NEET Dictionary

NEET Biology Glossary

Complete dictionary of 712+ NCERT terms, definitions, scientific names, and key processes tested in NEET 2027.

EFB

European Federation of Biotechnology

Ori

Origin of replication — controls copy number

Hind II

First restriction endonuclease discovered

EcoRI

Cuts between G and A in palindrome GAATTC

Sticky ends

Single-stranded overhangs after off-centre cut

DNA ligase

Enzyme that joins DNA fragments permanently

Insertional inactivation

Insert disrupts marker gene — recombinant identified

Blue-white selection

White colonies = recombinants (beta-gal inactivated)

Taq polymerase

Thermostable polymerase used in PCR

Bioreactor

Large-scale vessel for growing cells for product

Downstream processing

Separation, purification, formulation after biosynthesis

Competent cell

Bacterial cell made capable of taking up DNA

Osmotic Pressure

π = iCRT

Boiling Point Elevation

ΔT_b = i × K_b × m

Gibbs Energy & Cell Potential

ΔG° = -nFE°_cell

Equilibrium Constant

K_p = K_c(RT)^{Δn}

Collenchyma

Living support tissue, thickened at corners

Sclereid

Short stone cell giving pears their gritty feel

Tracheid

Water-conducting element present in all vascular plants

Companion cell

Regulates the enucleate sieve tube

Casparian strip

Suberin band in the endodermis

Exarch

Protoxylem toward periphery (roots)

Bulliform cells

Motor cells that roll a monocot leaf

Kranz anatomy

Bundle-sheath wreath in C₄ leaves

Phellogen

Cork cambium

Lenticel

Pore in cork for gas exchange

Heartwood

Inner dark dead durable wood

Annual ring

One season of spring + autumn wood

Porifera

Choanocytes; water canal system

Coelenterata

Cnidoblasts; polyp & medusa

Ctenophora

Comb plates; bioluminescent

Platyhelminthes

Flame cells; acoelomate

Aschelminthes

Round worms; pseudocoelomate

Annelida

Metameric segments; nephridia

Arthropoda

Jointed legs; chitin exoskeleton

Mollusca

Mantle; radula; muscular foot

Echinodermata

Water vascular system; marine

Cyclostomata

Jawless; sucking mouth

Aves

Feathers; pneumatic bones

Mammalia

Mammary glands; pinna

Monera

Prokaryotic kingdom

Mycoplasma

Smallest cell, no wall

Halophile

Lives in salty areas

Methanogen

Produces biogas

Heterocyst

N₂-fixing cell

Cyanobacteria

Blue-green algae

Vibrium

Comma-shaped bacterium

Diatoms

Silica soap-box walls

Gonyaulax

Red tides

Euglena

Pellicle + 2 flagella

Trypanosoma

Sleeping sickness

Plasmodium

Malaria

Slime mould

Forms plasmodium

Paramoecium

Ciliated, has gullet

Rhizopus

Phycomycete (bread mould)

Neurospora

Ascomycete (genetics)

Agaricus

Basidiomycete (mushroom)

Trichoderma

Deuteromycete

Capsid

Virus protein coat

Viroid

Free RNA, no coat

Phycobiont

Algal partner of lichen

Collagen

Most abundant animal protein

RuBisCO

Most abundant biosphere protein

Glycine

R group = H

Peptide bond

Joins amino acids

Zwitterion

Dual-charged amino acid

Haemoglobin

2α + 2β subunits

Trichloroacetic acid

Separates biomolecule pools

Cellulose

Glucose homopolymer

Starch

Helix; blue with iodine

Glycogen

Branched animal store

Inulin

Fructose polymer

Chitin

Arthropod exoskeleton

Glycerol

Trihydroxy propane

Lecithin

Membrane phospholipid

Adenine

Purine

Cytosine

Pyrimidine

A–T pair

2 hydrogen bonds

G–C pair

3 hydrogen bonds

Phosphodiester bond

Joins nucleotides

Malonate

Competitive inhibitor

Zinc

Carboxypeptidase cofactor

Plasma

Liquid matrix of blood (~55%)

Fibrinogen

Plasma protein for clotting

Albumin

Maintains osmotic balance

Serum

Plasma minus clotting factors

Erythrocyte

RBC — carries haemoglobin

Spleen

Graveyard of RBCs

Neutrophil

Most abundant WBC (phagocyte)

Basophil

Releases histamine & heparin

Monocyte

Largest WBC

Thrombocyte

Platelet — blood clotting

O group

Universal donor

AB group

Universal recipient

Heparin

Natural anticoagulant

SA node

Pacemaker of the heart

Tricuspid valve

Right atrioventricular valve

QRS complex

Ventricular depolarisation

Pulmonary artery

Artery with deoxygenated blood

Medulla oblongata

Site of cardiac centre

Robert Hooke

Coined the term "cell"

Virchow

Omnis cellula-e cellula

Singer & Nicolson

Fluid mosaic model (1972)

Robert Brown

Discovered the nucleus

George Palade

Discovered ribosomes

Mycoplasma

Smallest cell

Peptidoglycan

Bacterial cell wall

Mesosome

Infolding of prokaryotic membrane

Plasmid

Extra-chromosomal circular DNA

Cristae

Folds of inner mitochondrial membrane

Grana

Stacks of thylakoids

Amyloplast

Stores starch

Lysosome

Suicidal bag of the cell

Tonoplast

Membrane of the vacuole

9 + 2

Axoneme of cilia & flagella

Kinetochore

Spindle-attachment disc on centromere

Nucleolus

rRNA synthesis & ribosome assembly

Glyoxysome

Fat → sugar in fatty seeds

Pituitary

Master gland (sella turcica)

Hypothalamus

Releasing/inhibiting hormones

ADH deficiency

Diabetes insipidus

Excess GH (child)

Gigantism

Oxytocin

Uterine contraction & milk ejection

Melatonin

Circadian rhythm (pineal)

Iodine deficiency

Goitre

Graves’ disease

Hyperthyroid exophthalmos

Calcitonin

Lowers blood calcium

PTH

Raises blood calcium

Thymosins

T-lymphocyte differentiation

Adrenaline

Fight-or-flight (medulla)

Cortisol

Glucocorticoid

Aldosterone

Na⁺ & water balance

Insulin

Lowers glucose (β-cells)

Glucagon

Raises glucose (α-cells)

Progesterone

Maintains pregnancy

Erythropoietin

Stimulates RBC formation

Neuron

Unit of the nervous system

Nissl bodies

Granules in the cyton

Schwann cell

Forms the myelin sheath

Nodes of Ranvier

Gaps in myelin

−70 mV

Resting potential

Na⁺ influx

Causes depolarisation

K⁺ efflux

Causes repolarisation

Acetylcholine

A neurotransmitter

Dura mater

Outermost meninx

Corpus callosum

Joins cerebral hemispheres

Cerebellum

Balance and coordination

Medulla oblongata

Controls heartbeat & breathing

Hypothalamus

Temperature, hunger, thirst

Occipital lobe

Centre for vision

Rods

Dim-light photoreceptors

Cones

Colour vision

Organ of Corti

Hearing in the cochlea

Eustachian tube

Equalises ear pressure

Apical meristem

Primary (length) growth

Lateral meristem

Secondary (girth) growth

Intercalary meristem

At internode base of grasses

Sigmoid curve

S-shaped growth plot

Lₜ = L₀ + rt

Arithmetic growth

W₁ = W₀ e^(rt)

Exponential growth

Dedifferentiation

Mature cell divides again

Heterophylly

Different leaf shapes (plasticity)

IAA

Natural auxin

F.W. Went

Isolated auxin from Avena

2,4-D

Auxin herbicide

Gibberella fujikuroi

Source of gibberellins

Bolting

Internode elongation (gibberellin)

Zeatin

Natural cytokinin

Ethylene

Fruit ripening & abscission

Abscisic acid

Stress hormone, stomatal closure

Florigen

Hypothetical flowering hormone

Vernalization

Cold-induced flowering

Joseph Priestley

Plants restore 'damaged' air (discovered O₂)

Jan Ingenhousz

Sunlight essential; only green parts release O₂

Julius von Sachs

Glucose made in green parts, stored as starch

T.W. Engelmann

First action spectrum (prism + Cladophora)

Cornelius van Niel

O₂ comes from water, not CO₂

Melvin Calvin

Worked out the Calvin (C3) cycle with ¹⁴C

Chlorophyll a

Chief pigment; reaction centre

Chlorophyll b / carotenoids

Accessory pigments transferring energy

P700

Reaction centre of Photosystem I

P680

Reaction centre of Photosystem II

Carotenoids

Protect chlorophyll a from photo-oxidation

LHC / antenna

Pigment-protein complex harvesting light

RuBP

5-carbon primary CO₂ acceptor (C3)

PGA

3-carbon first product (C3)

PEP

Primary CO₂ acceptor in C4 mesophyll

OAA

4-carbon first product (C4)

RuBisCO

Most abundant enzyme; carboxylase + oxygenase

18 ATP + 12 NADPH

Needed to make one glucose

Glycolysis

Cytoplasm

Link reaction & Krebs cycle

Mitochondrial matrix

Electron Transport System

Inner mitochondrial membrane

Fermentation

Cytoplasm (anaerobic)

Pyruvate → Acetyl CoA

Oxidative decarboxylation

ATP synthase (F0/F1)

Synthesises ATP from proton gradient

Invertase

Splits sucrose into glucose + fructose

Hexokinase

Phosphorylates glucose to glucose-6-P

Lactate dehydrogenase

Pyruvate → lactic acid

Alcohol dehydrogenase

Forms ethanol in fermentation

Citrate synthase

Acetyl CoA + OAA → citric acid

Cytochrome c

Mobile carrier between Complex III & IV

Net ATP from glycolysis

2

ATP per NADH (ETS)

3

ATP per FADH₂ (ETS)

2

Total ATP per glucose (aerobic)

38

RQ of carbohydrates

1.0

RQ of fats

≈ 0.7

Larynx

Sound box; guarded by the epiglottis

Trachea

Windpipe with cartilage rings

Alveoli

Site of gas exchange

Pleura

Double membrane around the lungs

Bronchioles

Fine branches of the bronchi

Diaphragm

Dome muscle that flattens on inspiration

Tidal volume

~500 mL in a normal breath

Residual volume

~1100–1200 mL left after forced expiration

Vital capacity

ERV + TV + IRV

Total lung capacity

VC + RV (~6000 mL)

IRV

Extra air on a forced inspiration

Spirometer

Instrument that measures lung volumes

Oxyhaemoglobin

~97% of O₂ transport

Bicarbonate ions

~70% of CO₂ transport

Carbonic anhydrase

RBC enzyme for HCO₃⁻ formation

Medulla oblongata

Respiratory rhythm centre

Pneumotaxic centre (pons)

Reduces inspiration duration

Bohr effect

Right shift releases O₂ in tissues

Ammonotelic

Fishes — excrete ammonia

Ureotelic

Mammals — excrete urea

Uricotelic

Birds & reptiles — excrete uric acid

Nephron

Functional unit of the kidney

Glomerulus

Capillary tuft that filters blood

Bowman's capsule

Cup that collects the filtrate

PCT

Reabsorbs glucose, amino acids, most ions

Ascending loop of Henle

Impermeable to water; moves electrolytes out

Collecting duct

Reabsorbs water → concentrated urine

Vasa recta

Counter-current exchanger in the medulla

JGA

Releases renin when GFR falls

DCT

Conditional Na⁺/water reabsorption; secretes H⁺

ADH

Increases water reabsorption

Aldosterone

Increases Na⁺ & water reabsorption

ANF

Lowers blood pressure (checks RAAS)

GFR ≈ 125 mL/min

About 180 L filtered per day

Uremia

Urea accumulates in the blood

Renal calculi

Kidney stones (crystallised salts)

Sarcomere

Functional unit between two Z lines

Actin

Thin filament (with troponin & tropomyosin)

Myosin

Thick filament with cross-bridge head

Troponin

Masks actin binding sites at rest

Sarcoplasmic reticulum

Stores and releases calcium ions

A band

Region of the thick (myosin) filaments

Femur

Longest bone (hindlimb)

Scapula

Flat triangular bone with glenoid cavity

Acetabulum

Cavity of pelvic girdle for the femur

Atlas

First cervical vertebra

Floating ribs

11th & 12th pairs, no ventral attachment

Mandible

Only movable bone of the skull

Ball-and-socket joint

Shoulder and hip

Hinge joint

Knee and elbow

Pivot joint

Between atlas and axis

Tetany

Spasms from low calcium ions

Gout

Uric acid crystals in joints

Osteoporosis

Low bone mass, often from low oestrogen

Cell cycle

Sequence: duplicate genome, synthesise constituents, divide

Interphase

Longest phase (>95%); cell grows and copies DNA

G1 phase

Growth and metabolism, no DNA replication

S phase

DNA replication (2C → 4C)

G2 phase

Protein/tubulin synthesis, prepares for mitosis

G0 phase

Quiescent; active but non-dividing (e.g. neurons)

Karyokinesis

Division of the nucleus

Cytokinesis

Division of the cytoplasm

Prophase

Chromatin condenses; nuclear envelope disappears

Metaphase

Chromosomes most condensed; align at equator

Anaphase

Centromeres split; chromatids move to poles

Telophase

Two nuclei reform; chromosomes decondense

Metaphase plate

Equatorial plane where chromosomes align

Kinetochore

Protein disc on centromere for spindle attachment

Centromere

Constricted region joining sister chromatids

Cleavage furrow

Animal cytokinesis, pinches outside → in

Cell plate

Plant cytokinesis, grows centre → outward

Syncytium

Multinucleate cell; e.g. coconut liquid endosperm

Equational division

Mitosis / Meiosis II — chromatids separate, number kept

Reductional division

Meiosis I — homologues separate, number halved

Meiocyte

Gamete/spore mother cell where meiosis occurs

Leptotene

Chromosomes become gradually visible

Zygotene

Synapsis of homologues; synaptonemal complex

Pachytene

Crossing over at recombination nodules

Diplotene

Synaptonemal complex dissolves; chiasmata visible

Diakinesis

Terminalisation; nucleolus & envelope disappear

Synapsis

Pairing of homologous chromosomes

Synaptonemal complex

Protein framework between paired homologues

Bivalent / tetrad

Paired homologues containing four chromatids

Recombination nodule

Site where crossing over occurs

Recombinase

Enzyme that catalyses crossing over

Crossing over

Segment exchange between non-sister chromatids

Chiasma

X-shaped junction of crossing over

Terminalisation

Chiasmata move to chromosome ends

Anaphase I

Homologous chromosomes separate

Anaphase II

Sister chromatids separate

Interkinesis

Gap between Meiosis I and II; no DNA replication

Dyad

Two haploid cells formed after Meiosis I

Independent assortment

Random orientation of homologues at Metaphase I

Homologous chromosomes

Maternal-paternal pair, same genes at same loci

Nucleo-cytoplasmic ratio

Nuclear:cytoplasmic volume balance restored by mitosis

Fertilisation

Restores diploid number after meiosis

Big Bang

Origin of the universe (~20 bya)

Panspermia

Life came from outer space

Louis Pasteur

Disproved spontaneous generation

Oparin–Haldane

Chemical evolution

Miller–Urey

Amino acids from simple gases

Fossils

Palaeontological evidence

Homologous organs

Same origin, divergent evolution

Analogous organs

Same function, convergent evolution

Darwin's finches

Adaptive radiation

HMS Beagle

Darwin's voyage

Biston betularia

Peppered moth (industrial melanism)

Lamarck

Inheritance of acquired characters

Hugo de Vries

Mutation theory (saltation)

p² + 2pq + q² = 1

Hardy–Weinberg equation

Genetic drift

Random allele-frequency change

Founder effect

Drift in a new small population

Australopithecus

First upright primate (~3–4 mya)

Neanderthal

1400 cc brain; buried the dead

Widal test

Confirms typhoid fever

Haemozoin

Toxic substance causing malaria fever/chills

Rhino virus

Causes common cold

Entamoeba histolytica

Causes amoebiasis (amoebic dysentery)

Wuchereria

Filarial worm — causes elephantiasis

IgE

Antibody produced in allergic reactions

Interferons

Cytokine barrier — protects non-infected cells from virus

Colostrum

Rich in IgA — passive immunity for newborn

Metastasis

Spread of malignant cancer cells via blood

Reverse transcriptase

HIV enzyme — converts RNA to DNA

MALT

Mucosa-Associated Lymphoid Tissue — 50% of lymphoid tissue

Rheumatoid arthritis

Auto-immune disease

Scrotum

Maintains testicular temperature 2-2.5°C lower

Leydig cells

Secrete testicular androgens (testosterone)

Fimbriae

Finger-like projections on fallopian tube

Spermiation

Release of sperms from Sertoli cells

Acrosome

Sperm head cap containing fertilisation enzymes

Antrum

Fluid-filled cavity of tertiary follicle

LH surge

Triggers Graafian follicle rupture (ovulation)

Progesterone

Secreted by corpus luteum to maintain endometrium

Trophoblast

Outer cellular layer of blastocyst

IgA antibodies

Found in colostrum, provides passive immunity

Mangifera indica

Mango

Solanum tuberosum

Potato

Panthera leo

Lion

Musca domestica

Housefly

Triticum aestivum

Wheat

Homo sapiens

Human

Panthera tigris

Tiger

Felidae

Family of cats

Carnivora

Order of meat-eaters

Mammalia

Class with hair & ears

Chordata

Phylum with notochord

Solanaceae

Family of Solanum/Petunia/Datura

Primata

Order of monkey/gorilla/gibbon

Angiospermae

Division of flowering plants

Nomenclature

Assigning a standard name

Identification

Correctly describing an organism

Taxonomy

Classifying by characteristics

Systematics

Diversity + relationships

ICBN

Code for plants

ICZN

Code for animals

Taxon

A rank of classification

LAB

Increases Vitamin B12 in curd

Propionibacterium

Produces Swiss cheese large holes

Aspergillus niger

Fungal source of citric acid

Clostridium

Bacterial source of butyric acid

Streptokinase

Myocardial infarction clot buster

Cyclosporin A

Immunosuppressant from Trichoderma polysporum

Statins

Competitive cholesterol synthesis inhibitor

Flocs

Bacteria + fungal filaments mesh in sewage

Bt spore

Activated in caterpillar's alkaline gut

Glomus

Mycorrhizal fungus absorbing phosphorus

Watson & Crick

Double-helix model of DNA (1953)

Chargaff's rule

A=T, G=C

Griffith

Transforming principle

Avery, MacLeod, McCarty

Transforming principle is DNA

Hershey & Chase

DNA is genetic material (phage)

Meselson & Stahl

Semiconservative replication proof

DNA ligase

Joins Okazaki fragments

Template strand

Strand copied during transcription

Sigma factor

Initiation of bacterial transcription

Rho factor

Termination of bacterial transcription

RNA Pol II

Makes hnRNA (mRNA precursor)

Introns

Non-coding sequences removed by splicing

AUG

Start codon (methionine)

UAA/UAG/UGA

Stop codons

tRNA

Adaptor molecule

Jacob & Monod

lac operon model

Dystrophin

Largest human gene

Alec Jeffreys

DNA fingerprinting (VNTR)

Tap root

From radicle; dicots

Pneumatophore

Breathing root of mangroves

Potato

Underground stem tuber

Racemose

Axis grows; acropetal flowers

Cymose

Axis ends in a flower; basipetal

Marginal placentation

Pea

Axile placentation

Tomato / lemon

Hypogynous

Superior ovary (mustard)

Epigynous

Inferior ovary (guava)

Vexillary

Pea-flag aestivation

Diadelphous

A(9)+1 stamens (Fabaceae)

Pericarp

Epicarp + mesocarp + endocarp

Chlorophyceae

Green algae; chl a & b; starch

Phaeophyceae

Brown algae; fucoxanthin; laminarin

Rhodophyceae

Red algae; phycoerythrin; no flagella

Chara

Green alga

Sargassum

Brown alga

Porphyra

Red alga

Fucoxanthin

Brown-algae pigment

Phycoerythrin

Red-algae pigment

Floridean starch

Reserve food of red algae

Laminarin

Reserve food of brown algae

Agar

From Gelidium & Gracilaria

Algin

Hydrocolloid from brown algae

Spirulina

Protein-rich food supplement

Marchantia

A liverwort

Funaria

A moss

Sphagnum

Peat / bog moss

Protonema

Creeping first stage of moss

Gemmae

Asexual buds in gemma cups

Antheridium

Male sex organ (antherozoids)

Archegonium

Female sex organ (egg)

Rhizoids

Anchoring structures in bryophytes

Prothallus

Free-living gametophyte of a fern

Sori

Clusters of sporangia on fern leaves

Selaginella

Heterosporous pteridophyte

Cycas

Gymnosperm with coralloid roots

Pinus

Gymnosperm with mycorrhiza

Sequoia

One of the tallest trees

Double fertilisation

Unique to angiosperms

Endosperm

Triploid (3n) nourishing tissue

Haplontic

Gametophyte dominant (Volvox)

Diplontic

Sporophyte dominant (seed plants)

Haplo-diplontic

Both phases free-living (moss, fern)

Pisum sativum

Garden pea used by Mendel

3:1

Monohybrid F2 phenotypic ratio

1:2:1

Monohybrid F2 genotypic ratio

9:3:3:1

Dihybrid F2 phenotypic ratio

Law of Segregation

Alleles separate pure into gametes

Incomplete dominance

Red × White → Pink

Co-dominance

AB blood group

Multiple alleles

Iᴬ, Iᴮ, i

Punnett square

Grid predicting gamete combinations

Sutton & Boveri

Chromosomal Theory of Inheritance

Morgan

Linkage in Drosophila

Sturtevant

Genetic maps from recombination

Polygenic

Skin colour (many genes)

Pleiotropy

Phenylketonuria (one gene, many effects)

Down's syndrome

Trisomy 21

Klinefelter's

47, XXY

Turner's

45, X0

Sickle-cell

Glu→Val at 6th position of β-globin

Lippes loop

Non-medicated IUD

Saheli

Non-steroidal once-a-week oral contraceptive

GIFT

Donor ovum transferred to fallopian tube

ICSI

Sperm injected directly into ovum

Vasectomy

Surgical sterilisation in males

Tubectomy

Surgical sterilisation in females

Amniocentesis

Analysis of foetal cells from amniotic fluid

LNG-20

Hormone-releasing IUD

Dithecous anther

Two thecae per anther lobe

Tapetum

Multinucleate nutritive layer

Sporopollenin

Organic material resistant to enzymes and acids

Germ pore

Exine region lacking sporopollenin

Egg apparatus

Two synergids plus one egg cell

Cleistogamous

Flowers that remain closed

Vallisneria

Freshwater water-pollinated plant

Double fertilisation

Syngamy and triple fusion

Scutellum

Single lateral cotyledon in monocots

Apomixis

Seeds developed without fertilisation

Tendon

Muscle to bone

Ligament

Bone to bone

Chondrocyte

Cartilage cell

Osteocyte

Bone cell

Adipose

Stores fat

Intercalated disc

Specialised communication junctions at plasma membranes of cardiac muscle cells allowing cells to contract as a single coordinated unit.

Areolar

Support framework under skin

Prostomium

Covers earthworm mouth

Clitellum

Segments 14–16

Typhlosole

Increases absorption

Setae

Aid locomotion

Septal nephridia

Open into intestine

Gizzard

Grinds soil/food

Cocoon

Earthworm development site

Tegmina

Cockroach forewings

Ootheca

Cockroach egg-case

Haemolymph

Cockroach blood

Nictitating membrane

Protects frog eye

Conus arteriosus

Frog heart outflow

Bidder's canal

Frog sperm path

Mesorchium

Holds frog testes

Nucleus

Contains genetic material

Lysosome

Digestive enzymes

Energy of Photon

hc/λ

Drift Velocity

eEτ/m

Capacitance

Q/V

Torque

r × F

Ecology

Study of interactions among organisms and with the abiotic environment

Ramdeo Misra

Father of Ecology in India

W. H. Pearsall

Supervised Ramdeo Misra's PhD at Leeds (1937)

'How-type' question

Seeks the MECHANISM behind a process

'Why-type' question

Seeks the SIGNIFICANCE of a process

Four levels of ecology

Organisms, populations, communities, biomes

1972

National Committee for Environmental Planning and Coordination founded

Population

Group of a species in a defined area, sharing resources, potentially interbreeding

Birth rate

Per capita births — e.g., 8/20 = 0.4 offspring per lotus per year

Death rate

Per capita deaths — e.g., 4/40 = 0.1 individuals per fruitfly per week

Sex ratio

Population attribute: e.g., 60% females and 40% males

Age pyramid

Graphical plot of age distribution revealing growth status

Triangular pyramid (broad base)

Growing / expanding population

Urn-shaped pyramid (narrow base)

Declining population

Population density

Symbolised by N

Parthenium hysterophorus

Carrot grass — 200 plants vs 1 banyan

Per cent cover / biomass

Better density measure for a single huge banyan tree

Pug marks and faecal pellets

Basis of the tiger census

Fish caught per trap

A measure of relative density

Siberian crane at Bharatpur

Population size may be under 10

Chlamydomonas in a pond

Population size may run into millions

Natality

Births added — increases density

Immigration

Same-species individuals coming IN — increases density

Mortality

Deaths — decreases density

Emigration

Individuals leaving the habitat — decreases density

Nt+1 = Nt + [(B+I) − (D+E)]

The population density equation

dN/dt = rN

Exponential growth — unlimited resources, J-shaped curve

Nt = N0 e^(rt)

Integral form of the exponential growth equation

r

Intrinsic rate of natural increase (b − d)

K

Carrying capacity — nature's maximum sustainable number

e = 2.71828

Base of natural logarithms

dN/dt = rN[(K−N)/K]

Verhulst–Pearl logistic growth equation

Sigmoid (S-shaped) curve

Plot of logistic growth

Lag → Acceleration → Deceleration → Asymptote

The four phases of logistic growth

Norway rat = 0.015, Flour beetle = 0.12

NCERT's r values

India, 1981

Human population r value of 0.0205

Paramecium doubling for 64 days

Illustration of exponential growth

Darwinian fitness

Reproductive fitness — a high r value

Pacific salmon and bamboo

Breed only once in a lifetime

Oysters and pelagic fishes

Produce many small-sized offspring

Birds and mammals

Produce few large-sized offspring; breed many times

Mutualism (+ , +)

Both species benefit

Competition (− , −)

Both species lose

Commensalism (+ , 0)

One benefits, the other is unaffected

Amensalism (− , 0)

One is harmed, the other is unaffected

Pisaster

Starfish predator; its removal killed >10 invertebrate species in a year

Prickly pear + moth

Biological control in Australia, early 1920s

Monarch butterfly

Distasteful — chemical acquired as a caterpillar from a poisonous weed

Calotropis

Produces highly poisonous cardiac glycosides

Acacia and Cactus

Thorns — the commonest morphological anti-herbivore defence

Nicotine, caffeine, quinine, strychnine, opium

Commercial chemicals that evolved as plant defences

Flamingoes and resident fishes

Unrelated species competing for zooplankton in South American lakes

Abingdon tortoise

Extinct in a decade after goats reached the Galapagos

Balanus excludes Chthamalus

Connell's competition experiment on Scotland's rocky coasts

MacArthur's five warblers

Resource partitioning on the same tree

Competitive release

Range expands when a superior competitor is removed

Human liver fluke

Trematode needing two intermediate hosts — a snail and a fish

Cuscuta

Parasitic plant that lost chlorophyll and leaves

Cuckoo (koel) and crow

Brood parasitism with egg mimicry in size and colour

Lice on humans, ticks on dogs

Ectoparasites

Female mosquito

NOT a parasite — it does not live in or on the host

Cattle egret and grazing cattle

Commensalism — cattle flush out insects for the egret

Clown fish and sea anemone

Commensalism — fish gains protection from stinging tentacles

Lichen

Mutualism: fungus + photosynthesising alga or cyanobacterium

Mycorrhiza

Mutualism: fungus + roots of a higher plant

Fig and wasp

One-to-one obligate mutualism; wasp lays eggs, fig feeds larvae

Ophrys orchid

Sexual deceit — male bee pseudocopulates with a petal

Ecosystem

Functional unit of nature where organisms interact with each other and the physical environment

Species composition

Identification and enumeration of the plant and animal species of an ecosystem

Stratification

Vertical distribution of species at different levels

Trees, shrubs, herbs and grasses

Top, second and bottom strata of a forest

Abiotic components

Air, water and soil

Biotic components

Producers, consumers and decomposers

Forest, grassland, desert

Terrestrial ecosystems

Pond, lake, wetland, river, estuary

Aquatic ecosystems

Crop field and aquarium

Man-made ecosystems

Water plus dissolved substances plus bottom soil

The abiotic component of a pond

Phytoplankton, algae, floating and submerged plants

The autotrophic component of a pond

Zooplankton, free-swimming and bottom-dwelling forms

The consumers of a pond

Fungi, bacteria and flagellates

The decomposers of a pond, most abundant at the bottom

Solar input, temperature cycle, day-length

What regulates the rate of function of the entire pond

Primary production

The AMOUNT of biomass produced per unit area over a time period

Productivity

The RATE of biomass production

g per square metre per year

The unit of productivity

GPP

Rate of production of organic matter during photosynthesis

NPP

GPP minus respiration losses; the biomass available to heterotrophs

Secondary productivity

Rate of formation of new organic matter by consumers

170 billion tons

Annual NPP of the whole biosphere (dry weight)

55 billion tons

Annual NPP of the oceans

Light

The limiting factor for productivity in aquatic ecosystems

Detritus

Dead plant and animal remains including faecal matter — raw material for decomposition

Fragmentation

Detritivores break detritus into smaller particles

Leaching

Water-soluble nutrients sink into the soil and precipitate as unavailable salts

Catabolism

Bacterial and fungal enzymes degrade detritus into simpler inorganic substances

Humification

Accumulation of dark, amorphous, colloidal humus in the soil

Mineralisation

Microbes degrade humus and release inorganic nutrients

Earthworm

The farmer's friend — a detritivore that fragments detritus and loosens soil

Humus

Highly resistant to microbial action; colloidal; a reservoir of nutrients

Lignin and chitin

Detritus components that SLOW decomposition

Nitrogen and sugars

Detritus components that SPEED UP decomposition

Temperature and soil moisture

The two most important climatic factors regulating decomposition

Warm and moist

Conditions that favour decomposition

Low temperature and anaerobiosis

Conditions that inhibit decomposition and cause organic build-up

Deep-sea hydro-thermal ecosystem

The only ecosystem not powered by the sun

Less than 50%

Fraction of incident solar radiation that is PAR

2 to 10%

Fraction of PAR actually captured by plants

About 1%

Fraction of available sunlight converted to NPP in an ideal energy pyramid

10 per cent law

Only a tenth of the energy passes to the next trophic level

Second law of thermodynamics

Why ecosystems need a constant energy supply to counteract disorderliness

Herbaceous and woody plants

Major producers in a terrestrial ecosystem

Phytoplankton, algae and higher plants

Producers in an aquatic ecosystem

Molluscs

Common herbivores in an aquatic ecosystem

Grass, goat, man

NCERT's grazing food chain

Grazing food chain

Begins with living producers; the major conduit in aquatic ecosystems

Detritus food chain

Begins with dead organic matter; dominant in terrestrial ecosystems

Saprotroph

A decomposer; 'sapro' means to decompose

Cockroaches and crows

Omnivores that link the GFC and the DFC

Food web

The natural interconnection of many food chains

Trophic level

An organism's place in a food chain, based on its source of nutrition

Sparrow

Primary consumer on seeds; secondary consumer on insects and worms

Standing crop

Mass of living material at a trophic level at a particular time

Dry weight

The more accurate way to measure biomass

Base of an ecological pyramid

The producers, or first trophic level

Apex of an ecological pyramid

The tertiary or top-level consumer

Six million plants, three top carnivores

NCERT's upright grassland pyramid of numbers

Inverted pyramid of numbers

Found in a tree ecosystem

Inverted pyramid of biomass

Found in the sea — small phytoplankton crop supports large zooplankton crop

Pyramid of energy

ALWAYS upright — can never be inverted, because energy is lost as heat

Same species in two levels; simple chain; saprophytes ignored

The three limitations of ecological pyramids

Nutrient cycling

Storage and movement of nutrient elements through the ecosystem; nutrients are reused

Gaseous cycle

Reservoir is the atmosphere or hydrosphere — e.g., carbon

Sedimentary cycle

Reservoir is the Earth's crust — e.g., phosphorus

Oceans

The major reservoir of carbon on Earth

Ecosystem services

Products of ecosystem processes, e.g., purification of air and water by forests

Energy

Flows unidirectionally and is lost as heat; can never be recycled

Nutrients

Cycle through the ecosystem and are used repeatedly

Zooplankton

The second trophic level in a lake

Edward Wilson

Sociobiologist who popularised the term 'biodiversity'

Alexander von Humboldt

Discovered the species-area relationship in the South American jungles

Robert May

Estimated global species diversity at about 7 million

David Tilman

Outdoor-plot experiments: more species means less biomass variation and higher productivity

Paul Ehrlich

Proposed the Rivet Popper hypothesis

Bioprospecting

Exploring molecular, genetic and species-level diversity for products of economic importance

Endemism

Species confined to a region and found nowhere else

Genetic diversity

Variation WITHIN a single species over its distributional range

Rauwolfia vomitoria

Medicinal plant whose reserpine potency varies across Himalayan ranges

50,000 rice strains and 1,000 mango varieties

India's showcase of genetic diversity

Species diversity

Western Ghats have more amphibian species than the Eastern Ghats

Ecological diversity

India beats Norway — deserts, rain forests, mangroves, coral reefs, wetlands, estuaries, alpine meadows

1.5 million

Species described so far, according to IUCN 2004

7 million

Robert May's conservative estimate of global species diversity

More than 70 per cent

Share of described species that are animals

No more than 22 per cent

Share of described species that are plants

Insects

Most species-rich taxonomic group — 70 per cent of all animals

Fungi

Outnumber fishes, amphibians, reptiles and mammals combined

2.4 per cent and 8.1 per cent

India's share of world land area, and of global species diversity

12 mega-diversity countries

The group India belongs to

45,000 and 90,000

Plant and animal species recorded from India

23.5 degrees N to 23.5 degrees S

The latitudinal range of the tropics

Colombia

Near the equator — nearly 1,400 bird species

New York (41 degrees N)

105 bird species

Greenland (71 degrees N)

Only 56 bird species

Ecuador vs the Midwest USA

A tropical forest has up to 10 times the vascular plant species of a temperate one

Amazonian rain forest

The greatest biodiversity on Earth

427 and 427

Amazon mammal and amphibian species counts — identical

2 million insects

Estimated still undiscovered in the Amazon rain forest

TIME hypothesis

Tropics remained undisturbed by glaciations, giving long evolutionary time

CONSTANCY hypothesis

Less seasonal, more predictable environments promote niche specialisation

ENERGY hypothesis

More solar energy raises productivity, contributing indirectly to diversity

log S = log C + Z log A

The species-area relationship on a logarithmic scale

Rectangular hyperbola

Shape of the species-area curve on a normal scale

Z

Slope of the regression line

C

Y-intercept of the species-area line

0.1 to 0.2

Z value within a region, regardless of taxon

0.6 to 1.2

Z value across entire continents — a much steeper slope

1.15

Z value for frugivorous birds and mammals across tropical forests of different continents

Plants in Britain, birds in California, molluscs in New York

Taxa whose regression slopes are amazingly similar

Rivet Popper hypothesis

Airplane is the ecosystem; rivets are the species; wing rivets are the key species

Steady, sturdy, sealed

The three conditions of a stable community

784 species

Extinctions in the last 500 years, per the IUCN Red List 2004

338, 359 and 87

Vertebrates, invertebrates and plants among the 784 extinctions

15,500

Species worldwide presently facing the threat of extinction

100 to 1,000 times

How much faster current extinction rates are than pre-human rates

Amphibians (32 per cent)

The group most threatened with extinction

Birds (12 per cent)

The least threatened of the four groups NCERT lists

Dodo

Extinct — Mauritius

Quagga

Extinct — Africa

Thylacine

Extinct — Australia

Steller's Sea Cow

Extinct — Russia; also a victim of over-exploitation

Bali, Javan and Caspian

The three extinct subspecies of tiger

Habitat loss and fragmentation

The MOST IMPORTANT cause of extinction

14 per cent to 6 per cent

Shrinkage of the world's tropical rain forests

Soya beans and beef cattle

What the Amazon is being cleared for

When need turns to greed

The definition of over-exploitation

Nile perch in Lake Victoria

Alien invasion that wiped out more than 200 cichlid fish species

Parthenium, Lantana and Eichhornia

Invasive weed species threatening India's natives

Clarias gariepinus

African catfish illegally introduced for aquaculture

Co-extinction

A host fish dies and its obligate parasites die with it

In situ conservation

Save the entire forest to save the tiger — protection in the natural habitat

Ex situ conservation

Threatened species taken out of their habitat and given special care

Biodiversity hotspot

Region with very high species richness AND high endemism

25 plus 9 equals 34

How the world's hotspot count was reached

Less than 2 per cent

Land area covered by all hotspots put together

Almost 30 per cent

Reduction in mass extinctions achievable by strictly protecting hotspots

Western Ghats and Sri Lanka, Indo-Burma, Himalaya

The three hotspots covering India

14, 90 and 448

India's biosphere reserves, national parks and wildlife sanctuaries

Sacred groves

Forest tracts venerated and given total protection — in situ, community-driven

Meghalaya

Where sacred groves are the last refuges of many rare and threatened plants

Cryopreservation

Preserving gametes of threatened species in viable and fertile condition

Rio de Janeiro, 1992

The Earth Summit

Johannesburg, 2002

World Summit on Sustainable Development — 190 countries, 2010 target

Smallpox virus

A species deliberately driven extinct, justified by human welfare