structural gene: which will undergo transcription.
(c) A terminator: a site where transcription will end.
16) Write the goals of human genome project (HGP).
Answer:
(a) Identification of approximately 20,000-25,000 genes in human DNA.
(b) Determination of sequences of the 3 billion chemical base pairs that make up the human DNA.
(c) Store this information (above) in database and develop tools (software) for Data analysis.
(d) To develop ways of mapping the human genome at increasing fine level of expression.
(e) Transfer related technologies to other sectors, such as industries.
(f) It helps to address the ethical, legal and social issues (E1SI) about the various researches
related to this project.
Page 4


d o n e Biology - Sample Paper-3
1) Write the central dogma of molecular biology.
Answer:
 It is unidirectional flow of information DNA to mRNA and then decoding the information
present in mRNA in the formation of polypeptide chain or protein.
2) What are the Okazaki fragments?
Answer:
The replication of lagging strand generates small polynucleotide fragments called' Okazaki fragments'. One strand may
synthesize a continuous strand and the other Okazaki fragments, both new strands are synthesized in the direction.
3) Why the disease filariasis is also called elephantiasis?
Answer:
Filarial worms (W. bancrofti and W. malayi) cause proliferation of endothelial cells of the wall of lymph vessels which causes
blockage of lymph vessels and swelling of certain body parts. When swelling occurs in the legs, then the legs become swollen
like those of elephants.
4) Write the two uses of PCR technique. H
Answer:
(a) PCR is now routinely used to detect HIV in suspected AIDS patients. (b) It is being used to detect mutations in gene in
suspected cancer patients.
5) HIV infection causes cellular immunodeficiency. Explain how.
Answer:
HTV attacks helper T-lymphocytes, so their number is greatly reduced. This causes severe cellular immuno deficiency because
helper T-cells stimulate the B-lymphocytes to produce antibodies.
6) Write the ratio of phenotype and genotype when a heterozygous is crossed with recessive parent?
Answer:
Phenotypic ratio: Tall       :     Dwarf
2          :           2          =1:1
Genotypic ratio: 2 Tt      :           2tt
1          :           1
7) What is immunity? Explain the types of imunity.
  
Animal body has the ability to resist almost all types of organisms or toxins that damage the tissues and
organs.
Immunity is of two types:
(a) Innate immunity (Inborn immunity): It is inherited from parents and protect us from birth throughout
life.
(b) Acquired immunity (Adaptive immunity): It is developed by our body in response to a disease caused by
infection of a pathogen.
8)
Describe the function of restriction enzymes. Give an example.
OR
Write any two uses of gene cloning.
Answer:
Restriction enzymes are used in genetic engineering for the construction of recombinant DNA molecules.
When cut by the same restriction enzyme, the formed DNA fragments have the same kind of 'sticky ends'
which can be joined together end to end by use of DNA-ligases.
Example: EcoRI is an endonuclease enzyme isolated from strains of E.coli and a part of restriction
modified system.
OR
Uses of gene cloning are:
(a) Genes of interest can be inserted into animals, so as to produce better farm animals.
(b) Specific proteins like insulin, hormones, interferons, vitamins can be manufactured in bacteria on an
industrial basis.
9) Why is secondary succession faster than the primary succesion?
Answer:
Secondary succession is faster than the primary sucession b:
(a) Since the soil is already there, the rate of secondary succession is much faster and takes less time for
the climax to reach.
(b) Availability of water, the environment and also the seeds or other propagules are present.
10) Describe the importance of species diversity to the ecosystem.
Answer:
Importance of species diversity to the ecosystem : Ecologists believe that communities with more species tend to be more
stable than those with less species. (ii) There is very little variation in yearly total biomass if ecosystem is rich in species
diversity. This was confirmed by David Tilman. He told that plots with increased diversity showed higher productivity.
11)
(i) Why asexual reproduction does not produce the genetic variability?
(ii) Banana is a parthenocarpic fruit whereas oranges show polyembryony. How are they different from
each other with respect to seeds?
Answer:
(i)  Asexual reproduction does not produce the genetic variability because only mitotic division occurs
during asexual reproduction.
(ii) Banana develops from an ovary without fertilization having non-viable seeds so it is called a
parthenocarpic fruit. An orange contains seeds with more than one embryo, thus it shows polyembryony.
12) What are the different types of fertilization?
Answer:
The phenomenon effusion of the male and female germ cells or gametes is called fertilization. If the fusion takes place outside
the body of the parents, as in fishes and amphibians, it is called external fertilization, on the other hand, if the fusion takes place
within the body of the mother, as in reptiles, birds and mammals, it is called internal fertilization. Fertilization ensures restoration
of the original diploid nature of the parent. It causes new combinations of characters.
13) Although sexual reproduction is a long drawn, energy intensive complex form of reproduction, many groups of organism in
kingdom Animalia and Plantae prefer this mode of reproduction. Give at least three reasons for this.
Answer:
Three reasons for mode of sexual reproduction:
(a) Sexual reproduction results in offspring that are not identical to the parents or to themselves and
create variation in them.
(b) Since gamete formation is proceeded by meiosis, genetic recombination occuring during crossing
over in meosis-I leads to a great deal of variation in the DNA of gametes.
(c) The organism has better chance of survival in a changing environment.
14) Draw a labelled diagram of the sectional view of a mature pollen grain of angiosperm. Explain the features of each of its
labelled parts.
Answer:
Sectional view of mature pollen grain.
Features:
(a) Exine: It is the hard outer layer made up of sporopollenin which is resistant to physical and biological
decomposition. It protects the pollens from environmental extremes.
(b) Inline: The inner wall of pollen grain is called intine. It is a thin and continuous layer made up of
cellulose and pectin.
(c) Vegetative cell: It is the bigger cell and has abundant food reserve.
(d) Generative cell: It is small and floats in cytoplasm of the vegetative cell. It divides mitotically to give
rise to two male gametes.
15) Draw a labelled schematic structure of a transcription unit. Explain in one line the function of each region.
Answer:
The process of copying genetic information from one strand of the DNA into RNA is termed as
transcription. The transcription unit of DNA is defined primarily by the three regions in the DNA.
(a) A promoter: where RNA polymerase binds.
(b) A structural gene: which will undergo transcription.
(c) A terminator: a site where transcription will end.
16) Write the goals of human genome project (HGP).
Answer:
(a) Identification of approximately 20,000-25,000 genes in human DNA.
(b) Determination of sequences of the 3 billion chemical base pairs that make up the human DNA.
(c) Store this information (above) in database and develop tools (software) for Data analysis.
(d) To develop ways of mapping the human genome at increasing fine level of expression.
(e) Transfer related technologies to other sectors, such as industries.
(f) It helps to address the ethical, legal and social issues (E1SI) about the various researches
related to this project.
17)
Draw a schematic representation of dinucleotide. Label the
following.
(i) The components of a nucleotide phosphodiester linkage.
(ii) 5? end
(iii) N-glycosides linkage
(iv) Phosphodiester linkage.
Answer:
18) What is causative agent of malaria? How its infection can be confirmed? What are is symptoms?
Answer:
Causative agent: Plasmodium (commonly called malarial parasite). To confirm infections: By the presence of different stages of
gamogony of plasmodium inside the RBCs by staining a blood film slide of man. Symptoms: It is characterized by chilling and
shivering, followed by high temperature, faster respiration and heartbeat, and finally profuse sweating.
19)
Name the cells that produce antibodies. Explain their structure and fanctions.
OR
(i) What is meant by withdrawal symptoms?
(ii) Write the useful prevention and control methods of alcohol and drug abuse among
adolescents.
Answer:
B-lymphocytes of the immune system when stimulated by specific antigen, produce the antibodies B-
lymphocytes produce an army of proteins in reponse to pathogens into our blood to fight with them.
These cells produce the antibodies which counter those bacteria and viruses which enter the blood and
lymph.
OR
(i) It is the state experienced by addicts when their regular does of alcohol/drug is abruptly discontinued.
It is often characterised by anxiety, shakiness, and nausea and vomiting.
(ii) (a) Avoid undue peer pressure. A child should not be pushed to perform beyond his limits in sports,
studies and other activities.
(b) Educating and counselling to face problems and stresses and to accept failures and disappointments
as a part of life.
(c) Seeking help from parents and peers could help to vent their feeling of anxiety and guilt.
(d) Seeking professional and medical help for de-addiction and rehabilitation progammes would help
invidiuals to come out of the problem completely.
20) Describe briefly the functioning of a bioreactor.
Page 5


d o n e Biology - Sample Paper-3
1) Write the central dogma of molecular biology.
Answer:
 It is unidirectional flow of information DNA to mRNA and then decoding the information
present in mRNA in the formation of polypeptide chain or protein.
2) What are the Okazaki fragments?
Answer:
The replication of lagging strand generates small polynucleotide fragments called' Okazaki fragments'. One strand may
synthesize a continuous strand and the other Okazaki fragments, both new strands are synthesized in the direction.
3) Why the disease filariasis is also called elephantiasis?
Answer:
Filarial worms (W. bancrofti and W. malayi) cause proliferation of endothelial cells of the wall of lymph vessels which causes
blockage of lymph vessels and swelling of certain body parts. When swelling occurs in the legs, then the legs become swollen
like those of elephants.
4) Write the two uses of PCR technique. H
Answer:
(a) PCR is now routinely used to detect HIV in suspected AIDS patients. (b) It is being used to detect mutations in gene in
suspected cancer patients.
5) HIV infection causes cellular immunodeficiency. Explain how.
Answer:
HTV attacks helper T-lymphocytes, so their number is greatly reduced. This causes severe cellular immuno deficiency because
helper T-cells stimulate the B-lymphocytes to produce antibodies.
6) Write the ratio of phenotype and genotype when a heterozygous is crossed with recessive parent?
Answer:
Phenotypic ratio: Tall       :     Dwarf
2          :           2          =1:1
Genotypic ratio: 2 Tt      :           2tt
1          :           1
7) What is immunity? Explain the types of imunity.
  
Animal body has the ability to resist almost all types of organisms or toxins that damage the tissues and
organs.
Immunity is of two types:
(a) Innate immunity (Inborn immunity): It is inherited from parents and protect us from birth throughout
life.
(b) Acquired immunity (Adaptive immunity): It is developed by our body in response to a disease caused by
infection of a pathogen.
8)
Describe the function of restriction enzymes. Give an example.
OR
Write any two uses of gene cloning.
Answer:
Restriction enzymes are used in genetic engineering for the construction of recombinant DNA molecules.
When cut by the same restriction enzyme, the formed DNA fragments have the same kind of 'sticky ends'
which can be joined together end to end by use of DNA-ligases.
Example: EcoRI is an endonuclease enzyme isolated from strains of E.coli and a part of restriction
modified system.
OR
Uses of gene cloning are:
(a) Genes of interest can be inserted into animals, so as to produce better farm animals.
(b) Specific proteins like insulin, hormones, interferons, vitamins can be manufactured in bacteria on an
industrial basis.
9) Why is secondary succession faster than the primary succesion?
Answer:
Secondary succession is faster than the primary sucession b:
(a) Since the soil is already there, the rate of secondary succession is much faster and takes less time for
the climax to reach.
(b) Availability of water, the environment and also the seeds or other propagules are present.
10) Describe the importance of species diversity to the ecosystem.
Answer:
Importance of species diversity to the ecosystem : Ecologists believe that communities with more species tend to be more
stable than those with less species. (ii) There is very little variation in yearly total biomass if ecosystem is rich in species
diversity. This was confirmed by David Tilman. He told that plots with increased diversity showed higher productivity.
11)
(i) Why asexual reproduction does not produce the genetic variability?
(ii) Banana is a parthenocarpic fruit whereas oranges show polyembryony. How are they different from
each other with respect to seeds?
Answer:
(i)  Asexual reproduction does not produce the genetic variability because only mitotic division occurs
during asexual reproduction.
(ii) Banana develops from an ovary without fertilization having non-viable seeds so it is called a
parthenocarpic fruit. An orange contains seeds with more than one embryo, thus it shows polyembryony.
12) What are the different types of fertilization?
Answer:
The phenomenon effusion of the male and female germ cells or gametes is called fertilization. If the fusion takes place outside
the body of the parents, as in fishes and amphibians, it is called external fertilization, on the other hand, if the fusion takes place
within the body of the mother, as in reptiles, birds and mammals, it is called internal fertilization. Fertilization ensures restoration
of the original diploid nature of the parent. It causes new combinations of characters.
13) Although sexual reproduction is a long drawn, energy intensive complex form of reproduction, many groups of organism in
kingdom Animalia and Plantae prefer this mode of reproduction. Give at least three reasons for this.
Answer:
Three reasons for mode of sexual reproduction:
(a) Sexual reproduction results in offspring that are not identical to the parents or to themselves and
create variation in them.
(b) Since gamete formation is proceeded by meiosis, genetic recombination occuring during crossing
over in meosis-I leads to a great deal of variation in the DNA of gametes.
(c) The organism has better chance of survival in a changing environment.
14) Draw a labelled diagram of the sectional view of a mature pollen grain of angiosperm. Explain the features of each of its
labelled parts.
Answer:
Sectional view of mature pollen grain.
Features:
(a) Exine: It is the hard outer layer made up of sporopollenin which is resistant to physical and biological
decomposition. It protects the pollens from environmental extremes.
(b) Inline: The inner wall of pollen grain is called intine. It is a thin and continuous layer made up of
cellulose and pectin.
(c) Vegetative cell: It is the bigger cell and has abundant food reserve.
(d) Generative cell: It is small and floats in cytoplasm of the vegetative cell. It divides mitotically to give
rise to two male gametes.
15) Draw a labelled schematic structure of a transcription unit. Explain in one line the function of each region.
Answer:
The process of copying genetic information from one strand of the DNA into RNA is termed as
transcription. The transcription unit of DNA is defined primarily by the three regions in the DNA.
(a) A promoter: where RNA polymerase binds.
(b) A structural gene: which will undergo transcription.
(c) A terminator: a site where transcription will end.
16) Write the goals of human genome project (HGP).
Answer:
(a) Identification of approximately 20,000-25,000 genes in human DNA.
(b) Determination of sequences of the 3 billion chemical base pairs that make up the human DNA.
(c) Store this information (above) in database and develop tools (software) for Data analysis.
(d) To develop ways of mapping the human genome at increasing fine level of expression.
(e) Transfer related technologies to other sectors, such as industries.
(f) It helps to address the ethical, legal and social issues (E1SI) about the various researches
related to this project.
17)
Draw a schematic representation of dinucleotide. Label the
following.
(i) The components of a nucleotide phosphodiester linkage.
(ii) 5? end
(iii) N-glycosides linkage
(iv) Phosphodiester linkage.
Answer:
18) What is causative agent of malaria? How its infection can be confirmed? What are is symptoms?
Answer:
Causative agent: Plasmodium (commonly called malarial parasite). To confirm infections: By the presence of different stages of
gamogony of plasmodium inside the RBCs by staining a blood film slide of man. Symptoms: It is characterized by chilling and
shivering, followed by high temperature, faster respiration and heartbeat, and finally profuse sweating.
19)
Name the cells that produce antibodies. Explain their structure and fanctions.
OR
(i) What is meant by withdrawal symptoms?
(ii) Write the useful prevention and control methods of alcohol and drug abuse among
adolescents.
Answer:
B-lymphocytes of the immune system when stimulated by specific antigen, produce the antibodies B-
lymphocytes produce an army of proteins in reponse to pathogens into our blood to fight with them.
These cells produce the antibodies which counter those bacteria and viruses which enter the blood and
lymph.
OR
(i) It is the state experienced by addicts when their regular does of alcohol/drug is abruptly discontinued.
It is often characterised by anxiety, shakiness, and nausea and vomiting.
(ii) (a) Avoid undue peer pressure. A child should not be pushed to perform beyond his limits in sports,
studies and other activities.
(b) Educating and counselling to face problems and stresses and to accept failures and disappointments
as a part of life.
(c) Seeking help from parents and peers could help to vent their feeling of anxiety and guilt.
(d) Seeking professional and medical help for de-addiction and rehabilitation progammes would help
invidiuals to come out of the problem completely.
20) Describe briefly the functioning of a bioreactor.
Answer:
Small volume cultures cannot yield appreciable quantities of products. To produce products in large-quantities, bioreactors are
used. Bio-reactors are vessels in which raw materials are biologically converted into specific products, individual enzymes etc.
using microbial plant, animal and human cells. A bioreactor providing the optimal conditions such as temperature, pH, substrate,
vitamins, oxygen and salts for obtaining the desired products. 
Simple stirred-tank bioreactor: (b) Sparged stirred-tank bioreactor through which sterile air bubbles are sparged
21) Describe the important features that are required to facilitate cloning and drug abuse among adolescents.
Answer:
The following are the features that are required to facilitate cloning into a vector.
(a) Origin of replication (Ori):
The sequence where replication starts: ADNA sequence, that is responsible for initiating replication. Any
piece of DNA, when linked to this sequence can replicate within host cells. Ori also controls the copy
numbers of the linked DNA.
(b) Selectable markers: These help in identifying and eliminating non-trans formants and allow the growth
of trans formants.
Transformation is the process by which a piece of DNA is introduced in a host bacterium.
Example: Genes which are encoding resistance to antibodies such as ampicillin, chloramphenicol,
tetracycline or kanamycin etc. are used as useful selectable markers for E.coli.
(c) Cloning sites: When linking to the alien DNA, the vector should have very few recognition sites, on which
restriction enzyme can easily act. If more recognition sites are present on the vector, then it will generate
several fragments which will complicate the gene cloning. The ligation of alien DNA is carreid out at a
restriction site present in one of the two antibiotic resistance genes.
For Example, you can ligate a foreign DNA at the BamH I site of tetracyline resistance gene in the vector
pBR322.
22) Explain the phosphorus cycle with the help of a diagram.
Answer:
The cycling of phosphorus between biotic & abiotic components of the environment represent phosphorus cycle. Phosphorus is
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