datavorous/entrance-exam-dataset huggingface dataset:
Lead is only slightly attacked dilute hydrochloric acid, because

Options:
A Pb is less electropositive than hydrogen
B PbO2 film is always present on Pb, which resists chemical attack
C PbO film is formed, which resists chemical attack by acid
D a protective coating of PbCl2 is formed on the Pb surface

The correct answer is:
a protective coating of PbCl2 is formed on the Pb surface

Solution:
Lead is only slightly attacked by dilute hydrochloric acid, because a protective coating of PbCl2 is formed on the Pb surface which prevents the further reaction. Powdered lead is readily dissolved by boiling HCl, due to the formation of the soluble complex, H2[PbCl4] .
Pb+HCl→BoilingPbCl2+H2
PbCl2+2HCl→H2[PbCl4](Chloroplumbicacid)

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
________________ leads to accumulation of a dark coloured amorphous substance called ________ that is highly resistant to microbial action and undergoes decomposition at an extremely slow rate.

Options:
A Humification, humus
B Mineralisation, minerals
C Fragmentation, detritus
D Leaching, unavailable salts

The correct answer is:
Humification, humus

Solution:
Humification leads to accumulation of a dark coloured amorphous substance called humus that is highly resistant to microbial action and undergoes decomposition at an extremely slow rate. Being colloidal in nature it serves as a reservoir of nutrients. The humus is further degraded by some microbes and release of inorganic nutrients occur by the process known as mineralisation

Topic: Biology, Ecosystem, NEET
Leaf fall can be prevented by

Options:
A Florigen
B Auxin
C Cytokinin
D Abscisic acid

The correct answer is:
Cytokinin

Solution:
Cytokinin help in delaying senescence.
Cytokinins (CK) are a class of plant growth substances (phytohormones) that promote cell division, or cytokinesis, in plant roots and shoots. They are involved primarily in cell growth and differentiation, but also affect apical dominance, axillary bud growth, and leaf senescence.

Topic: Biology, Plant - Growth and Development, NEET
Leaf helps in vegetative propagation in

Options:
A Arabidopsis
B Bryophyllum
C Sensevieria
D Brassica

The correct answer is:
Bryophyllum

Solution:
Vegetative propagules are the plant parts or organs that are involved in the process of reproduction even though their primary function is not it. The reproductive process is called vegetative propagation as the non-reproductive parts/organs (leaf/stem/roots) are involved.
Bryophyllum is a plant group coming under the family Crassulaceae. These plants propagate by formation of buds on the edges of the leaf called leaf bud. These buds fall off and root wherever they land.

Topic: Biology, Reproduction in Organisms, NEET
Least stable hydride is

Options:
A stannane
B silane
C plumbane
D germane

The correct answer is:
plumbane

Solution:
Here least stable hydride is Plumbane as the stability order of carbon family hydride Silane > Germane > Stannane > Plumbane.

Topic: Chemistry, s Block Elements, NEET
Leaves become modified into spines in:

Options:
A Opuntia
B Pea
C Onion
D Silk Cotton

The correct answer is:
Opuntia

Solution:
Opuntia leaves get modified into spines to protect them from grazing animals, also reduce the area of transpiration. In this condition, the stem gets modified to phylloclade and performs photosynthesis.

Pea leaves are modified into tendrils.

Onion leaves become fleshy to store food in them.

Silk cotton gets modified from unifoliate leaves to multifoliate leaves.

Topic: Biology, Morphology of Flowering Plants, NEET, NEET 2015 (Phase 1)
Le-blanc process is employed in the manufacturing of

Options:
A Baking soda
B Caustic soda
C Soda ash and potash
D Plaster of Paris

The correct answer is:
Soda ash and potash

Solution:
In Le-blanc process, potassium chloride of carnallite is converted to K2SO4 which is then heated with coal and lime stone to give K2CO3. (Potash or pearl ash)

Topic: Chemistry, s Block Elements, NEET
Lecithin, a small molecular weight organic compound found in living tissues, is an example of:

Options:
A Phospholipids
B Glycerides
C Carbohydrates
D Amino acids

The correct answer is:
Phospholipids

Solution:
The correct answer is option (1).
Some lipids have phosphorous and a phosphorylated organic compound in them. These are phospholipids. They are found in cell membrane. Lecithin is one example.
Option (2) is incorrect as glycerides are another group of lipids in which both glycerol and fatty acids are present.
Option (3) and (4) are incorrect as amino acids and carbohydrates are separate groups of biomolecules.

Topic: Biology, Biomolecules (B), NEET, NEET 2024
Left shift of oxyhemoglobin curve is noticed under

Options:
A Normal temperature and pH
B Low temperature and high pH
C Low pH and high temperature
D Low pH and low temperature

The correct answer is:
Low temperature and high pH

Solution:
Due to a rise in temperature, the decrease in pH, and increase in carbon dioxide concentration, the rate of oxyhemoglobin dissociation is also increased. So, the oxygen dissociation curve shifts to right, while the left shift of the oxyhaemoglobin curve is noticed under low carbon dioxide concentration, low temperature and high pH.

Topic: Biology, Breathing and Exchange of Gases, NEET
Left systemic arch is absent in

Options:
A Reptiles only
B mammals only
C birds only
D both birds and mammals

The correct answer is:
birds only

Solution:
The systematic arch is involved in the transport of blood to all the body parts except the head. In reptiles and amphibians, both left and right arches are present. Birds have only right arch and mammals have only the left arch.

Topic: Biology, Animal Kingdom, NEET
\(\left[\mathrm{NH}\left(\mathrm{CH}_2\right) \mathrm{NHCO}\left(\mathrm{CH}_2\right)_4 \mathrm{CO}\right]_{\mathrm{n}}\) is a:-

Options:
A homopolymer
B copolymer
C addition polymer
D thermosetting polymer

The correct answer is:
copolymer

Solution:
$-\left[\mathrm{NH}(\mathrm{CH})_2 \mathrm{NHCO}\left(\mathrm{CH}_2\right)_4 \mathrm{CO}\right]$ - is a copolymer because polymer because polymers whose repeating structural units are derived from two or more types of monomer units are called copolymers.
Related Theory
Thermosetting polymers are the cross-linked polymers and have heavily branched chains. They cannot be reshaped. Thermoplastics have the capability to soften on heating and hard on cooling.

Topic: Chemistry, Polymers, NEET, NEET 2006
Leg-haemoglobin is found in the nodules in roots of leguminous plants. It acts as .......... scavenger and provides............ conditions for the action of nitrogenase enzyme.

Options:
A Oxygen, Aerobic
B Oxygen, Anaerobic
C CO2, Aerobic
D CO2 , Anaerobic.

The correct answer is:
Oxygen, Anaerobic

Solution:
Enzyme nitrogenase: It is a MoâFe protein. It requires anaerobic conditions to work. It is highly sensitive to molecular oxygen. It catalyzes the conversion of atmospheric nitrogen to ammonia. Ammonia is the first stable product of nitrogen fixation.
N2 + 8e- + 8H+ + 16ATP â 2NH3 + H2 + 16ADP + 16Pi

Topic: Biology, Mineral Nutrition, NEET
Length of one coil of B-DNA helix is

Options:
A 0.34 nm
B 3.4 nm
C 3.4 Ã
D 0.34 Ã

The correct answer is:
3.4 nm

Solution:
DNA is a double helical structure with two anti-parallel strands with 5I to 3I polarity. The two strands coil in a right-handed fashion. Each turn of the helix is 3.4nm (or 34 Angstrom units) consisting of 10 nucleotides.

Topic: Chemistry, Biomolecules, NEET
Lens of eyes is derived from

Options:
A Ectoderm
B Mesoderm
C Endoderm
D Both (mesoderm) and (endoderm)

The correct answer is:
Ectoderm

Solution:
Eye lens is derived from ectoderm. The lens is composed of transparent, flexible tissue and is located directly behind the iris and the pupil. It is the second part of the eye, after the ciliary muscles, which are part of the ciliary body, the lens is derived from the surface ectoderm.

Topic: Biology, Neural Control and Coordination, NEET
Lenticels are formed by rupturing of the epidermis by

Options:
A Collenchyma cells
B Parenchyma cells
C Sclerenchyma cells
D Vascular cambium

The correct answer is:
Parenchyma cells

Solution:
In certain regions, the phellogen cuts off closely arranged parenchymatous cells on the outer side instead of cork cells. These parenchymatous cells soon rupture the epidermis, forming lens-shaped openings called lenticels. Lenticels permit the exchange of gases between the outer atmosphere and the internal tissue of the stem. These occur in most woody trees.

Topic: Biology, Anatomy of Flowering Plants, NEET
Let âAâ be the methyl ester of an organic monocarboxylic acid. The vapour density of âAâ is 37. What is the molecular weight of the acid?

Options:
A 46
B 60
C 70
D 74

The correct answer is:
60

Solution:
mol. wt. for ester = V.D. × 2
=74
O       || R−CH− OCH 3 ⇒74 (mol.wt)
O       || R−C−OH⇒74 −14
=60 (mol. wt.)

Topic: Chemistry, Some Basic Concepts of Chemistry, NEET
Let An be the area enclosed by the nth orbit in a hydrogen atom. The graph of lnAnA1 against lnn

Options:
A will pass through the origin
B will be a straight line of slope 3
C will be a non-linear curve
D will be a circle

The correct answer is:
will pass through the origin

Solution:
We know that the radius of the nth stationary orbit is

Rn=R0n2
∴ An=4πR02⋅n4
and, A1=4πR02
∴ AnA1=n4
⇒ lnAnA1=4lnn
The graph is a straight line of slope 4 and passes through the origin.

Topic: Physics, Atomic Physics, NEET
Let a steel bar of length l, breadth b and depth d be loaded at the center by a load W. Then the sag of bending of beam is (Y = Young's modulus of steel)

Options:
A Wl32bd3Y
B Wl34bd3Y
C Wl32db3Y
D Wl34db3Y

The correct answer is:
Wl34bd3Y

Solution:
The sag of bending of beam is given by.
Î´=Wl348 YI Where W is load, L is length, Y is young's modulus and I is bd312 (area moment of inertia)
â´ Î´=Wl348YÃ12bd3=Wl34bd3Y

Topic: Physics, Mechanical Properties of Solids, NEET
Let a wire be suspended from the ceiling (rigid support) and stretched by a weight W attached at its free end. The longitudinal stress at any point of cross-sectional area A of the wire is:

Options:
A Zero
B 2WA
C WA
D W2A

The correct answer is:
WA

Solution:
Longitudinal stress is given by,

stress=forcearea=WA

In case of ideal wire, stress at each point will be the same and will be equal to WA.

Topic: Physics, Mechanical Properties of Solids, NEET, NEET 2023 (All India)
Let ω be the angular velocity of the earth's rotation about its axis. Assume that the acceleration due to gravity on the earth's surface has the same value at the equator and the poles. An object weighed at the equator gives the same reading as a reading taken at a depth d below earth's surface at a pole d<<R. The value of d is

Options:
A ω 2 R 2 g
B ω 2 R 2 2 g
C 2 ω 2 R 2 g
D ω2R24g

The correct answer is:
ω 2 R 2 g

Solution:
g eff due to rotation = g eff due to depth d
g - R ω 2 = g 1 - d R ⇒ R ω 2 = gd R ⇒ d = R 2 ω 2 g

Topic: Physics, Gravitation, NEET
Let E1 and E2 denotes gravitational field at distance r1 and r2 from the axis of an infinitely long solid cylinder of the radius R. Which of the following must hold true?

Options:
A E1<E2 if r1<r2<R
B E1 > E2 if R<r1<r2
C E1 > E2, if r1=R- E, r2=R+E E is positive constant <R
D All of the above

The correct answer is:
All of the above

Solution:
Graph of gravitational field versus distance from axis for a solid cylinder

Topic: Physics, Gravitation, NEET
Let I be the moment of inertia of a uniform square plate about an axis AB that passes through its centre and is parallel to two of its sides. CD is a line in the plane of the plate that passes through the centre of the plate and makes an angle Î¸ with AB. The moment of inertia of the plate about the axis CD is then equal to

Options:
A I
B Isin2Î¸
C Icos2θ
D Icos2Î¸2

The correct answer is:
I

Solution:
From symmetry IAB=IA'B' and ICD=IC'D'

From theorem of perpendicular axes
Izz=IAB+IA'B'=ICD+IC'D'

Izz=2IAB

Izz=2ICD

â´ICD=IC'D'

Topic: Physics, Rotational Motion, NEET
Let Nβ be the number of β particle emitted by 1 gram of Na24 radioactive nuclei having a half life of 15 h. In 7.5 h, the number Nβ is close to NA=6.023×1023 mole-1

Options:
A 1.75×1022
B 6.2×1021
C 7.5×1021
D 1.25×1022

The correct answer is:
7.5×1021

Solution:
âµNN0=12n
N = no. of un-decayed nuclei
N0 = initial no. of nuclei
Also t=nÃT12
âNN0=12tT12
âN=N0127.515
âN=N01212âN=N02
â´ Number of nuclei decayed
=N0-N02=N02-12
=0.4141.414N0
=0.29N0
âµN0=124Ã6.023Ã1023
â No. of nuclei decayed =0.29Ã124Ã6.023Ã1023
=0.0727Ã1023
=7.5Ã1021

Topic: Physics, Nuclear Physics, NEET
Let nr and nb be respectively the number of photons emitted by a red bulb and a blue bulb of equal power in a given time

Options:
A nr=nb
B nr<nb
C nr>nb
D the information is insufficient to get a relation between nr and nb

The correct answer is:
nr>nb

Solution:
PRed=PBlue
nrhcλr=nbhcλb
nrnb=λrλb
As λr>λb
∴ nr>nb

Topic: Physics, Dual Nature of Matter, NEET
Let $R_1$ be the radius of the second stationary orbit and $R_2$ be the radius of the fourth stationary orbit of an electron in Bohr's model. The ratio $\frac{R_1}{R_2}$ is:

Options:
A 0.25
B 0.5
C 2
D 4

The correct answer is:
0.25

Solution:
As,
$\begin{aligned}
\mathrm{R}_n & =0.529 \frac{n^2}{\mathrm{Z}} \\
\text { Hence, } \quad \frac{\mathrm{R}_1}{\mathrm{R}_2} & =\frac{0.529 \frac{n_1^2}{\mathrm{Z}_1}}{0.529 \frac{n_2^2}{\mathrm{Z}_2}} \\
\frac{\mathrm{R}_1}{\mathrm{R}_2} & =\frac{n_1^2}{n_2^2}=\frac{(2)^2}{(4)^2} \\
\therefore \quad \frac{\mathrm{R}_1}{\mathrm{R}_2} & =\frac{1}{4}=0.25
\end{aligned}$
(where, the symbols have their usual meanings)

Topic: Physics, Atomic Physics, NEET, NEET 2022 (Phase 2)
Let T1 and T2 be the energy of an electron in the first and second excited states of hydrogen atom, respectively. According to the Bohr's model of an atom, the ratio T1:T2 is

Options:
A 4:1
B 4:9
C 9:4
D 1:4

The correct answer is:
9:4

Solution:
Given T1⇒ Energy of 1st excited state

For T1⇒n=2

For T2⇒n=3

We know, Energy ∝1n2

∴ T1T2=3222=94

Topic: Physics, Atomic Physics, NEET, NEET 2022 (Phase 1)
Let us consider two solenoids $A$ and $B$, made from same magnetic material of relative permeability $\mu_r$ and equal area of cross-section. Length of $A$ is twice that of $B$ and the number of turns per unit length in $A$ is half that of $B$. The ratio of self inductances of the two solenoids, $L_A: L_B$ is

Options:
A $1: 2$
B $2: 1$
C $8: 1$
D $1: 8$

The correct answer is:
$1: 2$

Solution:
$L=\mu_0 \mu_r \times n \times A \times N$
$L=\mu_0 \mu_r n \times A \times \frac{N}{l} \times l$
$L=\mu_0 \mu_r \times n^2 \times A \times I \quad \Rightarrow L \propto n^2 I$
$\Rightarrow \frac{L_A}{L_B}=\frac{n_A^2}{n_B^2} \times \frac{I_A}{I_B}$
$\Rightarrow \frac{L_A}{L_B}=\frac{1}{4} \times 2=\frac{1}{2}$

Topic: Physics, Electromagnetic Induction, NEET, NEET 2024 (Re-NEET)
Let x=a2b2c be the physical quantity. If the percentage error in the measurement of physical quantities a, b and c is 2, 3 and 4 percent respectively then percentage error in the measurement of x is

Options:
A 7%
B 14%
C 21%
D 28%

The correct answer is:
14%

Solution:
Îx x =2 Îa a +2 Îb b + Îc c
Îx y =2Ã2+2Ã3+4
=4+6+4
Îx x =14%

Topic: Physics, Units and Dimensions, NEET
Leucine is one of the three amino acids which are coded by 6 codons. The codons that code for leucine are CUU, CUC, CUA, CUG, UUA, UUG. How many minimum types of t RNA will be required for reading all codons of leucine?

Options:
A 1
B 2
C 4
D 6

The correct answer is:
2

Solution:
Codons for Leucine are CUU, CUC, CUA, CUG, UUA, UUG . Out of these, CUU, CUC, CUA, CUG can be read by 1 t-RNA (as they satisfy conditions for Wobble hypothesis). But UUA and UUG can only be read by another t-RNA as even though they code for same amino acid they are very different form CUU, CUC, CUA, CUG. Thus at least two different t-RNAs are required for reading all codons of Leucine

Topic: Biology, Molecular Basis of Inheritance, NEET
Lewisite is a poisonous gas having formula

Options:
A CHCl=CHCl
B CHCl=CHAsCl2
C CHCl=CHCl2
D CHCl2CHCl2

The correct answer is:
CHCl=CHAsCl2

Solution:
Lewisite is a poisonous gas having formula CHCl=CHAsCl2 which can be prepared as follows

Topic: Chemistry, p Block Elements (Group 15, 16, 17 & 18), NEET
Leydig cells are located

Options:
A Between the testicular lobules
B In the seminiferous tubules.
C Outside the seminiferous tubules but in the testicular lobules
D Outside the seminiferous tubule but between the testicular lobules

The correct answer is:
Outside the seminiferous tubules but in the testicular lobules

Solution:
Each testis has about 250 compartments called testicular lobules. Each lobule contains one to three highly coiled seminiferous tubules in which sperms are produced. Each seminiferous tubule is lined on its inside by two types of cells called male germ cells (spermatogonia) and Sertoli cells. The regions outside the seminiferous tubules called interstitial spaces contain small blood vessels and interstitial cells or Leydig cells.

Topic: Biology, Human Reproduction, NEET
Leydig cells produce a group of hormones called

Options:
A Androgens
B Estrogens
C Aldosterone
D Gonadotropins

The correct answer is:
Androgens

Solution:
Option (a) is the answer.

Topic: Biology, Chemical Coordination and Integration, NEET
LH surge occurs during which phase of the menstrual cycle?

Options:
A Menstrual phase.
B At the beginning of proliferative phase.
C Just before the end of the proliferative phase.
D In the middle of the cycle.

The correct answer is:
In the middle of the cycle.

Solution:
LH surge is the rapid secretion of LH leading to its maximum level. Which occurs during the middle of the menstrual cycle. LH surge induces rupture of Graafian follicle and thereby the release of an ovum (ovulation).

Topic: Biology, Human Reproduction, NEET
Liberation of oxygen when green cells in water are exposed to sunlight in presence of suitable acceptor is called

Options:
A Arnon's reaction
B Emerson's enhance effect
C Blackman's reaction
D Hill's reaction

The correct answer is:
Hill's reaction

Solution:
Hill's reaction/photochemical/light reaction is initiated when specific light is absorbed by group of chlorophyll molecules primarily concerned with light harvesting.

Topic: Biology, Photosynthesis in Higher Plants, NEET
Lichen indicate

Options:
A air pollution due to its sensitivity to CO.
B air pollution due to its sensitivity to SO2.
C pollution due to smoke.
D noise pollution.

The correct answer is:
air pollution due to its sensitivity to SO2.

Solution:
Lichens are a symbiotic association of the algae (phycobiont) and fungi (mycobiont). The algal partner produces food and the fungal partner provides protection to the algae. The fungi also help in absorption of minerals and water. Lichens generally do not grow in polluted areas, hence they are good indicators of pollution due SO2. Air pollutants dissolved in rainwater, especially SO2 (sulphur dioxide) can damage lichens.

Topic: Biology, Biological Classification, NEET
Lichens are a well-known combination of an alga and a fungus where the fungus has

Options:
A An epiphytic relationship with the alga
B A parasitic relationship with the alga
C A symbiotic relationship with the alga
D A saprophytic relationship with alga

The correct answer is:
A symbiotic relationship with the alga

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
Lichens are an association of:

Options:
A bacteria and fungus
B alga and bacterium
C fungus and alga
D fungus and virus

The correct answer is:
fungus and alga

Solution:
Lichens are an association of fungus and alga.

Topic: Biology, Organisms and Populations, NEET
Lichens are ecologically important as they

Options:
A Purify air
B Are pioneers on barren rocks
C Are symbionts of algae and fungi
D Are associated with mycorrhizal roots

The correct answer is:
Are pioneers on barren rocks

Solution:
Lichens play the role of pioneer species in primary succession on rocks. Lichens secrete acids to dissolve rocks and thus help in weathering and soil formation. Later on lichens make favourable conditions for the growth of very small plants like bryophytes, which are able to hold small amount of soil. Lichens are also SO2 pollution indicators.

Topic: Biology, Biological Classification, NEET
Lichens are indicators of pollution as:

Options:
A They grow more on polluted areas
B They are not found in non-polluted areas
C They do not grow in polluted areas
D Not related to pollution

The correct answer is:
They do not grow in polluted areas

Solution:
Lichens: 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 is autotrophic and heterotrophic, respectively. Algae prepare food for fungi and fungi provide shelter and absorb mineral nutrients and water for its partner. Lichens are very good pollution indicators – they do not grow in polluted areas. They cannot grow in the atmosphere having a high concentration of oxides of sulphur.

Topic: Biology, Biological Classification, NEET
Lichens are symbiotic association between two organisms. Which of these statements about them is true?

Options:
A Lichens are fast growing organisms that live for a short period
B The algal component is called mycobiont and fungal component is called phycobiont
C They are pioneers of vegetation on rocks.
D They grow well in cities.

The correct answer is:
They are pioneers of vegetation on rocks.

Solution:
Lichens are symbiotic associations between algae and fungi. The autotrophic algal component is called phycobiont and the heterotrophic fungal component is called as mycobiont. Algae prepare food for fungi and fungi provide shelter and absorb mineral nutrients and water for its partner. Lichens are very good pollution indicators - they do not grow in polluted areas and in cities. Lichens are pioneers in the xerosere type of ecological succession on barren rocks.

Topic: Biology, Biological Classification, NEET
Lichens are symbiotic associations of an algal and fungal component. Respectively, they are termed as

Options:
A algobiont and mycobiont.
B algobiont and fungibiont.
C mycobiont and phycobiont.
D phycobiont and mycobiont.

The correct answer is:
phycobiont and mycobiont.

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 is 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
Lichens are well known combination of an alga and a fungus where fungus has:

Options:
A a saprophytic relationship with the alga
B an epiphytic relationship with the alga
C a parasitic relationship with alga
D a symbiotic relationship with alga.

The correct answer is:
a symbiotic relationship with alga.

Solution:
Lichens are the symbiotic relation that consist of two unrelated components, an alga and/or cyanobacterium (photobiont) and a fungus (mycobiont).

Topic: Biology, Organisms and Populations, NEET, NEET 2004
Lichens indicate SO2 pollution because they

Options:
A Show association between algae and fungi
B Grow faster than other
C Are sensitive to SO2
D Flourish in SO2 rich environment

The correct answer is:
Are sensitive to SO2

Solution:
Lichens typically do not grow in harsh environments in nature. Most lichens, particularly epiphytic fruticose species and those containing cyanobacteria, are sensitive to manufactured pollutants. Hence, they have been widely used as pollution indicator organisms.
Lichens are symbiotic associations of a fungus with a photosynthetic partner (called a photobiont or phycobiont) that can produce food for the lichen from sunlight.

Topic: Biology, Biological Classification, NEET