CBSE Class 12 Biology 2026 question paper (57/4)

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 $Choose the option that gives the correct number of pollen grains that will be formed after 325 microspore mother cells undergo microsporogenesis.$
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Q.21 mark $Select the phase of menstrual cycle in which the remaining parts of Graafian follicle transform into the corpus luteum.$
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Q.31 mark $A female undergoing IVF treatment has blocked fallopian tube. The technique by which the embryo with more than 8 blastomeres will be transferred into the female for further development is :$
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Q.41 mark $Select the correct statement. All genes located on the same chromosome :$
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Q.51 mark $Choose the correct statements : (i) Polycistronic mRNA is generally found in eukaryotes. (ii) The RNA polymerase II transcribes precursor of mRNA, the hnRNA. (iii) The process of translation of mRNA begins when the mRNA encounters the large subunit of ribosomes. (iv) Stop codons do not have any tRNAs.$
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Q.61 mark $Name the extinct ancestor of humans who ate only fruits and hunted with stone weapons.$
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Q.71 mark $Nicotine affects blood pressure and heart rate due to release of certain adrenal hormones. Following are some of the adrenal hormones : (i) Adrenaline (ii) Cortisol (iii) Noradrenaline (iv) Aldosterone Select the correct option :$
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Q.81 mark $Microbes used for biocontrol of pest butterfly caterpillars is :$
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Q.91 mark $The given diagram shows the skulls of two different mammals. Which of the following options accurately describes the differences between these skulls ?$
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Q.101 mark $In RNAi, genes are silenced using which of the following biomolecules ?$
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Q.111 mark $Connell's elegant field experiments on the rocky seacoast of Scotland, found that larger barnacles Balanus dominated the intertidal area and removed the smaller barnacles Chathamalus. This happened due to :$
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Q.121 mark $Protein encoded by gene Cry-I Ab controls the infestation of which of the following ?$
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For Questions number 13 to 16, two statements are given – one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
Q.131 mark $Assertion (A) : Cleistogamous flowers have assured seed set. Reason (R) : Cleistogamous flowers are invariably autogamous and do not depend on any pollinating agents.$
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Q.141 mark $\text{I}^{\text{A}}$
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Q.151 mark $Assertion (A) : Nucleopolyhedrovirus are useful as they are good biocontrol agents. Reason (R) : They are species-specific, narrow spectrum bioinsecticides.$
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Q.161 mark $Assertion (A) : The pyramid of biomass in a pond aquatic ecosystem is always inverted. Reason (R) : The biomass of consumers like fishes far exceeds that of the producers like phytoplanktons.$
Tap an option to check your answer.

Section B

2 marks each

Q.172 marks $How do 'implants' act as an effective method of contraception in human females ? Mention one advantage of implants over contraceptive pills.$
Q.182 marks $(a) Write one way by which apomictic seeds can be developed. (b) Why do farmers prefer apomictic seeds over hybrid seeds ?$
Q.192 marks $A laboratory assistant collected three water samples, namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant. But the laboratory attendant did not note which was which. The samples were labelled A, B and C and subjected to a BOD test. The BOD values of the three samples A, B and C were recorded as 30 mg/L, 8 mg/L and 400 mg/L respectively. (a) Which sample of the water is most polluted ? (b) Can you assign the correct label to each, assuming the river water is relatively clean ?$
Q.202 marks $Write the role of 'ori' and 'restriction' site in a cloning vector pBR322.$
Q.21 (a)2 marks $Biodiversity must be conserved as it plays an important role in many ecosystem services that nature provides. Explain any two ecosystem services.$
OR
Q.21 (b)2 marks $(i) State, what does 'standing crop' of a trophic level represent. (ii) List any two ways of measuring the standing crop of a trophic level.$

Section C

3 marks each

Q.223 marks $Differentiate between wind-pollinated and insect-pollinated flowers. Give an example of each type.$
Q.233 marks $(a) Construct a complete transcription unit with promoter and terminator on the basis of the hypothetical coding strand given below : A T G C A T G C A T A G (b) Write the RNA strand transcribed from the above transcription unit along with its polarity.$
Q.243 marks $Explain the three different ways in which natural selection operates. Explain with the help of graphs.$
Q.253 marks $(a) How do some viruses cause cancer in humans ? (b) How do benign tumours turn malignant ? How do malignant tumours harm the human body ?$
Q.263 marks $(a) How is insulin different from proinsulin ? (b) Explain all the stages of how human insulin is produced through rDNA technology.$
Q.27 (a)3 marks $Study the graph given below and answer the questions that follow : (i) Write the status of food and space in the curves a and b. (ii) In the absence of predators, which one of the two curves would appropriately depict the prey population ? (iii) 'Time' has been shown on x-axis and there is a parallel dotted line above it. Give the significance of this dotted line.$
OR
Q.27 (b)3 marks $Answer the following questions : (i) Define 'predation'. (ii) Why is predation required in a community of different organisms ? Give any two points. (iii) Why are predators 'prudent' in nature ?$
Q.283 marks $There are many animals, which have become extinct in the wild, but continue to be maintained in zoological parks. Answer the questions that follow : (a) What type of bio-diversity conservation is observed in this case ? (b) Explain any other two ways which help in this type of conservation. (c) Besides zoological parks, mention one place that serves this purpose.$

Section D

Gene expresses itself in a cell system as a protein/enzyme. How an expression of gene occurs in a cell system, when it needs to occur and how the gene expression is regulated in prokaryotic cell system was studied by the combined efforts of Francois Jacob, a geneticist and Jacques Monod, a biochemist. For their work on lactose metabolism in E. coli and introducing the concept of 'lac operon', they were awarded the Nobel Prize in 1965.
Q.29 (a)1 mark $It is said that 'lac operon' has to be operational at a very low level in the bacterial cell all the time. Justify.$
Q.29 (b)(i)1 mark $How are the structural genes activated in the lac operon in E. coli ?$
OR
Q.29 (b)(ii)1 mark $Why is the regulation of operon called negative regulation ?$
Q.29 (c)2 marks $Why is lac operon said to be a transcriptionally regulated system ?$
Immunity in our body is of two types (i) Innate immunity, and (ii) Acquired immunity. Innate immunity is a non-specific defence mechanism, whereas Acquired immunity is pathogen specific. Acquired immunity is characterised by memory. Antibodies are specific to antigens and there are four types of antibodies produced in our body — IgA, IgE, IgG and IgM. It shows primary response where it encounters the pathogen for the first time and secondary response during the subsequent encounters with the same antigen/pathogen. These immune responses are carried out with the help of two special types of lymphocytes present in the blood.
Q.30 (a)1 mark $Name the two types of specialised cells which carry out the primary and secondary responses.$
Q.30 (b)(i)1 mark $Name any two barriers present in our body that provide innate immunity.$
OR
Q.30 (b)(ii)1 mark $The organ transplants (grafts) are often rejected if not taken from suitable compatible persons. Mention the characteristic of our immune system that is responsible for the rejection.$
Q.30 (c)2 marks $How is active immunity different from passive immunity ? Write any two differences.$

Section E

5 marks each

Q.31 (a)5 marks $\downarrow$
OR
Q.31 (b)5 marks $(i) Draw a diagram of L.S. of maize grain and label its any six parts. (ii) Differentiate between perisperm and endosperm giving one example of each.$
Q.32 (a)5 marks $Write the types and locations of the genes causing thalassemia in humans. State the cause and symptoms of the disease. How is sickle-cell anemia different from this disease ?$
OR
Q.32 (b)5 marks $(i) Enlist any four prime goals of the Human Genome Project (HGP). (ii) List the two methodologies which were involved in the human genome project. Mention how they were used. (iii) Expand 'YAC' and mention what it was used for.$
Q.33 (a)5 marks $(i) EcoR I has played a very important role in rDNA technology. (I) Explain the convention for naming EcoR I. (II) Write the recognition site of this endonuclease restriction enzyme. (ii) Name the overhanging stretches of DNA produced by these restriction enzymes. Describe their role in the formation of rDNA.$
OR
Q.33 (b)5 marks $(i) Insertional inactivation is a method to detect the recombinant DNA. Explain this method. (ii) Name the commonly used vector for transferring genes in plants from bacteria. (iii) How is this able to transform a normal plant cell into a tumour ?$

Section A

1 mark each

Q.11 mark $Which of the following groups of cells in the male gonad represent haploid cells ?$
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Q.21 mark $Filiform apparatus in the embryo sac of an angiosperm is present at the micropylar tip of :$
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Q.31 mark $A man is found to have a sperm count of less than 20 million/mL and his wife is diagnosed with blockage in the oviduct. This couple would be advised to go for which of the following techniques ? (i) ZIFT (ii) AI (iii) IUT (iv) ICSI (v) GIFT$
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Q.41 mark $Which of the following amino acid substitutions is responsible for causing sickle cell anemia ?$
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Q.51 mark $Name the extinct ancestor of humans who ate only fruits and hunted with stone weapons.$
Tap an option to check your answer.
Q.61 mark $Choose the correct statements : (i) Polycistronic mRNA is generally found in eukaryotes. (ii) The RNA polymerase II transcribes precursor of mRNA, the hnRNA. (iii) The process of translation of mRNA begins when the mRNA encounters the large subunit of ribosomes. (iv) Stop codons do not have any tRNAs.$
Tap an option to check your answer.
Q.71 mark $Some cyanobacteria in aquatic and terrestrial environment that enrich the soil by fixing nitrogen are :$
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Q.81 mark $Nicotine affects blood pressure and heart rate due to release of certain adrenal hormones. Following are some of the adrenal hormones : (i) Adrenaline (ii) Cortisol (iii) Noradrenaline (iv) Aldosterone Select the correct option :$
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Q.91 mark $Elution means :$
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Q.101 mark $The recombinant protein obtained from transgenic animals that could be used to treat emphysema is :$
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Q.111 mark $The construction of the first recombinant DNA was done by using the native plasmid of :$
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Q.121 mark $Connell's elegant field experiments on the rocky seacoast of Scotland, found that larger barnacles Balanus dominated the intertidal area and removed the smaller barnacles Chathamalus. This happened due to :$
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). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
Q.131 mark $Assertion (A) : After implantation, finger-like projections appear on the trophoblast called chorionic villi. Reason (R) : Chorionic villi are surrounded by the uterine tissue and the maternal blood.$
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Q.141 mark $Assertion (A) : Nucleopolyhedrovirus are useful, as they are good biological control agents. Reason (R) : They are species-specific narrow spectrum bioinsecticides.$
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Q.151 mark $Assertion (A) : Decomposition process is slower, if detritus is rich in lignin and cutin. Reason (R) : Decomposition is largely an oxygen-requiring process.$
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Q.161 mark $\text{I}^{\text{A}}$
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Section B

2 marks each

Q.172 marks $(a) Write one way by which apomictic seeds can be developed. (b) Why do farmers prefer apomictic seeds over hybrid seeds ?$
Q.182 marks $Identify a, b, c and d in the following table with reference to birth control. Method Example a Diaphragm Female sterilisation b c Saheli d Cu-T$
Q.192 marks $Study the figures given below and answer the questions. Identify in which of the crosses the strength of linkage between the genes is higher. Give reason in support of your answer.$
Q.202 marks $A laboratory assistant collected three water samples, namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant. But the laboratory attendant did not note which was which. The samples were labelled A, B and C and subjected to a BOD test. The BOD values of the three samples A, B and C were recorded as 30 mg/L, 8 mg/L and 400 mg/L respectively. (a) Which sample of the water is most polluted ? (b) Can you assign the correct label to each, assuming the river water is relatively clean ?$
Q.21 (a)2 marks $Biodiversity must be conserved as it plays an important role in many ecosystem services that nature provides. Explain any two ecosystem services.$
OR
Q.21 (b)2 marks $(i) State, what does 'standing crop' of a trophic level represent. (ii) List any two ways of measuring the standing crop of a trophic level.$

Method	Example
a	Diaphragm
Female sterilisation	b
c	Saheli
d	Cu-T

Section C

3 marks each

Q.223 marks $Differentiate between wind-pollinated and insect-pollinated flowers. Give an example of each type.$
Q.233 marks $Explain the three different ways in which natural selection operates. Explain with the help of graphs.$
Q.243 marks $(a) Construct a complete transcription unit with promoter and terminator on the basis of the hypothetical coding strand given below : A T G C A T G C A T A G (b) Write the RNA strand transcribed from the above transcription unit along with its polarity.$
Q.253 marks $(a) What is primary productivity ? Why does it vary in different types of ecosystems ? (b) Why is the assimilation of energy at the herbivore level called secondary productivity ?$
Q.263 marks $There are many animals, which have become extinct in the wild, but continue to be maintained in zoological parks. Answer the questions that follow : (a) What type of bio-diversity conservation is observed in this case ? (b) Explain any other two ways which help in this type of conservation. (c) Besides zoological parks, mention one place that serves this purpose.$
Q.273 marks $(a) How is insulin different from proinsulin ? (b) Explain all the stages of how human insulin is produced through rDNA technology.$
Q.28 (a)3 marks $Name the cells of the human body attacked by HIV first, when it gains entry into a human body. How does this virus replicate further to cause immunodeficiency in the body ?$
OR
Q.28 (b)3 marks $Show with the help of a flow chart only, the life-cycle of malarial parasite in human.$

Section D

Immunity in our body is of two types (i) Innate immunity, and (ii) Acquired immunity. Innate immunity is a non-specific defence mechanism, whereas Acquired immunity is pathogen specific. Acquired immunity is characterised by memory. Antibodies are specific to antigens and there are four types of antibodies produced in our body — IgA, IgE, IgG and IgM. It shows primary response where it encounters the pathogen for the first time and secondary response during the subsequent encounters with the same antigen/pathogen. These immune responses are carried out with the help of two special types of lymphocytes present in the blood.
Q.29 (a)1 mark $Name the two types of specialised cells which carry out the primary and secondary responses.$
Q.29 (b)(i)1 mark $Name any two barriers present in our body that provide innate immunity.$
OR
Q.29 (b)(ii)1 mark $The organ transplants (grafts) are often rejected if not taken from suitable compatible persons. Mention the characteristic of our immune system that is responsible for the rejection.$
Q.29 (c)2 marks $How is active immunity different from passive immunity ? Write any two differences.$
Gene expresses itself in a cell system as a protein/enzyme. How an expression of gene occurs in a cell system, when it needs to occur and how the gene expression is regulated in prokaryotic cell system was studied by the combined efforts of Francois Jacob, a geneticist and Jacques Monod, a biochemist. For their work on lactose metabolism in E. coli and introducing the concept of 'lac operon', they were awarded the Nobel Prize in 1965.
Q.30 (a)1 mark $It is said that 'lac operon' has to be operational at a very low level in the bacterial cell all the time. Justify.$
Q.30 (b)(i)1 mark $How are the structural genes activated in the lac operon in E. coli ?$
OR
Q.30 (b)(ii)1 mark $Why is the regulation of operon called negative regulation ?$
Q.30 (c)2 marks $Why is lac operon said to be a transcriptionally regulated system ?$

Section E

5 marks each

Q.31 (a)5 marks $(i) EcoR I has played a very important role in rDNA technology. (I) Explain the convention for naming EcoR I. (II) Write the recognition site of this endonuclease restriction enzyme. (ii) Name the overhanging stretches of DNA produced by these restriction enzymes. Describe their role in the formation of rDNA.$
OR
Q.31 (b)5 marks $(i) Insertional inactivation is a method to detect the recombinant DNA. Explain this method. (ii) Name the commonly used vector for transferring genes in plants from bacteria. (iii) How is this able to transform a normal plant cell into a tumour ?$
Q.32 (a)5 marks $\downarrow$
OR
Q.32 (b)5 marks $(i) Draw a diagram of L.S. of maize grain and label its any six parts. (ii) Differentiate between perisperm and endosperm giving one example of each.$
Q.33 (a)5 marks $Write the types and locations of the genes causing thalassemia in humans. State the cause and symptoms of the disease. How is sickle-cell anemia different from this disease ?$
OR
Q.33 (b)5 marks $(i) Enlist any four prime goals of the Human Genome Project (HGP). (ii) List the two methodologies which were involved in the human genome project. Mention how they were used. (iii) Expand 'YAC' and mention what it was used for.$

Section A

1 mark each

Q.11 mark $A female undergoing IVF treatment has blocked fallopian tube. The technique by which the embryo with more than 8 blastomeres will be transferred into the female for further development is :$
Tap an option to check your answer.
Q.21 mark $Which one of the following statements is correct ?$
Tap an option to check your answer.
Q.31 mark $Choose the option that gives the correct number of pollen grains that will be formed after 325 microspore mother cells undergo microsporogenesis.$
Tap an option to check your answer.
Q.41 mark $The first movements of the foetus and appearance of hair on its head are usually observed during which month of pregnancy ?$
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Q.51 mark $Thorns of Bougainvillea and tendrils of Cucurbita are examples of :$
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Q.61 mark $Internal bleeding, muscular pain, blockage of the intestinal passage and anaemia are some of the symptoms caused due to infection by :$
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Q.71 mark $Choose the correct statements : (i) Polycistronic mRNA is generally found in eukaryotes. (ii) The RNA polymerase II transcribes precursor of mRNA, the hnRNA. (iii) The process of translation of mRNA begins when the mRNA encounters the large subunit of ribosomes. (iv) Stop codons do not have any tRNAs.$
Tap an option to check your answer.
Q.81 mark $Name the extinct ancestor of humans who ate only fruits and hunted with stone weapons.$
Tap an option to check your answer.
Q.91 mark $Bacillus thuringiensis is used to control which one of the following pathogens/pests ?$
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Q.101 mark $\text{tet}^{\text{R}}$
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Q.111 mark $In RNAi, genes are silenced using which of the following biomolecules ?$
Tap an option to check your answer.
Q.121 mark $The biomass available in plants for consumption by herbivores and decomposers, is called :$
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). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.
Q.131 mark $Assertion (A) : Nucleopolyhedrovirus are useful as they are good biocontrol agents. Reason (R) : They are species-specific, narrow spectrum bioinsecticides.$
Tap an option to check your answer.
Q.141 mark $Assertion (A) : The interaction between a whale and the small barnacles on its back is considered as commensalism. Reason (R) : In the above association, neither of the species is benefitted.$
Tap an option to check your answer.
Q.151 mark $Assertion (A) : The pyramid of biomass in a pond aquatic ecosystem is always inverted. Reason (R) : The biomass of consumers like fishes far exceeds that of the producers like phytoplanktons.$
Tap an option to check your answer.
Q.161 mark $Assertion (A) : Cleistogamous flowers have assured seed set. Reason (R) : Cleistogamous flowers are invariably autogamous and do not depend on any pollinating agents.$
Tap an option to check your answer.

Section B

2 marks each

Q.172 marks $Mention the sites of action of the hormones 'GnRH' and 'FSH' during spermatogenesis. Write one function of each of these hormones.$
Q.182 marks $A laboratory assistant collected three water samples, namely river water, untreated sewage water and secondary effluent discharged from a sewage treatment plant. But the laboratory attendant did not note which was which. The samples were labelled A, B and C and subjected to a BOD test. The BOD values of the three samples A, B and C were recorded as 30 mg/L, 8 mg/L and 400 mg/L respectively. (a) Which sample of the water is most polluted ? (b) Can you assign the correct label to each, assuming the river water is relatively clean ?$
Q.192 marks $How do 'implants' act as an effective method of contraception in human females ? Mention one advantage of implants over contraceptive pills.$
Q.202 marks $Why and how can bacteria be made 'competent' ?$
Q.21 (a)2 marks $Biodiversity must be conserved as it plays an important role in many ecosystem services that nature provides. Explain any two ecosystem services.$
OR
Q.21 (b)2 marks $(i) State, what does 'standing crop' of a trophic level represent. (ii) List any two ways of measuring the standing crop of a trophic level.$

Section C

3 marks each

Q.223 marks $(a) Construct a complete transcription unit with promoter and terminator on the basis of the hypothetical coding strand given below : A T G C A T G C A T A G (b) Write the RNA strand transcribed from the above transcription unit along with its polarity.$
Q.233 marks $(a) Draw a diagram of human ovum prior to fertilization. Label any four parts. (b) Explain how polyspermy is avoided during fertilization.$
Q.243 marks $(a) Draw a figure of E. coli vector pBR322 and label the following : (i) Origin of replication (ii) Ampicillin resistance site (iii) Tetracyclin resistance site (iv) "rop" (b) Mention the significance of origin of replication.$
Q.253 marks $Define adaptive radiation. How did Darwin explain adaptive radiation ?$
Q.263 marks $(a) How do some viruses cause cancer in humans ? (b) How do benign tumours turn malignant ? How do malignant tumours harm the human body ?$
Q.273 marks $There are many animals, which have become extinct in the wild, but continue to be maintained in zoological parks. Answer the questions that follow : (a) What type of bio-diversity conservation is observed in this case ? (b) Explain any other two ways which help in this type of conservation. (c) Besides zoological parks, mention one place that serves this purpose.$
Q.28 (a)3 marks $Study the graph given below and answer the questions that follow : (i) Write the status of food and space in the curves a and b. (ii) In the absence of predators, which one of the two curves would appropriately depict the prey population ? (iii) 'Time' has been shown on x-axis and there is a parallel dotted line above it. Give the significance of this dotted line.$
OR
Q.28 (b)3 marks $Answer the following questions : (i) Define 'predation'. (ii) Why is predation required in a community of different organisms ? Give any two points. (iii) Why are predators 'prudent' in nature ?$

Section D

Gene expresses itself in a cell system as a protein/enzyme. How an expression of gene occurs in a cell system, when it needs to occur and how the gene expression is regulated in prokaryotic cell system was studied by the combined efforts of Francois Jacob, a geneticist and Jacques Monod, a biochemist. For their work on lactose metabolism in E. coli and introducing the concept of 'lac operon', they were awarded the Nobel Prize in 1965.
Q.29 (a)1 mark $It is said that 'lac operon' has to be operational at a very low level in the bacterial cell all the time. Justify.$
Q.29 (b)(i)1 mark $How are the structural genes activated in the lac operon in E. coli ?$
OR
Q.29 (b)(ii)1 mark $Why is the regulation of operon called negative regulation ?$
Q.29 (c)2 marks $Why is lac operon said to be a transcriptionally regulated system ?$
Immunity in our body is of two types (i) Innate immunity, and (ii) Acquired immunity. Innate immunity is a non-specific defence mechanism, whereas Acquired immunity is pathogen specific. Acquired immunity is characterised by memory. Antibodies are specific to antigens and there are four types of antibodies produced in our body — IgA, IgE, IgG and IgM. It shows primary response where it encounters the pathogen for the first time and secondary response during the subsequent encounters with the same antigen/pathogen. These immune responses are carried out with the help of two special types of lymphocytes present in the blood.
Q.30 (a)1 mark $Name the two types of specialised cells which carry out the primary and secondary responses.$
Q.30 (b)(i)1 mark $Name any two barriers present in our body that provide innate immunity.$
OR
Q.30 (b)(ii)1 mark $The organ transplants (grafts) are often rejected if not taken from suitable compatible persons. Mention the characteristic of our immune system that is responsible for the rejection.$
Q.30 (c)2 marks $How is active immunity different from passive immunity ? Write any two differences.$

Section E

5 marks each

Q.31 (a)5 marks $Write the types and locations of the genes causing thalassemia in humans. State the cause and symptoms of the disease. How is sickle-cell anemia different from this disease ?$
OR
Q.31 (b)5 marks $(i) Enlist any four prime goals of the Human Genome Project (HGP). (ii) List the two methodologies which were involved in the human genome project. Mention how they were used. (iii) Expand 'YAC' and mention what it was used for.$
Q.32 (a)5 marks $(i) EcoR I has played a very important role in rDNA technology. (I) Explain the convention for naming EcoR I. (II) Write the recognition site of this endonuclease restriction enzyme. (ii) Name the overhanging stretches of DNA produced by these restriction enzymes. Describe their role in the formation of rDNA.$
OR
Q.32 (b)5 marks $(i) Insertional inactivation is a method to detect the recombinant DNA. Explain this method. (ii) Name the commonly used vector for transferring genes in plants from bacteria. (iii) How is this able to transform a normal plant cell into a tumour ?$
Q.33 (a)5 marks $\downarrow$
OR
Q.33 (b)5 marks $(i) Draw a diagram of L.S. of maize grain and label its any six parts. (ii) Differentiate between perisperm and endosperm giving one example of each.$