TOEFL · Natural Sciences · Advanced

• metabolism

  n. the chemical processes that keep an organism alive

  A fast metabolism burns energy quickly.

• symbiosis

  n. a close relationship between two species

  The clownfish lives in symbiosis with the anemone.

• mutation

  n. a permanent change in genetic material

  A random mutation gave the moth a darker color.

• catalyst

  n. a substance that speeds a reaction without changing

  A catalyst lowers the energy needed for a reaction.

• equilibrium

  n. a state of balance between opposing forces

  The reaction reached chemical equilibrium.

• oxidation

  n. a reaction in which a substance loses electrons

  Rust forms through the oxidation of iron.

• synthesis

  n. the combining of parts into a whole

  The synthesis of the drug took many steps.

• isotope

  n. a form of an element with a different mass

  Carbon has a radioactive isotope.

• viscosity

  n. the thickness or resistance of a fluid

  Honey has a higher viscosity than water.

• buoyancy

  n. the upward force a fluid exerts on an object

  Buoyancy keeps the ship afloat.

• inertia

  n. the tendency of an object to resist motion change

  Inertia keeps the ball rolling forward.

• momentum

  n. the quantity of motion of a moving body

  The heavy truck had great momentum.

• torque

  n. a force that causes rotation

  The wrench applies torque to the bolt.

• entropy

  n. a measure of disorder in a system

  Entropy tends to increase over time.

• photon

  n. a tiny particle of light

  A photon carries a packet of energy.

• neutron

  n. a particle in the nucleus with no charge

  A neutron has no electric charge.

• proton

  n. a positively charged particle in the nucleus

  The proton carries a positive charge.

• covalent

  adj. involving shared electrons between atoms

  Water has covalent bonds.

• ionic

  adj. involving charged atoms attracting each other

  Salt is held together by ionic bonds.

• quantum

  adj. relating to the smallest units of energy

  Quantum theory describes tiny particles.

• thermal

  adj. relating to heat

  Thermal energy flows from hot to cold.

• kinetic

  adj. relating to motion

  A moving car has kinetic energy.

• volatile

  adj. easily turning into vapor

  Gasoline is a volatile liquid.

• viscous

  adj. thick and sticky in texture

  The viscous lava moved slowly.

• porous

  adj. having tiny holes that let liquid through

  Porous rock absorbs rainwater.

• dormant

  adj. inactive but able to become active

  The volcano has been dormant for years.

• photosynthetic

  adj. able to make food using light

  Algae are photosynthetic organisms.

• terrestrial

  adj. relating to land or the Earth

  Terrestrial animals live on land.

• aquatic

  adj. living or growing in water

  Fish are aquatic creatures.

• nocturnal

  adj. active at night

  Owls are nocturnal hunters.

• metabolic

  adj. relating to the body's chemical processes

  Exercise raises the metabolic rate.

• cellular

  adj. relating to cells

  Cellular damage can cause disease.

• genome

  n. the complete set of genes in an organism

  Scientists mapped the human genome.

• protein

  n. a molecule that builds and repairs the body

  Muscles are made largely of protein.

• antibody

  n. a protein that fights specific germs

  An antibody attacks the invading virus.

• pathogen

  n. an organism that causes disease

  A pathogen can spread through dirty water.

• microbe

  n. a tiny living organism

  Useful microbes live in our gut.

• parasite

  n. an organism that lives off another

  A parasite feeds on its host.

• secrete

  v. to produce and release a substance

  Glands secrete useful chemicals.

• synthesize

  v. to make a substance by combining parts

  Plants synthesize sugar from carbon dioxide.

• diffuse

  v. to spread out evenly through a space

  The dye slowly diffused through the water.

• disperse

  v. to spread over a wide area

  The wind dispersed the seeds widely.

• oscillate

  v. to swing back and forth regularly

  The pendulum oscillates steadily.

• deteriorate

  v. to become gradually worse

  Coral reefs deteriorate in warm water.

• accumulate

  v. to gather and increase over time

  Plastic waste accumulates in the ocean.

• fluctuate

  v. to rise and fall irregularly

  Temperatures fluctuate during the day.

• permeate

  v. to spread throughout something

  Moisture permeates the porous soil.

• catalyze

  v. to speed up a chemical reaction

  Enzymes catalyze reactions in the body.

• replicate

  v. to copy or reproduce exactly

  DNA can replicate itself precisely.

• ferment

  v. to break down sugar without oxygen

  Yeast ferments sugar into alcohol.

• radiate

  v. to send out energy in all directions

  The hot stone radiates heat.

• sustain

  v. to keep something going over time

  Plants sustain life by making oxygen.

• deplete

  v. to use up a resource

  Overfishing depletes the fish supply.

• mitigate

  v. to make something less severe

  Forests help mitigate climate change.

• quantify

  v. to measure the amount of something

  Scientists quantify the carbon in the air.

• correlate

  v. to have a mutual relationship

  Pollution correlates with poor health.

• catalysis

  n. the speeding up of a reaction by a catalyst

  Catalysis makes the process efficient.

• solubility

  n. the ability of a substance to dissolve

  Sugar has a high solubility in water.

• conductivity

  n. the ability to transmit heat or electricity

  Copper has high electrical conductivity.

• luminosity

  n. the brightness of a star or object

  The star's luminosity is very high.

• nebula

  n. a cloud of gas and dust in space

  A new star formed inside the nebula.

• asteroid

  n. a small rocky body orbiting the Sun

  An asteroid passed close to Earth.

• comet

  n. an icy body that forms a glowing tail

  The comet appeared in the night sky.

• supernova

  n. the powerful explosion of a dying star

  The supernova lit up the galaxy.

• gravitation

  n. the force of attraction between masses

  Gravitation holds the planets in orbit.

• seismic

  adj. relating to earthquakes

  Seismic waves shook the city.

• tectonic

  adj. relating to the structure of Earth's crust

  Tectonic plates move very slowly.

• volcanic

  adj. relating to volcanoes

  Volcanic ash covered the village.

• geological

  adj. relating to the Earth's physical structure

  Geological surveys reveal hidden minerals.

• atmospheric

  adj. relating to the air around Earth

  Atmospheric pressure changes with altitude.

• ecological

  adj. relating to living things and environments

  The dam had a major ecological impact.

• biodiversity

  n. the variety of life in an area

  The reef supports rich biodiversity.

• sustainability

  n. the ability to last without harming nature

  Sustainability protects future resources.

• photovoltaic

  adj. converting light directly into electricity

  Photovoltaic cells power the satellite.

• respiratory

  adj. relating to breathing

  Smoke harms the respiratory system.

• cardiovascular

  adj. relating to the heart and blood vessels

  Exercise strengthens cardiovascular health.

• neural

  adj. relating to nerves or the brain

  Neural signals travel very fast.

• synaptic

  adj. relating to connections between nerve cells

  Learning strengthens synaptic links.

• hereditary

  adj. passed from parents to offspring

  Some diseases are hereditary.

• recessive

  adj. a trait shown only with two copies

  Blue eyes come from a recessive gene.

• dominant

  adj. a trait that appears with one copy

  Brown eyes are a dominant trait.

• microorganism

  n. a microscopic living thing

  A microorganism can survive in extreme heat.

• ozone

  n. a gas layer that blocks harmful rays

  The ozone layer shields us from radiation.

• precipitation

  n. rain, snow, or hail that falls from clouds

  Heavy precipitation flooded the fields.

• condensation

  n. the change of vapor into liquid

  Condensation formed on the window.

• combustion

  n. the process of burning

  Combustion of fuel releases energy.

• fusion

  n. the joining of atomic nuclei

  The Sun produces energy by fusion.

• fission

  n. the splitting of an atomic nucleus

  Nuclear fission powers some reactors.

• gradient

  n. a gradual change in a measured value

  A steep gradient drives the water flow.

• threshold

  n. the level at which something begins

  The sound passed the hearing threshold.

• catalogue

  v. to record items in an ordered list

  Scientists catalogue every new species.

• extract

  v. to remove or take out a substance

  They extract oil from the seeds.

• filter

  v. to remove unwanted parts from a liquid

  The plant filters dirty water.

• calibrate

  v. to adjust an instrument for accuracy

  The team calibrates the sensor daily.

• simulate

  v. to imitate a process for study

  Computers simulate the planet's climate.

• verify

  v. to check that something is true

  They verify the result with a second test.

• derive

  v. to obtain something from a source

  Energy is derived from sunlight.

• constitute

  v. to make up or form something

  Water molecules constitute most of a cell.

• phenomenon

  n. an observable event or fact

  The aurora is a beautiful natural phenomenon.

• homeostasis

  n. the keeping of a stable internal state

  The body uses homeostasis to control temperature.

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