CBSE Biology Outside Delhi Past year paper (Set - 1) Solutions - 2014, Class 12 | Additional Study Material for NEET PDF Download

 Page 1


  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2014 – Outside Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. The tassels of the corn-cob represent the male part of a plant which produces 
pollen grains. 
     
2. Ans. The contrasting traits with respect to seeds in pea plants are 
(i) Seed shape:  Seed shape is round (dominant) or wrinkled (recessive). 
(ii) Seed colour: Seed colour is yellow (dominant) or green (recessive). 
 
3. 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. 
 
4. 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. 
 
5. 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. 
  
6. Ans. Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
7. 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 species will be eliminated eventually. 
 
8. 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.  
Page 2


  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2014 – Outside Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. The tassels of the corn-cob represent the male part of a plant which produces 
pollen grains. 
     
2. Ans. The contrasting traits with respect to seeds in pea plants are 
(i) Seed shape:  Seed shape is round (dominant) or wrinkled (recessive). 
(ii) Seed colour: Seed colour is yellow (dominant) or green (recessive). 
 
3. 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. 
 
4. 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. 
 
5. 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. 
  
6. Ans. Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
7. 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 species will be eliminated eventually. 
 
8. 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.  
  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
SECTION B 
9. Ans. Human testes are located outside the abdominal cavity to avoid high 
abdominal temperature. The testes are suspended in a pouch called the scrotum. 
 
10.  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. 
 
11.  Ans. Codominance: When both alleles of a pair are fully expressed in a 
heterozygote, the genes and trait are said to be codominant. Example: A person of 
blood group AB is an example of codominance where allele I
A
 for A-type blood is 
codominant with its allele I
B
 for B-type blood. The heterozygote (I
A
I
B
) expresses the 
characteristics of both A and B antigens. 
Multiple allelism: It is a phenomenon which occurs when more than two alleles exist 
at a given locus of a chromosome. In a given individual, only two of these alleles 
occur, one derived from each parent. Example: The ABO blood typing in humans is 
an example of multiple allelism where alleles I
A
, I
B
 and i produce the four 
phenotypes (A, B, AB and O) of blood groups.  
 
12.  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. 
Page 3


  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2014 – Outside Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. The tassels of the corn-cob represent the male part of a plant which produces 
pollen grains. 
     
2. Ans. The contrasting traits with respect to seeds in pea plants are 
(i) Seed shape:  Seed shape is round (dominant) or wrinkled (recessive). 
(ii) Seed colour: Seed colour is yellow (dominant) or green (recessive). 
 
3. 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. 
 
4. 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. 
 
5. 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. 
  
6. Ans. Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
7. 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 species will be eliminated eventually. 
 
8. 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.  
  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
SECTION B 
9. Ans. Human testes are located outside the abdominal cavity to avoid high 
abdominal temperature. The testes are suspended in a pouch called the scrotum. 
 
10.  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. 
 
11.  Ans. Codominance: When both alleles of a pair are fully expressed in a 
heterozygote, the genes and trait are said to be codominant. Example: A person of 
blood group AB is an example of codominance where allele I
A
 for A-type blood is 
codominant with its allele I
B
 for B-type blood. The heterozygote (I
A
I
B
) expresses the 
characteristics of both A and B antigens. 
Multiple allelism: It is a phenomenon which occurs when more than two alleles exist 
at a given locus of a chromosome. In a given individual, only two of these alleles 
occur, one derived from each parent. Example: The ABO blood typing in humans is 
an example of multiple allelism where alleles I
A
, I
B
 and i produce the four 
phenotypes (A, B, AB and O) of blood groups.  
 
12.  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. 
  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
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 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. 
 
13.  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. 
 
14.  Ans. Nucleopolyhedroviruses are biological control agents which attack insects and 
other arthropods. These viruses are excellent candidates for species-specific crosses 
and have no negative impacts on plants and other organisms or even non-target 
insects. 
 
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, 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. 
 
Page 4


  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2014 – Outside Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. The tassels of the corn-cob represent the male part of a plant which produces 
pollen grains. 
     
2. Ans. The contrasting traits with respect to seeds in pea plants are 
(i) Seed shape:  Seed shape is round (dominant) or wrinkled (recessive). 
(ii) Seed colour: Seed colour is yellow (dominant) or green (recessive). 
 
3. 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. 
 
4. 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. 
 
5. 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. 
  
6. Ans. Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
7. 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 species will be eliminated eventually. 
 
8. 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.  
  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
SECTION B 
9. Ans. Human testes are located outside the abdominal cavity to avoid high 
abdominal temperature. The testes are suspended in a pouch called the scrotum. 
 
10.  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. 
 
11.  Ans. Codominance: When both alleles of a pair are fully expressed in a 
heterozygote, the genes and trait are said to be codominant. Example: A person of 
blood group AB is an example of codominance where allele I
A
 for A-type blood is 
codominant with its allele I
B
 for B-type blood. The heterozygote (I
A
I
B
) expresses the 
characteristics of both A and B antigens. 
Multiple allelism: It is a phenomenon which occurs when more than two alleles exist 
at a given locus of a chromosome. In a given individual, only two of these alleles 
occur, one derived from each parent. Example: The ABO blood typing in humans is 
an example of multiple allelism where alleles I
A
, I
B
 and i produce the four 
phenotypes (A, B, AB and O) of blood groups.  
 
12.  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. 
  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
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 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. 
 
13.  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. 
 
14.  Ans. Nucleopolyhedroviruses are biological control agents which attack insects and 
other arthropods. These viruses are excellent candidates for species-specific crosses 
and have no negative impacts on plants and other organisms or even non-target 
insects. 
 
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, 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. 
 
  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
 
 
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. 
(b) Chemical safety testing: Transgenic animals are tested to study the sensitivity of 
toxic substances. Toxicity testing in such animals helps obtain results in less 
time. 
 
17.  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 developing larvae. 
 
18.  Ans.  
 
 
 
 
 
 
 
 
 
 
Page 5


  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2014 – Outside Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. The tassels of the corn-cob represent the male part of a plant which produces 
pollen grains. 
     
2. Ans. The contrasting traits with respect to seeds in pea plants are 
(i) Seed shape:  Seed shape is round (dominant) or wrinkled (recessive). 
(ii) Seed colour: Seed colour is yellow (dominant) or green (recessive). 
 
3. 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. 
 
4. 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. 
 
5. 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. 
  
6. Ans. Lysozyme is used for the isolation of DNA from bacterial cells and chitinase is 
used for the isolation of DNA from fungal cells. 
 
7. 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 species will be eliminated eventually. 
 
8. 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.  
  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
SECTION B 
9. Ans. Human testes are located outside the abdominal cavity to avoid high 
abdominal temperature. The testes are suspended in a pouch called the scrotum. 
 
10.  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. 
 
11.  Ans. Codominance: When both alleles of a pair are fully expressed in a 
heterozygote, the genes and trait are said to be codominant. Example: A person of 
blood group AB is an example of codominance where allele I
A
 for A-type blood is 
codominant with its allele I
B
 for B-type blood. The heterozygote (I
A
I
B
) expresses the 
characteristics of both A and B antigens. 
Multiple allelism: It is a phenomenon which occurs when more than two alleles exist 
at a given locus of a chromosome. In a given individual, only two of these alleles 
occur, one derived from each parent. Example: The ABO blood typing in humans is 
an example of multiple allelism where alleles I
A
, I
B
 and i produce the four 
phenotypes (A, B, AB and O) of blood groups.  
 
12.  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. 
  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
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 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. 
 
13.  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. 
 
14.  Ans. Nucleopolyhedroviruses are biological control agents which attack insects and 
other arthropods. These viruses are excellent candidates for species-specific crosses 
and have no negative impacts on plants and other organisms or even non-target 
insects. 
 
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, 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. 
 
  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
 
 
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. 
(b) Chemical safety testing: Transgenic animals are tested to study the sensitivity of 
toxic substances. Toxicity testing in such animals helps obtain results in less 
time. 
 
17.  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 developing larvae. 
 
18.  Ans.  
 
 
 
 
 
 
 
 
 
 
  
 
CBSE XII  |  Biology 
Board Paper 2014 – Outside Delhi – Set 1 (Solution) 
 
     
SECTION C 
 
19.  Ans. The outbreeding devices in flowering plants which encourage cross-
pollination are 
(i) Dicliny: Flowers are unisexual so that self-pollination is not possible. The 
plants may be monoecious bearing both male and female flowers (e.g. maize) 
or dioecious bearing male and female flowers on individual plants (e.g. 
mulberry, papaya). 
(ii) Prepotency: Pollen grains of another flower germinate more rapidly over the 
stigma than the pollen grains of the same flower. Examples: Apple, grape 
(iii) Self-sterility: Pollen grains of a flower do not germinate on the stigma of the 
same flower because of the presence of similar self-sterile genes. Examples: 
Tobacco, potato, crucifers 
 
OR 
 
A typical angiosperm anther is broad, terminal and bilobed. Each lobe of the anther 
has two pollen sacs which fuse (at maturity) to form a single chamber called the 
thecus, so it is called dithecous. 
A microsporangium is a cylindrical sac which appears circular in the transverse 
section. It contains the following parts: 
(i) Outer wall 
(ii) Central homogeneous sporogenous tissue 
(iii) Epidermis 
(iv) Endothecium 
(v) 1–3 middle layers and tapetum 
The outer three layers perform the function of protection in the younger anther and 
the mechanism of dehiscence in the ripe anther. 
The endothecial cells develop fibrous thickening of a-cellulose on the inner and 
radial walls and die. The innermost layer is called the tapetum. It nourishes the 
developing pollen grain.