NEET 2026 Biology Questions with Solutions

Explanation

DNA has a double helical structure and contains adenine, guanine, cytosine and thymine. RNA is generally single stranded and contains uracil instead of thymine. Hence option (B) is correct.

Explanation

Root hairs develop from epidermal cells in the region of maturation (differentiation), increasing surface area for absorption. Hence option (D) is correct.

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Gymnosperms have naked ovules not enclosed within an ovary. Pinus is a gymnosperm. Hence option (B) is correct.

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In lac operon: z gene → β-galactosidase, y gene → permease, a gene → transacetylase. Hence option (C) is correct.

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Bioprospecting refers to exploring biodiversity for commercially valuable genetic, molecular or biochemical products. Hence option (C) is correct.

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Bt cotton is a genetically modified organism; thermostable DNA polymerase is obtained from Thermus aquaticus; Ti plasmid is from Agrobacterium tumefaciens; pBR322 is a cloning vector in Escherichia coli. Hence option (A) is correct.

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Productivity = rate of biomass production; NPP = GPP − respiration losses; GPP = rate of organic matter production during photosynthesis; secondary productivity = formation of new organic matter by consumers. Hence option (A) is correct.

Explanation

The ongoing sixth mass extinction is largely due to human activities, with extinction rates estimated to be 100–1000 times higher than pre-human levels. Hence option (C) is correct.

Explanation

Alpha-helix is a characteristic feature of the secondary structure of proteins formed by hydrogen bonding. Hence option (A) is correct.

Explanation

Bulliform cells lose water during drought, causing leaves to roll inward and reduce exposed surface area, thereby minimizing water loss. Hence option (D) is correct.

Explanation

PCR steps occur in the order: Denaturation (DNA strands separate) → Annealing (primers bind) → Extension (DNA synthesis by polymerase). Hence option (D) is correct.

Explanation

G₁: growth without DNA replication; S: DNA synthesis; G₂: protein synthesis and growth; M: cell division. Hence A-II, B-III, C-IV, D-I. Therefore option (D) is correct.

Explanation

A: habitat loss in Amazon rainforest is correct; B: Steller’s sea cow and passenger pigeon became extinct due to overexploitation; D: water hyacinth is an invasive species. C is false because Nile perch reduced native cichlid diversity; E is false because associated species may also become extinct. Hence option (B) is correct.

Explanation

A transcription unit contains promoter, structural gene and terminator. The promoter lies toward the 5′ end, binds RNA polymerase and determines coding/template strands. Terminator lies toward the 3′ end and signals transcription termination. Hence all statements are correct.

Explanation

In binomial nomenclature, the first word denotes the genus (capitalized) and the second word denotes the specific epithet (lowercase). Therefore statement (4) is incorrect.

Explanation

Decomposition → breakdown of organic matter; Detritus → dead remains; Mineralisation → release of inorganic nutrients; Humification → accumulation of dark humus. Hence A-III, B-IV, C-II, D-I. Therefore option (B) is correct.

Explanation

The nucleolus is the site of active ribosomal RNA (rRNA) synthesis and ribosome assembly in eukaryotic cells.

Explanation

Respiratory Quotient (RQ) = Volume of CO₂ evolved / Volume of O₂ consumed. For the given reaction: RQ = 102/145 = 0.70 Since 0.70 lies between 0.5 and 0.95, option (A) is correct. Such RQ values are characteristic of fats.

Explanation

Inheritance of flower colour in snapdragon (Antirrhinum sp.) shows incomplete dominance. ABO blood groups are examples of codominance because IA and IB express together in AB individuals. Phenylketonuria is an example of pleiotropy since one gene affects multiple phenotypic traits. Human skin colour is controlled by multiple genes, making it a case of polygenic inheritance.

Explanation

The sequence of DNA fingerprinting steps is: DNA isolation and restriction digestion → electrophoresis → transfer to membrane (Southern blotting) → hybridisation with labelled VNTR probe → autoradiography detection.

Explanation

Histones form an octamer (2 each of H2A, H2B, H3 and H4). Histones are positively charged proteins rich in lysine and arginine. DNA is negatively charged and wraps around histone octamers. Higher-order chromatin packaging requires non-histone chromosomal proteins.

Explanation

The water splitting complex is associated with PS II, not PS I, making statement A incorrect. Kranz anatomy is found in C4 plants, not C3 plants, making statement D incorrect. Statements B, C and E are correct.

Explanation

Somatic hybridization proceeds as: isolation of single cells → digestion of cell walls → isolation of protoplasts → fusion to form hybrid protoplast → regeneration into a new plant.

Explanation

Conjunctive tissue lies between xylem and phloem. Casparian strips are suberin deposits in endodermal cells. Subsidiary cells occur adjacent to guard cells. Starch sheath refers to endodermal cells rich in starch.

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Elongation phase is characterized by cell enlargement, vacuolation and new cell wall deposition. Large conspicuous nuclei are features of meristematic cells.

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2,4-D acts as a herbicide. GA3 is used in the brewing industry. Kinetin promotes nutrient mobilisation. ABA induces stomatal closure.

Explanation

RuBisCO (RuBP carboxylase-oxygenase) catalyses the carboxylation of RuBP during the Calvin cycle.

Explanation

Fixation of one CO₂ molecule in the Calvin cycle requires 3 ATP and 2 NADPH. Therefore, synthesis of one glucose molecule (6 CO₂) requires 18 ATP and 12 NADPH.

Explanation

The floral formula of Solanaceae is ⊕ ⚥ K(5) C(5) A5 G̲(2), showing actinomorphic, bisexual flowers with fused sepals and petals, five stamens and a superior bicarpellary ovary.

Explanation

In situ conservation protects species within their natural habitat. Sacred groves are examples of in situ conservation, whereas botanical gardens and seed banks are ex situ methods.

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Restriction endonucleases recognize specific palindromic sequences and act as molecular scissors. They do not necessarily cut at the exact center of palindromes, and removal of nucleotides from DNA ends is performed by exonucleases, not restriction endonucleases.

Explanation

In racemose inflorescence, the main axis continues to grow and flowers are arranged in acropetal succession, with younger flowers toward the apex.

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Development during microsporogenesis proceeds as: Sporogenous tissue → Pollen mother cells → Microspore tetrads → Pollen grains.

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Proteins are polypeptides, polysaccharides are polymers of sugars, and most enzymes are proteins. Lipids are generally water insoluble, and adenine and guanine are purines, not pyrimidines.

Explanation

Honeybees exhibit haplodiploid sex determination. Fertilized eggs develop into diploid females, while unfertilized eggs develop into haploid males by parthenogenesis. Male bees produce sperms by mitosis, not meiosis.

Explanation

Plasticity is the ability of plants to alter growth patterns or structures in response to environmental conditions or developmental phases. Heterophylly is an example of plasticity.

Explanation

Amino acids are substituted methanes. Valine is a neutral amino acid. Serine is a hydroxy amino acid, not aromatic, and lysine is a basic amino acid, not acidic.

Explanation

The ‘Evil Quartet’ responsible for biodiversity loss consists of habitat loss and fragmentation, over-exploitation, alien species invasions and co-extinctions.

Explanation

Glycolysis occurs in the cytoplasm, ETS is located on the inner mitochondrial membrane, proton accumulation occurs in the intermembrane space and Krebs cycle takes place in the mitochondrial matrix.

Explanation

The primary endosperm cell is triploid (3n), formed after fusion of one male gamete with two polar nuclei during triple fusion.

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Xenogamy involves transfer of pollen between different plants of the same species and introduces genetically different pollen grains.

Explanation

Marginal placentation occurs in pea, axile placentation in lemon, parietal placentation in mustard and basal placentation in marigold.

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Whittaker’s five kingdom classification was based on cell structure, body organization, mode of nutrition, reproduction and phylogenetic relationships. Presence of flagellum was not a criterion.

Explanation

Trypsin is an enzyme, morphine is an alkaloid, Concanavalin A is a lectin and collagen forms intercellular ground substance.

Explanation

Restriction enzymes (molecular scissors) cut DNA, and agarose gel electrophoresis separates fragments based on size. DNA fragments require staining with ethidium bromide and visualization under UV light; they cannot be seen directly or under visible light.

Explanation

Sickle-cell anaemia results from a point mutation in the β-globin gene, causing substitution of glutamic acid by valine at the sixth position of the β-chain of haemoglobin.

Explanation

Cortisol has anti-inflammatory effects. Aldosterone promotes Na⁺ and water reabsorption. Cholecystokinin stimulates pancreatic enzyme secretion and bile release. Progesterone promotes alveolar development in mammary glands.

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A fall in GFR stimulates renin release → Angiotensinogen converts to Angiotensin II → vasoconstriction and aldosterone release → Na⁺ and water reabsorption increase → blood pressure and GFR rise.

Explanation

Respiration occurs in the sequence: pulmonary ventilation → diffusion across alveolar membrane → transport by blood → diffusion between blood and tissues → cellular respiration.

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Plasmodium enters as sporozoites → reaches liver → multiplies in liver cells → infects RBCs and multiplies → gametocytes form in RBCs.

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The BamHI restriction site lies within the tetracycline resistance gene of pBR322. Insertional inactivation at this site causes loss of tetracycline resistance.

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Lyases catalyse removal of groups from substrates without hydrolysis, often resulting in formation of double bonds.

Explanation

Neurotransmitter receptors are located on the post-synaptic membrane, where they receive chemical signals from the synaptic cleft.

Explanation

Crossing Iᴬi × Iᴮi produces offspring: AB, A, B and O in equal proportions. Thus probability of O blood group (ii) is 25%.

Explanation

ERV = 1000–1100 mL, RV = 1100–1200 mL, IRV = 2500–3000 mL and TV = 500 mL.

Explanation

Forelimbs of whales and bats are homologous structures showing divergent evolution, not convergent evolution.

Explanation

Male frogs possess vocal sacs and copulatory (nuptial) pads on the first digit of forelimbs, which help during mating.

Explanation

Petromyzon (lamprey) belongs to Cyclostomata and has a cartilaginous endoskeleton, circular sucking mouth, ectoparasitic habit, absence of paired fins and scales, and multiple gill slits.

Explanation

65 mya → dinosaurs disappeared; 500 mya → invertebrates became active; 350 mya → jawless fishes evolved; 320 mya → seaweeds and early plants existed.

Explanation

Progestasert is a hormone-releasing IUD, Multiload 375 is a copper-releasing IUD, diaphragm is a female barrier contraceptive and Saheli is an oral contraceptive.

Explanation

Eosinophils constitute ~2–3% of WBCs → 160–240/cu mm. Lymphocytes constitute ~20–25% → 1600–2000/cu mm out of 8000/cu mm total WBC count.

Explanation

Nicotine stimulates adrenal release of catecholamines; morphine acts as a sedative and analgesic; heroin is a depressant; cocaine induces euphoria and increased energy.

Explanation

α-1-antitrypsin produced using transgenic animals is used in treatment of emphysema caused by deficiency of this protein.

Explanation

Flying fish (Exocoetus), Angel fish (Pterophyllum) and Fighting fish (Betta) belong to Osteichthyes (bony fishes).

Explanation

Adult echinoderms exhibit radial symmetry, not bilateral symmetry. Reptiles are ectothermic and do not maintain constant body temperature. Statements B and E are incorrect.

Explanation

Ribosomes are non-membrane bound organelles present in both prokaryotic and eukaryotic cells, where they function in protein synthesis.

Explanation

The Verhulst-Pearl logistic growth equation is dN/dt = rN((K−N)/K), where K is carrying capacity, r is intrinsic growth rate and N is population size.

Explanation

Erythroblastosis foetalis occurs when an Rh− mother carries an Rh+ fetus, not vice versa. Anti-Rh antibodies are administered after the first Rh+ childbirth, not after the second child.

Explanation

Streptokinase acts as a clot buster, statins lower blood cholesterol, lipases are used in detergents and Cyclosporin A is an immunosuppressive agent.

Explanation

Molluscs mainly show branchial respiration, reptiles use pulmonary respiration, adult amphibians use pulmonary and cutaneous respiration and Amoeba performs cellular respiration.

Explanation

In sickle-cell anaemia, mutation in the β-globin gene changes the codon from GAG (glutamic acid) to GUG (valine), leading to HbS formation and RBC sickling.

Explanation

Motor neuron signals trigger Ca²⁺ release, enabling actin-myosin cross-bridge formation and sliding of actin filaments toward the centre of the A band. Statement C is incorrect because Ca²⁺ binds troponin rather than directly activating actin to break cross bridges.

Explanation

Humans have 7 cervical vertebrae. Adjacent vertebrae are connected by cartilaginous joints, and the occipital bone articulates with the atlas. Human skull is dicondylic, and all ribs except the last two pairs are bicephalic.

Explanation

Secondary spermatocytes undergo meiosis II to form haploid spermatids, and spermatids transform into spermatozoa by spermiogenesis.

Explanation

JGA is formed by specialized cells of the distal convoluted tubule and afferent arteriole, helping regulate GFR and blood pressure.

Explanation

Ophrys orchids mimic female insects to attract male pollinators, an example of sexual deceit.

Explanation

Frogs have 10 pairs of cranial nerves, optic lobes belong to midbrain, and sinus venosus opens into the right atrium. Thus A, C and E are correct.

Explanation

8 weeks → limbs and digits develop; 12 weeks → external genital organs develop; 20 weeks → foetal movements and hair appear; 24 weeks → body covered with fine hair and eyelashes form.

Explanation

Grasshoppers exhibit XO sex determination. Males (XO) possess one fewer chromosome (23), while females (XX) have 24 chromosomes.

Explanation

Male honeybees are haploid and produce gametes through mitosis because of haplodiploid sex determination.

Explanation

The arrangement from outside to inside is: Corona radiata → Zona pellucida → Perivitelline space → Plasma membrane of ovum.

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Large holes in Swiss cheese are produced due to CO₂ released by Propionibacterium sharmanii during fermentation.

Explanation

The Bt toxin genes cryIAc and cryIIAb are used against cotton bollworms and corn borer respectively.

Explanation

Pyramid of biomass is inverted in aquatic ecosystems such as seas because phytoplankton biomass is lower than consumer biomass at a given time.

Explanation

GIFT (Gamete Intra Fallopian Transfer) involves transfer of donor ovum into the fallopian tube of a female who cannot produce ova but can support fertilization and development.

Explanation

RER bears ribosomes, mitochondria and plastids contain circular DNA, and cytoskeleton consists of microtubules, microfilaments and intermediate filaments. Mitochondria are not part of the endomembrane system and are double membrane-bound.

Explanation

Human RBC membranes contain ~52% proteins, phospholipids form a bilayer, and hydrophobic tails face inward. Mesosomes occur in prokaryotes, not eukaryotes.

Explanation

Tetany is caused by low Ca²⁺ leading to muscle spasms; arthritis is inflammation of joints; myasthenia gravis is an autoimmune disorder affecting neuromuscular junctions; muscular dystrophy involves progressive degeneration of skeletal muscles.

Explanation

Human evolution progressed as: Ramapithecus → Australopithecines → Homo habilis → Homo erectus → Neanderthals → Homo sapiens.

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Aptenodytes (penguin) is a flightless bird whose forelimbs are modified into flippers for swimming.

Explanation

Mutualism benefits both species; parasitism benefits one and harms the other; amensalism harms one species while the other remains unaffected.