Unique Nature of Pure Water
What is the chemical formula for water?
H₂O
What is the average salinity of ocean water?
35 parts per thousand (ppt)
What is the most common dissolved salt in seawater?
Sodium chloride
What gas causes ocean acidification when it dissolves into seawater?
Carbon dioxide (CO₂)
What is the first ocean layer, also called the Sunlight Zone?
Epipelagic Zone
What type of bond holds hydrogen and oxygen together within a water molecule?
Covalent bond
What happens to ocean water temperature as depth increases?
It generally decreases.
What dissolved gas do fish need to survive?
Oxygen
What process converts carbon dioxide into glucose?
Photosynthesis
What ocean layer is called the Twilight Zone and extends from 200 to 1,000 meters?
Mesopelagic Zone
What property allows water molecules to stick to each other?
Cohesion
What happens to ocean pressure as depth increases?
It increases.
What is the normal pH range of ocean water given in the notes?
8.0–8.3
What happens to ocean pH during ocean acidification?
It decreases, making the ocean less alkaline.
What ocean layer is called the Midnight Zone and contains animals that produce their own light?
Bathypelagic Zone
Why does ice float on liquid water?
Ice is less dense than liquid water.
How does evaporation affect seawater salinity?
It increases salinity because water evaporates, but salt stays behind.
What process allows marine plants to use carbon dioxide to make glucose?
Photosynthesis
Why does ocean acidification make it harder for oysters and other shell-building organisms to survive?
It reduces carbonate ions, making it harder to build shells.
What is the name and depth range of the Lower Midnight Zone?
Abyssopelagic Zone, 4,000–6,000 meters
How does water's high specific heat help regulate Earth's climate?
Water absorbs and releases large amounts of heat without changing temperature quickly.
How do temperature and salinity affect seawater density?
Colder, saltier water is generally denser than warmer, less salty water.
Why do marine organisms need carbonate ions?
To build and maintain their shells and skeletons.
How do photosynthesis and respiration move carbon through the ocean food chain?
Photosynthesis uses CO₂ to make organic compounds, while respiration breaks them down and releases CO₂ again.
Why are most animals in the Hadalpelagic Zone unable to see, and what is its depth range?
It is completely dark because sunlight cannot reach it, and it extends from 6,000–11,000 meters.