IGCSE Marine Science

Overview

For parents: Original GCSE/IGCSE-level practice with worked answers and hints. No exam board selection is needed; these are shared practice questions, not official papers or a complete board-specific syllabus.

Topics

Marine Science key terms

Original definitions for core course vocabulary, informed by the references below. Not an official or exhaustive board-specific glossary.

40 of 40 terms

Salinity

A measure of the amount of dissolved salts in water, commonly expressed in parts per thousand at this level.

Seawater and ocean processes

Seawater density

The mass per unit volume of seawater, influenced by temperature, salinity and pressure.

Seawater and ocean processes

Ocean current

A sustained movement of seawater in a particular direction.

Seawater and ocean processes

Tide

A regular rise and fall in sea level caused mainly by the gravitational effects of the Moon and Sun.

Seawater and ocean processes

Tidal range

The vertical difference between high tide and the following or preceding low tide.

Seawater and ocean processes

Spring tide

A tide with a relatively large tidal range, occurring around new and full moons when solar and lunar tidal effects reinforce one another.

Seawater and ocean processes

Neap tide

A tide with a relatively small tidal range, occurring near first and third quarter moons when solar and lunar tidal effects partly oppose one another.

Seawater and ocean processes

Upwelling

The movement of deeper water towards the surface, often bringing nutrients into sunlit water.

Seawater and ocean processes

Wave erosion

The wearing away and removal of coastal material by wave action.

Seawater and ocean processes

Sedimentation

The settling and accumulation of suspended particles when water can no longer keep them in suspension.

Seawater and ocean processes

Plankton

Organisms that drift in water and cannot consistently swim against the prevailing currents.

Marine organisms and adaptations

Phytoplankton

Photosynthetic plankton, including microscopic algae and cyanobacteria.

Marine organisms and adaptations

Zooplankton

Animal plankton and other non-photosynthetic drifting consumers that feed on organisms or organic matter.

Marine organisms and adaptations

Nekton

Aquatic animals that can swim actively enough to move independently of prevailing currents.

Marine organisms and adaptations

Benthos

Organisms that live on, in or closely associated with the seabed.

Marine organisms and adaptations

Adaptation

An inherited feature that improves an organism's ability to survive and reproduce in its environment.

Marine organisms and adaptations

Osmoregulation

The control of water and dissolved solute concentrations within an organism.

Marine organisms and adaptations

Gills

Respiratory surfaces adapted for gas exchange between an aquatic organism and the surrounding water.

Marine organisms and adaptations

Countershading

A colour pattern with a darker upper surface and lighter underside that can reduce an animal's visibility to predators or prey.

Marine organisms and adaptations

Symbiosis

A close, persistent association between organisms of different species; the partners may benefit, be unaffected or be harmed.

Marine organisms and adaptations

Habitat

The place where an organism lives, providing the conditions and resources it needs.

Marine habitats and food webs

Intertidal zone

The coastal area between high-tide and low-tide levels, alternately exposed to air and covered by seawater.

Marine habitats and food webs

Estuary

A coastal area where river water mixes with seawater, often creating variable salinity.

Marine habitats and food webs

Mangrove

A salt-tolerant tree or shrub living in tropical or subtropical intertidal habitats, or the coastal community dominated by these plants.

Marine habitats and food webs

Seagrass meadow

An underwater habitat dominated by marine flowering plants rooted in shallow seabed sediments.

Marine habitats and food webs

Coral reef

A marine structure built largely from calcium carbonate deposited by reef-building corals and other organisms.

Marine habitats and food webs

Producer

An organism that makes organic substances from inorganic materials, usually using light energy in marine ecosystems.

Marine habitats and food webs

Trophic level

An organism's feeding position in a food chain or food web.

Marine habitats and food webs

Food web

A network of linked food chains showing feeding relationships and routes of energy transfer in a community.

Marine habitats and food webs

Decomposer

An organism, such as a bacterium or fungus, that breaks down dead organic material and releases nutrients.

Marine habitats and food webs

Overfishing

Catching fish faster than populations can replace themselves through reproduction and growth.

Human impacts and conservation

Bycatch

Organisms caught unintentionally while fishing for a different target species.

Human impacts and conservation

Aquaculture

The farming of aquatic organisms under managed conditions, including fish, shellfish and seaweeds.

Human impacts and conservation

Sustainable fishery

A fishery managed to maintain productive fish populations and limit damage to the wider ecosystem over the long term.

Human impacts and conservation

Marine protected area

A defined marine area managed through legal or other effective measures to conserve nature.

Human impacts and conservation

Eutrophication

Nutrient enrichment of water that can promote algal growth and lead to oxygen depletion when organic matter decomposes.

Human impacts and conservation

Bioaccumulation

The build-up of a substance within an organism when uptake exceeds its removal or breakdown.

Human impacts and conservation

Biomagnification

An increase in the concentration of a persistent substance in organisms at successively higher trophic levels.

Human impacts and conservation

Ocean acidification

A decrease in seawater pH caused mainly by the absorption of atmospheric carbon dioxide and its reactions with water.

Human impacts and conservation

Coral bleaching

The paling of corals caused by loss of their symbiotic algae or algal pigments, often in response to heat stress.

Human impacts and conservation

Exams

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Revision

Tell GCSE.es which Marine Science topics feel weak. Your dashboard then picks a short, timed next step — learn the key idea, check yourself, review mistakes.

Practice

• ✓ Key terms you tap to reveal
• ✓ Quick multiple-choice quizzes
• ✓ 3, 6, 9 and 12-mark exam-style questions
• ✓ Marking with feedback and a model answer

Available free inside your IGCSE journey. Questions are written by GCSE.es, not taken from real past papers.

Resources

Short, focused tasks for the Marine Science topics you find hardest — learn the key idea, check yourself, then try a marked exam-style question.