Free marine science check

Check your understanding of ocean systems.

Explore seawater, tides, marine food webs, habitats, circulation, climate links, and conservation. You will receive an indicative MS1-MS4 result.

7 min: Typical time
12: Questions
MS1-MS4: Level range

Question 1 of 12 0 answered

1 Ocean basics

Approximately what portion of Earths surface is covered by ocean?

A About 10 percent B About 30 percent C About 71 percent D Exactly 100 percent

2 Tides

What is the main cause of ocean tides?

A Gravitational attraction, especially from the Moon and also the Sun B Only underwater volcanoes C Daily changes in salinity D Fish migration

3 Primary producers

Which organisms contribute a large share of marine photosynthesis?

A Phytoplankton B Sharks C Sea stars D Whales

4 Salinity

What does salinity measure?

A The amount of dissolved salts in water B Only water temperature C The depth of a beach D The speed of a fish

5 Habitats

What is an estuary?

A A place where river freshwater mixes with seawater B The deepest point of every ocean C A permanently frozen desert D A coral skeleton only

6 Coral reefs

Corals that build tropical reefs are best described as what?

A Animals often living with photosynthetic symbionts B Rocks that grow without organisms C Marine flowering plants D Types of fungi only

7 Food webs

If a major phytoplankton population declines, what may happen?

A Consumers throughout the connected food web may lose an energy source B Every predator gains unlimited food C Salinity becomes zero immediately D Tides permanently stop

8 Circulation

What helps drive deep thermohaline circulation?

A Differences in seawater density caused by temperature and salinity B Only coastal traffic C The color of the seafloor D Sound waves from ships

9 Ocean zones

Why does photosynthesis decrease with ocean depth?

A Less sunlight penetrates to deeper water B Deep water contains no molecules C Gravity disappears D All nutrients float away

10 Ocean change

How does added atmospheric carbon dioxide contribute to ocean acidification?

A Dissolved carbon dioxide forms carbonic acid and lowers pH B It removes all salt C It turns seawater into freshwater D It blocks the Moons gravity

11 Fisheries

What is overfishing?

A Removing fish faster than populations can replenish sustainably B Catching any fish at all C Measuring a fish population D Protecting nursery habitat

12 Conservation

Why can marine protected areas be useful?

A They can reduce selected pressures and protect habitats or life stages B They guarantee climate change stops globally C They eliminate the need for monitoring D They make all ocean uses identical

Before you begin

Use your own knowledge.

Choose one answer for every question.
Do not use calculators, compilers, search, or reference tools.
There is no timer, so read naturally.
You can retake the test as your skills improve.

This is an indicative self-assessment, not an accredited certificate or formal examination. It samples selected foundations and cannot measure every part of the subject.