Past Year Paper - Solutions, Biology (Set - 1), Delhi, 2014, Class 12, Biology | Additional Study Material for NEET PDF Download

 Page 1


Question Paper Code 57/1/1
SECTION – A
Q. Nos. 1 - 8 are of one marks each
1. Write the name of the organism that is referred to as the ‘Terror of Bengal’.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
2. What are ‘true breeding lines’ that are used to study inheritance pattern of traits in
plants ?
Ans. Self pollination continuous , for several generations / homozygous = ½ + ½
[1 mark]
3. 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]
4. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
5. 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]
6. Give an example of an organism that enters ‘diapause’ and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
7. Identify ‘a’ and ‘b’ in the figure given below representing proportionate number of
major vertebrate taxa.
Page 2


Question Paper Code 57/1/1
SECTION – A
Q. Nos. 1 - 8 are of one marks each
1. Write the name of the organism that is referred to as the ‘Terror of Bengal’.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
2. What are ‘true breeding lines’ that are used to study inheritance pattern of traits in
plants ?
Ans. Self pollination continuous , for several generations / homozygous = ½ + ½
[1 mark]
3. 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]
4. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
5. 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]
6. Give an example of an organism that enters ‘diapause’ and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
7. 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]
8. 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]
SECTION - B
9. Why do algae and fungi shift to sexual mode of reproduction just before the onset of
adverse conditions ?
Ans. For survival during unfavourable conditions / Fusion of gametes helps to pool their resources for
survival (hunger theory of sex) / Zygote develops a thick wall that is resistant to dessication and
damage which undergoes a period of rest before germination.
[2 marks]
10. 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]
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.
Page 3


Question Paper Code 57/1/1
SECTION – A
Q. Nos. 1 - 8 are of one marks each
1. Write the name of the organism that is referred to as the ‘Terror of Bengal’.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
2. What are ‘true breeding lines’ that are used to study inheritance pattern of traits in
plants ?
Ans. Self pollination continuous , for several generations / homozygous = ½ + ½
[1 mark]
3. 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]
4. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
5. 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]
6. Give an example of an organism that enters ‘diapause’ and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
7. 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]
8. 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]
SECTION - B
9. Why do algae and fungi shift to sexual mode of reproduction just before the onset of
adverse conditions ?
Ans. For survival during unfavourable conditions / Fusion of gametes helps to pool their resources for
survival (hunger theory of sex) / Zygote develops a thick wall that is resistant to dessication and
damage which undergoes a period of rest before germination.
[2 marks]
10. 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]
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.
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]
12. (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]
13. 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]
14. 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]
15. State how has Agrobacterium tumifaciens been made a useful cloning vector to transfer
DNA to plant cells.
= ½
Page 4


Question Paper Code 57/1/1
SECTION – A
Q. Nos. 1 - 8 are of one marks each
1. Write the name of the organism that is referred to as the ‘Terror of Bengal’.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
2. What are ‘true breeding lines’ that are used to study inheritance pattern of traits in
plants ?
Ans. Self pollination continuous , for several generations / homozygous = ½ + ½
[1 mark]
3. 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]
4. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
5. 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]
6. Give an example of an organism that enters ‘diapause’ and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
7. 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]
8. 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]
SECTION - B
9. Why do algae and fungi shift to sexual mode of reproduction just before the onset of
adverse conditions ?
Ans. For survival during unfavourable conditions / Fusion of gametes helps to pool their resources for
survival (hunger theory of sex) / Zygote develops a thick wall that is resistant to dessication and
damage which undergoes a period of rest before germination.
[2 marks]
10. 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]
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.
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]
12. (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]
13. 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]
14. 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]
15. State how has Agrobacterium tumifaciens been made a useful cloning vector to transfer
DNA to plant cells.
= ½
Ans. Agrobacterium tumifaciens has Ti plasmid , the plasmid modified into a cloning vector , which
is no more pathogenic to host plants , and is able to deliver genes of interest. = ½ × 4
[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)  ( 1 + 1)
[2 marks]
18. 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]
SECTION-C
19. Explain any three advantages the seeds offer to angiosperms.
Ans. - Since reproductive process such as pollination and fertilisation are independent of
water , seed formation is more dependable.
- Seeds have better adaptive strategies  for dispersal to new habitats and help the species
to colonise in other areas.
- As they have sufficient food reserves young seedlings are nourished until they are capable
of photosynthesis on their own.
- The hard seed coat provides protection to the young embryo.
- Being products of sexual reproduction , they generate new genetic combinations /
variations.
Page 5


Question Paper Code 57/1/1
SECTION – A
Q. Nos. 1 - 8 are of one marks each
1. Write the name of the organism that is referred to as the ‘Terror of Bengal’.
Ans. Eicchornia crassipes / W ater Hyacinth
[1 mark]
2. What are ‘true breeding lines’ that are used to study inheritance pattern of traits in
plants ?
Ans. Self pollination continuous , for several generations / homozygous = ½ + ½
[1 mark]
3. 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]
4. Mention the type of host cells suitable for the gene guns to introduce an alien DNA.
Ans. Plant cells
[1 mark]
5. 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]
6. Give an example of an organism that enters ‘diapause’ and why.
Ans. (Many species of) Zooplankton, unfavourable condition = ½ + ½
[1 mark]
7. 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]
8. 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]
SECTION - B
9. Why do algae and fungi shift to sexual mode of reproduction just before the onset of
adverse conditions ?
Ans. For survival during unfavourable conditions / Fusion of gametes helps to pool their resources for
survival (hunger theory of sex) / Zygote develops a thick wall that is resistant to dessication and
damage which undergoes a period of rest before germination.
[2 marks]
10. 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]
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.
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]
12. (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]
13. 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]
14. 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]
15. State how has Agrobacterium tumifaciens been made a useful cloning vector to transfer
DNA to plant cells.
= ½
Ans. Agrobacterium tumifaciens has Ti plasmid , the plasmid modified into a cloning vector , which
is no more pathogenic to host plants , and is able to deliver genes of interest. = ½ × 4
[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)  ( 1 + 1)
[2 marks]
18. 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]
SECTION-C
19. Explain any three advantages the seeds offer to angiosperms.
Ans. - Since reproductive process such as pollination and fertilisation are independent of
water , seed formation is more dependable.
- Seeds have better adaptive strategies  for dispersal to new habitats and help the species
to colonise in other areas.
- As they have sufficient food reserves young seedlings are nourished until they are capable
of photosynthesis on their own.
- The hard seed coat provides protection to the young embryo.
- Being products of sexual reproduction , they generate new genetic combinations /
variations.
- Dehydration and dormancy of mature seeds are crucial for survival under adverse
conditions.
(Any three points) = 1 + 1 + 1
[3 marks]
20. Name and explain the role of inner and middle walls of the human uterus.
Ans. Inner   - Endometrium  = ½ ,
supports foetal growth ,  helps in placenta formation  after implantation = ½  + ½,
Middle - Myometrium = ½,
Exhibits strong contraction during delivery of baby = 1
[3 marks]
21. 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]
22. 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