covalent bond
chemical bond that involves the sharing of electron pairs between atoms
ionic bond
chemical bond that involves the attraction between oppositely charged ions
hydrogen bond
a weak bond between two molecules due to the electrostatic attraction between a hydrogen atom in one molecule and an atom of oxygen, nitrogen or fluorine in the other molecule
halocline
a layer of water below the mixed surface layer where a rapid change in salinity can be measured as depth increases
thermocline
a layer between two layers of water with different temperatures
gradient
the rate of change in the y-axis value as the x-axis value increases
thermal insulator
a substance which reduces the rate of transfer of thermal energy
pycnocline
a layer of water between two layers of water with different densities
earthquake
a sudden release of energy inside the Earth that creates seismic waves
mid-ocean ridge
a mountain range with a central valley on an ocean floor at the boundary between two diverging tectonic plates, where new crust forms from upwelling magma
divergent boundary
where two tectonic plates are moving away from each other
convergent boundary
when two or more tectonic plates come together
subduction
the process where one lithospheric plate slides past below another at a convergent plate boundary
trench
a long, narrow and deep depression on the ocean floor with relatively steep sides
volcano
a mountain or hill with a crater or vent through which lava, rock fragments, hot vapour and gas are being forced from the Earth's crust
tsunami
a seismic sea wave created by an underwater earthquake or volcanic event
hydrothermal vent
an area where cold ocean water that has seeped into the Earth's crust is superheated by an underlying magma and forced through the vents in the ocean floor
transform boundary
when two plate are moving in an antiparallel direction, creating friction between them
abyssal plain
a flat, sandy region of the ocean floor found between trenches and the continental rise
semi-diurnal
occurring twice daily
diurnal
occurring daily
coriolis effect
a force that results from the Earth's rotation that causes objects or particles in motion to deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere
thermohaline circulation
large-scale ocean circulation caused by density differences due to temperature and salinity changes in the world's ocean
downwelling
the downward movement of water in the sea due to density differences
community
all the different populations interacting in one habitat at the same time
competition
a relationship between two organisms where both species are negatively is affected as they are trying to use the same resource
food chain
a way to describe the feeding relationships between organisms
decomposers
bacteria and fungi which break down dead organic matter and release the nutrients back into the environment
food web
a way to show all the different feeding relationships in an ecosystem
trophic level
the position on organism occupies in the food chain or web
apex predator
an organism at the end of the food chain which has no natural predators
respiration
the process by which all living things release energy from their food by oxidising glucose
eutrophication
the process by which a body of water becomes enriched in dissolved nutrients that stimulate the growth of producers, usually resulting in the depletion of dissolved oxygen
marine snow
particles of organic material that fall from surface layers to the deeper ocean