CBSE Biology Outside Delhi Past year paper (Set - 3) Solutions - 2014, Class 12 | Additional Study Material for NEET PDF Download

 Page 1


  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Question Paper 2014 – Outside Delhi (Set 3) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. It is not possible for an alien DNA to become part of a chromosome anywhere 
along its length and replicate normally because the replication process begins at a 
particular spot called the origin of replication. Also, replication in eukaryotes occurs 
in the nucleus during the S phase of the cell cycle when the chromosomes are in their 
extended form. 
  
2. Ans. Segregation of an independent pair of chromosomes occurs during the M phase 
(mitotic phase) of cell division. Homologous chromosomes line up independently on 
the metaphase plate. 
 
3. Ans.  SCP (single cell protein) is a microbial biomass rich in high-quality protein. It is 
used as an alternate source of protein and is a valuable supplement in human diet. 
Cells from a variety of microorganisms such as bacteria, yeasts, filamentous fungi and 
algae are treated in various ways and used as food to supplement proteins. 
  
4. Ans. Pollen grains of many species, allergic diseases and bronchial afflictions in some 
people. The pollen grains of Parthenium or carrot grass which came to India as 
contaminant with imported wheat cause pollen allergy.  
 
5. Ans. Glomus exhibits symbiotic association with higher plants called mycorrhiza. The 
root of the plant provides food and shelter to the fungus, and in return, the fungus 
helps the plant in solubilisation and absorption of minerals, water uptake and 
protection against pathogenic fungi.  
  
6. Ans. Gause’s competitive exclusion principle states that two closely related species 
competing for the same resources cannot co-exist indefinitely and the competitively 
inferior will be eliminated eventually. 
 
7. Ans. Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
8. Ans. Mammalian insulin is synthesised as a prohormone which undergoes 
processing to become fully mature and functional insulin molecule. The prohormone 
Page 2


  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Question Paper 2014 – Outside Delhi (Set 3) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. It is not possible for an alien DNA to become part of a chromosome anywhere 
along its length and replicate normally because the replication process begins at a 
particular spot called the origin of replication. Also, replication in eukaryotes occurs 
in the nucleus during the S phase of the cell cycle when the chromosomes are in their 
extended form. 
  
2. Ans. Segregation of an independent pair of chromosomes occurs during the M phase 
(mitotic phase) of cell division. Homologous chromosomes line up independently on 
the metaphase plate. 
 
3. Ans.  SCP (single cell protein) is a microbial biomass rich in high-quality protein. It is 
used as an alternate source of protein and is a valuable supplement in human diet. 
Cells from a variety of microorganisms such as bacteria, yeasts, filamentous fungi and 
algae are treated in various ways and used as food to supplement proteins. 
  
4. Ans. Pollen grains of many species, allergic diseases and bronchial afflictions in some 
people. The pollen grains of Parthenium or carrot grass which came to India as 
contaminant with imported wheat cause pollen allergy.  
 
5. Ans. Glomus exhibits symbiotic association with higher plants called mycorrhiza. The 
root of the plant provides food and shelter to the fungus, and in return, the fungus 
helps the plant in solubilisation and absorption of minerals, water uptake and 
protection against pathogenic fungi.  
  
6. Ans. Gause’s competitive exclusion principle states that two closely related species 
competing for the same resources cannot co-exist indefinitely and the competitively 
inferior will be eliminated eventually. 
 
7. Ans. Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
8. Ans. Mammalian insulin is synthesised as a prohormone which undergoes 
processing to become fully mature and functional insulin molecule. The prohormone 
  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
SECTION B 
9. Ans. The scientific name of fruit fly is Drosophila melanogaster. Morgan preferred  
           to work with fruit fly for his experiments because 
(i) It is simple and convenient to breed under laboratory conditions throughout 
the year. 
(ii) Its generation time is only 10–12 days. 
(iii) It breeds quickly and prolifically and so produces large progeny after each 
mating. 
(iv) Its contrasting features are easily observable. 
OR 
Linkage and crossing over of genes are alternatives of each other. Linkage is the 
tendency of the genes present in the same chromosome to stay together during 
hereditary transmission, while crossing over is the mutual exchange of segments of non-
sister chromatids of homologous chromosomes during the process of meiosis. 
An example of linkage: A double dominant female Drosophila homozygous for red eyes 
and normal wings is crossed with a double recessive male Drosophila homozygous for 
purple eyes and vestigial wings. The F 1 flies are heterozygous red-eyed and normal 
winged. It is then test crossed with a double recessive male having purple eyes and 
vestigial wings. The F 2 generation comprises two types of flies—red-eyed, normal 
winged and purple eyed, vestigial winged in the ratio of 1:1. No recombinant types are 
formed because linkage is complete and no crossing over occurs. 
An example of crossing over: A double dominant sweet pea plant homozygous for blue 
flowers and long pollen grains is crossed with a double recessive plant homozygous for 
red flowers and round pollen grains. The F 1 flies are heterozygous blue flowered and 
long pollen grains. It is then crossed with a double recessive plant having red flowers 
and round pollen grains. The F 2 generation of plants have new combination of traits—
blue flowers and round pollen grains and red flowers and long pollen grains. This is due 
to crossing over, i.e. separation of genes for flower colour and form of pollen grains 
during gamete formation. 
 
10.  Ans. Symptoms of Ascariasis: 
(i) Abdominal discomfort 
(ii) Colic pain 
(iii) Fever 
(iv) Indigestion 
(v) Diarrhoea 
(vi) Vomiting 
 
A healthy human being may acquire this infection directly and orally. It can occur 
through contaminated water, vegetables and fruits. 
 
 
Page 3


  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Question Paper 2014 – Outside Delhi (Set 3) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. It is not possible for an alien DNA to become part of a chromosome anywhere 
along its length and replicate normally because the replication process begins at a 
particular spot called the origin of replication. Also, replication in eukaryotes occurs 
in the nucleus during the S phase of the cell cycle when the chromosomes are in their 
extended form. 
  
2. Ans. Segregation of an independent pair of chromosomes occurs during the M phase 
(mitotic phase) of cell division. Homologous chromosomes line up independently on 
the metaphase plate. 
 
3. Ans.  SCP (single cell protein) is a microbial biomass rich in high-quality protein. It is 
used as an alternate source of protein and is a valuable supplement in human diet. 
Cells from a variety of microorganisms such as bacteria, yeasts, filamentous fungi and 
algae are treated in various ways and used as food to supplement proteins. 
  
4. Ans. Pollen grains of many species, allergic diseases and bronchial afflictions in some 
people. The pollen grains of Parthenium or carrot grass which came to India as 
contaminant with imported wheat cause pollen allergy.  
 
5. Ans. Glomus exhibits symbiotic association with higher plants called mycorrhiza. The 
root of the plant provides food and shelter to the fungus, and in return, the fungus 
helps the plant in solubilisation and absorption of minerals, water uptake and 
protection against pathogenic fungi.  
  
6. Ans. Gause’s competitive exclusion principle states that two closely related species 
competing for the same resources cannot co-exist indefinitely and the competitively 
inferior will be eliminated eventually. 
 
7. Ans. Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
8. Ans. Mammalian insulin is synthesised as a prohormone which undergoes 
processing to become fully mature and functional insulin molecule. The prohormone 
  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
SECTION B 
9. Ans. The scientific name of fruit fly is Drosophila melanogaster. Morgan preferred  
           to work with fruit fly for his experiments because 
(i) It is simple and convenient to breed under laboratory conditions throughout 
the year. 
(ii) Its generation time is only 10–12 days. 
(iii) It breeds quickly and prolifically and so produces large progeny after each 
mating. 
(iv) Its contrasting features are easily observable. 
OR 
Linkage and crossing over of genes are alternatives of each other. Linkage is the 
tendency of the genes present in the same chromosome to stay together during 
hereditary transmission, while crossing over is the mutual exchange of segments of non-
sister chromatids of homologous chromosomes during the process of meiosis. 
An example of linkage: A double dominant female Drosophila homozygous for red eyes 
and normal wings is crossed with a double recessive male Drosophila homozygous for 
purple eyes and vestigial wings. The F 1 flies are heterozygous red-eyed and normal 
winged. It is then test crossed with a double recessive male having purple eyes and 
vestigial wings. The F 2 generation comprises two types of flies—red-eyed, normal 
winged and purple eyed, vestigial winged in the ratio of 1:1. No recombinant types are 
formed because linkage is complete and no crossing over occurs. 
An example of crossing over: A double dominant sweet pea plant homozygous for blue 
flowers and long pollen grains is crossed with a double recessive plant homozygous for 
red flowers and round pollen grains. The F 1 flies are heterozygous blue flowered and 
long pollen grains. It is then crossed with a double recessive plant having red flowers 
and round pollen grains. The F 2 generation of plants have new combination of traits—
blue flowers and round pollen grains and red flowers and long pollen grains. This is due 
to crossing over, i.e. separation of genes for flower colour and form of pollen grains 
during gamete formation. 
 
10.  Ans. Symptoms of Ascariasis: 
(i) Abdominal discomfort 
(ii) Colic pain 
(iii) Fever 
(iv) Indigestion 
(v) Diarrhoea 
(vi) Vomiting 
 
A healthy human being may acquire this infection directly and orally. It can occur 
through contaminated water, vegetables and fruits. 
 
 
  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
 
11.  Ans. Nucleopolyhedroviruses are biocontrol agents and useful in controlling many 
insects and arthropods. They are species-specific narrow spectrum bioinsecticides 
and have no negative impacts on plants and other organisms or even non-target 
insects. 
 
12.  Ans.   
 
 
 
13.  Ans. Mutualism exists between fig tree and its pollinator species, wasp, where both 
individuals are benefited. A fig species can be pollinated only by its partner wasp 
species and no other species. The female wasp uses the fruit as the egg-laying site 
and the developing seeds within the fruit for nourishing its larvae. The wasp 
pollinates the fig inflorescence while finding egg-laying sites, and in turn, fig offers 
the wasp developing seeds as food for the developing larvae. 
14.  Ans.  
a. Biological products: Many human diseases are controlled by biological products. 
The transgenic animals which produce these products are introduced with DNA 
which codes for a particular product such as human protein (a-I-antitrypsin) for 
treating emphysema. In 1997, the first transgenic cow (Rosie) was produced, 
capable of secreting human protein-enriched milk. The milk contained the human 
alpha-lactalbumin and was nutritionally a more balanced product for human 
babies than cow milk. 
b. Chemical safety testing: The transgenic animals are tested to study the sensitivity 
of toxic substances. Toxicity testing in such animals helps obtain results in less 
time. 
 
15.  Ans. Restriction endonuclease functions by recognising its specific sequence. It 
binds to the DNA and cuts each to the two strands of the double helix at specific 
points in their sugar phosphate backbones. These enzymes cut the strand of DNA 
between the same two bases on the opposite strands leaving a single-stranded 
portion at their ends. These overhanging stretches are called sticky ends on each 
strand. The enzyme DNA ligase functions depending on the stickiness of these ends. 
For example, restriction endonuclease EcoRI found in the colon bacteria E. coli 
recognises the base sequence GAATTC in the DNA duplex and cuts its strands 
between G and A. 
Page 4


  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Question Paper 2014 – Outside Delhi (Set 3) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. It is not possible for an alien DNA to become part of a chromosome anywhere 
along its length and replicate normally because the replication process begins at a 
particular spot called the origin of replication. Also, replication in eukaryotes occurs 
in the nucleus during the S phase of the cell cycle when the chromosomes are in their 
extended form. 
  
2. Ans. Segregation of an independent pair of chromosomes occurs during the M phase 
(mitotic phase) of cell division. Homologous chromosomes line up independently on 
the metaphase plate. 
 
3. Ans.  SCP (single cell protein) is a microbial biomass rich in high-quality protein. It is 
used as an alternate source of protein and is a valuable supplement in human diet. 
Cells from a variety of microorganisms such as bacteria, yeasts, filamentous fungi and 
algae are treated in various ways and used as food to supplement proteins. 
  
4. Ans. Pollen grains of many species, allergic diseases and bronchial afflictions in some 
people. The pollen grains of Parthenium or carrot grass which came to India as 
contaminant with imported wheat cause pollen allergy.  
 
5. Ans. Glomus exhibits symbiotic association with higher plants called mycorrhiza. The 
root of the plant provides food and shelter to the fungus, and in return, the fungus 
helps the plant in solubilisation and absorption of minerals, water uptake and 
protection against pathogenic fungi.  
  
6. Ans. Gause’s competitive exclusion principle states that two closely related species 
competing for the same resources cannot co-exist indefinitely and the competitively 
inferior will be eliminated eventually. 
 
7. Ans. Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
8. Ans. Mammalian insulin is synthesised as a prohormone which undergoes 
processing to become fully mature and functional insulin molecule. The prohormone 
  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
SECTION B 
9. Ans. The scientific name of fruit fly is Drosophila melanogaster. Morgan preferred  
           to work with fruit fly for his experiments because 
(i) It is simple and convenient to breed under laboratory conditions throughout 
the year. 
(ii) Its generation time is only 10–12 days. 
(iii) It breeds quickly and prolifically and so produces large progeny after each 
mating. 
(iv) Its contrasting features are easily observable. 
OR 
Linkage and crossing over of genes are alternatives of each other. Linkage is the 
tendency of the genes present in the same chromosome to stay together during 
hereditary transmission, while crossing over is the mutual exchange of segments of non-
sister chromatids of homologous chromosomes during the process of meiosis. 
An example of linkage: A double dominant female Drosophila homozygous for red eyes 
and normal wings is crossed with a double recessive male Drosophila homozygous for 
purple eyes and vestigial wings. The F 1 flies are heterozygous red-eyed and normal 
winged. It is then test crossed with a double recessive male having purple eyes and 
vestigial wings. The F 2 generation comprises two types of flies—red-eyed, normal 
winged and purple eyed, vestigial winged in the ratio of 1:1. No recombinant types are 
formed because linkage is complete and no crossing over occurs. 
An example of crossing over: A double dominant sweet pea plant homozygous for blue 
flowers and long pollen grains is crossed with a double recessive plant homozygous for 
red flowers and round pollen grains. The F 1 flies are heterozygous blue flowered and 
long pollen grains. It is then crossed with a double recessive plant having red flowers 
and round pollen grains. The F 2 generation of plants have new combination of traits—
blue flowers and round pollen grains and red flowers and long pollen grains. This is due 
to crossing over, i.e. separation of genes for flower colour and form of pollen grains 
during gamete formation. 
 
10.  Ans. Symptoms of Ascariasis: 
(i) Abdominal discomfort 
(ii) Colic pain 
(iii) Fever 
(iv) Indigestion 
(v) Diarrhoea 
(vi) Vomiting 
 
A healthy human being may acquire this infection directly and orally. It can occur 
through contaminated water, vegetables and fruits. 
 
 
  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
 
11.  Ans. Nucleopolyhedroviruses are biocontrol agents and useful in controlling many 
insects and arthropods. They are species-specific narrow spectrum bioinsecticides 
and have no negative impacts on plants and other organisms or even non-target 
insects. 
 
12.  Ans.   
 
 
 
13.  Ans. Mutualism exists between fig tree and its pollinator species, wasp, where both 
individuals are benefited. A fig species can be pollinated only by its partner wasp 
species and no other species. The female wasp uses the fruit as the egg-laying site 
and the developing seeds within the fruit for nourishing its larvae. The wasp 
pollinates the fig inflorescence while finding egg-laying sites, and in turn, fig offers 
the wasp developing seeds as food for the developing larvae. 
14.  Ans.  
a. Biological products: Many human diseases are controlled by biological products. 
The transgenic animals which produce these products are introduced with DNA 
which codes for a particular product such as human protein (a-I-antitrypsin) for 
treating emphysema. In 1997, the first transgenic cow (Rosie) was produced, 
capable of secreting human protein-enriched milk. The milk contained the human 
alpha-lactalbumin and was nutritionally a more balanced product for human 
babies than cow milk. 
b. Chemical safety testing: The transgenic animals are tested to study the sensitivity 
of toxic substances. Toxicity testing in such animals helps obtain results in less 
time. 
 
15.  Ans. Restriction endonuclease functions by recognising its specific sequence. It 
binds to the DNA and cuts each to the two strands of the double helix at specific 
points in their sugar phosphate backbones. These enzymes cut the strand of DNA 
between the same two bases on the opposite strands leaving a single-stranded 
portion at their ends. These overhanging stretches are called sticky ends on each 
strand. The enzyme DNA ligase functions depending on the stickiness of these ends. 
For example, restriction endonuclease EcoRI found in the colon bacteria E. coli 
recognises the base sequence GAATTC in the DNA duplex and cuts its strands 
between G and A. 
  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
 
 
  
16.  Ans. Factors responsible for conferring stability to the double helix structure of  
            DNA are 
a. The two strands of DNA separated by heating come together when appropriate 
conditions are provided. 
b. The presence of thymine at the place of uracil confirms additional stability to 
DNA. 
 
17.  Ans.  
(a) When the red and white flowers varieties of snapdragon are crossed, the F 1 
progeny exhibits pink colour flowers. It is not known as blending inheritance 
because in blending inheritance, the characters are mixed in the offspring and do 
not segregate. 
(b) This phenomenon is known as incomplete dominance. 
 
18.  Ans. The high concentration of LH surge induces the mature Graafian follicle to burst 
and eject its egg into the fallopian tube. This is called ovulation. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Page 5


  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Question Paper 2014 – Outside Delhi (Set 3) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. It is not possible for an alien DNA to become part of a chromosome anywhere 
along its length and replicate normally because the replication process begins at a 
particular spot called the origin of replication. Also, replication in eukaryotes occurs 
in the nucleus during the S phase of the cell cycle when the chromosomes are in their 
extended form. 
  
2. Ans. Segregation of an independent pair of chromosomes occurs during the M phase 
(mitotic phase) of cell division. Homologous chromosomes line up independently on 
the metaphase plate. 
 
3. Ans.  SCP (single cell protein) is a microbial biomass rich in high-quality protein. It is 
used as an alternate source of protein and is a valuable supplement in human diet. 
Cells from a variety of microorganisms such as bacteria, yeasts, filamentous fungi and 
algae are treated in various ways and used as food to supplement proteins. 
  
4. Ans. Pollen grains of many species, allergic diseases and bronchial afflictions in some 
people. The pollen grains of Parthenium or carrot grass which came to India as 
contaminant with imported wheat cause pollen allergy.  
 
5. Ans. Glomus exhibits symbiotic association with higher plants called mycorrhiza. The 
root of the plant provides food and shelter to the fungus, and in return, the fungus 
helps the plant in solubilisation and absorption of minerals, water uptake and 
protection against pathogenic fungi.  
  
6. Ans. Gause’s competitive exclusion principle states that two closely related species 
competing for the same resources cannot co-exist indefinitely and the competitively 
inferior will be eliminated eventually. 
 
7. Ans. Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
8. Ans. Mammalian insulin is synthesised as a prohormone which undergoes 
processing to become fully mature and functional insulin molecule. The prohormone 
  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
SECTION B 
9. Ans. The scientific name of fruit fly is Drosophila melanogaster. Morgan preferred  
           to work with fruit fly for his experiments because 
(i) It is simple and convenient to breed under laboratory conditions throughout 
the year. 
(ii) Its generation time is only 10–12 days. 
(iii) It breeds quickly and prolifically and so produces large progeny after each 
mating. 
(iv) Its contrasting features are easily observable. 
OR 
Linkage and crossing over of genes are alternatives of each other. Linkage is the 
tendency of the genes present in the same chromosome to stay together during 
hereditary transmission, while crossing over is the mutual exchange of segments of non-
sister chromatids of homologous chromosomes during the process of meiosis. 
An example of linkage: A double dominant female Drosophila homozygous for red eyes 
and normal wings is crossed with a double recessive male Drosophila homozygous for 
purple eyes and vestigial wings. The F 1 flies are heterozygous red-eyed and normal 
winged. It is then test crossed with a double recessive male having purple eyes and 
vestigial wings. The F 2 generation comprises two types of flies—red-eyed, normal 
winged and purple eyed, vestigial winged in the ratio of 1:1. No recombinant types are 
formed because linkage is complete and no crossing over occurs. 
An example of crossing over: A double dominant sweet pea plant homozygous for blue 
flowers and long pollen grains is crossed with a double recessive plant homozygous for 
red flowers and round pollen grains. The F 1 flies are heterozygous blue flowered and 
long pollen grains. It is then crossed with a double recessive plant having red flowers 
and round pollen grains. The F 2 generation of plants have new combination of traits—
blue flowers and round pollen grains and red flowers and long pollen grains. This is due 
to crossing over, i.e. separation of genes for flower colour and form of pollen grains 
during gamete formation. 
 
10.  Ans. Symptoms of Ascariasis: 
(i) Abdominal discomfort 
(ii) Colic pain 
(iii) Fever 
(iv) Indigestion 
(v) Diarrhoea 
(vi) Vomiting 
 
A healthy human being may acquire this infection directly and orally. It can occur 
through contaminated water, vegetables and fruits. 
 
 
  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
 
11.  Ans. Nucleopolyhedroviruses are biocontrol agents and useful in controlling many 
insects and arthropods. They are species-specific narrow spectrum bioinsecticides 
and have no negative impacts on plants and other organisms or even non-target 
insects. 
 
12.  Ans.   
 
 
 
13.  Ans. Mutualism exists between fig tree and its pollinator species, wasp, where both 
individuals are benefited. A fig species can be pollinated only by its partner wasp 
species and no other species. The female wasp uses the fruit as the egg-laying site 
and the developing seeds within the fruit for nourishing its larvae. The wasp 
pollinates the fig inflorescence while finding egg-laying sites, and in turn, fig offers 
the wasp developing seeds as food for the developing larvae. 
14.  Ans.  
a. Biological products: Many human diseases are controlled by biological products. 
The transgenic animals which produce these products are introduced with DNA 
which codes for a particular product such as human protein (a-I-antitrypsin) for 
treating emphysema. In 1997, the first transgenic cow (Rosie) was produced, 
capable of secreting human protein-enriched milk. The milk contained the human 
alpha-lactalbumin and was nutritionally a more balanced product for human 
babies than cow milk. 
b. Chemical safety testing: The transgenic animals are tested to study the sensitivity 
of toxic substances. Toxicity testing in such animals helps obtain results in less 
time. 
 
15.  Ans. Restriction endonuclease functions by recognising its specific sequence. It 
binds to the DNA and cuts each to the two strands of the double helix at specific 
points in their sugar phosphate backbones. These enzymes cut the strand of DNA 
between the same two bases on the opposite strands leaving a single-stranded 
portion at their ends. These overhanging stretches are called sticky ends on each 
strand. The enzyme DNA ligase functions depending on the stickiness of these ends. 
For example, restriction endonuclease EcoRI found in the colon bacteria E. coli 
recognises the base sequence GAATTC in the DNA duplex and cuts its strands 
between G and A. 
  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
 
 
  
16.  Ans. Factors responsible for conferring stability to the double helix structure of  
            DNA are 
a. The two strands of DNA separated by heating come together when appropriate 
conditions are provided. 
b. The presence of thymine at the place of uracil confirms additional stability to 
DNA. 
 
17.  Ans.  
(a) When the red and white flowers varieties of snapdragon are crossed, the F 1 
progeny exhibits pink colour flowers. It is not known as blending inheritance 
because in blending inheritance, the characters are mixed in the offspring and do 
not segregate. 
(b) This phenomenon is known as incomplete dominance. 
 
18.  Ans. The high concentration of LH surge induces the mature Graafian follicle to burst 
and eject its egg into the fallopian tube. This is called ovulation. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
CBSE XII |  Biology 
Board Paper 2014 – Outside Delhi – Set 3 (Solution) 
 
     
SECTION C 
19. Ans. The function of the reservoir is to meet the deficit which occurs because of an 
imbalance in the rate of influx and efflux. 
Carbon cycle in nature: 
(i) The main source of carbon in this Universe is CO 2 which is dissolved in water 
and present in air (0.03–0.04%). 
(ii) Plants take up carbon dioxide from the atmosphere and form organic 
compounds during photosynthesis. These organic compounds are transferred to 
animals as their food. 
(iii) The carbon dioxide is returned to the atmosphere during respiration, decay and 
combustion of plants and animals. 
(iv) The organic compounds of plants and animals are buried in the deep soil where 
they are acted by decomposers to change them in petroleum, coal, oil and 
carbonate rocks. These substances on their combustion release carbon dioxide 
in the atmosphere.  
(v) Some carbon dioxide is found in the dissolved state in water. This gets converted 
to calcium carbonate in limestone. The weathering and combustion of 
carbonate-containing rocks or treatment of their minerals give CO 2. 
(vi) The hot springs and volcanic eruptions also give out CO 2 in the atmosphere.