CBSE Class 12 Biology 2024
276 questions · 566 marks · every one with the board’s own marking-scheme answer.
Marks by chapter
Counted from the 276 questions listed below, as the 2024 papers print them. CBSE allocates marks per unit, not per chapter — this is what was observed, not an official CBSE weightage. Every year compared →
| Chapter | Marks | Share |
|---|---|---|
| Principles of Inheritance and Variation41 questions | 84 | 14.8% |
| Molecular Basis of Inheritance36 questions | 69 | 12.2% |
| Human Health and Disease28 questions | 58 | 10.2% |
| Human Reproduction17 questions | 57 | 10.1% |
| Biotechnology : Principles and Processes26 questions | 46 | 8.1% |
| Sexual Reproduction in Flowering Plants25 questions | 46 | 8.1% |
| Biotechnology and its Applications21 questions | 44 | 7.8% |
| Reproductive Health17 questions | 36 | 6.4% |
| Microbes in Human Welfare14 questions | 32 | 5.7% |
| Evolution19 questions | 28 | 4.9% |
| Ecosystem13 questions | 24 | 4.2% |
| Biodiversity and Conservation10 questions | 24 | 4.2% |
| Organisms and Populations9 questions | 18 | 3.2% |
276 questions from 2024
- Q1A single gene that controls the expression of more than one trait is said to show1 mk
- Q1Homologous organs indicate:1 mk
- Q1In which of the following plants are both male and female flowers born on the same plant and the mode of pollination…1 mk
- Q1An angiosperm embryo sac is located within the:1 mk
- Q1In a fertilized ovule of an angiosperm, the cells in which n, 2 n and 3 n conditions respectively occur are:1 mk
- Q1The ploidy of the apomictic embryos developing from the integument cells and synergids respectively would be:1 mk
- Q1The part of the ovule that develops into protective coats of a seed after fertilization in a typical flowering plant is:1 mk
- Q1Embryo formation without fertilization is observed in some species of:1 mk
- Q1Refer to the Venn diagram given below. Select the option with correct examples P, Q, and R:1 mk
- Q2The type of bond represented by the dotted line '-----' in a schematic polynucleotide chain is:1 mk
- Q2Select the option that has the correct sequence of events of human female reproductive cycle: (i) Secretion of FSH (ii)…1 mk
- Q2A person with trisomy of 21^st chromosome shows (i) Furrowed tongue (ii) Characteristic palm crease (iii) Rudimentary…1 mk
- Q2The origin of life according to the early Greek philosophers was transfer of unit of life from outer space to the…1 mk
- Q2Which one of the following is not used as a vector for rDNA technology?1 mk
- Q2A DNA fragment has 2500 nucleotides, out of which 240 are Guanine. How many bases having double hydrogen bonds between…1 mk
- Q2How many base pairs will be there in 20 nucleosomes in a DNA double helix?1 mk
- Q2Match the items in Column I with those in Column II and select the correctly matched option from those given below:1 mk
- Q2Which one of the following chromosomal event will not result in genetic variation amongst the offsprings?1 mk
- Q2Which one of the following hormones is secreted by the human placenta that helps in the maintenance of pregnancy?1 mk
- Q2A DNA fragment has 2000 nucleotides, out of which 140 are Adenine. How many bases does this DNA segment possess that…1 mk
- Q3The ploidy of apomictic embryos developing from the nucellus and antipodal cells respectively would be:1 mk
- Q3The periodic abstinence by a couple for family planning should be from:1 mk
- Q3During the 1850s in the pre-industrialisation era in England, the expected effect of natural selection on the number of…1 mk
- Q3Study the table given below: Select the option where contraceptive/contraceptive method are correctly matched with…1 mk
- Q3The mechanism to produce seeds without fertilisation has evolved in the given family of the flowering plants:1 mk
- Q3In humans, the secondary oocyte completes meiotic division when:1 mk
- Q4Interferons are proteins secreted by1 mk
- Q4In which one of the following floral plants are many embryos formed in the seeds without fertilisation of the egg cell?1 mk
- Q4Allergic reactions are countered by the administration of:1 mk
- Q4Louis Pasteur dismissed the theory of spontaneous generation by his experiments using pre-sterilised flasks and:1 mk
- Q4A DNA fragment has 3000 nucleotides, out of which 160 are Guanine. How many bases having double hydrogen bonds between…1 mk
- Q4Identify the category of genetic disorder depicted in the pedigree chart given below:1 mk
- Q4Select the incorrect match from the following: Human Karyotype Characters1 mk
- Q4Single step large mutation leading to speciation is also called1 mk
- Q4The specific Bt toxin genes which protect the cotton plants against the cotton bollworms are:1 mk
- Q4Which one of the following statements is not true?1 mk
- Q5After the 1850s in the post-industrialization era in England, the expected effect of natural selection on the number of…1 mk
- Q5During biological treatment of sewage, the masses of bacteria held together by fungal filaments to form mesh like…1 mk
- Q5Observe the schematic representation of assisted reproductive technology given below: Identify the most appropriate…1 mk
- Q5Hugo de Vries proposed the mutation theory of organic evolution after his experiments on1 mk
- Q5The scientist who proposed that "embryos of all vertebrates including humans develop a row of vestigial gill slits…1 mk
- Q5A Snapdragon plant bearing pink colour flowers is crossed with a Snapdragon plant bearing white colour flowers. The…1 mk
- Q5Select the option that gives the correct identification of ovum, morula and blastocyst in a human female reproduction…1 mk
- Q5Which one of the following option denotes mating between relatives in human pedigree analysis?1 mk
- Q5You know that there are twenty different types of naturally occurring amino acids and four different types of bases in…1 mk
- Q5Which was the last of the 24 human chromosome to be completely sequenced?1 mk
- Q5Listed below are some amino acids and their corresponding mRNA codons: Select the DNA sequence that would code for the…1 mk
- Q5A population is in genetic equilibrium/Hardy-Weinberg equilibrium for a gene with 2 alleles (dominant allele is 'A' and…1 mk
- Q6In which of the given chromosomal disorders does the individual have tall stature with feminised character?1 mk
- Q6A list of organisms is given in column 'R', whereas in column 'S' a list of products produced by them: Select the…1 mk
- Q6In which of the following chromosomal disorders do the individuals have short stature, small head, furrowed tongue and…1 mk
- Q6Which one of the following statements is correct in the context of observing DNA separation by agarose gel…1 mk
- Q6In the double helical structure of DNA molecule, the strands are:1 mk
- Q6Study the following diagram of Transverse Section of a young anther of an angiosperm: Select the option where parts…1 mk
- Q6The expected phenotypic ratio amongst the progeny of 60 individuals, obtained from a cross between heterozygous tall…1 mk
- Q6A Snapdragon plant bearing red colour flowers was crossed with a Snapdragon plant bearing white colour flowers. The F_1…1 mk
- Q7A Snapdragon plant bearing pink colour flowers is crossed with a Snapdragon plant bearing white colour flowers. Their…1 mk
- Q7Which one of the following enzymes a fungal cell should be treated with to get the DNA along with other macro molecules…1 mk
- Q7During an allergic reaction, the binding of antigen to IgE antibodies initiates release of:1 mk
- Q7In which of the following conditions/diseases is there a substantial increase in the activity of mast cells observed in…1 mk
- Q7In which of the following chromosomal disorders do individuals have short stature, underdeveloped feminine character…1 mk
- Q7A phenomenon where a male insect mistakenly identified the patterns of a orchid flower as the female insect partner,…1 mk
- Q7Turner's syndrome in humans occurs due to1 mk
- Q7In a 'transcription unit', the 'terminator' is located towards the:1 mk
- Q7S.L. Miller in 1953, to support the theory of chemical evolution, created conditions in the closed flask that included:1 mk
- Q8Which of the following is not required for PCR?1 mk
- Q8Which of the options has correct identification of 'P', 'Q' and 'R' in the illustration of 'Central Dogma' given below?1 mk
- Q8Lactobacillus that sets milk into curd is categorised as:1 mk
- Q8In an experiment, E. coli is grown in a medium containing ^14 NH_4 Cl. ( ^14 N is the light isotope of Nitrogen)…1 mk
- Q8A woman with normal vision has a colour blind father. She marries a man with normal vision. The percentage chance of…1 mk
- Q8Identify the correct labellings in the figure of a fertilised embryo sac of an angiosperm given below:1 mk
- Q8The source of 'Smack' is:1 mk
- Q8A patient is suffering from the infection of the alveoli of lungs and is showing the symptoms of fever, chills, cough,…1 mk
- Q9The linking of the antibiotic resistance gene with the plasmid vector of Salmonella typhimurium by Stanley Cohen and…1 mk
- Q9The commonly used vector for human genome sequencing was/were:1 mk
- Q9Which one of the following is not a characteristic feature of "humus" that is formed during decomposition of detritus?1 mk
- Q9The vector for dengue fever is:1 mk
- Q9A patient is suffering from fever, chills, cough, headache and bluish finger nails and lips. These symptoms are of the…1 mk
- Q9Who proposed the mutation theory in favour of organic evolution?1 mk
- Q9Study the pedigree chart of a family showing the inheritance pattern of a certain disorder. Select the option that…1 mk
- Q9The first antibiotic was discovered accidentally by A while working on B. 'A' and 'B' are 11 mk
- Q9Homologous organs indicate1 mk
- Q9Which one of the following transgenic animals is being used to test the safety of the polio vaccine?1 mk
- Q9Which disease is the patient suffering from who is showing symptoms such as sustained high fever (39°C to 40°C),…1 mk
- Q10Which native plasmid did Stanley Cohen and Herbert Boyer use for the construction of the first recombinant DNA?1 mk
- Q10Restriction Endonuclease - Hind II always cuts DNA molecules at a particular point by recognising a specific sequence…1 mk
- Q10Match the following genes of the lac operon listed in column 'A' with their respective products listed in column 'B':…1 mk
- Q10Which one of the following pairs is not correctly matched?1 mk
- Q10Select the incorrect match from the following:1 mk
- Q10In the absence of fertilization, corpus luteum:1 mk
- Q10Study the following list of bioactive substances and their action: 1 Select the option in which the bioactive…1 mk
- Q11If both the parents are carriers for thalassaemia, the chances of an afflicted child to be born to them is:1 mk
- Q11For the replication of the first recombinant DNA, Stanley Cohen and Herbert Boyer used the DNA polymerase of:1 mk
- Q11Using a DNA template, how many new DNA molecules would be generated after 10 cycles of amplification in PCR?1 mk
- Q11Which one of the following bacteria were used by Stanley Cohen and Herbert Boyer to accomplish the construction of the…1 mk
- Q11The 'molecular scissors' fall in the category of:1 mk
- Q11The population growth curve applicable for a population of beetles growing in nature under unlimited resource…1 mk
- Q11Which one of the following represents the correct annealing of primers to the DNA to be amplified in the PCR?1 mk
- Q11The improved trait that is found in the genetically modified transgenic crop - Golden rice is:1 mk
- Q11Match the items in Column I with those in Column II and select the correctly matched option from those given below:…1 mk
- Q11Which one of the following is not a feature of plasmids?1 mk
- Q11Which of the chromosome in a human possesses the least number of genes?1 mk
- Q12The rate of formation of new organic matter by consumers, and the biomass available for consumption of herbivores as…1 mk
- Q12Given below is a list of some commercially important products in column A, whereas in column B are names of source…1 mk
- Q12The human chromosome with the highest and least number of genes in them are respectively:1 mk
- Q12The functional megaspore of an angiosperm develops into:1 mk
- Q12ELISA technique is based on the principle of1 mk
- Q12The organism that occupies more than one trophic level in a pond ecosystem is:1 mk
- Q12The pyramid of biomass in sea is generally inverted because in sea:1 mk
- Q12The population growth curve applicable for a population growing in a geometric fashion, when the resources are not…1 mk
- Q12Read the four statements given below and select the option having two correct statements: (i) A lion eating a deer and…1 mk
- Q12The population growth curve applicable for a population growing in nature with limited resources available to them will…1 mk
- Q12If the sequence of nitrogen bases of the coding strand in a transcription unit is 5^′ - ATGAATG - 3', the sequence of…1 mk
- Q13Assertion: The laws of our country permit legal adoption and it is as yet, one of the best methods for childless…1 mk
- Q13Assertion: Primary transcripts in eukaryotes are subjected to splicing to remove the introns. Reason (R): Primary…1 mk
- Q13Assertion: AIDS is a syndrome caused by HIV. Reason (R): HIV is a virus that damages the immune system with DNA as its…1 mk
- Q13Assertion: A given fig species can be pollinated only by its partner' wasp. Reason (R): The wasp pollinates the fig…1 mk
- Q13Assertion: RNA is unstable and can mutate at a faster rate. Reason (R): The presence of 2' - OH group in every…1 mk
- Q14Assertion: Virus-infected cells produce interferons. Reason (R): Interferons can cause inflammation of virus-infected…1 mk
- Q14Assertion: The sugar-phosphate backbone of two chains in DNA double helix show anti-parallel polarity. Reason (R): The…1 mk
- Q14Assertion: The chronic use of alcohol by a person leads to cirrhosis. Reason (R): Alcohol addiction at times becomes…1 mk
- Q14Assertion: Plasmids are autonomously replicating circular extra- chromosomal DNA. Reason (R): Plasmids are usually…1 mk
- Q14Assertion (A): Linked genes do not show dihybrid F_2 ratio 9: 3: 3: 1. Reason (R): Linked genes do not undergo…1 mk
- Q14Assertion: In genetic engineering, antibiotic genes are used as selectable markers. Reason (R): Selectable markers help…1 mk
- Q14Assertion: "Biodiversity hotspots" are the regions which possess high levels of species richness, high degree of…1 mk
- Q14Assertion: In molecular diagnosis, single stranded DNA or RNA tagged with radioactive molecule is called a probe.…1 mk
- Q14Assertion: Gene flow increases genetic variations. Reason (R): The random introduction of new alleles into a recipient…1 mk
- Q15Assertion: In birds the sex of the offspring is determined by males. Reason (R): Males are homogametic while females…1 mk
- Q15Assertion: Specific enzymes are used to degrade the cell wall in organisms to isolate the DNA from the cell. Reason…1 mk
- Q15Assertion: Agrobacterium tumefaciens is a pathogen of several monocot plants. Reason (R): It is able to deliver a piece…1 mk
- Q15Assertion: Patents are granted by government to an inventor. Reason (R): Patents prevents others from commercial use of…1 mk
- Q15Assertion: The zygote gives rise to heart-shaped embryo and subsequently proembryo in most angiosperms. Reason (R): The…1 mk
- Q16Assertion: The stirrer facilitates the even mixing of oxygen availability in a bioreactor. Reason (R): Stirred-tank…1 mk
- Q16Assertion: A recombinant DNA which is inserted within the coding sequence of β -galactosidase does not produce blue…1 mk
- Q16Assertion: Some aquatic ecosystems have inverted biomass pyramids. Reason (R): More energy is required by the organisms…1 mk
- Q16Assertion: Functional ADA cDNA genes must be inserted in the lymphocytes at the early embryonic stage in gene therapy…1 mk
- Q16Assertion: Indian Government has set up an organisation known as GEAC to decide the validity of GM research. Reason…1 mk
- Q16Assertion: Communities that comprise of more species tend to be more stable. Reason (R): A higher number of species…1 mk
- Q16Assertion: Loss of biodiversity can occur due to overexploitation of resources. Reason (R): Introduction of Clarias…1 mk
- Q17"Farmers prefer apomictic seeds to hybrid seeds." Justify giving two reasons. OR Mention one advantage and one…2 mk
- Q17Identify A, B, C and D in the table given below:2 mk
- Q17"Amniocentesis is a very useful and important technique, but due to some reason there is a statutory ban on…2 mk
- Q17Do you think apomixis can be compared to asexual reproduction? Justify your answer. State the benefits of apomixis to…2 mk
- Q17Name the first developed transgenic cow. Explain the improvement in the quality of the milk produced by it.2 mk
- Q17What is artificial insemination in ART? Under what conditions is the person medically advised to go for it?2 mk
- Q17Oral contraceptives are widely accepted for controlling the increasing rate of population. Name the two important…2 mk
- Q17Study the diagram of a pyramid of biomass given below. Name the two standing crops that could be occupying level 'A'…2 mk
- Q17Name any two copper releasing intra-uterine devices. State two reasons that make them effective contraceptives. OR Name…2 mk
- Q17Answer the questions based on the typical biogas plant diagram given below: Identify 'X', 'Y' and 'Z'. Why is dung…2 mk
- Q18How is a restriction endonuclease named? Explain with the help of a suitable example.2 mk
- Q18Study the graph given below that represents the changes in the thickening of the uterine wall in women 'X' and women…2 mk
- Q18Although Haemophilia and sickle cell anemia are two blood related Mendelian disorders, yet, they differ in their…2 mk
- Q18What is a vaccine? Write the basis on which it acts when administered in the body.2 mk
- Q18Why does a patient of ADA - deficiency require repeated infusions of genetically engineered lymphocytes? Suggest a…2 mk
- Q18If the base adenine constitutes 31% of an isolated DNA fragment, then write what will be the expected percentage of the…2 mk
- Q18Given below is an illustration of the experiment performed by Louis Pasteur. Explain the experiment and its conclusion.2 mk
- Q18Observe the picture given below. Name the naturalist and write the explanation given by him that evolution of life…2 mk
- Q185^′-G^↓ A A T T C-3^′ 3^′-C T T A A_↑ G-5^′ Name the restriction enzyme that recognises the given specific sequence of…2 mk
- Q18Intensely lactating mothers generally do not conceive. Why? Our government has intentionally imposed strict conditions…2 mk
- Q19Name the source from which insulin was extracted in earlier times. Why is this insulin no more in use by the diabetic…2 mk
- Q19Consider the given data of a hypothetical small portion of mRNA that codes for a functional polypeptide chain and…2 mk
- Q19Write the basic steps followed in the Assisted Reproductive Technologies (ART) programme to help childless couples. Why…2 mk
- Q19Identify A, B, C and D in the following table:2 mk
- Q19Mention any two ways by which HIV and Hepatitis-B can be transmitted to a healthy person. Why is an early detection of…2 mk
- Q19Observe the population growth curve and answer the questions given below: State the conditions under which growth curve…2 mk
- Q19State the procedure followed in the technique of amniocentesis. List any two advantages of this technique.2 mk
- Q20List the events that reduce the Biochemical Oxygen Demand (BOD) of a primary effluent during sewage treatment.2 mk
- Q20Differentiate between grazing food chain and detritus food chain. OR Explain Brood parasitism with the help of a…2 mk
- Q20A farmer while working on his farm was bitten by a poisonous snake. He was rushed to a nearby health centre where the…2 mk
- Q20Write the role of 'ori' and restriction site in the cloning vector pBR322.2 mk
- Q20Explain how are plants benefitted by their association with “Glomus species”.2 mk
- Q20Different varieties of cheese are known by their characteristic texture, flavour and taste, the specificity coming from…2 mk
- Q21With reference to the set-ups (A, B and C) given below, of the electrophoretic separation of a mixture of DNA fragments…2 mk
- Q21Study the diagram of a pyramid of biomass given below. Name the two standing crops that could be occupying level 'A'…2 mk
- Q21How is Ti plasmid of Agrobacterium tumefaciens modified to act as a cloning vector?2 mk
- Q21A specific plant species was introduced into Australia in 1920 and later it became invasive spreading over millions of…2 mk
- Q21Write important features of 'humus' formed during the decomposition cycle in a terrestrial ecosystem. OR (i)…2 mk
- Q21Biodiversity hotspots cover less than 2% of Earth's land area. Strict protection of these areas can reduce the rate of…2 mk
- Q21How is the rate of decomposition affected by the nature of detritus and temperature?2 mk
- Q22Draw a T.S. of a mature anther of an angiosperm. Label its any three wall layers and mention their functions.3 mk
- Q22Given below is a pie chart representing global diversity of vertebrates. Redraw the pie chart identifying the groups…3 mk
- Q22Explain the mode of action of contraceptive pills taken by human females. Mention the schedule to be followed for…3 mk
- Q22Why is "in vitro fertilization (IVF)" so named? State its importance. Distinguish between GIFT and ZIFT.3 mk
- Q22Identify a, b, c, d, e and f in the table given below: 3 Sl. No. Organism Bioactive Molecule Use 1. Monascus purpureus…3 mk
- Q22How is the grazing food chain different from the detritus food chain? "The detritus food chain may be connected to the…3 mk
- Q22Draw a diagram of a human sperm. Label the following parts in it: (i) Which helps in the motility of the sperm (ii)…3 mk
- Q22Draw a longitudinal section of pistil of a flower showing growth of the pollen tube. Label the part: through which the…3 mk
- Q22Draw a schematic diagram of the E.coli vector pBR 322 and mark the following in it: ori rop ampicillin resistant gene…3 mk
- Q22With reference to flower colour two independent crosses were made, one between true breeding garden pea plants and…3 mk
- Q22Draw a well labelled diagram of sectional view of male gametophyte/microspore of an angiosperm and write the functions…3 mk
- Q23Tropical regions harbour more species than the temperate regions. How have biologists tried to explain this in their…3 mk
- Q23"Mother's milk is considered very essential for the new born infant." Justify. What is a 'vaccine'? Explain the…3 mk
- Q23Name and write two characteristics of the type of DNA that forms the basis of DNA fingerprinting technique. Mention any…3 mk
- Q23How has the use of Agrobacterium as vector helped in controlling Meloidogyne incognita infestation in tobacco plants?…3 mk
- Q23A man with blood group 'A' marries a woman with blood group 'AB'. The first child born to them has blood group 'B'.…3 mk
- Q23Identify the picture given below and name the tool under which it was viewed. What do the dark spots represent in the…3 mk
- Q23Explain the IUI and IUT methods of assisted reproductive technologies.3 mk
- Q23(i) Write the karyotype and the genetic disorder of an individual who has developed from a zygote formed from an 'XX'…3 mk
- Q24Explain the role of the following during the sewage treatment: flocs anaerobic sludge digester3 mk
- Q24Three crosses were carried out in pea plants with respect to flower colour violet/white (V/v) and flower position…3 mk
- Q24Explain the process by which amino acid gets attached to the tRNA molecule during translation process. How does the…3 mk
- Q24What are transgenic animals? Name the transgenic animal having the largest number amongst all the existing transgenic…3 mk
- Q24The first clinical gene therapy was given in 1990 to a 4-year-old girl with ADA deficiency. Mention the cause of this…3 mk
- Q24Why must a cell be made 'competent' in biotechnology experiments? How does calcium ion help in doing so? State the role…3 mk
- Q24Explain the significance of the experiment carried out by S.L. Miller. Name the scientists whose hypothesis prompted…3 mk
- Q25If the cells in the leaves of a maize plant contain 10 chromosomes each, write the number of chromosomes in its…3 mk
- Q25Mention the advantages of 'ART'. Explain the 'ICSI' and 'AI' methods of assisted reproductive technologies.3 mk
- Q25State why plant breeders are interested in artificial hybridisation programme. How do they carry out this process?3 mk
- Q25Whose skulls 'A', 'B', and 'C' are shown below? Which of the two are more similar to each other? Name the (i) ape like…3 mk
- Q25(i) Name the group of drugs whose skeletal molecule is shown below: (ii) How are such drugs consumed? (iii) Name the…3 mk
- Q25Describe any three assisted reproductive techniques practised to treat infertility.3 mk
- Q25Explain the mechanism of haplo-diploid pattern of sex determination with the help of a suitable example. Why is this…3 mk
- Q25Differentiate between humoral immune response and cell-mediated immune response. Draw a schematic diagram of an…3 mk
- Q25Identify A and B in the diagram below. Explain their role in the immune system of the body.3 mk
- Q25A population of snakes lived in a desert with brown sand. Study the drawings given below showing the change in the…3 mk
- Q25Differentiate between spermatogenesis and oogenesis in humans on the basis of the following: When the process is…3 mk
- Q25Identify A, B, C, D, E and F in the table given below:3 mk
- Q26The schematic representation as above is showing the linking of two DNA fragments. Name 'A' and 'B' fragments. Write…3 mk
- Q26"Human blood group (ABO group) inheritance is a good example of multiple allelism and co-dominance." Justify the…3 mk
- Q26The picture given below shows: Roots of a typical control tobacco crop plant (infected). Transgenic tobacco plant…3 mk
- Q26In a family, the father, the daughter and the son are colour blind, whereas the mother has normal vision. Do you think…3 mk
- Q26(i) List two major reasons for using cow-dung in a biogas plant instead of using domestic sewage. (ii) Mention one use…3 mk
- Q26Why does DNA replication occur within a replication fork and not in its entire length simultaneously? "DNA replication…3 mk
- Q26Expression of different genes for different traits may show dominance, incomplete dominance or co-dominance. Write…3 mk
- Q26Given below is a picture that shows the magnified blood smear of a patient under a microscope. Name the disease the…3 mk
- Q27Explain the processing of heterogeneous nuclear RNA (hnRNA) into a fully functional mRNA in eukaryotes. Where does this…3 mk
- Q27(i) What are transgenic animals? (ii) Name the first transgenic cow and state its importance. OR (i) Explain the…3 mk
- Q27List the salient features of Darwin's theory of natural selection. Microbes have proved to be suitable examples to…3 mk
- Q27Construct a pyramid of biomass in sea with phytoplankton and fishes. Explain giving reasons about the characteristic of…3 mk
- Q27Study the steps shown below, that are carried during a specific technique: Identify the steps 'A' and 'D' in the…3 mk
- Q27How do the following organisms act as bio-fertilisers? Explain. Mycorrhiza Anabaena Rhizobium3 mk
- Q27A pea plant with purple flowers, when crossed with a plant with white, produced 50 plants with only purple flowers. On…3 mk
- Q27Explain any three roles of 'predation' in an ecosystem with the help of suitable examples.3 mk
- Q27Describe the mutualistic relationship that exists between the Mediterranean orchid Ophrys and a bee species.3 mk
- Q27Give the scientific name of the bacteria widely used in biotechnology to create a GM cotton crop resistant to bollworm…3 mk
- Q28State what is primary productivity and mention its units. 1 1/2 Some ecologists observed that primary productivity of a…3 mk
- Q28Explain the role of transgenic animals in: Production of Biological products Studying diseases Chemical safety testing3 mk
- Q28The world is facing accelerated rates of species extinction largely due to human activities. Explain any three human…3 mk
- Q28Explain how it is ensured that the orchid Ophrys is pollinated by a specific species of bee. Describe co-evolution with…3 mk
- Q28Predation is referred to as a detrimental interaction. Explain any three positive roles, supported by an example each,…3 mk
- Q28Describe how fig tree and wasp relationship is a spectacular example of mutualism.3 mk
- Q28The diagram given below is a biomolecule needed for sugar metabolism in human beings. Name this biomolecule and mention…3 mk
- Q28Identify a, b, c, d, e and f in the table given below: 3 Sl. No. Organism Bioactive Molecule Use 1. Monascus purpureus…3 mk
- Q29Read the following passage and answer the questions that follow. Spermatogenesis is an important primary sex…4 mk
- Q29In a human female, the reproductive phase starts on the onset of puberty and ceases around middle age of the female.…4 mk
- Q29Read the following passage and answer the questions that follow. Isn't it incredible that India's land area is only 2 ·…4 mk
- Q29Read the passage given below and answer the questions that follow. In recombinant DNA technology, restriction enzymes…4 mk
- Q30Generally, in eukaryotic cells the average length of a transcription unit along a DNA molecule is about 8,000…4 mk
- Q30Read the following passage and answer the questions that follow. In 1981, the health workers of United States of…4 mk
- Q30Read the following passage and answer the questions that follow: "Mosquitoes are drastically affecting the human health…4 mk
- Q30Read the following passage: Populations evolve to maximise their reproductive fitness in the habitat in which they…4 mk
- Q30Study the diagram given below that shows the steps involved in the procedure of selecting transformed bacteria and…4 mk
- Q30Study the figures given below that depict the comparative age distribution of human populations in Sweden and Rwanda.…4 mk
- Q31(i) Explain any four devices that flowering plants have developed to encourage cross-pollination. (ii) Why do plants…5 mk
- Q31The given diagram shows the sectional view of a seminiferous tubule of Human testis: (i) Name and describe the process…5 mk
- Q31(i) Explain the process of double fertilization in an angiosperm starting from the germination of pollen grains on the…5 mk
- Q31(i) Draw a schematic diagram of the cloning vector pBR 322 and label (1) Bam HI site (2) gene for ampicillin resistance…5 mk
- Q31Answer the following questions that are based on "Hershey and Chase" experiment using E. coli and bacteriophage: (i)…5 mk
- Q31(i) Draw a labelled diagram of the embryonic stage that gets implanted in the human female leading to pregnancy. 1 1/2…5 mk
- Q31(i) Explain the following phases in the menstrual cycle of a human female: (1) Menstruation (2) Follicular phase (3)…5 mk
- Q31(i) Explain the development of male gametophyte in an angiosperm. (ii) Draw a labelled diagram of a three-celled male…5 mk
- Q32(i) Describe the events of spermatogenesis with the help of a A schematic diagram. (ii) Explain the role of hormones in…5 mk
- Q32(i) Draw a diagram of a human sperm. Label any four parts and write their functions. (ii) In a human female,…5 mk
- Q32Stability, as one of the properties of genetic material, was very evident in one of the very early experiments in…5 mk
- Q32(i) Compare the pattern of inheritance of flower colour in garden pea plant (violet/white) with snapdragon plant…5 mk
- Q32Study the schematic diagram given below and answer the questions that follow: (i) Identify the polarity from 'X' to '…5 mk
- Q32Many patterns of inheritance deviate considerably from the pattern of inheritance as explained by Mendel. List any four…5 mk
- Q32"The influence of both the alleles in a heterozygous state is clearly expressed in codominance." Explain with the help…5 mk
- Q33(i) Describe the life cycle of Plasmodium from the time it enters the human body till a female Anopheles mosquito bites…5 mk
- Q33(i) Why should a cell be made competent to take up an alien DNA? How can a bacterial cell be made competent using…5 mk
- Q33Natural selection operates in different ways in nature. (i) Identify the type of natural selection depicted in the…5 mk
- Q33(i) State Mendel's law of independent assortment. (ii) Explain this law by taking the example of a cross between two…5 mk
- Q33(i) State the objective of adopting artificial hybridisation programme in plants. (ii) Describe the steps followed in…5 mk
- Q33Describe the life cycle of HIV from the time of its entry into the human body till full blown AIDS sets in. OR (i)…5 mk
- Q33Work out a dihybrid cross upto F_2 generation between pea plants bearing violet coloured axial flowers and white…5 mk
- Q33(i) Name and explain the property present in normal cells but is lost in cancer cells. (ii) All normal human cells have…5 mk
Other Biology years
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