CBSE Biology Outside Delhi Past year paper (Set - 2) Solutions - 2014, Class 12 | Additional Study Material for NEET PDF Download

 Page 1


  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2014 – Outside Delhi (Set 2) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. Gambusia is a natural enemy of larva and pupa of mosquitoes as it feeds upon 
them and thus helps control the breeding of mosquitoes. So, it is introduced into 
drains and ponds. 
  
2. 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. 
 
3. Ans.  Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
4. Ans. Mammalian insulin is synthesised as a prohormone which undergoes 
processing to become a fully mature and functional insulin molecule. The 
prohormone contains an extra chain called C peptide which is removed during the 
conversion of prohormone to the mature hormone, insulin. 
 
5. 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. 
  
6. Ans. The secondary immune response is more intense than the primary immune 
response in humans because the memory B cells deal with the invading microbes by 
producing antibodies. The cells of the body remember that they have previously 
encountered this type of infection. 
 
7. Ans. Analogous structures are the result of convergent evolution as they have arisen 
in the evolutionary process through adaptation of quite different organisms to a 
similar mode of life. 
  
8. Ans.  
(a) Bulbil of Agave 
(b)  Leaf bud of Bryophyllum 
Page 2


  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2014 – Outside Delhi (Set 2) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. Gambusia is a natural enemy of larva and pupa of mosquitoes as it feeds upon 
them and thus helps control the breeding of mosquitoes. So, it is introduced into 
drains and ponds. 
  
2. 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. 
 
3. Ans.  Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
4. Ans. Mammalian insulin is synthesised as a prohormone which undergoes 
processing to become a fully mature and functional insulin molecule. The 
prohormone contains an extra chain called C peptide which is removed during the 
conversion of prohormone to the mature hormone, insulin. 
 
5. 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. 
  
6. Ans. The secondary immune response is more intense than the primary immune 
response in humans because the memory B cells deal with the invading microbes by 
producing antibodies. The cells of the body remember that they have previously 
encountered this type of infection. 
 
7. Ans. Analogous structures are the result of convergent evolution as they have arisen 
in the evolutionary process through adaptation of quite different organisms to a 
similar mode of life. 
  
8. Ans.  
(a) Bulbil of Agave 
(b)  Leaf bud of Bryophyllum 
  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
SECTION B 
9. 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. 
 
10. 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 
with 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 has a 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. 
 
11.  Ans.  
Page 3


  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2014 – Outside Delhi (Set 2) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. Gambusia is a natural enemy of larva and pupa of mosquitoes as it feeds upon 
them and thus helps control the breeding of mosquitoes. So, it is introduced into 
drains and ponds. 
  
2. 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. 
 
3. Ans.  Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
4. Ans. Mammalian insulin is synthesised as a prohormone which undergoes 
processing to become a fully mature and functional insulin molecule. The 
prohormone contains an extra chain called C peptide which is removed during the 
conversion of prohormone to the mature hormone, insulin. 
 
5. 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. 
  
6. Ans. The secondary immune response is more intense than the primary immune 
response in humans because the memory B cells deal with the invading microbes by 
producing antibodies. The cells of the body remember that they have previously 
encountered this type of infection. 
 
7. Ans. Analogous structures are the result of convergent evolution as they have arisen 
in the evolutionary process through adaptation of quite different organisms to a 
similar mode of life. 
  
8. Ans.  
(a) Bulbil of Agave 
(b)  Leaf bud of Bryophyllum 
  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
SECTION B 
9. 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. 
 
10. 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 
with 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 has a 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. 
 
11.  Ans.  
  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
(a) In prokaryotes, the structural genes are polycistronic and continuous, whereas 
in eukaryotes, the structural genes are monocistronic and split. 
(b) In prokaryotes, there is a single DNA-dependent RNA polymerase which 
synthesises all the types of RNAs (mRNA, tRNA and rRNA), whereas eukaryotes 
have three RNA polymerases—Pol I, Pol II and Pol III—to synthesise different 
types of RNAs. 
12. Ans.   
(a) When the red and white flower 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. 
 
13. Ans.  
(a) Sertoli cells are found in the seminiferous epithelium within the seminiferous 
tubules of the testes. They provide nutrition and shape to the developing germ 
cells and spermatozoa. 
(b) Leydig cells are found in the connective tissue around the seminiferous tubules. 
They secrete testosterone into the blood. 
  
14. Ans.  
 
 
15. 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. 
 
16. 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. 
She was 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. 
Page 4


  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2014 – Outside Delhi (Set 2) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. Gambusia is a natural enemy of larva and pupa of mosquitoes as it feeds upon 
them and thus helps control the breeding of mosquitoes. So, it is introduced into 
drains and ponds. 
  
2. 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. 
 
3. Ans.  Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
4. Ans. Mammalian insulin is synthesised as a prohormone which undergoes 
processing to become a fully mature and functional insulin molecule. The 
prohormone contains an extra chain called C peptide which is removed during the 
conversion of prohormone to the mature hormone, insulin. 
 
5. 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. 
  
6. Ans. The secondary immune response is more intense than the primary immune 
response in humans because the memory B cells deal with the invading microbes by 
producing antibodies. The cells of the body remember that they have previously 
encountered this type of infection. 
 
7. Ans. Analogous structures are the result of convergent evolution as they have arisen 
in the evolutionary process through adaptation of quite different organisms to a 
similar mode of life. 
  
8. Ans.  
(a) Bulbil of Agave 
(b)  Leaf bud of Bryophyllum 
  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
SECTION B 
9. 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. 
 
10. 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 
with 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 has a 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. 
 
11.  Ans.  
  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
(a) In prokaryotes, the structural genes are polycistronic and continuous, whereas 
in eukaryotes, the structural genes are monocistronic and split. 
(b) In prokaryotes, there is a single DNA-dependent RNA polymerase which 
synthesises all the types of RNAs (mRNA, tRNA and rRNA), whereas eukaryotes 
have three RNA polymerases—Pol I, Pol II and Pol III—to synthesise different 
types of RNAs. 
12. Ans.   
(a) When the red and white flower 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. 
 
13. Ans.  
(a) Sertoli cells are found in the seminiferous epithelium within the seminiferous 
tubules of the testes. They provide nutrition and shape to the developing germ 
cells and spermatozoa. 
(b) Leydig cells are found in the connective tissue around the seminiferous tubules. 
They secrete testosterone into the blood. 
  
14. Ans.  
 
 
15. 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. 
 
16. 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. 
She was 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. 
  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
(b) Chemical safety testing: Transgenic animals are tested to study the sensitivity of 
the toxic substances. Toxicity testing in such animals helps obtain results in less 
time. 
17. 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, the 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. 
 
 
18. 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. 
 
 
 
 
 
 
 
 
 
 
Page 5


  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2014 – Outside Delhi (Set 2) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. Gambusia is a natural enemy of larva and pupa of mosquitoes as it feeds upon 
them and thus helps control the breeding of mosquitoes. So, it is introduced into 
drains and ponds. 
  
2. 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. 
 
3. Ans.  Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
4. Ans. Mammalian insulin is synthesised as a prohormone which undergoes 
processing to become a fully mature and functional insulin molecule. The 
prohormone contains an extra chain called C peptide which is removed during the 
conversion of prohormone to the mature hormone, insulin. 
 
5. 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. 
  
6. Ans. The secondary immune response is more intense than the primary immune 
response in humans because the memory B cells deal with the invading microbes by 
producing antibodies. The cells of the body remember that they have previously 
encountered this type of infection. 
 
7. Ans. Analogous structures are the result of convergent evolution as they have arisen 
in the evolutionary process through adaptation of quite different organisms to a 
similar mode of life. 
  
8. Ans.  
(a) Bulbil of Agave 
(b)  Leaf bud of Bryophyllum 
  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
SECTION B 
9. 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. 
 
10. 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 
with 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 has a 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. 
 
11.  Ans.  
  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
(a) In prokaryotes, the structural genes are polycistronic and continuous, whereas 
in eukaryotes, the structural genes are monocistronic and split. 
(b) In prokaryotes, there is a single DNA-dependent RNA polymerase which 
synthesises all the types of RNAs (mRNA, tRNA and rRNA), whereas eukaryotes 
have three RNA polymerases—Pol I, Pol II and Pol III—to synthesise different 
types of RNAs. 
12. Ans.   
(a) When the red and white flower 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. 
 
13. Ans.  
(a) Sertoli cells are found in the seminiferous epithelium within the seminiferous 
tubules of the testes. They provide nutrition and shape to the developing germ 
cells and spermatozoa. 
(b) Leydig cells are found in the connective tissue around the seminiferous tubules. 
They secrete testosterone into the blood. 
  
14. Ans.  
 
 
15. 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. 
 
16. 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. 
She was 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. 
  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
(b) Chemical safety testing: Transgenic animals are tested to study the sensitivity of 
the toxic substances. Toxicity testing in such animals helps obtain results in less 
time. 
17. 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, the 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. 
 
 
18. 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. 
 
 
 
 
 
 
 
 
 
 
  
 
CBSE Board XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 2 (Solution) 
 
     
SECTION C 
19. Ans.  
 
No. Syndrome Cause Characteristics of affected 
individuals 
Sex/Male/Fe
male/Both 
1. Down’s Triso
my of 
21 
(i) Broad forehead 
(ii) Permanently open mouth, 
protruding and furrowed 
tongue and projecting lower lip 
Both 
2. Klinefelter’
s 
XXY Overall masculine development Male 
3. Turner’s 45 
with 
XO 
(i) Short stature females with 
webbed neck 
(ii) Body hair absent 
Female 
 
20. Ans.  Pedigree analysis is done in the study of human genetics as 
(i) It helps genetic counsellors to guide couples about the possibility of having 
children with genetic defects such as haemophilia. 
(ii) It indicates that Mendel’s principles are also applicable to human genetics 
with some modifications found out later such as quantitative inheritance, 
sex-linked characters and other linkages. 
Pedigree analysis is the study of the pedigree for the transmission of a particular 
trait and finding the possibility of the absence or presence of that trait in the 
homozygous or heterozygous state in a particular individual. 
 
21.  Ans.  
(a) Birth control pills or oral contraceptive pills contain two hormones—
oestrogen and progesterone. They inhibit ovulation and implantation by 
making changes in the cervical mucus impairing its ability to allow the 
passage and transport of sperms and alters the uterine endometrium to 
make it unsuitable for implantation. 
(b) Oral pills have to be taken daily for a period of 21 days starting within the 
first five days of the menstrual cycle.