Past Year Paper - Solutions, Biology (Set - 3), Delhi, 2014, Class 12, Biology | Additional Study Material for NEET PDF Download

 Page 1


Question Paper Code 57/1/3
SECTION - A (1 × 8 = 8)
1. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
2. Name any two types of cells which act as 'Cellular barriers' to provide Innate Immunity in
humans.
Ans. Polymorpho-nuclear Leukocytes /  Neutrophils /  Monocyte , Natural Killer (type of lymphocyte),
macrophages
(Any two) = ½ + ½
[1 mark]
3. How is repetitive / satellite DNA separated from bulk genomic DNA for various genetic
experiments?
Ans. Density gradient centrifugation = 1
[1 mark]
4, Write the name of the organism that is referred to as the 'Terror of Bengal'.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
5. Name the Green House gases that contribute to total global warming.
Ans. All four gases - N
2
O, CFC, CH
4
, CO
2 
(if less than four mentioned  = ½)
[1 mark]
6. Identify ‘a’ and ‘b’ in the figure given below representing proportionate number of major
vertebrate taxa.
Ans. (a) Mammals
(b) Amphibians = ½ + ½
[1 mark]
Page 2


Question Paper Code 57/1/3
SECTION - A (1 × 8 = 8)
1. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
2. Name any two types of cells which act as 'Cellular barriers' to provide Innate Immunity in
humans.
Ans. Polymorpho-nuclear Leukocytes /  Neutrophils /  Monocyte , Natural Killer (type of lymphocyte),
macrophages
(Any two) = ½ + ½
[1 mark]
3. How is repetitive / satellite DNA separated from bulk genomic DNA for various genetic
experiments?
Ans. Density gradient centrifugation = 1
[1 mark]
4, Write the name of the organism that is referred to as the 'Terror of Bengal'.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
5. Name the Green House gases that contribute to total global warming.
Ans. All four gases - N
2
O, CFC, CH
4
, CO
2 
(if less than four mentioned  = ½)
[1 mark]
6. Identify ‘a’ and ‘b’ in the figure given below representing proportionate number of major
vertebrate taxa.
Ans. (a) Mammals
(b) Amphibians = ½ + ½
[1 mark]
7. Give an example of an organism that enters 'diapause' and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
8. How is 'stratification' represented in a forest ecosystem ?
Ans. Trees occupy vertical stratra , shrubs the second layer and herbs / grasses occupy the bottom
layers // vertical distribution of species , at different levels = ½ + ½
[1 mark]
SECTION - B (2×10=20)
9. i) Name the scientist who suggested that the genetic code should be made of a
combination of three nucleotides.
ii) Explain the basis on which he arrived at this conclusion.
Ans. (i) George Gamow = ½
(ii) There are four bases and 20 amino acids = ½
(There should be atleast 20 different genetic codes for these 20 amino acids)
Only possible combinations that would meet the requirement is combinations of 3 bases that
will give 64 codons = 1
[2 marks]
10. State the disadvantage of inbreeding among cattle. How it can be overcome ?
Ans. - Inbreeding depression / reduce fertility and productivity = 1
- Selected animals should be mated with unrelated superior animals of the same breed /
outbreeding  =1
[2 marks]
11. Explain with the help of a suitable example the naming of a restriction endonuclease.
Ans. EcoRI = ½
Eco stands for the genus and species of the prokaryotic cell from which the enzyme was isolated i.e
E.coli = ½
R stands for strain = ½
‘I’ follows order in which enzyme was isolated = ½
[2 marks]
12. What is gene therapy ? Name the first clinical case where it was used.
Ans. – (Collection of methods that allows) correction of a gene defect that has been diagnosed in a
child / embryo = 1
– Adenosine deaminase (ADA) deficiency  =  1
[2 marks]
13. Apart from being part of the food chain , predators play other important roles. Mention
any two such roles supported by examples.
Ans. - Keeps prey population under control
Page 3


Question Paper Code 57/1/3
SECTION - A (1 × 8 = 8)
1. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
2. Name any two types of cells which act as 'Cellular barriers' to provide Innate Immunity in
humans.
Ans. Polymorpho-nuclear Leukocytes /  Neutrophils /  Monocyte , Natural Killer (type of lymphocyte),
macrophages
(Any two) = ½ + ½
[1 mark]
3. How is repetitive / satellite DNA separated from bulk genomic DNA for various genetic
experiments?
Ans. Density gradient centrifugation = 1
[1 mark]
4, Write the name of the organism that is referred to as the 'Terror of Bengal'.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
5. Name the Green House gases that contribute to total global warming.
Ans. All four gases - N
2
O, CFC, CH
4
, CO
2 
(if less than four mentioned  = ½)
[1 mark]
6. Identify ‘a’ and ‘b’ in the figure given below representing proportionate number of major
vertebrate taxa.
Ans. (a) Mammals
(b) Amphibians = ½ + ½
[1 mark]
7. Give an example of an organism that enters 'diapause' and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
8. How is 'stratification' represented in a forest ecosystem ?
Ans. Trees occupy vertical stratra , shrubs the second layer and herbs / grasses occupy the bottom
layers // vertical distribution of species , at different levels = ½ + ½
[1 mark]
SECTION - B (2×10=20)
9. i) Name the scientist who suggested that the genetic code should be made of a
combination of three nucleotides.
ii) Explain the basis on which he arrived at this conclusion.
Ans. (i) George Gamow = ½
(ii) There are four bases and 20 amino acids = ½
(There should be atleast 20 different genetic codes for these 20 amino acids)
Only possible combinations that would meet the requirement is combinations of 3 bases that
will give 64 codons = 1
[2 marks]
10. State the disadvantage of inbreeding among cattle. How it can be overcome ?
Ans. - Inbreeding depression / reduce fertility and productivity = 1
- Selected animals should be mated with unrelated superior animals of the same breed /
outbreeding  =1
[2 marks]
11. Explain with the help of a suitable example the naming of a restriction endonuclease.
Ans. EcoRI = ½
Eco stands for the genus and species of the prokaryotic cell from which the enzyme was isolated i.e
E.coli = ½
R stands for strain = ½
‘I’ follows order in which enzyme was isolated = ½
[2 marks]
12. What is gene therapy ? Name the first clinical case where it was used.
Ans. – (Collection of methods that allows) correction of a gene defect that has been diagnosed in a
child / embryo = 1
– Adenosine deaminase (ADA) deficiency  =  1
[2 marks]
13. Apart from being part of the food chain , predators play other important roles. Mention
any two such roles supported by examples.
Ans. - Keeps prey population under control
- Biological control methods
- Maintains species diversity
- Reduces intensity of competition among prey species
(Any two roles and relevant examples each)
[2 marks]
14. Construct an age pyramid which reflects a stable growth status of human population.
Ans.
Pre-reproductive
Reproductive
Post-reproductive (½)
(½)
(½)
Construction of pyramid = ½
NOTE : Proceed marking only when pyramid is correctly drawn.
[2 marks]
15. Why does the Bt toxin not kill the bacterium that produces it but kills the insect that ingests
it ?
Ans. Exists as inactive protoxins = 1
Becomes active in the gut of insect due to alkaline pH = 1
[2 marks]
16. How does the gene 'I' control ABO blood groups in humans ? Write the effect the gene has
on the structure of red blood cells.
Ans. – Gene ‘I’ has three different alleles  I
A
 , I
B
 , i = ½
–I
A
 produces A type of sugar / Antigen   A group
I
B
 produces B type of sugar / Antigen   B group
– i - No sugar - O group = ½
– Structure - sugar polymers protrude from  the surface of plasma membrane of RBCs = ½
[2 marks]
OR
Write the types of sex-determination mechanisms the following crosses show. Give an
example of each type.
(i) Female XX with Male XO
(ii) Female ZW with Male ZZ
Ans. (i) Male heterogamety , Grasshopper = ½ + ½
(ii) Female heterogamety , Birds  = ½ + ½
[2 marks]
= ½
Page 4


Question Paper Code 57/1/3
SECTION - A (1 × 8 = 8)
1. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
2. Name any two types of cells which act as 'Cellular barriers' to provide Innate Immunity in
humans.
Ans. Polymorpho-nuclear Leukocytes /  Neutrophils /  Monocyte , Natural Killer (type of lymphocyte),
macrophages
(Any two) = ½ + ½
[1 mark]
3. How is repetitive / satellite DNA separated from bulk genomic DNA for various genetic
experiments?
Ans. Density gradient centrifugation = 1
[1 mark]
4, Write the name of the organism that is referred to as the 'Terror of Bengal'.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
5. Name the Green House gases that contribute to total global warming.
Ans. All four gases - N
2
O, CFC, CH
4
, CO
2 
(if less than four mentioned  = ½)
[1 mark]
6. Identify ‘a’ and ‘b’ in the figure given below representing proportionate number of major
vertebrate taxa.
Ans. (a) Mammals
(b) Amphibians = ½ + ½
[1 mark]
7. Give an example of an organism that enters 'diapause' and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
8. How is 'stratification' represented in a forest ecosystem ?
Ans. Trees occupy vertical stratra , shrubs the second layer and herbs / grasses occupy the bottom
layers // vertical distribution of species , at different levels = ½ + ½
[1 mark]
SECTION - B (2×10=20)
9. i) Name the scientist who suggested that the genetic code should be made of a
combination of three nucleotides.
ii) Explain the basis on which he arrived at this conclusion.
Ans. (i) George Gamow = ½
(ii) There are four bases and 20 amino acids = ½
(There should be atleast 20 different genetic codes for these 20 amino acids)
Only possible combinations that would meet the requirement is combinations of 3 bases that
will give 64 codons = 1
[2 marks]
10. State the disadvantage of inbreeding among cattle. How it can be overcome ?
Ans. - Inbreeding depression / reduce fertility and productivity = 1
- Selected animals should be mated with unrelated superior animals of the same breed /
outbreeding  =1
[2 marks]
11. Explain with the help of a suitable example the naming of a restriction endonuclease.
Ans. EcoRI = ½
Eco stands for the genus and species of the prokaryotic cell from which the enzyme was isolated i.e
E.coli = ½
R stands for strain = ½
‘I’ follows order in which enzyme was isolated = ½
[2 marks]
12. What is gene therapy ? Name the first clinical case where it was used.
Ans. – (Collection of methods that allows) correction of a gene defect that has been diagnosed in a
child / embryo = 1
– Adenosine deaminase (ADA) deficiency  =  1
[2 marks]
13. Apart from being part of the food chain , predators play other important roles. Mention
any two such roles supported by examples.
Ans. - Keeps prey population under control
- Biological control methods
- Maintains species diversity
- Reduces intensity of competition among prey species
(Any two roles and relevant examples each)
[2 marks]
14. Construct an age pyramid which reflects a stable growth status of human population.
Ans.
Pre-reproductive
Reproductive
Post-reproductive (½)
(½)
(½)
Construction of pyramid = ½
NOTE : Proceed marking only when pyramid is correctly drawn.
[2 marks]
15. Why does the Bt toxin not kill the bacterium that produces it but kills the insect that ingests
it ?
Ans. Exists as inactive protoxins = 1
Becomes active in the gut of insect due to alkaline pH = 1
[2 marks]
16. How does the gene 'I' control ABO blood groups in humans ? Write the effect the gene has
on the structure of red blood cells.
Ans. – Gene ‘I’ has three different alleles  I
A
 , I
B
 , i = ½
–I
A
 produces A type of sugar / Antigen   A group
I
B
 produces B type of sugar / Antigen   B group
– i - No sugar - O group = ½
– Structure - sugar polymers protrude from  the surface of plasma membrane of RBCs = ½
[2 marks]
OR
Write the types of sex-determination mechanisms the following crosses show. Give an
example of each type.
(i) Female XX with Male XO
(ii) Female ZW with Male ZZ
Ans. (i) Male heterogamety , Grasshopper = ½ + ½
(ii) Female heterogamety , Birds  = ½ + ½
[2 marks]
= ½
17. Identify the following pairs as Homologous or Analogous organs :
(i) Sweet potato and potato
(ii) Eye of octopus and eye of mammals
(iii) Thorns of Bougainvillea and tendrils of Cucurbits.
(iv) Fore limbs of Bat and Whale.
Ans. (i)  &  (ii) Analogous
(iii)  &  (iv) Homologous  =   ½ × 4
[2 marks]
18. List the post-fertilization events in angiosperms.
Ans. – Development of endosperm
– Embryogeny / development of embryo
– Seed formation
– Fruit formation   = ½ × 4
[2 marks]
SECTION-C (3 ×9 = 27)
19. Study the graph given below and answer the question that follow :
POPULATION DENSITY(N)
TIME (t)
a
b
(i) Write the status of food and space in the curves (a) and (b).
(ii) In the absence of predators, which one of the two curves would appropriately
depict the prey population ?
(iii) Time has been shown on X-axis and there is a parallel dotted line above it. Give
the significance of this dotted line.
Ans. (i) a - unlimited food and space =  ½
b - limited food and space  =  ½
(ii) Curve a =  1
(iii) Carrying capacity / a given habitat has enough resources to support maximum possible
number - beyond which no further growth is possible = 1
[3 marks]
Page 5


Question Paper Code 57/1/3
SECTION - A (1 × 8 = 8)
1. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
2. Name any two types of cells which act as 'Cellular barriers' to provide Innate Immunity in
humans.
Ans. Polymorpho-nuclear Leukocytes /  Neutrophils /  Monocyte , Natural Killer (type of lymphocyte),
macrophages
(Any two) = ½ + ½
[1 mark]
3. How is repetitive / satellite DNA separated from bulk genomic DNA for various genetic
experiments?
Ans. Density gradient centrifugation = 1
[1 mark]
4, Write the name of the organism that is referred to as the 'Terror of Bengal'.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
5. Name the Green House gases that contribute to total global warming.
Ans. All four gases - N
2
O, CFC, CH
4
, CO
2 
(if less than four mentioned  = ½)
[1 mark]
6. Identify ‘a’ and ‘b’ in the figure given below representing proportionate number of major
vertebrate taxa.
Ans. (a) Mammals
(b) Amphibians = ½ + ½
[1 mark]
7. Give an example of an organism that enters 'diapause' and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
8. How is 'stratification' represented in a forest ecosystem ?
Ans. Trees occupy vertical stratra , shrubs the second layer and herbs / grasses occupy the bottom
layers // vertical distribution of species , at different levels = ½ + ½
[1 mark]
SECTION - B (2×10=20)
9. i) Name the scientist who suggested that the genetic code should be made of a
combination of three nucleotides.
ii) Explain the basis on which he arrived at this conclusion.
Ans. (i) George Gamow = ½
(ii) There are four bases and 20 amino acids = ½
(There should be atleast 20 different genetic codes for these 20 amino acids)
Only possible combinations that would meet the requirement is combinations of 3 bases that
will give 64 codons = 1
[2 marks]
10. State the disadvantage of inbreeding among cattle. How it can be overcome ?
Ans. - Inbreeding depression / reduce fertility and productivity = 1
- Selected animals should be mated with unrelated superior animals of the same breed /
outbreeding  =1
[2 marks]
11. Explain with the help of a suitable example the naming of a restriction endonuclease.
Ans. EcoRI = ½
Eco stands for the genus and species of the prokaryotic cell from which the enzyme was isolated i.e
E.coli = ½
R stands for strain = ½
‘I’ follows order in which enzyme was isolated = ½
[2 marks]
12. What is gene therapy ? Name the first clinical case where it was used.
Ans. – (Collection of methods that allows) correction of a gene defect that has been diagnosed in a
child / embryo = 1
– Adenosine deaminase (ADA) deficiency  =  1
[2 marks]
13. Apart from being part of the food chain , predators play other important roles. Mention
any two such roles supported by examples.
Ans. - Keeps prey population under control
- Biological control methods
- Maintains species diversity
- Reduces intensity of competition among prey species
(Any two roles and relevant examples each)
[2 marks]
14. Construct an age pyramid which reflects a stable growth status of human population.
Ans.
Pre-reproductive
Reproductive
Post-reproductive (½)
(½)
(½)
Construction of pyramid = ½
NOTE : Proceed marking only when pyramid is correctly drawn.
[2 marks]
15. Why does the Bt toxin not kill the bacterium that produces it but kills the insect that ingests
it ?
Ans. Exists as inactive protoxins = 1
Becomes active in the gut of insect due to alkaline pH = 1
[2 marks]
16. How does the gene 'I' control ABO blood groups in humans ? Write the effect the gene has
on the structure of red blood cells.
Ans. – Gene ‘I’ has three different alleles  I
A
 , I
B
 , i = ½
–I
A
 produces A type of sugar / Antigen   A group
I
B
 produces B type of sugar / Antigen   B group
– i - No sugar - O group = ½
– Structure - sugar polymers protrude from  the surface of plasma membrane of RBCs = ½
[2 marks]
OR
Write the types of sex-determination mechanisms the following crosses show. Give an
example of each type.
(i) Female XX with Male XO
(ii) Female ZW with Male ZZ
Ans. (i) Male heterogamety , Grasshopper = ½ + ½
(ii) Female heterogamety , Birds  = ½ + ½
[2 marks]
= ½
17. Identify the following pairs as Homologous or Analogous organs :
(i) Sweet potato and potato
(ii) Eye of octopus and eye of mammals
(iii) Thorns of Bougainvillea and tendrils of Cucurbits.
(iv) Fore limbs of Bat and Whale.
Ans. (i)  &  (ii) Analogous
(iii)  &  (iv) Homologous  =   ½ × 4
[2 marks]
18. List the post-fertilization events in angiosperms.
Ans. – Development of endosperm
– Embryogeny / development of embryo
– Seed formation
– Fruit formation   = ½ × 4
[2 marks]
SECTION-C (3 ×9 = 27)
19. Study the graph given below and answer the question that follow :
POPULATION DENSITY(N)
TIME (t)
a
b
(i) Write the status of food and space in the curves (a) and (b).
(ii) In the absence of predators, which one of the two curves would appropriately
depict the prey population ?
(iii) Time has been shown on X-axis and there is a parallel dotted line above it. Give
the significance of this dotted line.
Ans. (i) a - unlimited food and space =  ½
b - limited food and space  =  ½
(ii) Curve a =  1
(iii) Carrying capacity / a given habitat has enough resources to support maximum possible
number - beyond which no further growth is possible = 1
[3 marks]
20. How did the process of RNA interference help to control the nematode from infecting roots
of tobacco plants? Explain.
Ans. Using Agrobacterium vectors , nematode specific genes introduced into host plant , produced
sense - antisense RNA in host cells , ds RNA - initiated RNAi , silenced specific mRNA of
nematode , parasite could not survive in transgenic host = ½ × 6
[3 marks]
21. What are Methanogens ? Name the animals they are present in and the role they play
there.
Ans. – Bacteria which grow anaerobically on cellulosic material = 1
– Present in cattle (rumen) = 1
– Breakdown of cellulose , helps in nutrition of animal // digestion of cellulose = 1
[3 marks]
22. (a) Name the tropical sugar cane variety grown in South India. How has it helped in
improving the sugar cane quality grown in North India ?
(b) Identify ‘a’, ‘b’ and ‘c’ in the following table :
No. Crop Variety Insect Pests
1.
2.
3.
Brassica
Flat bean
    (c)
Pusa Gaurav
Pusa Sem 2
Pusa Sem 3
Pusa Sawani
Pusa A-4
    (a)
    (b)
Shoot and fruit borer
Ans. (a) Saccharum officinarum , crossed with , North Indian variety (Saccharum barberi) to
increase quality = ½ × 3
(b) (a) Aphids
(b) Jassids / aphids / fruit borer
(c) Okra (Bhindi)               = ½ × 3
[1½ + 1½ =  marks]
23. Women are often blamed for producing female children. Consequently, they are ill treated
and ostracized. How will you address this issue scientifically if you were to conduct an
awareness programme to highlight the values involved?
Ans. – Male produces two types of sperms ( X & Y type in the ratio 1 : 1) , Female produces only
one type of ovum (X type) , hence the sex of baby is determined by the type of sperm fertilising
the ovum therefore women should not be blamed  //  A genetic cross showing sex determination
in human beings covering above value points can be considered in lieu of the above explanation
= ½ × 3
– Sensitivity towards community  / Social awareness  / Self discipline / Responsible behaviour /
Leadership quality / Caring attitude / Responsible attitude towards society / Concern for others