Past Year Paper - Solutions, Biology (Set - 2), Delhi, 2014, Class 12, Biology | Additional Study Material for NEET PDF Download

 Page 1


Question Paper Code 57/1/2
SECTION – A
Q. Nos. 1 - 8 are of one marks each
1. State the cause of Accelerated Eutrophication
Ans. Pollutants from human activities /effluents from industries / effluents from home / sewage /
agricultural (chemical) wastes radically accelerate the ageing process.
[1 mark]
2. 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]
3. Give an example of an organism that enters ‘diapause’ and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
4. Name the two intermediate hosts which the human liver fluke depends on to complete its
life cycle so as to facilitate parasitization of its primary host.
Ans. Snail and Fish = ½ + ½
[1 mark]
5. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
6. 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]
Page 2


Question Paper Code 57/1/2
SECTION – A
Q. Nos. 1 - 8 are of one marks each
1. State the cause of Accelerated Eutrophication
Ans. Pollutants from human activities /effluents from industries / effluents from home / sewage /
agricultural (chemical) wastes radically accelerate the ageing process.
[1 mark]
2. 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]
3. Give an example of an organism that enters ‘diapause’ and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
4. Name the two intermediate hosts which the human liver fluke depends on to complete its
life cycle so as to facilitate parasitization of its primary host.
Ans. Snail and Fish = ½ + ½
[1 mark]
5. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
6. 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]
7. Mention how does DNA polymorphism arise in a population.
Ans. Inheritable mutations (in a population) , at high frequency = ½ + ½
[1 mark]
8. Write the name of the organism that is referred to as the ‘Terror of Bengal’.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
SECTION - B
9. Name the organic materials the exine and intine of an angiosperm pollen grains are made
up of. Explain the role of exine.
Ans. Exine - Sporopollenin = ½
Intine - Cellulose and pectin = ½
Role - most resistant organic material  // can withstand high temperature  , acid and alkali = 1
[2 marks]
10. (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]
11. How does the gene ‘I’ control ABO blood groups in humans ? Write the effect the gene has
on the structure of red blood cells.
[2 marks]
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
= ½
Page 3


Question Paper Code 57/1/2
SECTION – A
Q. Nos. 1 - 8 are of one marks each
1. State the cause of Accelerated Eutrophication
Ans. Pollutants from human activities /effluents from industries / effluents from home / sewage /
agricultural (chemical) wastes radically accelerate the ageing process.
[1 mark]
2. 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]
3. Give an example of an organism that enters ‘diapause’ and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
4. Name the two intermediate hosts which the human liver fluke depends on to complete its
life cycle so as to facilitate parasitization of its primary host.
Ans. Snail and Fish = ½ + ½
[1 mark]
5. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
6. 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]
7. Mention how does DNA polymorphism arise in a population.
Ans. Inheritable mutations (in a population) , at high frequency = ½ + ½
[1 mark]
8. Write the name of the organism that is referred to as the ‘Terror of Bengal’.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
SECTION - B
9. Name the organic materials the exine and intine of an angiosperm pollen grains are made
up of. Explain the role of exine.
Ans. Exine - Sporopollenin = ½
Intine - Cellulose and pectin = ½
Role - most resistant organic material  // can withstand high temperature  , acid and alkali = 1
[2 marks]
10. (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]
11. How does the gene ‘I’ control ABO blood groups in humans ? Write the effect the gene has
on the structure of red blood cells.
[2 marks]
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
= ½
Ans. (i) Male heterogamety , Grasshopper = ½ + ½
(ii) Female heterogamety , Birds  = ½ + ½
[2 marks]
12. A cross was carried out between two pea plants showing the contrasting traits of height
of the plant. The result of the cross showed 50% of parental characters.
(i) Work out the cross with the help of a Punnett square.
(ii) Name the type of the cross carried out.
Ans. (i) Tt     ×     tt   = ½
Tt
t
t
Tt tt
Tt tt
= ½
= ½
(ii) Test cross = ½
[2 marks]
13. How can healthy potato plants be obtained from a desired potato variety which is viral
infected ? Explain.
Ans. Remove meristem (apical or axillary) and grow = 1 ,
in vitro / sterile and special nutrient medium / culture medium = 1
[2 marks]
14. How are ‘sticky ends’ formed on a DNA strand ? Why are they so called ?
Ans. Restriction enzymes  cut the strands of the DNA , a little away from the centre of  the palindromic
sites , but between the same two bases on opposite strands. = ½ × 3 = 1½
They form hydrogen bonds with their complementary cut counterparts. = ½
[2 marks]
15. What is Bio piracy? State the initiative taken by the Indian Parliament towards it.
Ans. (i) Use of bio resources without authorisation , compensation = ½ + ½
(ii) The govt has cleared patent terms , emergency provisions , research and development
initiative (Any two) = ½ + ½
[2 marks]
16. 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]
Page 4


Question Paper Code 57/1/2
SECTION – A
Q. Nos. 1 - 8 are of one marks each
1. State the cause of Accelerated Eutrophication
Ans. Pollutants from human activities /effluents from industries / effluents from home / sewage /
agricultural (chemical) wastes radically accelerate the ageing process.
[1 mark]
2. 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]
3. Give an example of an organism that enters ‘diapause’ and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
4. Name the two intermediate hosts which the human liver fluke depends on to complete its
life cycle so as to facilitate parasitization of its primary host.
Ans. Snail and Fish = ½ + ½
[1 mark]
5. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
6. 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]
7. Mention how does DNA polymorphism arise in a population.
Ans. Inheritable mutations (in a population) , at high frequency = ½ + ½
[1 mark]
8. Write the name of the organism that is referred to as the ‘Terror of Bengal’.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
SECTION - B
9. Name the organic materials the exine and intine of an angiosperm pollen grains are made
up of. Explain the role of exine.
Ans. Exine - Sporopollenin = ½
Intine - Cellulose and pectin = ½
Role - most resistant organic material  // can withstand high temperature  , acid and alkali = 1
[2 marks]
10. (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]
11. How does the gene ‘I’ control ABO blood groups in humans ? Write the effect the gene has
on the structure of red blood cells.
[2 marks]
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
= ½
Ans. (i) Male heterogamety , Grasshopper = ½ + ½
(ii) Female heterogamety , Birds  = ½ + ½
[2 marks]
12. A cross was carried out between two pea plants showing the contrasting traits of height
of the plant. The result of the cross showed 50% of parental characters.
(i) Work out the cross with the help of a Punnett square.
(ii) Name the type of the cross carried out.
Ans. (i) Tt     ×     tt   = ½
Tt
t
t
Tt tt
Tt tt
= ½
= ½
(ii) Test cross = ½
[2 marks]
13. How can healthy potato plants be obtained from a desired potato variety which is viral
infected ? Explain.
Ans. Remove meristem (apical or axillary) and grow = 1 ,
in vitro / sterile and special nutrient medium / culture medium = 1
[2 marks]
14. How are ‘sticky ends’ formed on a DNA strand ? Why are they so called ?
Ans. Restriction enzymes  cut the strands of the DNA , a little away from the centre of  the palindromic
sites , but between the same two bases on opposite strands. = ½ × 3 = 1½
They form hydrogen bonds with their complementary cut counterparts. = ½
[2 marks]
15. What is Bio piracy? State the initiative taken by the Indian Parliament towards it.
Ans. (i) Use of bio resources without authorisation , compensation = ½ + ½
(ii) The govt has cleared patent terms , emergency provisions , research and development
initiative (Any two) = ½ + ½
[2 marks]
16. 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]
17. 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]
18. Write the role of 'Ori' and 'restriction’ site in a cloning vector pBR322.
Ans. Ori - site where replication starts , responsible for controlling copy number = ½ + ½
Restriction site - site of ligation of alien / foreign DNA , in one of the two antibiotic resistance site /
coding sequence of  galactosidase = ½ + ½
[2 marks]
SECTION - C
19. A colourblind child is born to a normal couple. Work out a cross to show how it is
possible. Mention the sex of this child.
Ans.
XY
X Y 
XX
c
XX
c
X X X Y
c
X = 1 
= 1
Male = 1
[3 marks]
OR
Mendel published his work on inheritance of characters in 1865, but it remained
unrecognized till 1900. Give three reasons for the delay in accepting his work.
Ans. - The communication was not easy in those days and his work could not be widely publicised.
- His concept of genes as stable and discrete units that controlled the expression of traits and of
the pair of alleles which did not ‘blend’ with each other was not accepted by contemporaries
as an explanation for the apparently continuous variation seen in nature.
- Mendel’s approach of using mathematics to explain biological phenomena  was totally new
and unacceptable to many of the biologists  of his time.
- Though Mendel’ s work suggested that factors (genes) were discrete units , he could not provide
any physical proof for the existence of factors and what they were made of.
(Any three points) = 1 + 1 + 1
[3 marks]
Page 5


Question Paper Code 57/1/2
SECTION – A
Q. Nos. 1 - 8 are of one marks each
1. State the cause of Accelerated Eutrophication
Ans. Pollutants from human activities /effluents from industries / effluents from home / sewage /
agricultural (chemical) wastes radically accelerate the ageing process.
[1 mark]
2. 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]
3. Give an example of an organism that enters ‘diapause’ and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
4. Name the two intermediate hosts which the human liver fluke depends on to complete its
life cycle so as to facilitate parasitization of its primary host.
Ans. Snail and Fish = ½ + ½
[1 mark]
5. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
6. 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]
7. Mention how does DNA polymorphism arise in a population.
Ans. Inheritable mutations (in a population) , at high frequency = ½ + ½
[1 mark]
8. Write the name of the organism that is referred to as the ‘Terror of Bengal’.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
SECTION - B
9. Name the organic materials the exine and intine of an angiosperm pollen grains are made
up of. Explain the role of exine.
Ans. Exine - Sporopollenin = ½
Intine - Cellulose and pectin = ½
Role - most resistant organic material  // can withstand high temperature  , acid and alkali = 1
[2 marks]
10. (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]
11. How does the gene ‘I’ control ABO blood groups in humans ? Write the effect the gene has
on the structure of red blood cells.
[2 marks]
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
= ½
Ans. (i) Male heterogamety , Grasshopper = ½ + ½
(ii) Female heterogamety , Birds  = ½ + ½
[2 marks]
12. A cross was carried out between two pea plants showing the contrasting traits of height
of the plant. The result of the cross showed 50% of parental characters.
(i) Work out the cross with the help of a Punnett square.
(ii) Name the type of the cross carried out.
Ans. (i) Tt     ×     tt   = ½
Tt
t
t
Tt tt
Tt tt
= ½
= ½
(ii) Test cross = ½
[2 marks]
13. How can healthy potato plants be obtained from a desired potato variety which is viral
infected ? Explain.
Ans. Remove meristem (apical or axillary) and grow = 1 ,
in vitro / sterile and special nutrient medium / culture medium = 1
[2 marks]
14. How are ‘sticky ends’ formed on a DNA strand ? Why are they so called ?
Ans. Restriction enzymes  cut the strands of the DNA , a little away from the centre of  the palindromic
sites , but between the same two bases on opposite strands. = ½ × 3 = 1½
They form hydrogen bonds with their complementary cut counterparts. = ½
[2 marks]
15. What is Bio piracy? State the initiative taken by the Indian Parliament towards it.
Ans. (i) Use of bio resources without authorisation , compensation = ½ + ½
(ii) The govt has cleared patent terms , emergency provisions , research and development
initiative (Any two) = ½ + ½
[2 marks]
16. 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]
17. 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]
18. Write the role of 'Ori' and 'restriction’ site in a cloning vector pBR322.
Ans. Ori - site where replication starts , responsible for controlling copy number = ½ + ½
Restriction site - site of ligation of alien / foreign DNA , in one of the two antibiotic resistance site /
coding sequence of  galactosidase = ½ + ½
[2 marks]
SECTION - C
19. A colourblind child is born to a normal couple. Work out a cross to show how it is
possible. Mention the sex of this child.
Ans.
XY
X Y 
XX
c
XX
c
X X X Y
c
X = 1 
= 1
Male = 1
[3 marks]
OR
Mendel published his work on inheritance of characters in 1865, but it remained
unrecognized till 1900. Give three reasons for the delay in accepting his work.
Ans. - The communication was not easy in those days and his work could not be widely publicised.
- His concept of genes as stable and discrete units that controlled the expression of traits and of
the pair of alleles which did not ‘blend’ with each other was not accepted by contemporaries
as an explanation for the apparently continuous variation seen in nature.
- Mendel’s approach of using mathematics to explain biological phenomena  was totally new
and unacceptable to many of the biologists  of his time.
- Though Mendel’ s work suggested that factors (genes) were discrete units , he could not provide
any physical proof for the existence of factors and what they were made of.
(Any three points) = 1 + 1 + 1
[3 marks]
20. A cross between a normal couple resulted in a son who was haemophilic and a normal
daughter. In course of time, when the daughter was married to a normal man, to their
surprise, the grandson was also haemophilic.
(a) Represent this cross in the form of a pedigree chart. Give the genotypes of the
daughter and her husband.
(b) Write the conclusion you draw of the inheritance pattern of this disease.
Ans.
XY X
X  Y
h
X
h
X
h
X
XY
X  Y
h
(½)
(½)
Construction of pedigree chart  = 1
(b) Sex - linked recessive inheritance pattern = 1
[3 marks]
21. 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
/ Sharing of knowledge or information / Presence of mind /Being proactive / any other relevant
value.
(Any three values) = ½ × 3
[3 marks]
22. Draw a labelled diagram of the sectional view of a human seminiferous tubule  (six parts
to be labelled)