⚡ Quick quiz

Test yourself in under a minute: NEET Biology Practice Test

See how closely your recall matches the exact NCERT lines behind Botany and Zoology, the standard NEET Biology actually tests.

1. 1. In a monohybrid cross between two heterozygous tall pea plants (Tt x Tt), what is the expected phenotypic ratio in the F1 generation?

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2. 2. Which phylum of the animal kingdom is characterized by the presence of a true coelom, jointed appendages, and a chitinous exoskeleton?

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3. 3. Which hormone, secreted by the islets of Langerhans, lowers blood glucose levels by promoting glucose uptake into cells?

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4. 4. In a food chain, at which trophic level do decomposers act, and what is their primary ecological role?

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   A) They occupy the topmost trophic level, feeding only on primary consumersB) They recycle only energy, not nutrients, back into the ecosystemC) They act outside the fixed trophic levels, breaking down dead organic matter and releasing nutrients back into the soilD) They are producers that convert sunlight into chemical energy for the food chain

5. 5. Which organelle is referred to as the 'powerhouse of the cell' because it generates ATP through aerobic respiration?

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6. 6. In human females, which structure releases a secondary oocyte during ovulation, roughly midway through the menstrual cycle?

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7. 7. Which biotechnology technique uses a bacterium's natural ability to transfer DNA into plant cells, commonly employed to produce genetically modified crops?

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Genetics & Evolution

Covers the molecular basis of inheritance, Mendelian and population genetics through dihybrid ratios, codominance, incomplete dominance and Hardy-Weinberg equilibrium, and Darwinian evolution including adaptive radiation.

1. 1. Which enzyme is responsible for unwinding the DNA double helix ahead of the replication fork during DNA replication?

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   DNA helicase🔊

   DNA helicase uses energy from ATP hydrolysis to break the hydrogen bonds between complementary base pairs, unwinding the double helix ahead of the replication fork so that DNA polymerase can access the single-stranded template. Single-strand binding proteins then keep the separated strands apart until replication proceeds.

2. 2. In a dihybrid cross between two pea plants heterozygous for seed shape and seed colour (RrYy x RrYy), what phenotypic ratio is expected in the F2 generation according to Mendel's law of independent assortment?

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   9:3:3:1🔊

   Because the two gene pairs assort independently during gamete formation, each RrYy parent produces four types of gametes (RY, Ry, rY, ry) in equal proportion, and their random combination in a Punnett square yields nine round-yellow, three round-green, three wrinkled-yellow, and one wrinkled-green offspring. This 9:3:3:1 ratio was the key evidence Mendel used to formulate independent assortment.

3. 3. In cattle, a red-coated bull (RR) crossed with a white-coated cow (WW) produces roan-coated offspring, whose coat shows distinct red and white hairs side by side rather than a blended colour. What term describes this pattern of inheritance?

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   Codominance🔊

   In codominance, both alleles are expressed fully and independently in the heterozygote rather than blending into an intermediate shade. The roan coat literally carries separate patches of red and white hair, showing both parental phenotypes side by side, unlike incomplete dominance where the two colours would blend into a uniform intermediate tone.

4. 4. In snapdragons (Antirrhinum majus), crossing a red-flowered plant (RR) with a white-flowered plant (rr) produces pink-flowered F1 offspring, with neither allele completely dominant. What term describes this pattern of inheritance?

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   Incomplete dominance🔊

   In incomplete dominance, neither allele fully masks the other, so the heterozygote shows a blended, intermediate phenotype. Here the red and white pigment alleles combine to produce a uniform pink colour throughout the petal, rather than distinct patches of red and white as codominance would produce.

5. 5. According to the Hardy-Weinberg principle, if the frequency of a recessive allele 'q' in a population at genetic equilibrium is 0.2, what is the expected frequency of homozygous dominant individuals (p^2) in that population?

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   0.64🔊

   The Hardy-Weinberg equation states that p + q = 1 and p^2 + 2pq + q^2 = 1, where p^2, 2pq, and q^2 represent the frequencies of the homozygous dominant, heterozygous, and homozygous recessive genotypes respectively. Given q = 0.2, p works out to 0.8, so the homozygous dominant frequency p^2 equals 0.8 squared, which is 0.64.

6. 6. According to Darwin's theory of natural selection, what is the primary raw material within a population upon which selection acts?

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   Heritable variation among individuals🔊

   Darwin proposed that individuals within a population naturally vary in their traits, and that some of this variation is heritable. Natural selection acts on this existing heritable variation, favouring individuals whose traits improve survival and reproduction in a given environment, rather than creating new variation itself.

7. 7. Which evolutionary process describes how a single ancestral species gives rise to several different species that occupy different habitats or niches, as exemplified by Darwin's finches on the Galapagos Islands?

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   Adaptive radiation🔊

   Adaptive radiation occurs when a single ancestral lineage diversifies rapidly into many descendant species, each becoming specialized for a distinct ecological niche within a relatively confined geographic area. Darwin observed exactly this among the Galapagos finches, where beak shapes and sizes diverged from a common ancestor to suit different available food sources such as seeds, insects, and cactus flowers.

8. 8. What term describes a random, chance-driven change in allele frequency in a small population, unrelated to natural selection?

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   Genetic drift🔊

   Genetic drift is a random fluctuation in allele frequencies caused by chance events during reproduction, sampling, or survival, and its effect is strongest in small populations where chance events are not averaged out. Unlike natural selection, drift is not driven by any fitness advantage and can even fix a harmful allele purely by chance.

Diversity & Plant Systems

Covers animal kingdom phyla classification, flowering-plant morphology and anatomy, and plant kingdom groups from algae to angiosperms, including biological classification criteria.

1. 1. Which animal phylum is characterized by a unique water-vascular system used in locomotion, and shows an exclusively deuterostome pattern of embryonic development?

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   Echinodermata🔊

   Echinoderms such as starfish and sea urchins possess a distinctive water-vascular system with tube feet that function in locomotion, capture of food, and respiration. Unlike most other invertebrate phyla, which are protostomes, echinoderms share the deuterostome developmental pattern (blastopore becomes the anus) with chordates, hinting at their closer evolutionary relationship to vertebrates.

2. 2. Presence of a notochord, a dorsal hollow nerve cord, and pharyngeal gill slits at some stage of life are diagnostic features of which animal phylum?

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   Chordata🔊

   All chordates, from fish to mammals, show a notochord, a dorsal tubular nerve cord, and pharyngeal gill slits at least at some embryonic stage, even if these structures are later modified or lost in adults. These three features together distinguish chordates from all other animal phyla.

3. 3. Which group of plants is referred to as the 'amphibians of the plant kingdom' because, although they can grow on soil, water is still required for the sexual/fertilization process?

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   Bryophytes🔊

   Bryophytes, such as mosses and liverworts, lack true vascular tissue and true roots, so their gametes (particularly the motile male gametes) must swim through a film of surface water to reach the egg. This dependence on external water for fertilization despite an otherwise terrestrial existence is the basis for the amphibian analogy.

4. 4. Which group of plants possesses true vascular tissue (xylem and phloem) but, like bryophytes, still requires water for its motile male gamete to reach the egg?

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   Pteridophytes🔊

   Pteridophytes, such as ferns, are the first plant group to evolve true vascular tissue, allowing them to grow larger and colonize drier ground than bryophytes. However, their male gametes are still flagellated and motile, so a film of external water remains necessary for fertilization, just as in bryophytes.

5. 5. Which accessory pigment, in addition to chlorophyll, gives brown algae (Phaeophyceae) their characteristic colour, and is stored alongside the carbohydrate laminarin?

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   Fucoxanthin🔊

   Brown algae contain fucoxanthin, a brown carotenoid pigment, in addition to chlorophyll a and c, and it is this pigment that masks the green chlorophyll and gives the algae their characteristic brown or olive colour. Their stored food reserve is the polysaccharide laminarin rather than starch, unlike green algae.

6. 6. Which simple plant tissue, located just beneath the epidermis of a young dicot stem, provides mechanical support through living cells with unevenly thickened corners?

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   Collenchyma🔊

   Collenchyma cells are living cells with cellulose and pectin thickened unevenly at their corners, giving young, actively growing dicot stems flexible mechanical support while still allowing some elongation. This distinguishes it from sclerenchyma, whose cells are dead at maturity with uniformly thickened, lignified walls.

7. 7. Which taxonomic category groups organisms that can interbreed and produce fertile offspring, and is considered the smallest fundamental unit of classification?

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   Species🔊

   A species is defined as a group of organisms capable of interbreeding among themselves and producing fertile offspring in nature, reproductively isolated from other such groups. It is the basic taxonomic unit from which broader categories like genus, family, and order are built.

Human Physiology

Covers neural and chemical (hormonal) coordination, locomotion and the joints/muscle types involved, circulation through the heart's valves and chambers, and the breathing, excretory and digestive systems.

1. 1. What is the approximate residual volume of the human lungs, that is, the volume of air remaining in the lungs even after the most forcible expiration?

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   Approximately 1200 mL🔊

   Even after the most forceful possible expiration, the alveoli and airways cannot be completely emptied, and around 1200 mL of air remains trapped in the lungs; this is the residual volume. Its presence keeps the alveoli slightly inflated between breaths and allows some gas exchange to continue even during expiration.

2. 2. Which part of the nephron is chiefly responsible for reabsorbing nearly 70-80% of the glomerular filtrate, including glucose, amino acids, and a major fraction of electrolytes and water?

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   Proximal convoluted tubule (PCT)🔊

   The PCT is lined with cells bearing extensive microvilli that vastly increase the absorptive surface area, allowing it to reclaim the bulk of the filtered glucose, amino acids, and a large share of sodium, chloride, and water back into the peritubular capillaries. Only the remaining, more concentrated filtrate passes on to the loop of Henle for further processing.

3. 3. During an action potential in a neuron, the rapid influx of which ion into the cell causes membrane depolarization?

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   Sodium (Na+) ions🔊

   When a neuron is stimulated past its threshold, voltage-gated sodium channels open and Na+ ions rush into the cell down their electrochemical gradient, rapidly reversing the membrane potential from negative to positive; this is depolarization. Repolarization then follows as potassium channels open and K+ ions flow out of the cell.

4. 4. Which endocrine gland, often called the 'master gland,' regulates hormone secretion from most other endocrine glands in the body?

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   Pituitary gland🔊

   The pituitary gland, situated at the base of the brain, secretes tropic hormones such as TSH, ACTH, FSH, and LH that in turn control the activity of the thyroid, adrenal cortex, and gonads. Because it coordinates the output of so many other glands, it has earned the nickname the 'master gland' of the endocrine system.

5. 5. A ball-and-socket joint, such as at the shoulder or hip, permits movement in which manner compared to a hinge joint like the knee?

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   A ball-and-socket joint allows movement in almost every direction (multiaxial), while a hinge joint permits movement in only one plane (uniaxial)🔊

   In a ball-and-socket joint, the rounded head of one bone fits into a cup-shaped socket of another, permitting rotation, flexion, extension, and circular movement in multiple planes. A hinge joint, in contrast, only allows a back-and-forth swinging motion in a single plane, much like a door hinge.

6. 6. Which chamber of the heart pumps deoxygenated blood into the pulmonary artery towards the lungs for oxygenation?

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   Right ventricle🔊

   Deoxygenated blood returning from the body collects in the right atrium, passes through the tricuspid valve into the right ventricle, and is then pumped through the pulmonary artery to the lungs for gas exchange. The oxygenated blood returns via the pulmonary vein to the left side of the heart to be pumped out to the body.

7. 7. Which enzyme, secreted by gastric glands in an inactive form (pepsinogen) and activated by hydrochloric acid, begins protein digestion in the stomach?

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   Pepsin🔊

   Chief cells of the gastric glands secrete the inactive precursor pepsinogen, which is converted into active pepsin by the hydrochloric acid secreted by parietal cells in the same glands. Pepsin then begins breaking dietary proteins into smaller peptides within the acidic environment of the stomach.

Ecology & Environment

Covers organisms and populations (growth curves, population interactions), and ecosystem/biodiversity concepts including biomass pyramids, biogeochemical cycles, and biodiversity hotspot criteria.

1. 1. In which type of ecosystem is the pyramid of biomass typically inverted, with the standing biomass of producers (phytoplankton) being smaller than that of the primary consumers (zooplankton) at any given moment?

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   A marine/sea ecosystem🔊

   In the sea, producers such as phytoplankton are tiny, short-lived, and reproduce extremely rapidly, so their standing crop biomass at any single instant is small even though their overall rate of production is high. Because zooplankton graze on them continuously while living longer, the biomass of these primary consumers can exceed that of the producers, giving an inverted pyramid of biomass despite energy still flowing normally from producers upward.

2. 2. As per the biodiversity hotspot criteria proposed by Norman Myers, a region must contain at least how many endemic vascular plant species, in addition to having lost 70% or more of its original habitat, to qualify as a hotspot?

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   1500 endemic vascular plant species🔊

   Myers defined biodiversity hotspots using two quantitative criteria: the region must harbour at least 1500 species of vascular plants found nowhere else (endemics), and it must have already lost 70% or more of its original natural habitat to human activity. India's Western Ghats-Sri Lanka and Indo-Burma regions are among the global hotspots identified using these thresholds.

3. 3. A population growing in an environment with unlimited resources and no restriction on growth follows which type of growth curve, described mathematically as dN/dt = rN?

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   Exponential (J-shaped) growth curve🔊

   When resources are effectively unlimited, a population's growth rate is proportional to its current size, giving the exponential model dN/dt = rN. Plotting population size against time produces a characteristic J-shaped curve, which contrasts with the S-shaped logistic curve seen when growth is limited by carrying capacity.

4. 4. In a relationship where a tapeworm benefits by absorbing nutrients from its host's intestine while the host is harmed, what type of population interaction is this?

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   Parasitism🔊

   Parasitism is an interspecific interaction in which one organism, the parasite, benefits by deriving nutrients directly from its host, while the host suffers harm from this relationship. A tapeworm living in the intestine of a mammal absorbs digested nutrients directly, depriving its host and often causing malnutrition or disease.

5. 5. Atmospheric nitrogen (N2) is converted into ammonia by nitrogen-fixing bacteria such as Rhizobium living in the root nodules of leguminous plants. What is this biological process called?

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   Biological nitrogen fixation🔊

   In biological nitrogen fixation, symbiotic bacteria such as Rhizobium use the enzyme nitrogenase to convert inert atmospheric N2 into ammonia, a form plants can use to build amino acids and nucleic acids. In return, the leguminous host plant supplies the bacteria with carbohydrates within specialized root nodules.

6. 6. According to Lindeman's ten percent law of energy transfer, if producers in an ecosystem fix 10,000 kcal of energy, approximately how much energy becomes available to the primary consumers at the next trophic level?

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   Approximately 1,000 kcal🔊

   Lindeman's ten percent law states that only about 10% of the energy present at one trophic level is transferred to the next, with the remainder lost as heat through respiration and metabolic activity. Starting from 10,000 kcal at the producer level, roughly 1,000 kcal is available to the primary consumers that feed on them.

Cell Biology & Biomolecules

Covers the cell cycle and cell division (mitosis, meiosis, and the phases of interphase), the structure and function of major biomolecules, and cell organelles as the basic unit of life.

1. 1. During which phase of the cell cycle does DNA replication occur, resulting in each chromosome consisting of two identical sister chromatids joined at the centromere?

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   S (Synthesis) phase of interphase🔊

   Interphase is divided into G1, S, and G2 phases, and it is specifically during the S phase that the cell duplicates its entire genome. Because replication produces two identical copies of each chromosome held together at the centromere, a cell entering mitosis after S phase has chromosomes made of two sister chromatids rather than one.

2. 2. During which stage of meiosis I do homologous chromosomes pair up and exchange genetic material through crossing over?

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   Pachytene stage of Prophase I🔊

   During pachytene, the paired homologous chromosomes (bivalents) formed in zygotene develop crossovers at points called chiasmata, where non-sister chromatids exchange corresponding segments of genetic material. This exchange is the main source of genetic recombination and variation among gametes.

3. 3. Which type of chemical bond links amino acids together to form a polypeptide chain?

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   Peptide bond🔊

   A peptide bond forms between the carboxyl group (-COOH) of one amino acid and the amino group (-NH2) of the next, releasing a molecule of water in a condensation reaction. Repeated peptide bond formation links many amino acids into a long polypeptide chain, the primary structure of a protein.

4. 4. Which single-membrane organelle contains hydrolytic enzymes and carries out intracellular digestion, earning it the nickname 'suicide bag' of the cell?

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   Lysosome🔊

   Lysosomes are membrane-bound vesicles produced by the Golgi apparatus and packed with hydrolytic enzymes capable of digesting proteins, lipids, carbohydrates, and nucleic acids. If a lysosome ruptures, these enzymes can also digest the cell's own components, which is why lysosomes are nicknamed the cell's 'suicide bags.'

5. 5. At which checkpoint in the cell cycle does the cell verify that DNA replication is complete and undamaged before entering mitosis?

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   G2/M checkpoint🔊

   The G2/M checkpoint occurs at the end of the G2 phase and confirms that the entire genome has been accurately replicated and any DNA damage has been repaired before the cell is allowed to proceed into mitosis. A cell that fails this checkpoint is halted or directed towards repair or programmed cell death rather than dividing with faulty DNA.

Reproduction: Human & Plant

Covers sexual reproduction in flowering plants (pollination, fertilization routes, and gametophyte development), and human reproduction and reproductive health including the male and female reproductive systems.

1. 1. In the human male reproductive system, which cells located within the seminiferous tubules nourish the developing germ cells and secrete the hormone inhibin?

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   Sertoli cells🔊

   Sertoli cells, also called nurse cells, are found in the germinal epithelium of the seminiferous tubules and provide nutrients to the dividing and differentiating spermatogenic cells. They also secrete inhibin, which exerts negative feedback control on FSH secretion from the anterior pituitary, helping regulate the rate of spermatogenesis.

2. 2. In angiosperms, entry of the pollen tube into the ovule through the micropyle is called porogamy. What is the term for entry through the chalaza instead?

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   Chalazogamy🔊

   Most angiosperms show porogamy, where the pollen tube grows straight through the micropylar opening to reach the embryo sac, but in a few plants such as Casuarina the tube instead enters through the chalazal end of the ovule, a route termed chalazogamy. A third, rarer route through the integuments rather than the micropyle or chalaza is called mesogamy.

3. 3. Transfer of pollen grains from the anther of one flower to the stigma of a flower on a different plant of the same species is called which type of pollination?

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   Xenogamy🔊

   Xenogamy is cross-pollination in the truest sense: pollen travels from the anther of one plant to the stigma of a genetically different plant of the same species, ensuring genetic recombination between two distinct individuals. This differs from geitonogamy, where pollen moves between two flowers on the very same plant, and autogamy, self-pollination within a single flower.

4. 4. The mature embryo sac (female gametophyte) in most angiosperms, formed via the common Polygonum type of development, contains how many nuclei and how many cells at maturity?

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   8 nuclei and 7 cells🔊

   In the Polygonum-type embryo sac, a single functional megaspore undergoes three rounds of mitotic division to give 8 nuclei, which then organize into 7 cells: one egg cell flanked by two synergids at the micropylar end, three antipodal cells at the opposite end, and a large central cell that contains two polar nuclei but remains a single binucleate cell.

5. 5. The phase of the menstrual cycle during which the endometrium regenerates and thickens under rising estrogen levels, occurring roughly between days 5-13, is called what?

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   Proliferative (follicular) phase🔊

   During the proliferative phase, rising estrogen secreted by the growing ovarian follicles stimulates regeneration and thickening of the endometrial lining that was shed during menstruation. This phase runs alongside the follicular phase of the ovarian cycle and ends around ovulation, after which the secretory (luteal) phase begins.

Biotechnology & Applications

Covers the principles and processes of recombinant DNA technology (restriction enzymes, gel electrophoresis, vectors), and biotechnology applications in agriculture and medicine.

1. 1. Which restriction endonuclease, isolated from Escherichia coli and commonly used in recombinant DNA technology, recognizes the palindromic sequence GAATTC?

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   EcoRI🔊

   EcoRI is one of the earliest and most widely used restriction enzymes, obtained from a strain of Escherichia coli, and it cleaves double-stranded DNA specifically at the palindromic sequence GAATTC. The cut is made between the G and the adjacent A on each strand, generating short single-stranded overhangs known as sticky ends that facilitate the joining of foreign DNA into a vector.

2. 2. In agarose gel electrophoresis, DNA fragments of different sizes moving through the gel under an electric field are separated primarily based on which property?

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   Fragment size (molecular weight)🔊

   As DNA fragments move through the pores of the agarose gel matrix under the electric field, smaller fragments thread through the pores more easily and migrate farther in a given time than larger fragments. This size-dependent separation lets researchers estimate a fragment's length by comparing its migration distance against a DNA ladder of known sizes.

3. 3. Which naturally occurring, small circular extrachromosomal DNA molecule found in bacteria is commonly used as a cloning vector in recombinant DNA technology?

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   Plasmid🔊

   Plasmids are small, circular, self-replicating DNA molecules found naturally in many bacteria, separate from the main bacterial chromosome. Because they can be cut open with restriction enzymes, carry a foreign gene of interest, and be reintroduced into a host cell where they replicate independently, they are widely used as cloning vectors.

4. 4. Human insulin produced commercially through recombinant DNA technology was first manufactured using which genetically engineered organism?

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   Escherichia coli (E. coli)🔊

   The human insulin gene was inserted into plasmid vectors and introduced into Escherichia coli, which was then cultured to produce the A and B polypeptide chains of human insulin separately. These chains were later combined and linked by disulfide bonds outside the bacterial cells to form biologically active human insulin, marketed as Humulin.