CBSE Class 12 Biology 2025 question paper (57/1)

Maximum marks 70 · Time 3 hours · 3 sets

Try each question first, then open its model answer. Where the paper offers a choice, both questions are shown with OR between them.

Section A

1 mark each

Q.11 mark $A man whose father was colour-blind marries a woman who had a colour-blind mother and normal father. What percentage of male children of this couple will be colour-blind ?$
Tap an option to check your answer.
Q.21 mark $GEAC stands for$
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Q.31 mark $Match the items in Column-A with that of Column-B : Column-A Column-B (i) Lady bird beetle (a) Methanobacterium (ii) Mycorrhiza (b) Trichoderma (iii) Biological control (c) Aphids (iv) Biogas (d) Glomus Choose the option that matches the items of Column A with that of B correctly :$
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Q.41 mark $The process of mineralization by microorganisms help in the release of :$
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Q.51 mark $Transplantation of tissues/organs to some patients often fails due to rejection of such tissues/organs by the body of the patient. Which type of immune response is responsible for such rejections ?$
Tap an option to check your answer.

Column-A	Column-B
(i) Lady bird beetle	(a) Methanobacterium
(ii) Mycorrhiza	(b) Trichoderma
(iii) Biological control	(c) Aphids
(iv) Biogas	(d) Glomus

Q.61 mark

Match the following items of Column-I with that of Column-II : Column-I Column-II (a) Trophoblast (i) Embedding of blastocyst in the endometrium (b) Implantation (ii) Group of cells that would differentiate as embryo (c) Inner cell mass (iii) Embryo with 8-16 blastomeres (d) Morula (iv) Outer layer of blastocyst Choose the option that matches Column-I with Column-II correctly.

Column-I	Column-II
(a) Trophoblast	(i) Embedding of blastocyst in the endometrium
(b) Implantation	(ii) Group of cells that would differentiate as embryo
(c) Inner cell mass	(iii) Embryo with 8-16 blastomeres
(d) Morula	(iv) Outer layer of blastocyst

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Q.71 mark $The diagram given below shows labelling of four parts of a dicot embryo during its development as P, Q, R and S. Choose the option that indicates correct labelling of 'P', 'Q', 'R' and 'S' of embryo in different stages of its development :$
Tap an option to check your answer.
Q.81 mark $Amplification of gene of interest by using DNA polymerase may go upto$
Tap an option to check your answer.
Q.91 mark $The sequence of nitrogenous bases in a segment of a coding strand of DNA is 5' - AATGCTAGGCAC - 3'. Choose the option that shows the correct sequence of nitrogenous bases in the mRNA transcribed by the DNA.$
Tap an option to check your answer.
Q.101 mark $How many pollen grains and ovules are likely to be formed in the anther and the ovary of an angiosperm bearing 50 microspore mother cells and 50 megaspore mother cells respectively ?$
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Q.111 mark $Evolution of modern man involves the following man-like primates. Choose the correct series of human evolution.$
Tap an option to check your answer.
Q.121 mark $RNA interference (RNAi) helps in making tobacco-plant resistant to a nematode (Meloidegyne incognitia) Choose the correct option that shows how RNAi is achieved :$
Tap an option to check your answer.
For Question numbers 13 to 16, two statements are given – one labelled as Assertion (A) and the other labelled as Reason (R). Answer these questions by selecting the appropriate option given below :
Q.131 mark $Assertion (A) : Saheli is the World's first non-steroidal oral contraceptive pill. Reason (R) : It has been developed by National Institute of Immunology, New Delhi.$
Tap an option to check your answer.
Q.141 mark $Assertion (A) : One of the property of genetic code is degeneracy. Reason (R) : Some amino acids can be coded by more than one codon.$
Tap an option to check your answer.
Q.151 mark $Assertion (A) : A bioreactor provides the optimal conditions for achieving the desired product by providing optimum growth conditions. Reason (R) : The most commonly used bioreactors are of stirring type.$
Tap an option to check your answer.
Q.161 mark $Assertion (A) : When the two genes in a dihybrid cross are situated on the same chromosome, the proportion of parental gene combinations is much higher than non-parental type. Reason (R) : Higher parental gene combinations can be attributed to crossing over between two genes.$
Tap an option to check your answer.

Section B

2 marks each

Q.17 (A)2 marks $How are morphine and heroin related ? Mention their effect on the human body.$
OR
Q.17 (B)2 marks $(i) Name an alcoholic drink which is produced by the help of microbes : (1) With distillation (2) Without distillation (ii) Explain how cyanobacteria can be used as bio-fertilizer.$
Q.18 (A)2 marks $Analyse the following ecosystems and discuss, which will be more productive in terms of primary productivity : A young forest, a natural old forest, a shallow polluted lake.$
OR
Q.18 (B)2 marks $Differentiate between Net primary productivity and Gross primary productivity in an ecosystem.$
Q.192 marks $Study the cross given below : Identify the abnormalities '1' and '2' in the offsprings of a cross done between a couple and distinguish between them.$
Q.202 marks $Study the pedigree chart given below, showing the inheritance pattern of blood group in a family : Answer the following questions : (a) Give the possible genotypes of individual 1 and 2. (b) Which antigen or antigens will be present on the plasma membranes of the R.B.Cs of individuals '5' and '8' ?$
Q.21 (A)2 marks $A patient with ADA deficiency requires periodic infusion of genetically engineered lymphocytes. Explain why such periodic infusion is required and also suggest a permanent cure for such ADA deficiency.$
OR
Q.21 (B)2 marks $Describe in brief any two techniques that can be utilised to transfer recombinant DNA into the host cell directly without using any vector.$

Section C

3 marks each

Q.223 marks $(a) Write the palindromic nucleotide sequence for following sequence of DNA segment : 5' - GAATTC - 3' (b) Name the restriction endonuclease that recognizes this sequence. (c) How are sticky ends produced ? Mention their role.$
Q.233 marks $Study a part of life cycle of Plasmodium given below : Answer the following questions : (a) Name the infective stage of Plasmodium that is stored in the female Anopheles mosquito. (b) Where does fertilization and development of parasite take place ? (c) Identify labels P and Q in the given diagram. (d) Asexual and sexual phase of the life cycle of the Plasmodium takes place in two different hosts. Write their names.$
Q.243 marks $(a) Indiscriminate human activities such as alien species invasion, fragmentation and habitat loss have accelerated the loss of biodiversity. Justify by taking one example for each. (b) State the importance of the following : (i) IUCN Red data list (ii) Hot spots in conservation of biodiversity$
Q.253 marks $Study the diagram given below and answer the questions that follows : (a) Identify the structure shown in the above figure. (b) Identify the labels P and Q. (c) Write the nature of histone proteins. (d) Distinguish between Euchromatin and Heterochromatin.$
Q.263 marks $Shyam and Radha are expecting their first child with Radha being in her second month of pregnancy with no complications. Shyam's family has a history of cystic fibrosis while Radha's family has a history of Down's syndrome, leading to a concern that the baby may have one of these conditions. (a) Suggest and explain a way of testing if their baby is at risk for any genetic disorders. (b) In case of presence of one or both of the abnormalities and posing a risk to the mother's health, mention one possible option for them to consider. Is that option safe for Radha at the current gestational age ? Justify. (c) Under what conditions is the process mentioned in (b) illegal ?$
Q.273 marks $Explain the basis on which gel electrophoresis technique works. Write any two ways the products obtained through this technique can be utilised.$
Q.283 marks $Compare and contrast convergent and divergent evolution.$

Section D

Study the graphs given below for Case 1 and Case 2 showing different levels of certain hormones and answer the question that follows :
Q.29 (a)1 mark $Which hormone is responsible for the peak observed in Case 1 and Case 2 ? Write one function of that hormone.$
Q.29 (b)2 marks $Write changes that take place in the ovary and uterus during follicular phase.$
Q.29 (c)1 mark $Name the hormone Q of Case 2. Write one function of hormone Q.$
OR
Q.29 (d)1 mark $Which structure in the ovary will remain functional in Case 2 ? How is it formed ?$
In nature, we rarely find isolated, single individuals of any species; majority of them live in groups in a well-defined geographical area, share or compete for similar resources, potentially interbreed and thus constitute a population. The population has certain attributes whereas, an individual organism does not. A population at a given time is composed of individuals of different ages. The size of the population tells us a lot about its status in the habitat. Whatever ecological processes we wish to investigate in a population, be it the outcome of competition with another species, the impact of the predator or the effect of pesticide application, we always evaluate in terms of any change in the population size. The size, in nature, could be low or go into millions. Population size, technically called population density (N) need not necessarily be measured in numbers only. The size of a population for any species is not a static parameter. It keeps on changing with time depending on various factors including food availability, predation pressure and adverse weather.
Q.30 (a)1 mark $The Monarch butterfly is highly distasteful to its predator because of a special chemical present in its body. How does the butterfly acquire this chemical ?$
Q.30 (b)2 marks $If population density at a time t + 1 is 800, Emigration = 100, Immigration = 200, Natality = 200 and Mortality = 150, calculate the population density at time t and comment upon the type of age pyramid that will be formed in this case.$
Q.30 (c)1 mark $What is the difference in a method of measuring population density in an area if there are 200 carrot grass plants to only single huge banyan tree ?$
OR
Q.30 (d)1 mark $Name two methods to measure the population density of tigers.$

Section E

5 marks each

Q.31 (A)5 marks $Answer the following questions : (i) State what do you understand by "MALT" ? Where it is located inside our body ? (ii) Explain cytokine barriers. (iii) Name the diagnostic test for AIDS. On what principle does it work ? (iv) Bone marrow and thymus play an important role in human immune system. Explain how are they able to achieve this.$

Q.31 (B)5 marks

(i) Study the following table & fill 'H', 'I', 'J', 'K', 'L' and 'M' in following table with suitable words : Chemical / Bioactive Molecule Micro-organism Category Use (a) Butyric acid H I Important applications in food, chemical & pharma industry (b) J Monoscus purpureus K Inhibit cholesterol biosynthesis pathway (c) Cyclosporin A L Fungus M (ii) Why are baculoviruses used as biological control agents ?

Q.32 (A)5 marks $(a) Distinguish between the two cells enclosed in a mature male gametophyte of an angiosperm. (b) Study the diagram given below showing the modes of pollination. Answer the questions that follow. (i) The given diagram shows three methods of pollen transfer in plants. Examine them carefully and write the technical terms used for pollen transfer methods '1', '2' and '3'. (ii) How do the following plants achieve pollination successfully ? (a) Water lily (b) Vallisneria (iii) Write advantages of pollen transfer in method '3'.$
OR
Q.32 (B)5 marks $Given below is the diagram of human ovum surrounded by a few sperms. Observe the diagram and answer the questions that follows : (i) Compare the fate of sperms 'P', 'Q' and 'R' shown in the diagram. (ii) Write the role of Zona pellucida in this process. (iii) Analyse the changes occurring in the ovum after the entry of sperm. (iv) How acrosome and middle piece of a human sperm are able to play an important role in human fertilization ?$
Q.33 (A)5 marks $\text{F}_1$
OR
Q.33 (B)5 marks $Explain with the help of well-labelled diagrams how lac operon operates in E. coli : (i) In presence of an inducer. (ii) In absence of an inducer.$

	Chemical / Bioactive Molecule	Micro-organism	Category	Use
(a)	Butyric acid	H	I	Important applications in food, chemical & pharma industry
(b)	J	Monoscus purpureus	K	Inhibit cholesterol biosynthesis pathway
(c)	Cyclosporin A	L	Fungus	M

Section A

1 mark each

Q.11 mark $Mohit performed an analysis of two different soil samples from two areas A and B. He recorded these results : Soil Sample A : Lignin 40%, Sugar 10%, Chitin 45%, Nitrogen 5% Soil Sample B : Lignin 5%, Sugar 35%, Chitin 15%, Nitrogen 45% Which of these is true about their rate of decomposition in both the soil ?$
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Q.21 mark $Diameter of the pollen grain generally is$
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Q.31 mark $Menstrual cycle in human females consists of various events. Select the option that indicates the correct sequence of these events of menstrual cycle.$
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Q.41 mark $\text{F}_2$
Tap an option to check your answer.
Q.51 mark $RNA interference (RNAi) helps in making tobacco-plant resistant to a nematode (Meloidegyne incognita) Choose the correct option that shows how RNAi is achieved :$
Tap an option to check your answer.
Q.61 mark $The sequence of nitrogenous bases in a segment of a coding strand of DNA is 5' - AATGCTAGGCAC - 3'. Choose the option that shows the correct sequence of nitrogenous bases in the mRNA transcribed by the DNA.$
Tap an option to check your answer.
Q.71 mark $A man whose father was colour-blind marries a woman who had a colour-blind mother and normal father. What percentage of male children of this couple will be colour-blind ?$
Tap an option to check your answer.
Q.81 mark $Evolution of modern man involves the following man-like primates. Choose the correct series of human evolution.$
Tap an option to check your answer.
Q.91 mark $GEAC stands for$
Tap an option to check your answer.
Q.101 mark $Transplantation of tissues/organs to some patients often fails due to rejection of such tissues/organs by the body of the patient. Which type of immune response is responsible for such rejections ?$
Tap an option to check your answer.
Q.111 mark $Amplification of gene of interest by using DNA polymerase may go upto$
Tap an option to check your answer.
Q.121 mark $The diagram given below shows labelling of four parts of a dicot embryo during its development as P, Q, R and S. Choose the option that indicates correct labelling of 'P', 'Q', 'R' and 'S' of embryo in different stages of its development :$
Tap an option to check your answer.
For Question numbers 13 to 16, two statements are given – one labelled as Assertion (A) and the other labelled as Reason (R). Answer these questions by selecting the appropriate option given below :
Q.131 mark $Assertion (A) : Perisperm is a diploid tissue. Reason (R) : Perisperm is the remains of nucellus which surrounds the embryo in certain seeds.$
Tap an option to check your answer.
Q.141 mark $Assertion (A) : While working on Staphylococci, Alexander Fleming observed that Penicillium notatum inhibits the growth of bacteria. Reason (R) : The inhibiting chemical was commercially extracted and its full potential was established by Alexander Fleming.$
Tap an option to check your answer.
Q.151 mark $Assertion (A) : One of the property of genetic code is degeneracy. Reason (R) : Some amino acids can be coded by more than one codon.$
Tap an option to check your answer.
Q.161 mark $Assertion (A) : A bioreactor provides the optimal conditions for achieving the desired product by providing optimum growth conditions. Reason (R) : The most commonly used bioreactors are of stirring type.$
Tap an option to check your answer.

Section B

2 marks each

Q.172 marks $Study the two different crosses given below : Identify the abnormalities 1 and 2 in the offsprings of given crosses and distinguish between them.$
Q.182 marks $Study the pedigree analysis of Myotonic dystrophy given below : Answer the following questions : (a) Write genotype of A, B, C and D (b) Identify whether the trait is (i) Sex linked or autosomal (ii) Dominant or recessive$
Q.19 (A)2 marks $A patient with ADA deficiency requires periodic infusion of genetically engineered lymphocytes. Explain why such periodic infusion is required and also suggest a permanent cure for such ADA deficiency.$
OR
Q.19 (B)2 marks $Describe in brief any two techniques that can be utilised to transfer recombinant DNA into the host cell directly without using any vector.$
Q.20 (A)2 marks $How are morphine and heroin related ? Mention their effect on the human body.$
OR
Q.20 (B)2 marks $(i) Name an alcoholic drink which is produced by the help of microbes : (1) With distillation (2) Without distillation (ii) Explain how cyanobacteria can be used as bio-fertilizer.$
Q.21 (A)2 marks $Analyse the following ecosystems and discuss, which will be more productive in terms of primary productivity : A young forest, a natural old forest, a shallow polluted lake.$
OR
Q.21 (B)2 marks $Differentiate between Net primary productivity and Gross primary productivity in an ecosystem.$

Section C

3 marks each

Q.223 marks $(a) Explain the importance of 'ori' and 'rop' in the E. coli cloning vector shown in the above given diagram. (b) Differentiate between exonucleases and endonucleases.$
Q.233 marks $The great German naturalist and geographer Alexander Von Humboldt observed that within a region species richness increased with increasing explored area, but only upto a limit. (a) For the above situation, construct a graph and write an equation. (b) Also write various values of Z (regression coefficient).$
Q.243 marks $Shyam and Radha are expecting their first child with Radha being in her second month of pregnancy with no complications. Shyam's family has a history of cystic fibrosis while Radha's family has a history of Down's syndrome, leading to a concern that the baby may have one of these conditions. (a) Suggest and explain a way of testing if their baby is at risk for any genetic disorders. (b) In case of presence of one or both of the abnormalities and posing a risk to the mother's health, mention one possible option for them to consider. Is that option safe for Radha at the current gestational age ? Justify. (c) Under what conditions is the process mentioned in (b) is illegal ?$
Q.253 marks $(a) Write the palindromic nucleotide sequence for following sequence of DNA segment : 5' - GAATTC - 3' (b) Name the restriction endonuclease that recognizes this sequence. (c) How are sticky ends produced ? Mention their role.$
Q.263 marks $Study a part of life cycle of Plasmodium given below : Answer the following questions : (a) Name the infective stage of Plasmodium that is stored in the female Anopheles mosquito. (b) Where does fertilization and development of parasite take place ? (c) Identify labels P and Q in the given diagram. (d) Asexual and sexual phase of the life cycle of the Plasmodium takes place in two different hosts. Write their names.$
Q.273 marks $Compare and contrast convergent and divergent evolution.$
Q.283 marks $Study the diagram given below and answer the questions that follows : (a) Identify the structure shown in the above figure. (b) Identify the labels P and Q. (c) Write the nature of histone proteins. (d) Distinguish between Euchromatin and Heterochromatin.$

Section D

In nature, we rarely find isolated, single individuals of any species; majority of them live in groups in a well-defined geographical area, share or compete for similar resources, potentially interbreed and thus constitute a population. The population has certain attributes whereas, an individual organism does not. A population at a given time is composed of individuals of different ages. The size of the population tells us a lot about its status in the habitat. Whatever ecological processes we wish to investigate in a population, be it the outcome of competition with another species, the impact of the predator or the effect of pesticide application, we always evaluate in terms of any change in the population size. The size, in nature, could be low or go into millions. Population size, technically called population density (N) need not necessarily be measured in numbers only. The size of a population for any species is not a static parameter. It keeps on changing with time depending on various factors including food availability, predation pressure and adverse weather.
Q.29 (a)1 mark $The Monarch butterfly is highly distasteful to its predator because of a special chemical present in its body. How does the butterfly acquire this chemical ?$
Q.29 (b)2 marks $If population density at a time t + 1 is 800, Emigration = 100, Immigration = 200, Natality = 200 and Mortality = 150, calculate the population density at time t and comment upon the type of age pyramid that will be formed in this case.$
Q.29 (c)1 mark $What is the difference in a method of measuring population density in an area if there are 200 carrot grass plants to only single huge banyan tree ?$
OR
Q.29 (d)1 mark $Name two methods to measure the population density of tigers.$
Study the graphs given below for Case 1 and Case 2 showing different levels of certain hormones and answer the questions that follows :
Q.30 (a)1 mark $Which hormone is responsible for the peak observed in Case 1 and Case 2 ? Write one function of that hormone.$
Q.30 (b)2 marks $Write changes that take place in the ovary and uterus during follicular phase.$
Q.30 (c)1 mark $Name the hormone Q of Case 2. Write one function of hormone Q.$
OR
Q.30 (d)1 mark $Which structure in the ovary will remain functional in Case 2 ? How is it formed ?$

Section E

5 marks each

Q.31 (A)5 marks $(a) Distinguish between the two cells enclosed in a mature male gametophyte of an angiosperm. (b) Study the diagram given below showing the modes of pollination. Answer the questions that follow. (i) The given diagram shows three methods of pollen transfer in plants. Examine them carefully and write the technical terms used for pollen transfer in methods '1', '2' and '3'. (ii) How do the following plants achieve pollination successfully ? (a) Water lily (b) Vallisneria (iii) Write advantages of pollen transfer method '3'.$
OR
Q.31 (B)5 marks $Given below is the diagram of human ovum surrounded by a few sperms. Observe the diagram and answer the questions that follows : (i) Compare the fate of sperms 'P', 'Q' and 'R' shown in the diagram. (ii) Write the role of Zona pellucida in this process. (iii) Analyse the changes occurring in the ovum after the entry of sperm. (iv) How acrosome and middle piece are able to play an important role in human fertilization ?$
Q.32 (A)5 marks $Answer the following questions : (i) State what do you understand by "MALT" ? Where it is located inside our body ? (ii) Explain cytokine barriers. (iii) Name the diagnostic test for AIDS. On what principle does it work ? (iv) Bone marrow and thymus play an important role in human immune system. Explain how are they able to achieve this.$

Q.32 (B)5 marks

(i) Fill 'H', 'I', 'J', 'K', 'L' and 'M' in following table with suitable words : Chemical / Bioactive Molecule Micro-organism Category Use (a) Butyric acid H I Important applications in food, chemical & pharma industry (b) J Monoscus purpureus K Inhibit cholesterol biosynthesis pathway (c) Cyclosporin A L Fungus M (ii) Why are baculoviruses used as biological control agents ?

Q.33 (A)5 marks $(i) Haemophilia and red green colourblindness is usually observed in men. Why ? (ii) Perform a cross(es) where haemophilic daughter(s) and haemophilic son(s) are produced in same ratio.$
OR
Q.33 (B)5 marks $(i) Where do transcription and translation occur in bacteria and eukaryotes respectively ? (ii) Draw a labelled schematic sketch of replication fork of DNA. (iii) A DNA segment has a total of 1000 nucleotides, out of which 240 of them are Adenine containing nucleotides. How many pyrimidine bases this segment possesses ?$

	Chemical / Bioactive Molecule	Micro-organism	Category	Use
(a)	Butyric acid	H	I	Important applications in food, chemical & pharma industry
(b)	J	Monoscus purpureus	K	Inhibit cholesterol biosynthesis pathway
(c)	Cyclosporin A	L	Fungus	M

Section A

1 mark each

Q.11 mark $What type of ecological pyramid would be obtained with the following data ? Primary producer = 10 g Secondary consumer = 120 g Primary consumer = 60 g$
Tap an option to check your answer.
Q.21 mark $Flowers which have single ovule in the ovary and are packed into inflorescence are usually pollinated by$
Tap an option to check your answer.
Q.31 mark $The diagram given below shows labelling of four parts of a dicot embryo during its development as P, Q, R and S. Choose the option that indicates correct labelling of 'P', 'Q', 'R' and 'S' of embryo in different stages of its development :$
Tap an option to check your answer.
Q.41 mark $Evolution of modern man involves the following man-like primates. Choose the correct series of human evolution.$
Tap an option to check your answer.
Q.51 mark $A man whose father was colour-blind marries a woman who had a colour-blind mother and normal father. What percentage of male children of this couple will be colour-blind ?$
Tap an option to check your answer.
Q.61 mark $Endosperm is completely consumed by the developing embryo in which of the following ?$
Tap an option to check your answer.
Q.71 mark $GEAC stands for$
Tap an option to check your answer.
Q.81 mark $Transplantation of tissues/organs to some patients often fails due to rejection of such tissues/organs by the body of the patient. Which type of immune response is responsible for such rejections ?$
Tap an option to check your answer.
Q.91 mark $Amplification of gene of interest by using DNA polymerase may go upto$
Tap an option to check your answer.
Q.101 mark $RNA interference (RNAi) helps in making tobacco-plant resistant to a nematode (Meloidegyne incognita) Choose the correct option that shows how RNAi is achieved :$
Tap an option to check your answer.
Q.111 mark $The sequence of nitrogenous bases in a segment of a coding strand of DNA is 5' - AATGCTAGGCAC - 3'. Choose the option that shows the correct sequence of nitrogenous bases in the mRNA transcribed by the DNA.$
Tap an option to check your answer.
Q.121 mark $Which of the following is correct for the condition when plant YyRr is back crossed with the double recessive parent ?$
Tap an option to check your answer.
For Questions number 13 to 16 two statements are given – one labelled as Assertion (A) and the other labelled as Reason (R). Answer these questions by selecting the appropriate option given below :
Q.131 mark $Assertion (A) : The mammary glands secrete milk for the nourishment of the young ones. Reason (R) : These are modified sweat glands.$
Tap an option to check your answer.
Q.141 mark $Assertion (A) : Scaffold proteins are non-histone chromosomal proteins. Reason (R) : They are rich in lysine and arginine.$
Tap an option to check your answer.
For Question numbers 13 to 16, two statements are given – one labelled as Assertion (A) and the other labelled as Reason (R). Answer these questions by selecting the appropriate option given below :
Q.151 mark $Assertion (A) : When the two genes in a dihybrid cross are situated on the same chromosome, the proportion of parental gene combinations is much higher than non-parental type. Reason (R) : Higher parental gene combinations can be attributed to crossing over between two genes.$
Tap an option to check your answer.
Q.161 mark $Assertion (A) : A bioreactor provides the optimal conditions for achieving the desired product by providing optimum growth conditions. Reason (R) : The most commonly used bioreactors are of stirring type.$
Tap an option to check your answer.

Section B

2 marks each

Q.172 marks $Study the pedigree analysis given below : Answer the following questions : (A) Write genotypes of c and d. (B) Identify whether the trait is (i) Sex-linked or autosomal (ii) Dominant or recessive$
Q.182 marks $Study the two different crosses given below : Identify the abnormalities '1' and '2' in the offsprings of given crosses and distinguish between them.$
Q.19 (A)2 marks $How are morphine and heroin related ? Mention their effect on the human body.$
OR
Q.19 (B)2 marks $(i) Name an alcoholic drink which is produced by the help of microbes : (1) With distillation (2) Without distillation (ii) Explain how cyanobacteria can be used as bio-fertilizer.$
Q.20 (A)2 marks $Analyse the following ecosystems and discuss which will be more productive in terms of primary productivity : A young forest, a natural old forest, a shallow polluted lake.$
OR
Q.20 (B)2 marks $Differentiate between Net primary productivity and Gross primary productivity in an ecosystem.$
Q.21 (A)2 marks $A patient with ADA deficiency requires periodic infusion of genetically engineered lymphocytes. Explain why such periodic infusion is required and also suggest a permanent cure for such ADA deficiency.$
OR
Q.21 (B)2 marks $Describe in brief any two techniques that can be utilised to transfer recombinant DNA into the host cell directly without using any vector.$

Section C

3 marks each

Q.223 marks $Compare and contrast convergent and divergent evolution.$
Q.233 marks $Shyam and Radha are expecting their first child with Radha being in her second month of pregnancy with no complications. Shyam's family has a history of cystic fibrosis while Radha's family has a history of Down's syndrome, leading to a concern that the baby may have one of these conditions. (a) Suggest and explain a way of testing if their baby is at risk for any genetic disorders. (b) In case of presence of one or both of the abnormalities and posing a risk to the mother's health, mention one possible option for them to consider. Is that option safe for Radha at the current gestational age ? Justify. (c) Under what conditions is the process mentioned in (b) illegal ?$
Q.243 marks $(a) Write the palindromic nucleotide sequence for following sequence of DNA segment : 5' - GAATTC - 3' (b) Name the restriction endonuclease that recognizes this sequence. (c) How are sticky ends produced ? Mention their role.$
Q.253 marks $Study a part of life cycle of Plasmodium given below : Answer the following questions : (a) Name the infective stage of Plasmodium that is stored in the female Anopheles mosquito. (b) Where does fertilization and development of parasite take place ? (c) Identify labels P and Q in the given diagram. (d) Asexual and sexual phase of the life cycle of the Plasmodium takes place in two different hosts. Write their names.$
Q.263 marks $Study the diagram given below and answer the questions that follows : (a) Identify the structure shown in the above figure. (b) Identify the labels P and Q. (c) Write the nature of histone proteins. (d) Distinguish between Euchromatin and Heterochromatin.$
Q.273 marks $(A) Who is having more species diversity - Columbia or Greenland and why ? (B) Explain the concept proposed by Paul Ehlrich.$
Q.283 marks $(A) Differentiate between Recombinant DNA and cDNA. (B) Explain the method to increase the competency of the bacterial cell membrane to take up recombinant DNA.$

Section D

In nature, we rarely find isolated, single individuals of any species; majority of them live in groups in a well-defined geographical area, share or compete for similar resources, potentially interbreed and thus constitute a population. The population has certain attributes whereas, an individual organism does not. A population at a given time is composed of individuals of different ages. The size of the population tells us a lot about its status in the habitat. Whatever ecological processes we wish to investigate in a population, be it the outcome of competition with another species, the impact of the predator or the effect of pesticide application, we always evaluate in terms of any change in the population size. The size, in nature, could be low or go into millions. Population size, technically called population density (N) need not necessarily be measured in numbers only. The size of a population for any species is not a static parameter. It keeps on changing with time depending on various factors including food availability, predation pressure and adverse weather.
Q.29 (a)1 mark $The Monarch butterfly is highly distasteful to its predator because of a special chemical present in its body. How does the butterfly acquire this chemical ?$
Q.29 (b)2 marks $If population density at a time t + 1 is 800, Emigration = 100, Immigration = 200, Natality = 200 and Mortality = 150, calculate the population density at time t and comment upon the type of age pyramid that will be formed in this case.$
Q.29 (c)1 mark $What is the difference in a method of measuring population density in an area if there are 200 carrot grass plants to only single huge banyan tree ?$
OR
Q.29 (d)1 mark $Name two methods to measure the population density of tigers.$
Study the graphs given below for Case 1 and Case 2 showing different levels of certain hormones and answer the questions that follows :
Q.30 (a)1 mark $Which hormone is responsible for the peak observed in Case 1 and Case 2 ? Write one function of that hormone.$
Q.30 (b)2 marks $Write changes that take place in the ovary and uterus during follicular phase.$
Q.30 (c)1 mark $Name the hormone Q of Case 2. Write one function of hormone Q.$
OR
Q.30 (d)1 mark $Which structure in the ovary will remain functional in Case 2 ? How is it formed ?$

Section E

5 marks each

Q.31 (A)5 marks $(i) You are given axial pea flowers with violet colour whose genotypes are unknown. How would you find the genotype of these plants ? Explain with the help of cross. (ii) Explain Haplodiploidy in honey-bees.$
OR
Q.31 (B)5 marks $Explain the steps of DNA fingerprinting that will help in processing of the two blood samples R and S picked up from the crime scene.$
Q.32 (A)5 marks $Answer the following questions : (i) State what do you understand by "MALT" ? Where it is located inside our body ? (ii) Explain cytokine barriers. (iii) Name the diagnostic test for AIDS. On what principle does it work ? (iv) Bone marrow and thymus play an important role in human immune system. Explain how are they able to achieve this.$

Q.32 (B)5 marks

(i) Fill 'H', 'I', 'J', 'K', 'L' and 'M' in following table with suitable words : Chemical / Bioactive Molecule Micro-organism Category Use (a) Butyric acid H I Important applications in food, chemical & pharma industry (b) J Monoscus purpureus K Inhibit cholesterol biosynthesis pathway. (c) Cyclosporin A L Fungus M (ii) Why are baculoviruses used as biological control agents ?

Q.33 (A)5 marks $(a) Distinguish between the two cells enclosed in a mature male gametophyte of an angiosperm. (b) Study the diagram given below showing the modes of pollination. Answer the questions that follow. (i) The given diagram shows three methods of pollen transfer in plants. Examine them carefully and write the technical terms used for pollen transfer methods '1', '2' and '3'. (ii) How do the following plants achieve pollination successfully ? (a) Water lily (b) Vallisneria (iii) Write advantages of pollen transfer method '3'.$
OR
Q.33 (B)5 marks $Given below is the diagram of human ovum surrounded by a few sperms. Observe the diagram and answer the questions that follows : (i) Compare the fate of sperms P, Q and R shown in the diagram. (ii) Write the role of Zona pellucida in this process. (iii) Analyse the changes occurring in the ovum after the entry of sperm. (iv) How acrosome and middle piece of a human sperm are able to play an important role in human fertilization ?$