CBSE Biology Past year paper Delhi (Set - 1) Solutions - 2013, Class 12 | Additional Study Material for NEET PDF Download

 Page 1


  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2013 – Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. An anther with malfunctioning tapetum often fails to produce viable 
gametophytes because the tapetum provides nutritive materials to the 
dividing microsporocytes. 
 
2. Ans. Sharing of injection needles between two individuals is not 
recommended because it causes fatal and dangerous diseases such as AIDS 
and hepatitis which are incurable. 
 
3. Ans. DNA-dependent DNA polymerase is the enzyme which polymerises the 
DNA  
               strand in the 5' to 3' direction resulting in continuous and discontinuous     
               replication. 
 
4. Ans. Examples of convergent evolution are 
(i) Wings of insect, bird and bat 
(ii) Australian marsupials and placental mammals 
 
5. Ans. MOET stands for multiple ovulation embryo transfer technology which is 
a programme for herd improvement. The importance of MOET is to increase 
herd size in a short time.  
 
6. Ans. Cellulase enzyme is used for isolating genetic material from plant cells 
and not from animal cells because it breaks down the plant cell  
 wall made of cellulose. Animal cells do not have a cell wall. 
 
7. Ans.  
(a) 50,000 different strains of rice: Genetic diversity 
(b) Estuarine and alpine meadows: Ecological diversity 
 
8. Ans. The equation of net primary productivity of an ecosystem is 
                 NPP = GPP - R 
where NPP = Net primary productivity 
                 GPP = Gross primary productivity 
            R = Respiratory rate 
 
Page 2


  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2013 – Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. An anther with malfunctioning tapetum often fails to produce viable 
gametophytes because the tapetum provides nutritive materials to the 
dividing microsporocytes. 
 
2. Ans. Sharing of injection needles between two individuals is not 
recommended because it causes fatal and dangerous diseases such as AIDS 
and hepatitis which are incurable. 
 
3. Ans. DNA-dependent DNA polymerase is the enzyme which polymerises the 
DNA  
               strand in the 5' to 3' direction resulting in continuous and discontinuous     
               replication. 
 
4. Ans. Examples of convergent evolution are 
(i) Wings of insect, bird and bat 
(ii) Australian marsupials and placental mammals 
 
5. Ans. MOET stands for multiple ovulation embryo transfer technology which is 
a programme for herd improvement. The importance of MOET is to increase 
herd size in a short time.  
 
6. Ans. Cellulase enzyme is used for isolating genetic material from plant cells 
and not from animal cells because it breaks down the plant cell  
 wall made of cellulose. Animal cells do not have a cell wall. 
 
7. Ans.  
(a) 50,000 different strains of rice: Genetic diversity 
(b) Estuarine and alpine meadows: Ecological diversity 
 
8. Ans. The equation of net primary productivity of an ecosystem is 
                 NPP = GPP - R 
where NPP = Net primary productivity 
                 GPP = Gross primary productivity 
            R = Respiratory rate 
 
  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
SECTION B 
 
9. Ans. Geitonogamy is a kind of pollination in which the pollen grains are  
              transferred from the anther of a flower to the stigma of another flower on the 
same plant. It usually occurs in plants which show monoecious condition in 
which male and female flowers are borne on the same plant. 
The plants are genetically autogamous as the gametes come from the same 
parent plant, but because the pollen grains are being transferred to a different 
flower which needs a pollinating agent, it is functionally an example of cross-
pollination. 
 
10. Ans. Chorionic villi are finger-like projections which arise from the 
trophoblast layer and develop in the zygote after it has undergone 
implantation. 
      Functions of chorionic villi: 
(a) They take part in the formation of the placenta, which is the connecting 
link between the mother and the foetus. 
(b) They supply oxygen and nutrients to the growing embryo. 
 
11. Ans. In a cross between two tall pea plants, some offspring produced were 
dwarf which ensures that both parents are heterozygous (Tt). 
 
 
Phenotypic ratio: 3:1 
Genotypic ratio: 1:2:1 
 
12. Ans. Sneezing and wheezing in a particular environment and their sudden 
disappearance in another environment is due to allergy to pollen and mites. 
When the body is exposed to an antigen, a substance which causes the 
immune system to make antibodies against it, a complex set of reactions 
begins. The job of the antibodies is to detect and destroy substances which 
cause disease and sickness. In allergic reactions, the antibody is 
immunoglobulin E or IgE. 
 
 
Page 3


  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2013 – Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. An anther with malfunctioning tapetum often fails to produce viable 
gametophytes because the tapetum provides nutritive materials to the 
dividing microsporocytes. 
 
2. Ans. Sharing of injection needles between two individuals is not 
recommended because it causes fatal and dangerous diseases such as AIDS 
and hepatitis which are incurable. 
 
3. Ans. DNA-dependent DNA polymerase is the enzyme which polymerises the 
DNA  
               strand in the 5' to 3' direction resulting in continuous and discontinuous     
               replication. 
 
4. Ans. Examples of convergent evolution are 
(i) Wings of insect, bird and bat 
(ii) Australian marsupials and placental mammals 
 
5. Ans. MOET stands for multiple ovulation embryo transfer technology which is 
a programme for herd improvement. The importance of MOET is to increase 
herd size in a short time.  
 
6. Ans. Cellulase enzyme is used for isolating genetic material from plant cells 
and not from animal cells because it breaks down the plant cell  
 wall made of cellulose. Animal cells do not have a cell wall. 
 
7. Ans.  
(a) 50,000 different strains of rice: Genetic diversity 
(b) Estuarine and alpine meadows: Ecological diversity 
 
8. Ans. The equation of net primary productivity of an ecosystem is 
                 NPP = GPP - R 
where NPP = Net primary productivity 
                 GPP = Gross primary productivity 
            R = Respiratory rate 
 
  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
SECTION B 
 
9. Ans. Geitonogamy is a kind of pollination in which the pollen grains are  
              transferred from the anther of a flower to the stigma of another flower on the 
same plant. It usually occurs in plants which show monoecious condition in 
which male and female flowers are borne on the same plant. 
The plants are genetically autogamous as the gametes come from the same 
parent plant, but because the pollen grains are being transferred to a different 
flower which needs a pollinating agent, it is functionally an example of cross-
pollination. 
 
10. Ans. Chorionic villi are finger-like projections which arise from the 
trophoblast layer and develop in the zygote after it has undergone 
implantation. 
      Functions of chorionic villi: 
(a) They take part in the formation of the placenta, which is the connecting 
link between the mother and the foetus. 
(b) They supply oxygen and nutrients to the growing embryo. 
 
11. Ans. In a cross between two tall pea plants, some offspring produced were 
dwarf which ensures that both parents are heterozygous (Tt). 
 
 
Phenotypic ratio: 3:1 
Genotypic ratio: 1:2:1 
 
12. Ans. Sneezing and wheezing in a particular environment and their sudden 
disappearance in another environment is due to allergy to pollen and mites. 
When the body is exposed to an antigen, a substance which causes the 
immune system to make antibodies against it, a complex set of reactions 
begins. The job of the antibodies is to detect and destroy substances which 
cause disease and sickness. In allergic reactions, the antibody is 
immunoglobulin E or IgE. 
 
 
  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
 
13. Ans. Two commonly used bioreactors are batch type and stirred tank 
bioreactors. 
The importance of using bioreactors is 
(i) It provides a large volume for cultures. Thus, products are obtained in 
high quantity.  
(ii) It also provides the optimal conditions for achieving the growth of 
desired products such as temperature, pH, vitamins and oxygen. 
 
14. Ans. Adenosine deaminase enzyme (ADA) is very crucial for the proper 
functioning of the immune system. The deficiency of ADA causes severe 
combined immunodeficiency disease. The patients lack functional T-
lymphocytes and fail to fight infectious pathogens. A permanent cure for ADA 
deficiency is gene therapy in which lymphocytes are extracted from the 
patient’s bone marrow and a normal functional gene for ADA is introduced 
into the lymphocytes with the help of a retrovirus. 
 
15.  Ans. 
(i) PCR: Polymerase chain reaction  
Application of PCR: It is useful to detect genetic disease in the foetus 
before birth. 
(ii) ELISA: Enzyme-linked immunosorbent assay 
Application of ELISA: It is useful in the early diagnosis of diseases using 
antigen–antibody interactions.  
OR 
(a) Exonucleases remove nucleotides from the ends of the DNA, whereas 
endonucleases make cuts at specific positions within the DNA. 
(b) Each restriction endonuclease inspects the DNA molecule in search of a 
specific recognition sequence. When it gets its specific recognition 
sequence, it binds to the site and cuts each of the two strands of the double 
helix at specific points by hydrolysing the phosphodiester backbones.   
 
16. Ans. Two sources of e-wastes are 
(i) Parts of computers and television sets 
(ii) Smart phones, parts of air conditioners and refrigerators 
Two ways for disposal of e-wastes are 
(i) Recycling of e-wastes 
(ii) Incineration of e-wastes, i.e. burning e-wastes completely into ashes 
 
 
 
 
 
Page 4


  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2013 – Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. An anther with malfunctioning tapetum often fails to produce viable 
gametophytes because the tapetum provides nutritive materials to the 
dividing microsporocytes. 
 
2. Ans. Sharing of injection needles between two individuals is not 
recommended because it causes fatal and dangerous diseases such as AIDS 
and hepatitis which are incurable. 
 
3. Ans. DNA-dependent DNA polymerase is the enzyme which polymerises the 
DNA  
               strand in the 5' to 3' direction resulting in continuous and discontinuous     
               replication. 
 
4. Ans. Examples of convergent evolution are 
(i) Wings of insect, bird and bat 
(ii) Australian marsupials and placental mammals 
 
5. Ans. MOET stands for multiple ovulation embryo transfer technology which is 
a programme for herd improvement. The importance of MOET is to increase 
herd size in a short time.  
 
6. Ans. Cellulase enzyme is used for isolating genetic material from plant cells 
and not from animal cells because it breaks down the plant cell  
 wall made of cellulose. Animal cells do not have a cell wall. 
 
7. Ans.  
(a) 50,000 different strains of rice: Genetic diversity 
(b) Estuarine and alpine meadows: Ecological diversity 
 
8. Ans. The equation of net primary productivity of an ecosystem is 
                 NPP = GPP - R 
where NPP = Net primary productivity 
                 GPP = Gross primary productivity 
            R = Respiratory rate 
 
  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
SECTION B 
 
9. Ans. Geitonogamy is a kind of pollination in which the pollen grains are  
              transferred from the anther of a flower to the stigma of another flower on the 
same plant. It usually occurs in plants which show monoecious condition in 
which male and female flowers are borne on the same plant. 
The plants are genetically autogamous as the gametes come from the same 
parent plant, but because the pollen grains are being transferred to a different 
flower which needs a pollinating agent, it is functionally an example of cross-
pollination. 
 
10. Ans. Chorionic villi are finger-like projections which arise from the 
trophoblast layer and develop in the zygote after it has undergone 
implantation. 
      Functions of chorionic villi: 
(a) They take part in the formation of the placenta, which is the connecting 
link between the mother and the foetus. 
(b) They supply oxygen and nutrients to the growing embryo. 
 
11. Ans. In a cross between two tall pea plants, some offspring produced were 
dwarf which ensures that both parents are heterozygous (Tt). 
 
 
Phenotypic ratio: 3:1 
Genotypic ratio: 1:2:1 
 
12. Ans. Sneezing and wheezing in a particular environment and their sudden 
disappearance in another environment is due to allergy to pollen and mites. 
When the body is exposed to an antigen, a substance which causes the 
immune system to make antibodies against it, a complex set of reactions 
begins. The job of the antibodies is to detect and destroy substances which 
cause disease and sickness. In allergic reactions, the antibody is 
immunoglobulin E or IgE. 
 
 
  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
 
13. Ans. Two commonly used bioreactors are batch type and stirred tank 
bioreactors. 
The importance of using bioreactors is 
(i) It provides a large volume for cultures. Thus, products are obtained in 
high quantity.  
(ii) It also provides the optimal conditions for achieving the growth of 
desired products such as temperature, pH, vitamins and oxygen. 
 
14. Ans. Adenosine deaminase enzyme (ADA) is very crucial for the proper 
functioning of the immune system. The deficiency of ADA causes severe 
combined immunodeficiency disease. The patients lack functional T-
lymphocytes and fail to fight infectious pathogens. A permanent cure for ADA 
deficiency is gene therapy in which lymphocytes are extracted from the 
patient’s bone marrow and a normal functional gene for ADA is introduced 
into the lymphocytes with the help of a retrovirus. 
 
15.  Ans. 
(i) PCR: Polymerase chain reaction  
Application of PCR: It is useful to detect genetic disease in the foetus 
before birth. 
(ii) ELISA: Enzyme-linked immunosorbent assay 
Application of ELISA: It is useful in the early diagnosis of diseases using 
antigen–antibody interactions.  
OR 
(a) Exonucleases remove nucleotides from the ends of the DNA, whereas 
endonucleases make cuts at specific positions within the DNA. 
(b) Each restriction endonuclease inspects the DNA molecule in search of a 
specific recognition sequence. When it gets its specific recognition 
sequence, it binds to the site and cuts each of the two strands of the double 
helix at specific points by hydrolysing the phosphodiester backbones.   
 
16. Ans. Two sources of e-wastes are 
(i) Parts of computers and television sets 
(ii) Smart phones, parts of air conditioners and refrigerators 
Two ways for disposal of e-wastes are 
(i) Recycling of e-wastes 
(ii) Incineration of e-wastes, i.e. burning e-wastes completely into ashes 
 
 
 
 
 
  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
 
17. Ans. The pyramid of energy is a graphical representation of the amount of 
accumulated energy per unit area in different trophic levels of a food chain. 
An energy pyramid is always upright because there is a gradual decrease in 
energy at successive trophic levels. This happens because according to the 
10% law of energy transfer, only 10% of the total energy is transferred from 
one trophic level to another.   
 
18.  Ans. Small animals are cold-blooded organisms. They do not have constant 
body temperature and need to spend energy to generate heat through 
metabolism. So, they are rarely found in the polar regions. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Page 5


  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2013 – Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. An anther with malfunctioning tapetum often fails to produce viable 
gametophytes because the tapetum provides nutritive materials to the 
dividing microsporocytes. 
 
2. Ans. Sharing of injection needles between two individuals is not 
recommended because it causes fatal and dangerous diseases such as AIDS 
and hepatitis which are incurable. 
 
3. Ans. DNA-dependent DNA polymerase is the enzyme which polymerises the 
DNA  
               strand in the 5' to 3' direction resulting in continuous and discontinuous     
               replication. 
 
4. Ans. Examples of convergent evolution are 
(i) Wings of insect, bird and bat 
(ii) Australian marsupials and placental mammals 
 
5. Ans. MOET stands for multiple ovulation embryo transfer technology which is 
a programme for herd improvement. The importance of MOET is to increase 
herd size in a short time.  
 
6. Ans. Cellulase enzyme is used for isolating genetic material from plant cells 
and not from animal cells because it breaks down the plant cell  
 wall made of cellulose. Animal cells do not have a cell wall. 
 
7. Ans.  
(a) 50,000 different strains of rice: Genetic diversity 
(b) Estuarine and alpine meadows: Ecological diversity 
 
8. Ans. The equation of net primary productivity of an ecosystem is 
                 NPP = GPP - R 
where NPP = Net primary productivity 
                 GPP = Gross primary productivity 
            R = Respiratory rate 
 
  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
SECTION B 
 
9. Ans. Geitonogamy is a kind of pollination in which the pollen grains are  
              transferred from the anther of a flower to the stigma of another flower on the 
same plant. It usually occurs in plants which show monoecious condition in 
which male and female flowers are borne on the same plant. 
The plants are genetically autogamous as the gametes come from the same 
parent plant, but because the pollen grains are being transferred to a different 
flower which needs a pollinating agent, it is functionally an example of cross-
pollination. 
 
10. Ans. Chorionic villi are finger-like projections which arise from the 
trophoblast layer and develop in the zygote after it has undergone 
implantation. 
      Functions of chorionic villi: 
(a) They take part in the formation of the placenta, which is the connecting 
link between the mother and the foetus. 
(b) They supply oxygen and nutrients to the growing embryo. 
 
11. Ans. In a cross between two tall pea plants, some offspring produced were 
dwarf which ensures that both parents are heterozygous (Tt). 
 
 
Phenotypic ratio: 3:1 
Genotypic ratio: 1:2:1 
 
12. Ans. Sneezing and wheezing in a particular environment and their sudden 
disappearance in another environment is due to allergy to pollen and mites. 
When the body is exposed to an antigen, a substance which causes the 
immune system to make antibodies against it, a complex set of reactions 
begins. The job of the antibodies is to detect and destroy substances which 
cause disease and sickness. In allergic reactions, the antibody is 
immunoglobulin E or IgE. 
 
 
  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
 
13. Ans. Two commonly used bioreactors are batch type and stirred tank 
bioreactors. 
The importance of using bioreactors is 
(i) It provides a large volume for cultures. Thus, products are obtained in 
high quantity.  
(ii) It also provides the optimal conditions for achieving the growth of 
desired products such as temperature, pH, vitamins and oxygen. 
 
14. Ans. Adenosine deaminase enzyme (ADA) is very crucial for the proper 
functioning of the immune system. The deficiency of ADA causes severe 
combined immunodeficiency disease. The patients lack functional T-
lymphocytes and fail to fight infectious pathogens. A permanent cure for ADA 
deficiency is gene therapy in which lymphocytes are extracted from the 
patient’s bone marrow and a normal functional gene for ADA is introduced 
into the lymphocytes with the help of a retrovirus. 
 
15.  Ans. 
(i) PCR: Polymerase chain reaction  
Application of PCR: It is useful to detect genetic disease in the foetus 
before birth. 
(ii) ELISA: Enzyme-linked immunosorbent assay 
Application of ELISA: It is useful in the early diagnosis of diseases using 
antigen–antibody interactions.  
OR 
(a) Exonucleases remove nucleotides from the ends of the DNA, whereas 
endonucleases make cuts at specific positions within the DNA. 
(b) Each restriction endonuclease inspects the DNA molecule in search of a 
specific recognition sequence. When it gets its specific recognition 
sequence, it binds to the site and cuts each of the two strands of the double 
helix at specific points by hydrolysing the phosphodiester backbones.   
 
16. Ans. Two sources of e-wastes are 
(i) Parts of computers and television sets 
(ii) Smart phones, parts of air conditioners and refrigerators 
Two ways for disposal of e-wastes are 
(i) Recycling of e-wastes 
(ii) Incineration of e-wastes, i.e. burning e-wastes completely into ashes 
 
 
 
 
 
  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
 
17. Ans. The pyramid of energy is a graphical representation of the amount of 
accumulated energy per unit area in different trophic levels of a food chain. 
An energy pyramid is always upright because there is a gradual decrease in 
energy at successive trophic levels. This happens because according to the 
10% law of energy transfer, only 10% of the total energy is transferred from 
one trophic level to another.   
 
18.  Ans. Small animals are cold-blooded organisms. They do not have constant 
body temperature and need to spend energy to generate heat through 
metabolism. So, they are rarely found in the polar regions. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
CBSE XII  |  Biology  
Board Paper 2013 – Delhi – Set 1 (Solution) 
 
     
 
SECTION C 
 
19.  Ans.  
 
Structure of human sperm 
20. Ans. Effect of anthropogenic actions on organic evolution can be explained by 
the following examples: 
(i) Use of chemicals such as mosquito repellents, pesticides and fungicides 
has enabled the selection of mosquito and pest species which are better 
adaptive to the environment. Because of the anthropogenic action, the rate 
of evolution has increased, and as a result, in a very short time, a new 
species has evolved which can resist chemicals. 
(ii) Use of antibiotics has increased the rate of evolution of bacteria and virus. 
Among many species of bacteria, mutation occurred in few individuals. 
Because of selection using antibiotics, individuals who have got resistive 
properties got selected and produced a large number of progeny. 
 
21.  Ans. 
(a) In multiple allelism, a character is controlled by three or more alleles. 
Because the ABO blood group has three alleles—i, I
A
 and I
B
, it is 
considered a good example of multiple alleles.  
 
(b) Genotype of mother: I
A
  I
A
; Genotype of father: I
B
  I
B
 
            Parents        I
A
  I
A
       ×      I
B
  I
B
 
                      Gametes  I
A
                      I
B
 
 
 
            F 1 Progeny                I
A
  I
B
 
    Blood group of the child will be AB. This is due to co-dominance, where allele                                
    I
A
, for A-type blood group is co-dominant with its allele I
B
 for the B-type blood  
    group.