CBSE Biology Past year paper Delhi (Set - 1) Solutions - 2010, Class 12 | Additional Study Material for NEET PDF Download

 Page 1


  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2010 – Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. There are four microsporangia or pollen sacs in an anther. In this case, the 
anther will have 400 microspore mother cells. As each microspore mother cell 
forms four pollen grains, 400 microspore mother cells will form 1600 pollen grains 
or male gametophytes. 
 
2. Ans. AUG has dual function. 
(i) It codes for Methionine (Met). 
(ii) It also acts as the initiator codon. 
 
3. Ans. Louis Pasteur disproved the spontaneous generation theory. According to this 
theory, life originated repeatedly from non-living materials spontaneously. 
However, according to Louis Pasteur, life originated from pre-existing organisms of 
their own kind. 
 
4. Ans. On exposure to antigens or vaccines, the antibodies produced in the body 
neutralise the pathogenic agent during infection. The vaccines generate memory B 
cells and T cells during primary response. When the vaccinated person is attacked 
by the same pathogen, the existing memory T or B cells recognise the antigen 
quickly and attack the invaders with a massive production of lymphocytes and 
antibodies. 
 
5. Ans. Cellulase is used for isolating genetic material from plant cells because the cell 
wall of plants is made of cellulose. Animal cells do not have a cell wall or cellulose, so 
cellulase is not required for isolating genetic material from animal cells. 
 
6. Ans. Different viral and bacterial DNA in a host body can be detected by polymerase 
chain reaction (PCR). PCR can detect very low amounts of DNA. PCR is now usually 
used to detect HIV in suspected AIDS patients. It is a good technique to identify 
many other genetic disorders. 
 
7. Ans. If 8 individuals in a laboratory population of 80 fruit flies died during a 
specified time interval (suppose a week), the death rate in the population during 
that period is 8/80 = 0.1 individuals per fruit fly per week. 
 
8. Ans. Reproduction is essential because it enables the continuity of species 
generation after generation and introduces variations in the organisms essential for 
adaptations and evolution. 
 
 
Page 2


  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2010 – Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. There are four microsporangia or pollen sacs in an anther. In this case, the 
anther will have 400 microspore mother cells. As each microspore mother cell 
forms four pollen grains, 400 microspore mother cells will form 1600 pollen grains 
or male gametophytes. 
 
2. Ans. AUG has dual function. 
(i) It codes for Methionine (Met). 
(ii) It also acts as the initiator codon. 
 
3. Ans. Louis Pasteur disproved the spontaneous generation theory. According to this 
theory, life originated repeatedly from non-living materials spontaneously. 
However, according to Louis Pasteur, life originated from pre-existing organisms of 
their own kind. 
 
4. Ans. On exposure to antigens or vaccines, the antibodies produced in the body 
neutralise the pathogenic agent during infection. The vaccines generate memory B 
cells and T cells during primary response. When the vaccinated person is attacked 
by the same pathogen, the existing memory T or B cells recognise the antigen 
quickly and attack the invaders with a massive production of lymphocytes and 
antibodies. 
 
5. Ans. Cellulase is used for isolating genetic material from plant cells because the cell 
wall of plants is made of cellulose. Animal cells do not have a cell wall or cellulose, so 
cellulase is not required for isolating genetic material from animal cells. 
 
6. Ans. Different viral and bacterial DNA in a host body can be detected by polymerase 
chain reaction (PCR). PCR can detect very low amounts of DNA. PCR is now usually 
used to detect HIV in suspected AIDS patients. It is a good technique to identify 
many other genetic disorders. 
 
7. Ans. If 8 individuals in a laboratory population of 80 fruit flies died during a 
specified time interval (suppose a week), the death rate in the population during 
that period is 8/80 = 0.1 individuals per fruit fly per week. 
 
8. Ans. Reproduction is essential because it enables the continuity of species 
generation after generation and introduces variations in the organisms essential for 
adaptations and evolution. 
 
 
  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
 
              SECTION B 
 
9. Ans. The eggs are located in the archegonium in moss. For fertilisation to occur, 
antherozoids swim in water to reach the eggs. Moss produces a large number of 
antherozoids to increase the chances of fertilisation.  
 
10. Ans. The zygote is formed because of fusion of two haploid gametes; hence, it is 
diploid (2n). An endosperm develops from a triploid (3n) primary endosperm 
nucleus formed because of fusion of male gamete (n) and two polar nuclei (n). 
 
11. Ans. Electrostatic precipitators are the most efficient devices where the particles 
present in the dirty air are charged electrically to form a corona of negative charges 
around them. The charged dust particles are passed over collection plates connected 
electrically with the earth. Dust particles lose their charge and settle. 
  
12. Ans. Aquatic ecosystem: Pond ecosystem 
         Terrestrial ecosystem: Detritus food chain 
 
 
Aquatic Ecosystem Terrestrial Ecosystem 
It describes the ecosystem in 
water. Example: Pond 
ecosystem 
 
 
It describes the ecosystem on 
land. Example: Detritus food 
chain 
 
 
 
13. Ans.  Test cross is a cross between F 1 hybrid and the recessive parent.  
To know the genotypic composition from the phenotype of a dominant trait, a cross 
is made between the unknown genotype of the F 1 generation with the homozygous 
recessive. If the result shows 100% dominant trait, this means that the unknown 
genotype of the F 1 generation is homozygous dominant. If the test cross yields 
offspring of 50% dominant and 50% recessive character, then the F 1 hybrid is 
heterozygous. It shows (1:1) test ratio for the monohybrid cross and (1:1:1:1) for 
the dihybrid cross. 
 
Page 3


  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2010 – Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. There are four microsporangia or pollen sacs in an anther. In this case, the 
anther will have 400 microspore mother cells. As each microspore mother cell 
forms four pollen grains, 400 microspore mother cells will form 1600 pollen grains 
or male gametophytes. 
 
2. Ans. AUG has dual function. 
(i) It codes for Methionine (Met). 
(ii) It also acts as the initiator codon. 
 
3. Ans. Louis Pasteur disproved the spontaneous generation theory. According to this 
theory, life originated repeatedly from non-living materials spontaneously. 
However, according to Louis Pasteur, life originated from pre-existing organisms of 
their own kind. 
 
4. Ans. On exposure to antigens or vaccines, the antibodies produced in the body 
neutralise the pathogenic agent during infection. The vaccines generate memory B 
cells and T cells during primary response. When the vaccinated person is attacked 
by the same pathogen, the existing memory T or B cells recognise the antigen 
quickly and attack the invaders with a massive production of lymphocytes and 
antibodies. 
 
5. Ans. Cellulase is used for isolating genetic material from plant cells because the cell 
wall of plants is made of cellulose. Animal cells do not have a cell wall or cellulose, so 
cellulase is not required for isolating genetic material from animal cells. 
 
6. Ans. Different viral and bacterial DNA in a host body can be detected by polymerase 
chain reaction (PCR). PCR can detect very low amounts of DNA. PCR is now usually 
used to detect HIV in suspected AIDS patients. It is a good technique to identify 
many other genetic disorders. 
 
7. Ans. If 8 individuals in a laboratory population of 80 fruit flies died during a 
specified time interval (suppose a week), the death rate in the population during 
that period is 8/80 = 0.1 individuals per fruit fly per week. 
 
8. Ans. Reproduction is essential because it enables the continuity of species 
generation after generation and introduces variations in the organisms essential for 
adaptations and evolution. 
 
 
  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
 
              SECTION B 
 
9. Ans. The eggs are located in the archegonium in moss. For fertilisation to occur, 
antherozoids swim in water to reach the eggs. Moss produces a large number of 
antherozoids to increase the chances of fertilisation.  
 
10. Ans. The zygote is formed because of fusion of two haploid gametes; hence, it is 
diploid (2n). An endosperm develops from a triploid (3n) primary endosperm 
nucleus formed because of fusion of male gamete (n) and two polar nuclei (n). 
 
11. Ans. Electrostatic precipitators are the most efficient devices where the particles 
present in the dirty air are charged electrically to form a corona of negative charges 
around them. The charged dust particles are passed over collection plates connected 
electrically with the earth. Dust particles lose their charge and settle. 
  
12. Ans. Aquatic ecosystem: Pond ecosystem 
         Terrestrial ecosystem: Detritus food chain 
 
 
Aquatic Ecosystem Terrestrial Ecosystem 
It describes the ecosystem in 
water. Example: Pond 
ecosystem 
 
 
It describes the ecosystem on 
land. Example: Detritus food 
chain 
 
 
 
13. Ans.  Test cross is a cross between F 1 hybrid and the recessive parent.  
To know the genotypic composition from the phenotype of a dominant trait, a cross 
is made between the unknown genotype of the F 1 generation with the homozygous 
recessive. If the result shows 100% dominant trait, this means that the unknown 
genotype of the F 1 generation is homozygous dominant. If the test cross yields 
offspring of 50% dominant and 50% recessive character, then the F 1 hybrid is 
heterozygous. It shows (1:1) test ratio for the monohybrid cross and (1:1:1:1) for 
the dihybrid cross. 
 
  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
 
 
14. Ans. 
(a) Formation of gametocytes occurs in the red blood cells of human host. 
(b) Fertilisation of gametocytes occurs in the mosquito’s stomach. 
 
15. Ans. Bee farms or apiaries are established in an area where abundance of wild 
shrubs, fruit orchards and cultivated crops is available in 1–2 km radius. Availability 
of flowering plants for the collection of nectar and pollen is called pasturage. It plays 
an important role in the quality and quantity of honey. The beehives when kept in 
the fields of sunflower, Brassica, apple and pear increase the pollination efficiency of 
flowering plants and improve the yields. 
OR 
When a small amount of curd is added to milk, the fermentation process begins. 
During this process, the lactose sugar of milk is converted to lactic acid which 
acidifies the fermenting media. The acidic medium helps in coagulating milk protein 
by partially digesting it so that a thick concentrated curd is prepared. 
 Lactic acid bacteria improve its nutritional quality by increasing vitamin B 12. 
 
16. Ans. Adenosine deaminase deficiency can be cured by enzyme replacement therapy 
but the cure is not permanent even after infusion of genetically engineered 
lymphocytes into the patient as cells are not immortal. The patient does not have 
functional T-lymphocytes, so they cannot provide immune responses against 
invading pathogens. The patient requires periodic infusion of such genetically 
engineered lymphocytes. However, if the gene isolated from bone marrow cells 
producing ADA is introduced into cells at early embryonic stages, it could prove to 
be a permanent cure. 
 
 
 
 
 
 
 
Page 4


  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2010 – Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. There are four microsporangia or pollen sacs in an anther. In this case, the 
anther will have 400 microspore mother cells. As each microspore mother cell 
forms four pollen grains, 400 microspore mother cells will form 1600 pollen grains 
or male gametophytes. 
 
2. Ans. AUG has dual function. 
(i) It codes for Methionine (Met). 
(ii) It also acts as the initiator codon. 
 
3. Ans. Louis Pasteur disproved the spontaneous generation theory. According to this 
theory, life originated repeatedly from non-living materials spontaneously. 
However, according to Louis Pasteur, life originated from pre-existing organisms of 
their own kind. 
 
4. Ans. On exposure to antigens or vaccines, the antibodies produced in the body 
neutralise the pathogenic agent during infection. The vaccines generate memory B 
cells and T cells during primary response. When the vaccinated person is attacked 
by the same pathogen, the existing memory T or B cells recognise the antigen 
quickly and attack the invaders with a massive production of lymphocytes and 
antibodies. 
 
5. Ans. Cellulase is used for isolating genetic material from plant cells because the cell 
wall of plants is made of cellulose. Animal cells do not have a cell wall or cellulose, so 
cellulase is not required for isolating genetic material from animal cells. 
 
6. Ans. Different viral and bacterial DNA in a host body can be detected by polymerase 
chain reaction (PCR). PCR can detect very low amounts of DNA. PCR is now usually 
used to detect HIV in suspected AIDS patients. It is a good technique to identify 
many other genetic disorders. 
 
7. Ans. If 8 individuals in a laboratory population of 80 fruit flies died during a 
specified time interval (suppose a week), the death rate in the population during 
that period is 8/80 = 0.1 individuals per fruit fly per week. 
 
8. Ans. Reproduction is essential because it enables the continuity of species 
generation after generation and introduces variations in the organisms essential for 
adaptations and evolution. 
 
 
  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
 
              SECTION B 
 
9. Ans. The eggs are located in the archegonium in moss. For fertilisation to occur, 
antherozoids swim in water to reach the eggs. Moss produces a large number of 
antherozoids to increase the chances of fertilisation.  
 
10. Ans. The zygote is formed because of fusion of two haploid gametes; hence, it is 
diploid (2n). An endosperm develops from a triploid (3n) primary endosperm 
nucleus formed because of fusion of male gamete (n) and two polar nuclei (n). 
 
11. Ans. Electrostatic precipitators are the most efficient devices where the particles 
present in the dirty air are charged electrically to form a corona of negative charges 
around them. The charged dust particles are passed over collection plates connected 
electrically with the earth. Dust particles lose their charge and settle. 
  
12. Ans. Aquatic ecosystem: Pond ecosystem 
         Terrestrial ecosystem: Detritus food chain 
 
 
Aquatic Ecosystem Terrestrial Ecosystem 
It describes the ecosystem in 
water. Example: Pond 
ecosystem 
 
 
It describes the ecosystem on 
land. Example: Detritus food 
chain 
 
 
 
13. Ans.  Test cross is a cross between F 1 hybrid and the recessive parent.  
To know the genotypic composition from the phenotype of a dominant trait, a cross 
is made between the unknown genotype of the F 1 generation with the homozygous 
recessive. If the result shows 100% dominant trait, this means that the unknown 
genotype of the F 1 generation is homozygous dominant. If the test cross yields 
offspring of 50% dominant and 50% recessive character, then the F 1 hybrid is 
heterozygous. It shows (1:1) test ratio for the monohybrid cross and (1:1:1:1) for 
the dihybrid cross. 
 
  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
 
 
14. Ans. 
(a) Formation of gametocytes occurs in the red blood cells of human host. 
(b) Fertilisation of gametocytes occurs in the mosquito’s stomach. 
 
15. Ans. Bee farms or apiaries are established in an area where abundance of wild 
shrubs, fruit orchards and cultivated crops is available in 1–2 km radius. Availability 
of flowering plants for the collection of nectar and pollen is called pasturage. It plays 
an important role in the quality and quantity of honey. The beehives when kept in 
the fields of sunflower, Brassica, apple and pear increase the pollination efficiency of 
flowering plants and improve the yields. 
OR 
When a small amount of curd is added to milk, the fermentation process begins. 
During this process, the lactose sugar of milk is converted to lactic acid which 
acidifies the fermenting media. The acidic medium helps in coagulating milk protein 
by partially digesting it so that a thick concentrated curd is prepared. 
 Lactic acid bacteria improve its nutritional quality by increasing vitamin B 12. 
 
16. Ans. Adenosine deaminase deficiency can be cured by enzyme replacement therapy 
but the cure is not permanent even after infusion of genetically engineered 
lymphocytes into the patient as cells are not immortal. The patient does not have 
functional T-lymphocytes, so they cannot provide immune responses against 
invading pathogens. The patient requires periodic infusion of such genetically 
engineered lymphocytes. However, if the gene isolated from bone marrow cells 
producing ADA is introduced into cells at early embryonic stages, it could prove to 
be a permanent cure. 
 
 
 
 
 
 
 
  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
 
17. Ans. The Mediterranean orchid Ophrys has a very strange relationship with its 
insect pollinator Colpa aurea (a hairy wasp). The orchid bears flowers which 
resemble the female wasp in colour, odour and appearance. The male wasp matures 
first and leaves the burrow about four weeks before the females come out for open 
air mating. The inexperienced males try to pseudocopulate the orchid flowers 
presuming them as their female partners and bring about pollination.  
 
18. Ans. In the biosphere, immense biodiversity exists at all levels of biological 
organisation ranging from macromolecules within cells to biomes. The most 
important levels of biological diversity are genetic diversity, species diversity and 
ecological diversity. 
i. Genetic diversity: It is related to the variations of genes within species. The 
variations may be in different variants of the same genes (alleles), in entire 
genes or in chromosomal structures. On account of genetic differences, all the 
individuals of the same species become different from one another in the details 
of the body structure giving rise to multitude of intraspecific categories such as 
sub-species, varieties, races and strains, all of these show variations of one kind 
or the other. For example, there are various varieties of mangoes. 
ii. Species diversity: It is related to the variety in the number and richness of the 
species within a region and is measured at the level of ‘species’. For example, big 
cats such as tiger, lion and snow leopard belong to the same genus but all differ 
at the species level.  
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Page 5


  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
CBSE 
Class XII Biology (Theory) 
Board Paper 2010 – Delhi (Set 1) 
SOLUTION 
Time: 3 hrs Total Marks: 70 
 
SECTION A 
1. Ans. There are four microsporangia or pollen sacs in an anther. In this case, the 
anther will have 400 microspore mother cells. As each microspore mother cell 
forms four pollen grains, 400 microspore mother cells will form 1600 pollen grains 
or male gametophytes. 
 
2. Ans. AUG has dual function. 
(i) It codes for Methionine (Met). 
(ii) It also acts as the initiator codon. 
 
3. Ans. Louis Pasteur disproved the spontaneous generation theory. According to this 
theory, life originated repeatedly from non-living materials spontaneously. 
However, according to Louis Pasteur, life originated from pre-existing organisms of 
their own kind. 
 
4. Ans. On exposure to antigens or vaccines, the antibodies produced in the body 
neutralise the pathogenic agent during infection. The vaccines generate memory B 
cells and T cells during primary response. When the vaccinated person is attacked 
by the same pathogen, the existing memory T or B cells recognise the antigen 
quickly and attack the invaders with a massive production of lymphocytes and 
antibodies. 
 
5. Ans. Cellulase is used for isolating genetic material from plant cells because the cell 
wall of plants is made of cellulose. Animal cells do not have a cell wall or cellulose, so 
cellulase is not required for isolating genetic material from animal cells. 
 
6. Ans. Different viral and bacterial DNA in a host body can be detected by polymerase 
chain reaction (PCR). PCR can detect very low amounts of DNA. PCR is now usually 
used to detect HIV in suspected AIDS patients. It is a good technique to identify 
many other genetic disorders. 
 
7. Ans. If 8 individuals in a laboratory population of 80 fruit flies died during a 
specified time interval (suppose a week), the death rate in the population during 
that period is 8/80 = 0.1 individuals per fruit fly per week. 
 
8. Ans. Reproduction is essential because it enables the continuity of species 
generation after generation and introduces variations in the organisms essential for 
adaptations and evolution. 
 
 
  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
 
              SECTION B 
 
9. Ans. The eggs are located in the archegonium in moss. For fertilisation to occur, 
antherozoids swim in water to reach the eggs. Moss produces a large number of 
antherozoids to increase the chances of fertilisation.  
 
10. Ans. The zygote is formed because of fusion of two haploid gametes; hence, it is 
diploid (2n). An endosperm develops from a triploid (3n) primary endosperm 
nucleus formed because of fusion of male gamete (n) and two polar nuclei (n). 
 
11. Ans. Electrostatic precipitators are the most efficient devices where the particles 
present in the dirty air are charged electrically to form a corona of negative charges 
around them. The charged dust particles are passed over collection plates connected 
electrically with the earth. Dust particles lose their charge and settle. 
  
12. Ans. Aquatic ecosystem: Pond ecosystem 
         Terrestrial ecosystem: Detritus food chain 
 
 
Aquatic Ecosystem Terrestrial Ecosystem 
It describes the ecosystem in 
water. Example: Pond 
ecosystem 
 
 
It describes the ecosystem on 
land. Example: Detritus food 
chain 
 
 
 
13. Ans.  Test cross is a cross between F 1 hybrid and the recessive parent.  
To know the genotypic composition from the phenotype of a dominant trait, a cross 
is made between the unknown genotype of the F 1 generation with the homozygous 
recessive. If the result shows 100% dominant trait, this means that the unknown 
genotype of the F 1 generation is homozygous dominant. If the test cross yields 
offspring of 50% dominant and 50% recessive character, then the F 1 hybrid is 
heterozygous. It shows (1:1) test ratio for the monohybrid cross and (1:1:1:1) for 
the dihybrid cross. 
 
  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
 
 
14. Ans. 
(a) Formation of gametocytes occurs in the red blood cells of human host. 
(b) Fertilisation of gametocytes occurs in the mosquito’s stomach. 
 
15. Ans. Bee farms or apiaries are established in an area where abundance of wild 
shrubs, fruit orchards and cultivated crops is available in 1–2 km radius. Availability 
of flowering plants for the collection of nectar and pollen is called pasturage. It plays 
an important role in the quality and quantity of honey. The beehives when kept in 
the fields of sunflower, Brassica, apple and pear increase the pollination efficiency of 
flowering plants and improve the yields. 
OR 
When a small amount of curd is added to milk, the fermentation process begins. 
During this process, the lactose sugar of milk is converted to lactic acid which 
acidifies the fermenting media. The acidic medium helps in coagulating milk protein 
by partially digesting it so that a thick concentrated curd is prepared. 
 Lactic acid bacteria improve its nutritional quality by increasing vitamin B 12. 
 
16. Ans. Adenosine deaminase deficiency can be cured by enzyme replacement therapy 
but the cure is not permanent even after infusion of genetically engineered 
lymphocytes into the patient as cells are not immortal. The patient does not have 
functional T-lymphocytes, so they cannot provide immune responses against 
invading pathogens. The patient requires periodic infusion of such genetically 
engineered lymphocytes. However, if the gene isolated from bone marrow cells 
producing ADA is introduced into cells at early embryonic stages, it could prove to 
be a permanent cure. 
 
 
 
 
 
 
 
  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
 
17. Ans. The Mediterranean orchid Ophrys has a very strange relationship with its 
insect pollinator Colpa aurea (a hairy wasp). The orchid bears flowers which 
resemble the female wasp in colour, odour and appearance. The male wasp matures 
first and leaves the burrow about four weeks before the females come out for open 
air mating. The inexperienced males try to pseudocopulate the orchid flowers 
presuming them as their female partners and bring about pollination.  
 
18. Ans. In the biosphere, immense biodiversity exists at all levels of biological 
organisation ranging from macromolecules within cells to biomes. The most 
important levels of biological diversity are genetic diversity, species diversity and 
ecological diversity. 
i. Genetic diversity: It is related to the variations of genes within species. The 
variations may be in different variants of the same genes (alleles), in entire 
genes or in chromosomal structures. On account of genetic differences, all the 
individuals of the same species become different from one another in the details 
of the body structure giving rise to multitude of intraspecific categories such as 
sub-species, varieties, races and strains, all of these show variations of one kind 
or the other. For example, there are various varieties of mangoes. 
ii. Species diversity: It is related to the variety in the number and richness of the 
species within a region and is measured at the level of ‘species’. For example, big 
cats such as tiger, lion and snow leopard belong to the same genus but all differ 
at the species level.  
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
 
CBSE XII  |  Biology 
Board Paper 2010 – Delhi – Set 1 (Solution) 
 
     
 
SECTION C 
 
19. Ans. Longitudinal section of a post-pollinated pistil: 
 
 
OR 
 
       Sectional view of the seminiferous tubule of a human male: