datavorous/entrance-exam-dataset huggingface dataset:
In Li++,electron in first Bohr orbit is excited to a level by a radiation of wavelength λ.When the ion gets de excited to the ground state in all possible ways (including intermediate emissions), a total of six spectral lines are observed. What is the value of λ ?
(Given: h=6.63×10-34 J s ;c=3×108 m s-1 )

Options:
A 10.8 nm
B 9.4Â nm
C 11.4Â nm
D 12.3Â nm

The correct answer is:
10.8 nm

Solution:
Total Number of possible spectral lines that can be emmited when atom de-excites from state n to groundstate is C2n
∴ nC2=6⇒n(n-1)2=6⇒n=4
1λ=R z2112-142=1.097×107×9×1-116
⇒λ=10.8 nm

Topic: Physics, Atomic Physics, NEET
In lac operon, promoter gene provides the binding site for

Options:
A β -galactosidase
B Lactose
C Repressor protein
D RNA polymerase

The correct answer is:
RNA polymerase

Solution:
LAC OPERON GENES:

1. Structural genes: Three structural genes are:

i) lac z: The z gene codes for Ã - galactosidase which is primarily responsible for the hydrolysis of the disaccharide, lactose into its monomeric units galactose and glucose.

ii) lac y: The y gene codes for permease, which increases permeability of the cell to Ã - galactoside.

iii) lac a: The a gene codes for transacetylase which can transfer acetyl group to Ã - galactoside.

2. Operator gene: It interacts with a protein molecule or regulator molecule, which prevents the transcription of structural genes.

3. Promoter gene: The gene possess site for RNA polymerase attachment

4. Regulator gene (i): The gene codes for a protein known as repressor protein, it is synthesized all the time from the i-gene, thatâs why it is constitutive gene which is functional always.

Topic: Biology, Molecular Basis of Inheritance, NEET
In lac operon, $z$ gene codes for :

Options:
A $\beta$-galactosidase
B Permease
C Repressor
D Transacetylase

The correct answer is:
$\beta$-galactosidase

Solution:
lac operon is an example of polycistronic operon in which 3 gene are present namely $Z, Y$ and $A$.
$\mathrm{Z}-\beta$-galactosidase
$\mathrm{Y}$ - Permease
A - Transacetylase

Topic: Biology, Molecular Basis of Inheritance, NEET, NEET 2022 (Phase 2)
In lac-operon, which protein is not regulated by the repressor?

Options:
A Galactosidase
B Lactose Permease
C Tryptophan synthetase
D Transacetylase

The correct answer is:
Tryptophan synthetase

Solution:
Lac operon consists of three structural gene X, Y, and A. Gene X synthesizes enzyme beta-galactosidase which breaks lactose into glucose and galactose. Gene Y synthesizes enzyme Lactose permease which increases membrane permeability for lactose. Gene A synthesizes enzyme transacetylase which degrades the galactose.

Topic: Biology, Molecular Basis of Inheritance, NEET
In Lamarck's theory, what drove the evolution of life forms?

Options:
A Use and disuse of organs
B Inheritance of acquired characteristics
C Natural selection
D Adaptation to the environment

The correct answer is:
Use and disuse of organs

Solution:
According to Lamarck, evolution of life forms was driven by use and disuse of organs, where organisms would adapt to their environment through the use or disuse of certain body parts and then pass on these traits to their offspring.

Topic: Biology, Evolution, NEET
In land plants, the guard cells differ from other epidermal cells in having

Options:
A mitochondria
B endoplasmic reticulum
C chloroplasts
D cytoskeleton

The correct answer is:
chloroplasts

Solution:
The guard cells of stomata in land plants are specialised epidermal cells which contain chloroplasts. In rest of epidermal cells, chloroplasts are absent. But chloroplasts of guard cells are capable of poor photosynthesis as there is absence of NADP reductase enzyme.

Topic: Biology, Anatomy of Flowering Plants, NEET, NEET 2011 (Screening)
In Langmuir's model of adsorption of a gas on a solid surface

Options:
A the rate of dissociation of adsorbed molecules from the surface does not depend on the surface covered
B the adsorption at a single site on the surface may involve multiple molecules at the same time
C the mass of gas striking a given area of surface is proportional to the pressure of the gas
D the mass of gas striking a given area of surface is independent of the pressure of the gas

The correct answer is:
the mass of gas striking a given area of surface is proportional to the pressure of the gas

Solution:
In Langmuir's model of adsorption of a gas on a solid surface the mass of gas striking a given area of surface is proportional to the pressure of the gas.
Pressure of gas ∝ Number of gas moles (mass) striking the given area of surface of adsorbent.

Topic: Chemistry, Surface Chemistry, NEET
In Lassaigne's extract of organic compound both nitrogen and sulphur are present, which gives blood-red colour with Fe3+ due to the formation of

Options:
A FeSCN2+
B Fe4FeCN63.xH2O
C NaSCN
D FeCN5NOS4-

The correct answer is:
FeSCN2+

Solution:
When the organic sample containing nitrogen and sulphur is strongly heated with sodium metal the ionic compound sodium thiocyanate is formed. Sodium thiocyanate gives blood-red colour with neutral FeCl3.

Na +N+C+S→NaSCNSCN- + Fe3+→FeSCN2+

Topic: Chemistry, General Organic Chemistry, NEET, NEET 2023 (All India)
In Lassaigne’s test, a blue colour is obtained if the organic compound contains nitrogen. The blue colour is due to

Options:
A K4[Fe(CN)6]
B Fe4[Fe(CN)6]3
C Na3[Fe(CN)6]
D Cu2[Fe(CN)6]

The correct answer is:
Fe4[Fe(CN)6]3

Solution:
In Lassaigne’s test, a blue colour is obtained if the organic compound contains nitrogen. The Prussian blue is due to Fe4[Fe(CN)6]3 is formed.

Topic: Chemistry, General Organic Chemistry, NEET
In Lassaigne’s test for the detection of halogens, the sodium fusion extract is first boiled with concentrated nitric acid. This is

Options:
A To dissolve Ag2S
B To remove silver halides
C To decompose Na2S and NaCN, if present
D Because Ag2S and AgCN are insoluble in nitric acid

The correct answer is:
To decompose Na2S and NaCN, if present

Solution:
For the test of halogens, it is necessary to remove sodium cyanide and sodium sulphide from the sodium extract if N and S are present. It is possible by boiling sodium extract with cocn. HNO3 as follows
NaCN+HNO3→NaNO3+HCN↑
Na2S+2HNO3→2NaNO3+H2S↑

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
In Lassaigne's test sodium metal is used because -

Options:
A It is very reactive
B Its melting point is low
C Its compounds are soluble in water
D All of the above

The correct answer is:
All of the above

Solution:
Lassaigne extract is prepared to convert covalent compound to ionic by using reactive metal like sodium having low melting point.

Topic: Chemistry, General Organic Chemistry, NEET
In leaves of $\mathrm{C}_4$-plants malic acid synthesis during $\mathrm{CO}_2$-fixation occurs in

Options:
A epidermal cells
B mesophyll cells
C bundle sheath
D guard cells

The correct answer is:
mesophyll cells

Solution:
$\mathrm{C}_4$-plants show Kranz anatomy. In the leaves of $\mathrm{C}_4$-plants the vascular bundles are surrounded by bundle sheath of parenchymatous cells, which in turn are surrounded by mesophyll cells. In $\mathrm{C}_4$-plants the Hatch and Slack pathway involves two carboxylation reaction one taking place in chloroplast of mesophyll cells and other in chloroplast of bundle sheath cells. The initial $\mathrm{CO}_2$ fixation occurs in mesophyll cells where primary $\mathrm{CO}_2$ acceptor is phosphoenol pyruvate and formed oxaloacetate. The oxaloacetate is reduced to malic acid. From chloroplasts of mesophyll cells the malic acid is transferred to chloroplast of bundle sheath cells and decarboxylated to form $\mathrm{CO}_2$ and pyruvic acid. The $\mathrm{CO}_2$ is again fixed by $\mathrm{C}_3$ cycle.
In plants, stoma is surrounded by two small, specialized, green epidermal cells called guard cells. The guard cells are small in size and therefore, rapidly influenced by turgor changes.

Topic: Biology, Photosynthesis in Higher Plants, NEET, NEET 2008 (Screening)
In leaves the protoxylem elements

Options:
A face towards the abaxial surface
B face towards the adaxial surface
C are scattered in the middle
D are surrounded by the metaxylem

The correct answer is:
face towards the abaxial surface

Solution:
In leaves, vascular bundles xylem is present toward the adaxial surface and phloem is present towards the abaxial surface. Arrangement of protoxylem is towards the abaxial surface and metaxylem toward the adaxial surface.

Topic: Biology, Anatomy of Flowering Plants, NEET
In leguminous plants, there exists a symbiotic association between the plant and the bacterium. Choose the correct statement regarding this.

Options:
A The bacteria derive reduced N2 from plant
B The bacteria supply reduced N2 to the plant and receive sugars from plant
C The nodule is produced by the plant independent of bacteria
D The plant growth is inhibited by the factors produced by bacteria

The correct answer is:
The bacteria supply reduced N2 to the plant and receive sugars from plant

Solution:
Legumes form a unique symbiotic relationship with bacteria known as Rhizobium, which they allow to infect their roots. This leads to root nodule formation where bacteria are accommodated to convert nitrogen from the air into ammonia that the plant can use for growth. In turn, bacteria receive food from the plants in the form of sugars.

Topic: Biology, Mineral Nutrition, NEET
In leptotene, the chromosomes are

Options:
A Attached to nuclear envelope by one end
B Attached to nuclear envelope by both end directly
C Attached to nuclear envelope by both end through attachment plate
D Both 1 and 2

The correct answer is:
Attached to nuclear envelope by both end through attachment plate

Solution:
In leptotene, the tips of chromosome are generally associated with the nuclear membrane through attachment plate. The ends of all the chromosomes are directed towards one side and are attached to the nuclear envelope.

Topic: Biology, Cell Cycle and Cell Division, NEET
In lichen, the role of mycobiont is

Options:
A

Provides food for the alga

B

Provides protection, anchorage and absorption for the alga

C

Releases oxygen for the alga

D

Fixes the atmospheric nitrogen for the alga

The correct answer is:

Provides protection, anchorage and absorption for the alga

Solution:
Lichens (term coined by Theophrastus) are composite or dual organisms which are formed by a fungus partner or mycobiont (mostly ascomycetes) and an algal partner (mostly blue green algae). Fungus forms the body of lichen as well as its attaching and absorbing structures. Algae performs photosynthesis and provides food to the fungus.

Topic: Biology, Biological Classification, NEET
In lichens, sexual reproduction belongs to

Options:
A Fungal partner only
B Algal partner only
C Both Fungal and algal partners
D Neither fungal or algal partner

The correct answer is:
Fungal partner only

Solution:
Lichens exhibit the symbiotic association between algae and fungi. The fungal partner is involved in sexual reproduction with the help of reproductive structures called apothecia.

Topic: Biology, Biological Classification, NEET
In lichens, the phycobiont and mycobiont are _______________ and ______________, respectively.

Options:
A heterotrophic, autotrophic
B heterotrophic, heterotrophic
C autotrophic, heterotrophic
D autotrophic, autotrophic

The correct answer is:
autotrophic, heterotrophic

Solution:
Lichens are symbiotic associations i.e. mutually useful associations, between algae and fungi. The algal component is known as phycobiont and fungal component as mycobiont, which are autotrophic and heterotrophic, respectively. Algae prepare food for fungi and fungi provide shelter and absorb mineral nutrients and water for its partner.

Topic: Biology, Biological Classification, NEET
In light reaction, pigments are organised into two photochemical complexes called

Options:
A Photosystem-I and Photosystem-II
B Light harvesting complexes
C Antennae
D None of the above

The correct answer is:
Light harvesting complexes

Solution:
Light reactions or the âPhotochemicalâ phase include light absorption, water splitting, oxygen release, and the formation of high-energy chemical intermediates, ATP and NADPH. Several complexes are involved in the process. The pigments are organised into two discrete photochemical light harvesting complexes (LHC) within the Photosystem I (PS I) and Photosystem II (PS II). The LHCs are made up of hundreds of pigment molecules bound to proteins.

Topic: Biology, Photosynthesis in Higher Plants, NEET
In light reaction, plastoquinone facilitates the transfer of electrons from

Options:
A Cytb6f complex to PS-I
B PS-I to NADP+
C PS-I to ATP synthase
D PS-II to Cytb6f complex

The correct answer is:
PS-II to Cytb6f complex

Solution:
In chloroplast, both light and dark reaction of photosynthesis takes place. In the disc of thylakoid, the light reaction takes place where water is oxidized to release oxygen. The transfer of electrons is facilitated by plastoquinone from PS-II to Cytb6f complex, in the light reaction. The electrons which are freed from water a transfer to ATP and NADPH. The dark reaction occurs outside the thylakoid, in the stroma and cytoplasm, and in this reaction, the energy from ATP and NADPH are utilized to fix carbon dioxide. Sugar molecules and other organic molecules which are necessary for the cell function in metabolism are products of this reaction.

Topic: Biology, Photosynthesis in Higher Plants, NEET, NEET 2020 (Phase 1)
In light reaction, the assimilatory powers produced are

Options:
A ATP,Â NADH2
B ATP, NADPH+H+
C ATP,Â FADH2
D NADP

The correct answer is:
ATP, NADPH+H+

Solution:
In light reaction, light energy is trapped by pigments and is converted into chemical energy through photophosphorylation, forming ATP and NADPH+H+ which is used in dark reaction to synthesizes glucose through the Calvin cycle, thus known as assimilatory power.

Topic: Biology, Photosynthesis in Higher Plants, NEET
In linkage isomerism, what is it that varies between isomers?

Options:
A The spatial arrangement of ligands
B The oxidation state of the metal
C The coordination number of the metal
D The type of metal ion used

The correct answer is:
The coordination number of the metal

Solution:
In linkage isomerism, the coordination number of the metal varies between isomers.

Topic: Chemistry, Coordination Compounds, NEET
In Litchi, the third integument which develops from the funicle at the base of the ovule is

Options:
A sarcotesta
B operculum
C caruncle
D aril

The correct answer is:
aril

Solution:
Thick fleshy outer integument as seen in Magnolia is called sarcotesta. An operculum is a structure found in Lemna formed by the elongation of inner integuments over the micropyle. The caruncle is a structure found in the castor that develops from the micropylar region of the integument. In Litchi, the third integument which develops from the funicle is called the aril.

Topic: Biology, Sexual Reproduction in Flowering Plants, NEET
In litchi, the third integument which develops from the funicle at the base of the ovule is

Options:
A sarcotesta
B operculum
C caruncle
D aril

The correct answer is:
aril

Solution:
In Litchi the third integument which develops from the base of the funicle becomes thich and fleshy and form the edible portion and is known as aril.

Topic: Biology, Sexual Reproduction in Flowering Plants, NEET
In lung, maximum gaseous exchange is due to

Options:
A Simple diffusion
B Active transport
C Passive transport
D Fascilitated diffusion

The correct answer is:
Simple diffusion

Solution:
Maximum gaseous exchange between blood (dissolved phase) and alveolar (lungs) air (gaseous phase) across respiratory membrane occurs by simple diffusion. The exchange depends upon the concentration gradients (partial pressure) of the concerned gases in blood and alveolar air. Both O2 and CO2 are highly and equally soluble in lipid and hence, easily diffusible through cell membrane.
In passive transport an ion on molecule crossing a membrane moves down its concentration gradient and no metabolic energy is consumed. Facilitated diffusion is special type of passive transport where specific permeases in membrane facilitate the crossing of solutes.
Active transport uses specific transport protein called pumps, which use metabolic energy (ATP) to move ions or molecule against their concentration gradient.

Topic: Biology, Breathing and Exchange of Gases, NEET
In maize, a meiocyte has 20 chromosomes. What will be the number of chromosomes in its vegetative cell of pollen grain and nucellus cell of ovule respectively?

Options:
A 20, 40
B 20, 10
C 10, 20
D 40, 20

The correct answer is:
10, 20

Solution:
Maize in an angiosperm. Meiocyte is a mother cell that undergoes meiosis to form spores in angiosperms. Meiocytes are diploid 2n. The vegetative cell of the pollen grain is haploid n while the nucellus cell of the ovule is diploid 2n. Thus their values will be 10 and 20 respectively

Topic: Biology, Sexual Reproduction in Flowering Plants, NEET
In maize, hybrid vigour is exploited by:

Options:
A crossing of two inbred parental lines
B harvesting seeds from the most productive plants
C inducing mutations
D bombarding the seeds with DNA.

The correct answer is:
crossing of two inbred parental lines

Solution:
Hybrid vigour or heterosis is exploited by crossing of two inbred parental lines. The very objective of getting homozygous inbred parental lines is so that a perfect heterozygous can be formed.

Topic: Biology, Strategies for Enhancement in Food Production, NEET, NEET 2007
In maize, hybrid vigour is exploited by:

Options:
A inducing mutation
B bombarding the protoplast with DNA
C crossing of two inbred parental lines
D harvesting seeds from the most productive plants

The correct answer is:
crossing of two inbred parental lines

Solution:
The increase in the traits of hybrid strength due to crossing over is called hybrid vigour or heterosis. The hybrid vigour in maize is exploited by crossing of an inbred parental line.
Related Theory
The explanation for heterosis phenomenon is based on ideas: (i) every trait of an organism depends on many genes. (ii) Inbreeding depression and heterosis are related to individual genetic diversity. The changes of individual genetic diversity caused by selfpollination and cross-pollination reveals that self-pollinating plants of natural crosspollinating leads to the decrease in individual genetic diversity of offspring and crossing between pure lines of genetic difference leads to the increase in individual genetic diversity. Thus, the decrease in individual genetic diversity is the cause the of depression and the increase in individual genetic diversity is the cause of heterosis.

Topic: Biology, Strategies for Enhancement in Food Production, NEET, NEET 2006
In majority of nephrons, the loop of Henle is

Options:
A Too long and extends deep into the medulla
B Too short and extends only very little into the medulla
C Too long and doesn't extend in the medulla at all
D Too short and doesn't extend in the medulla at all

The correct answer is:
Too short and extends only very little into the medulla

Solution:
In kidneys, with regard to their location, there are two types of nephrons are present and they are cortical and juxtamedullary nephrons. The cortical nephrons share the maximum percentage of about 80% to 85% of the total nephron. These nephrons are present in the renal cortex with very short loops of Henle that extend only little into the medulla.

Topic: Biology, Excretory Products and their Elimination, NEET
In male cockroaches, sperms are stored in which part of the reproductive system?

Options:
A Seminal vesicles
B Mushroom glands
C Testes
D Vas deferens

The correct answer is:
Seminal vesicles

Solution:
In male cockroach, sperms are stored in the seminal vesicles. The sperms are produced in testes, while the cockroach is still young, is brought by the vasa deferentia into the seminal vesicles for storage. The sperms in the seminal vesicles are glued together in the form of bundles called spermatophores.

Topic: Biology, Structural Organisation in Animals, NEET, NEET 2016 (Phase 2)
In male cockroaches, sperms are stored in which part of the reproductive system?

Options:
A Seminal vesicles
B Mushroom glands
C Testes
D Vas deferens

The correct answer is:
Seminal vesicles

Solution:
In male cockroach, sperms are stored in the seminal vesicles. The sperms are produced in testes, while the cockroach is still young, is brought by the vasa deferentia into the seminal vesicles for storage. The sperms in the seminal vesicles are glued together in the form of bundles called spermatophores.

Topic: Biology, Structural Organisation in Animals, NEET
In males, FSH stimulates

Options:
A Sertoli cells
B Spermatogonia
C Interstitial cells
D Cells of ejaculatory duct

The correct answer is:
Sertoli cells

Solution:
FSH acts on the Sertoli cells and stimulates the secretion of some factors which help in the process of spermiogenesis.

Topic: Biology, Human Reproduction, NEET
In malignant tumours, the cells proliferate, grow rapidly and move to other parts of the body to form new tumours. This stage of the disease is called:

Options:
A metagenesis
B metastasis
C teratogenesis
D mitosis

The correct answer is:
metastasis

Solution:
Cells sloughed from such tumors reach distant sites through blood, and wherever they get lodged in the body, they start a new tumor there. This property called metastasis is the most feared property of malignant tumors.

Topic: Biology, Human Health and Diseases, NEET
In maltose, which carbon of one glucose unit is linked to which carbon of the other glucose unit?

Options:
A C1 of glucose I is linked to C1 of glucose II
B C1 of glucose I is linked to C4 of glucose II
C C4 of glucose I is linked to C4 of glucose II
D C4 of glucose I is linked to C1 of glucose II

The correct answer is:
C1 of glucose I is linked to C4 of glucose II

Solution:
In maltose, C1 of one glucose unit is linked to C4 of another glucose unit.

Topic: Chemistry, Biomolecules, NEET
In mammals, which blood vessel would normally carry the largest amount of urea?

Options:
A Renal vein
B Dorsal aorta
C Hepatic vein
D Hepatic portal vein

The correct answer is:
Hepatic vein

Solution:
Urea -Ornithine cycle takes place in liver so the hepatic vein leaving liver possesses maximum urea. The hepatic veins carry oxygen-depleted blood from the liver to the inferior vena cava.

Harmful nitrogenous waste like ammonia is converted into urea in liver which is later removed by kidneys. Thus, the blood is detoxified of harmful nitrogenous waste.

Topic: Biology, Excretory Products and their Elimination, NEET, NEET 2016 (Phase 1)
In man, during inspiration, the dome-shaped diaphragm becomes:

Options:
A More convex anteriorly
B More concave posteriorly
C More or less flat
D Contract to small size

The correct answer is:
More or less flat

Solution:
Inspiration is the process in which air is taken inside the lungs. During inspiration, the dome-shaped diaphragm becomes more or less flat. As a result, the volume of the thoracic cavity increases.

Topic: Biology, Breathing and Exchange of Gases, NEET
In mango and coconut, the fruit is known as a drupe. They develop from the monocarpellary superior ovary and are one-seeded. Identify the edible part of these two fruits.

Options:
A Mesocarp and endocarp, respectively
B Mesocarp in both
C Mesocarp and endosperm, respectively
D Mesocarp and epicarp, respectively.

The correct answer is:
Mesocarp and endosperm, respectively

Solution:
In mango, the edible part is mesocarp which forms the fleshy and juicy part. In coconut mesocarp becomes fibrous and the edible part is the endosperm, which is liquid initially but later on maturity becomes solid and cellular.

Topic: Biology, Morphology of Flowering Plants, NEET
In many cases, the chromosomes do undergo some dispersion, they do not reach an extremely extended state of the interphase nucleus. This statement is related with ________

Options:
A Telophase II
B Anaphase II
C Anaphase I
D Telophase I

The correct answer is:
Telophase I

Solution:
In telophase I, chromatin formation will not occur and many times the cell directly enters to meiosis II or prophase II.

Topic: Biology, Cell Cycle and Cell Division, NEET