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NCERT Biology Quiz

NEET Biology: Exam Pattern and NCERT Revision

Biology is half of the NEET paper. Of the 180 questions and 720 marks, 90 questions and 360 marks come from Botany and Zoology together, which is exactly as much as Physics and Chemistry combined. The syllabus is the rationalised NCERT text for classes 11 and 12 and very little in the paper strays outside it, so the examination rewards a candidate who knows the NCERT lines precisely far more than one who has read widely. These notes give the current pattern, the unit structure of the syllabus, and a dense set of the facts and figures that NEET returns to year after year, arranged so that they can be revised quickly and repeatedly. A 20-question practice set follows.

The Paper and How Biology Sits In It

The pattern was simplified for the 2025 cycle and continues in the same form. The optional section and the extra time that had been introduced during the pandemic years are gone: every question is compulsory and the paper is a straight three hours.

Always confirm the current syllabus document on the National Testing Agency and National Medical Commission websites before planning revision, because the rationalised NCERT has had chapters and topics removed and the official list is the only reliable one.

  • 180 questions, 720 marks, three hours. All questions compulsory, with no optional section.
  • Four subject sections of 45 questions and 180 marks each: Physics, Chemistry, Botany and Zoology.
  • Botany and Zoology together give 90 questions and 360 marks, so Biology alone is half the paper.
  • Marking: four marks for a correct answer and one mark deducted for a wrong answer. An unattempted question scores zero.
  • Because of the negative marking, a blind guess among four options has a negative expected value. Attempt a question when you can eliminate at least two options.
  • The syllabus is the rationalised NCERT for classes 11 and 12. NCERT remains the overwhelming source of the questions, including its diagrams, tables and the examples given in passing.
  • Practical target for a strong score: attempt close to all 90 Biology questions in roughly 45 to 50 minutes, leaving the remaining time for Physics and Chemistry.

The Units and What They Cover

The syllabus divides into five units in each year. Ecology, Genetics and Evolution, Human Physiology and Plant Physiology are consistently the heaviest sections of the paper, and Ecology in particular gives a high return for the time spent because the content is short and largely factual.

  • Class 11, Unit 1, Diversity in the Living World: taxonomy and nomenclature, the five kingdom system, and the survey of the plant and animal kingdoms with their classifying characters.
  • Class 11, Unit 2, Structural Organisation in Plants and Animals: the morphology and anatomy of flowering plants, plant tissues, animal tissues, and the study of the cockroach and the frog where prescribed.
  • Class 11, Unit 3, Cell Structure and Function: cell theory, the prokaryotic and eukaryotic cell, all the organelles, biomolecules, enzymes, and the cell cycle with mitosis and meiosis.
  • Class 11, Unit 4, Plant Physiology: transport in plants, mineral nutrition, photosynthesis, respiration, and plant growth and development including the hormones.
  • Class 11, Unit 5, Human Physiology: digestion, breathing, body fluids and circulation, excretion, locomotion, neural control and chemical coordination.
  • Class 12, Unit 1, Reproduction: sexual reproduction in flowering plants, human reproduction, reproductive health.
  • Class 12, Unit 2, Genetics and Evolution: the Mendelian principles and their deviations, the molecular basis of inheritance, and evolution.
  • Class 12, Unit 3, Biology and Human Welfare: human health and disease, and microbes in human welfare.
  • Class 12, Unit 4, Biotechnology: the principles and processes of genetic engineering, and its applications in agriculture and medicine.
  • Class 12, Unit 5, Ecology and Environment: organisms and populations, the ecosystem, and biodiversity and its conservation.

Facts NEET Returns To

The list below is deliberately compressed. It is not a substitute for the NCERT text but a check on whether you have retained it. Read a line, cover it, and see whether you can restate it before moving on.

  • Classification: binomial nomenclature was given by Linnaeus. The five kingdom system was proposed by Whittaker in 1969, dividing life into Monera, Protista, Fungi, Plantae and Animalia. The taxonomic hierarchy runs kingdom, phylum or division, class, order, family, genus, species.
  • Cell: the cell theory was put forward by Schleiden and Schwann and completed by Virchow, who added that every cell arises from a pre-existing cell. Prokaryotic ribosomes are 70S, made of a 50S and a 30S subunit; eukaryotic ribosomes are 80S, made of 60S and 40S. Lysosomes are called the suicide bags of the cell. The inner mitochondrial membrane is folded into cristae and carries the elementary particles of the ATP synthase.
  • Cell division: the cell cycle is G1, S, G2 and M. DNA replicates in the S phase. Prophase I of meiosis has five stages, leptotene, zygotene, pachytene, diplotene and diakinesis; crossing over occurs at pachytene and the chiasmata become visible at diplotene.
  • Photosynthesis: the light reaction takes place in the thylakoid membrane and the Calvin cycle in the stroma. RuBisCO is the most abundant enzyme in the world. The first stable product of the C3 pathway is 3-phosphoglyceric acid, a three carbon compound, and of the C4 or Hatch and Slack pathway is oxaloacetic acid, a four carbon compound. C4 plants show Kranz anatomy and use PEP carboxylase, which has no oxygenase activity, so they do not photorespire appreciably.
  • Respiration: glycolysis occurs in the cytoplasm, the Krebs cycle in the mitochondrial matrix and the electron transport system on the inner mitochondrial membrane. The NCERT calculation gives a net yield of 36 ATP from the complete aerobic oxidation of one molecule of glucose.
  • Plant hormones: auxin causes apical dominance, gibberellin causes bolting and stem elongation, cytokinin promotes cell division and delays senescence, ethylene is the ripening hormone and abscisic acid is the stress hormone that closes stomata.
  • Human physiology: the sinoatrial node is the pacemaker of the heart; normal cardiac output is about five litres per minute and normal blood pressure about 120 over 80. The glomerular filtration rate is about 125 millilitres per minute, that is roughly 180 litres a day. About 97 per cent of oxygen is carried by red blood cells and about 70 per cent of carbon dioxide as bicarbonate. The resting membrane potential of a neuron is about minus 70 millivolts. Insulin is secreted by the beta cells and glucagon by the alpha cells of the islets of Langerhans.
  • Mendelian genetics: Mendel worked on the garden pea, Pisum sativum. A monohybrid cross gives a 3 to 1 phenotypic ratio in the second generation and a dihybrid cross gives 9 to 3 to 3 to 1. A test cross with the recessive parent gives 1 to 1. Incomplete dominance is seen in the flower colour of Mirabilis jalapa and codominance in the human ABO blood groups, which also illustrate multiple allelism.
  • Human genetics: humans have 46 chromosomes with XX female and XY male; grasshoppers show XX and XO and birds ZZ and ZW. Haemophilia and red green colour blindness are X linked recessive. Sickle cell anaemia is autosomal recessive and arises from the substitution of valine for glutamic acid at the sixth position of the beta globin chain. Down syndrome is trisomy of chromosome 21, Klinefelter syndrome is XXY and Turner syndrome is XO.
  • Molecular biology: Griffith demonstrated transformation, Avery, MacLeod and McCarty identified the transforming principle as DNA, and Hershey and Chase confirmed it in 1952 using bacteriophage. Watson and Crick proposed the double helix in 1953. In B form DNA there are ten base pairs per turn, a rise of 0.34 nanometres per base pair and a pitch of 3.4 nanometres. Meselson and Stahl showed semi-conservative replication in Escherichia coli. The lac operon was described by Jacob and Monod. The Human Genome Project was completed in 2003.
  • Evolution: Darwin published On the Origin of Species in 1859. The Hardy Weinberg principle states that allele frequencies in a population remain constant in the absence of evolutionary influences. Industrial melanism in the peppered moth is the standard example of natural selection observed in historic time. The Miller and Urey experiment supported chemical evolution.
  • Biotechnology: the first restriction endonuclease isolated was Hind II and the commonly used EcoRI comes from Escherichia coli. Common vectors include pBR322 and the Ti plasmid of Agrobacterium tumefaciens. The polymerase chain reaction was devised by Kary Mullis and uses the heat stable Taq polymerase. Bt cotton carries cry genes from Bacillus thuringiensis. The first gene therapy was given for adenosine deaminase deficiency.
  • Ecology: the ten per cent law of energy transfer between trophic levels is due to Lindeman. Population interactions include mutualism, competition, predation, parasitism, commensalism and amensalism. The pyramid of energy is always upright, while pyramids of number and biomass may be inverted. In situ conservation protects a species in its habitat, as in national parks and biosphere reserves; ex situ conservation removes it, as in zoos and seed banks.

Strategy and Common Traps

Most marks lost in NEET Biology are not lost for want of knowledge but for want of precision. The paper is written to punish approximate memory, so revision should be aimed at exactness.

  • Read the NCERT line by line, including the small print, the boxed matter and the labelled diagrams. Questions are regularly set on a single clause of a single sentence.
  • Learn the exceptions along with the rule. NEET prefers the exception: the inverted pyramid of numbers in a tree ecosystem, the plant that is an exception to a family character, the hormone that acts against the general pattern.
  • Trap: confusing similar numbers. The pitch of DNA is 3.4 nanometres and the distance between base pairs 0.34 nanometres. Note which is which.
  • Trap: confusing the site of a process with the site of its products, for example placing the Krebs cycle on the inner membrane rather than in the matrix.
  • Trap: assertion and reason questions where both statements are true but the reason does not explain the assertion. Read the two parts separately before judging the link.
  • Practise full length papers under a three hour clock, and keep an error notebook of every question you got wrong, with one line on why. Revise that notebook rather than rereading chapters in the final weeks.
  • Attempt Biology first in the hall. It is the section where speed is highest and confidence gained there carries into the Physics section.

Key Terms

Kranz anatomy
The wreath-like arrangement of large bundle sheath cells around the vascular bundles in the leaves of C4 plants. It separates the initial fixation of carbon dioxide from the Calvin cycle and so suppresses photorespiration.
Double fertilisation
The event unique to flowering plants in which one male gamete fuses with the egg to form the diploid zygote and the second fuses with the two polar nuclei to form the triploid primary endosperm nucleus.
Semi-conservative replication
The mode of DNA replication in which each daughter molecule keeps one parental strand and gains one newly made strand. It was demonstrated by Meselson and Stahl using heavy nitrogen in Escherichia coli.
Ten per cent law
Lindeman's generalisation that only about ten per cent of the energy at one trophic level is transferred to the next, which is why food chains are short and the pyramid of energy is always upright.

Practice Quiz — 20 Questions

correct out of 20

  1. How many questions in the NEET paper come from Biology, and what are they worth?

    • A.45 questions and 180 marks
    • B.90 questions and 360 marks
    • C.100 questions and 400 marks
    • D.180 questions and 720 marks
    B. 90 questions and 360 marks — Botany and Zoology give 45 questions each, so 90 questions and 360 marks, exactly half of the 720 mark paper.

  2. The marking scheme in NEET awards and deducts:

    • A.Four marks for a correct answer and no deduction
    • B.Four marks for a correct answer and one mark deducted for a wrong answer
    • C.One mark for a correct answer and one third deducted
    • D.Two marks for a correct answer and half a mark deducted
    B. Four marks for a correct answer and one mark deducted for a wrong answer — Each correct answer gives four marks and each wrong answer costs one mark, so uninformed guessing is a losing strategy.

  3. The five kingdom classification was proposed in 1969 by:

    • A.Carolus Linnaeus
    • B.R. H. Whittaker
    • C.Ernst Haeckel
    • D.Copeland
    B. R. H. Whittaker — Whittaker's system uses Monera, Protista, Fungi, Plantae and Animalia.

  4. Which statement about ribosomes is correct?

    • A.Prokaryotic ribosomes are 80S and eukaryotic 70S
    • B.Prokaryotic ribosomes are 70S with 50S and 30S subunits
    • C.Both are 70S
    • D.Eukaryotic ribosomes have 50S and 30S subunits
    B. Prokaryotic ribosomes are 70S with 50S and 30S subunits — The prokaryotic 70S ribosome has 50S and 30S subunits; the eukaryotic 80S has 60S and 40S.

  5. Crossing over between homologous chromosomes takes place in which stage of prophase I?

    • A.Leptotene
    • B.Zygotene
    • C.Pachytene
    • D.Diplotene
    C. Pachytene — Pairing occurs at zygotene, crossing over at pachytene, and the chiasmata become visible at diplotene.

  6. The first stable product of carbon fixation in a C4 plant is:

    • A.3-phosphoglyceric acid
    • B.Oxaloacetic acid
    • C.Phosphoenolpyruvate
    • D.Ribulose bisphosphate
    B. Oxaloacetic acid — C4 plants fix carbon dioxide first into the four carbon oxaloacetic acid using PEP carboxylase. C3 plants form 3-phosphoglyceric acid.

  7. The Krebs cycle takes place in the:

    • A.Cytoplasm
    • B.Mitochondrial matrix
    • C.Inner mitochondrial membrane
    • D.Outer mitochondrial membrane
    B. Mitochondrial matrix — Glycolysis is cytoplasmic, the Krebs cycle occurs in the matrix and the electron transport system on the inner membrane.

  8. Which hormone is known as the stress hormone of plants and closes the stomata?

    • A.Auxin
    • B.Gibberellin
    • C.Cytokinin
    • D.Abscisic acid
    D. Abscisic acid — Abscisic acid promotes dormancy and stomatal closure under water stress.

  9. The pacemaker of the human heart is the:

    • A.Atrioventricular node
    • B.Sinoatrial node
    • C.Bundle of His
    • D.Purkinje fibres
    B. Sinoatrial node — The sinoatrial node in the right atrium generates the impulse that sets the heart rate.

  10. The normal glomerular filtration rate in a healthy adult is about:

    • A.25 millilitres per minute
    • B.125 millilitres per minute
    • C.180 millilitres per minute
    • D.1250 millilitres per minute
    B. 125 millilitres per minute — About 125 millilitres per minute, which works out to roughly 180 litres of filtrate a day.

  11. A dihybrid cross between two heterozygotes gives a phenotypic ratio of:

    • A.3 to 1
    • B.1 to 2 to 1
    • C.9 to 3 to 3 to 1
    • D.1 to 1 to 1 to 1
    C. 9 to 3 to 3 to 1 — The 9 to 3 to 3 to 1 ratio in the second generation demonstrates independent assortment.

  12. The human ABO blood group system illustrates:

    • A.Incomplete dominance only
    • B.Codominance and multiple allelism
    • C.Pleiotropy
    • D.Polygenic inheritance
    B. Codominance and multiple allelism — Alleles A and B are codominant in the AB genotype, and the gene has three alleles in the population.

  13. Sickle cell anaemia results from the substitution of:

    • A.Valine by glutamic acid at position six of the alpha chain
    • B.Glutamic acid by valine at position six of the beta chain
    • C.Lysine by valine at position six of the beta chain
    • D.Glutamic acid by lysine at position four of the alpha chain
    B. Glutamic acid by valine at position six of the beta chain — A single base change replaces glutamic acid with valine at the sixth position of the beta globin chain.

  14. Turner syndrome in humans has the chromosomal constitution:

    • A.XXY
    • B.XO
    • C.Trisomy 21
    • D.XYY
    B. XO — Turner syndrome is 45 chromosomes with a single X. Klinefelter syndrome is XXY and Down syndrome is trisomy 21.

  15. Hershey and Chase, in 1952, established that the genetic material is DNA by working with:

    • A.Pneumococcus in mice
    • B.Bacteriophage and Escherichia coli
    • C.Drosophila melanogaster
    • D.Neurospora crassa
    B. Bacteriophage and Escherichia coli — They labelled phage protein with radioactive sulphur and phage DNA with radioactive phosphorus and showed that only the DNA entered the bacterium.

  16. In the B form of DNA, the distance between two adjacent base pairs is:

    • A.0.34 nanometres
    • B.3.4 nanometres
    • C.2 nanometres
    • D.20 nanometres
    A. 0.34 nanometres — The rise per base pair is 0.34 nanometres and the pitch of one complete turn, containing ten base pairs, is 3.4 nanometres.

  17. The lac operon model of gene regulation was proposed by:

    • A.Watson and Crick
    • B.Jacob and Monod
    • C.Meselson and Stahl
    • D.Beadle and Tatum
    B. Jacob and Monod — Francois Jacob and Jacques Monod described the lac operon in Escherichia coli.

  18. The enzyme used in the polymerase chain reaction is heat stable because it is obtained from:

    • A.Escherichia coli
    • B.Thermus aquaticus
    • C.Agrobacterium tumefaciens
    • D.Bacillus thuringiensis
    B. Thermus aquaticus — Taq polymerase from the thermophilic bacterium Thermus aquaticus survives the repeated denaturation step.

  19. Bt cotton is resistant to bollworm because it carries genes from:

    • A.Agrobacterium tumefaciens
    • B.Bacillus thuringiensis
    • C.Thermus aquaticus
    • D.Rhizobium leguminosarum
    B. Bacillus thuringiensis — The cry genes of Bacillus thuringiensis code for a protein that becomes toxic in the alkaline gut of the insect.

  20. Which ecological pyramid is always upright?

    • A.The pyramid of numbers
    • B.The pyramid of biomass
    • C.The pyramid of energy
    • D.All three are always upright
    C. The pyramid of energy — Energy is lost at every transfer, so the pyramid of energy can never be inverted, while pyramids of number and biomass sometimes are.

References