UGC NET Environmental Science Unit-III: Environmental Biology Syllabus

Write the exponential population growth equation and its curve shape.

dN/dt = rN, where N = population size, r = intrinsic rate of natural increase, t = time. It produces a J-shaped curve, occurring when resources are unlimited.

Write the logistic population growth equation and define K.

dN/dt = rN[(K − N)/K], producing an S-shaped (sigmoid) curve; K is the carrying capacity, the maximum population size the environment can sustain with available resources.

Compare r-selected and K-selected species.

r-strategists: small body size, short lifespan, many small offspring, little parental care, high r, unstable habitats (e.g. insects, weeds). K-strategists: large body, long lifespan, few offspring, much parental care, populations near K, stable habitats (e.g. elephants, humans).

Name the three types of survivorship curves.

Type I (convex; low juvenile mortality, high survival until old age, e.g. humans), Type II (diagonal/straight; constant mortality rate at all ages, e.g. birds, hydra), Type III (concave; very high juvenile mortality, e.g. fish, oysters).

What is the difference between a community and a population in ecology?

A population is one species in an area; a community (biotic community) is an assemblage of all the interacting populations of different species living together in a defined area.

Define ecological succession and its two main types.

Ecological succession is the gradual, orderly and predictable change in community structure over time at a site. Primary succession begins on a lifeless substrate with no soil (e.g. bare rock, lava); secondary succession occurs where a community was disturbed but soil remains (e.g. abandoned field).

What is a climax community?

The final, relatively stable, self-perpetuating community in equilibrium with the prevailing climate that develops at the end of ecological succession; energy use and species composition remain steady.

Define ecological niche and distinguish fundamental from realized niche.

A niche is the functional role and position of a species in its ecosystem (its use of resources and conditions). The fundamental niche is the full range a species could occupy; the realized niche is the actual smaller range occupied due to competition and biotic limits.

State Gause's competitive exclusion principle.

Two species competing for the exact same limiting resources cannot coexist indefinitely at constant population values; one will outcompete and eliminate the other unless niches differentiate (resource partitioning).

Name the major types of interspecific interactions and their (+/−) signs.

Mutualism (+/+), commensalism (+/0), competition (−/−), predation and parasitism (+/−), amensalism (−/0), neutralism (0/0).

What are the three levels/types of biodiversity?

Genetic diversity (variation of genes within a species), species diversity (variety of species in a region), and ecosystem diversity (variety of habitats, communities and ecological processes in a region).

What is an ecological 'biodiversity hotspot' and its two qualifying criteria?

A biogeographic region with exceptional biodiversity under threat. Criteria: it must contain at least 1,500 endemic vascular plant species AND have lost ≥70% of its original primary vegetation.

Differentiate in-situ and ex-situ conservation with examples.

In-situ conservation protects species in their natural habitats (national parks, wildlife sanctuaries, biosphere reserves). Ex-situ conservation protects species outside their habitats (zoos, botanical gardens, gene/seed banks, cryopreservation).

Differentiate alpha, beta and gamma diversity (Whittaker).

Alpha (α) diversity is species diversity within a single community/habitat; beta (β) diversity is the change in species composition between habitats along a gradient; gamma (γ) diversity is the total diversity over a large landscape/region.

What does the IUCN Red List 'Critically Endangered' category indicate?

That a species faces an extremely high risk of extinction in the wild in the immediate future; it is the highest-risk category before Extinct in the Wild and Extinct.

What is industrial ecology?

The study of material and energy flows through industrial systems, aiming to model them on natural ecosystems by closing material loops, minimizing waste, and treating one industry's waste as another's raw material.

What is industrial symbiosis / an eco-industrial park (e.g. Kalundborg)?

An arrangement where separate industries cooperate to exchange materials, energy, water and by-products so that waste from one becomes input for another, improving resource efficiency; Kalundborg, Denmark is the classic example.

What are the four ADME processes governing the fate of a toxicant in the body?

Absorption (entry into the bloodstream), Distribution (transport to tissues/organs), Metabolism/Biotransformation (chemical alteration), and Excretion (elimination, mainly via kidneys/urine, also bile, lungs, sweat).

Differentiate acute and chronic toxicity.

Acute toxicity results from a single or short-term high-dose exposure producing rapid effects (within hours to days); chronic toxicity results from repeated/continuous low-dose exposure over a long period (weeks to years), often with cumulative or delayed effects.

What is a bioassay?

A procedure that determines the concentration, potency or biological effect of a substance by measuring its effect on living organisms, tissues or cells under controlled conditions (e.g. LC50/LD50 determinations).

Define LD50 and LC50.

LD50 (median lethal dose) is the dose of a substance that kills 50% of a test population; LC50 (median lethal concentration) is the concentration in air or water that kills 50% of test organisms in a set time. Lower values mean higher toxicity.

What is the Threshold Limit Value (TLV)?

The maximum airborne concentration of a chemical substance to which nearly all workers may be repeatedly exposed (typically 8 hours/day, 40 hours/week) over a working lifetime without adverse health effects.

Define Margin of Safety (toxicology).

The ratio indicating the gap between a therapeutic/safe dose and a toxic dose; commonly Margin of Safety = LD1 / ED99, expressing how much dose can be increased before harm occurs. A larger margin means a safer substance.

What is the Therapeutic Index (TI) and how is it calculated?

A measure of drug safety: TI = LD50 / ED50 (median lethal dose divided by median effective dose). A higher therapeutic index indicates a wider safety margin between effective and toxic doses.

What is biotransformation, and name its two phases?

Biotransformation is the enzymatic chemical modification of a xenobiotic (mainly in the liver) into more water-soluble, excretable forms. Phase I: oxidation/reduction/hydrolysis (e.g. cytochrome P450). Phase II: conjugation (e.g. glucuronidation, sulfation) to aid excretion.

Name three major water-borne diseases and their causative agents.

Cholera (Vibrio cholerae), Typhoid (Salmonella typhi), and Hepatitis A (Hepatitis A virus); others include dysentery (Shigella/Entamoeba histolytica) and giardiasis (Giardia lamblia).

Give examples of air-borne microbial diseases and their pathogens.

Tuberculosis (Mycobacterium tuberculosis), Influenza (influenza virus), Measles (measles virus), Diphtheria (Corynebacterium diphtheriae), and fungal aspergillosis (Aspergillus spp.) — transmitted via airborne droplets/spores.

Define bioremediation and distinguish in-situ from ex-situ bioremediation.

Bioremediation is the use of living organisms (microbes, plants) to degrade, detoxify or remove environmental pollutants. In-situ treats contamination at the original site (e.g. bioventing, biosparging, bioaugmentation); ex-situ removes contaminated material for treatment elsewhere (e.g. landfarming, composting, bioreactors, biopiles).

Name the main types of phytoremediation.

Phytoextraction (plant uptake/accumulation of contaminants in shoots), phytostabilization (immobilizing contaminants in soil/roots), phytodegradation (breakdown within plant), rhizodegradation/rhizofiltration (degradation/uptake in root zone), and phytovolatilization (release of volatile forms).

What is a bioindicator? Give examples.

A bioindicator is an organism (or species/group) whose presence, absence, abundance or condition reveals environmental quality or pollution levels. Examples: lichens (air/SO2 pollution), mayfly/stonefly larvae (clean water), frogs (ecosystem health), and E. coli (faecal water contamination).

What are biofertilizers? Give examples.

Biofertilizers are preparations of living microorganisms that enrich soil fertility by fixing atmospheric nitrogen, solubilizing phosphorus, or producing growth substances. Examples: Rhizobium (legume symbiont), Azotobacter and Azospirilum (free-living N-fixers), Cyanobacteria/Anabaena-Azolla, and mycorrhizae (P uptake).

What are biofuels, and distinguish first- and second-generation biofuels?

Biofuels are fuels derived from biomass. First-generation come from food crops (e.g. bioethanol from sugarcane/corn, biodiesel from edible oils); second-generation come from non-food lignocellulosic biomass and agricultural/forest residues, avoiding the food-versus-fuel conflict.

What is a biosensor and what are its two essential components?

A biosensor is an analytical device that detects a chemical/biological analyte by combining a biological recognition element with a transducer. Components: (1) bioreceptor (enzyme, antibody, DNA, cell or microbe) for specificity, and (2) transducer (electrochemical, optical, thermal, piezoelectric) that converts the biological response into a measurable signal.