Coral Bleaching & Acidification

Question 1

Which short explanation correctly describes both how higher water temperature makes corals turn white and how increased carbon dioxide in the ocean hurts their skeletons?

Accepted Answer

When water gets too warm, coral polyps become stressed and push out the zooxanthellae that give them color, so they turn white. At the same time, the extra CO₂ turns into carbonic acid, which lowers the seawater’s pH and slowly melts the calcium‑carbonate skeletons.

Answer

Higher water temperature makes zooxanthellae multiply, giving corals brighter colors, while CO₂ makes the water more basic, helping the skeleton grow faster.

Answer

Warm water causes corals to release oxygen, which turns them white, and the CO₂ reacts with salt to create a protective coating on the skeleton.

Answer

When the ocean warms, corals eat more zooxanthellae for energy, but the CO₂ only changes the water’s temperature, not its chemistry.

Question 2

Which paragraph most accurately explains both why a coral reef becomes white during a hot summer and how rising carbon dioxide in the ocean weakens the reef's skeleton?

Accepted Answer

When water gets too warm, the coral polyps become stressed and force the tiny photosynthetic algae living inside them to leave, so the coral looks white. At the same time, extra CO₂ dissolves in seawater, turning it into carbonic acid, which lowers the pH and causes the calcium‑carbonate skeleton to dissolve.

Answer

Warmer water causes corals to grow more algae, which darkens their color. Increased CO₂ adds minerals that harden the skeleton, protecting it from damage.

Answer

When the temperature rises, corals release extra oxygen that bleaches them white. Higher CO₂ levels raise the water's pH, making the skeleton stronger.

Answer

Heat makes the algae inside corals die, so the coral loses its color. More CO₂ makes the ocean colder, which causes the calcium‑carbonate skeleton to crack.

Question 3

Which brief statement best explains both why a rise in sea temperature makes corals turn white and how increasing carbon dioxide weakens their calcium‑carbonate skeletons?

Accepted Answer

Higher water temperature stresses coral polyps, causing them to expel their zooxanthellae, which makes the coral look white; at the same time, more CO₂ dissolves in seawater, forming carbonic acid that lowers pH and slowly dissolves the calcium‑carbonate skeleton.

Answer

Warmer water makes the zooxanthellae grow faster, turning the coral white, and the extra CO₂ makes the water more alkaline, which strengthens the coral skeleton.

Answer

Heat causes corals to release their zooxanthellae, so they lose color, and the CO₂ reacts with the skeleton directly, turning calcium carbonate into a harmless gas.

Answer

When water gets warm, corals die instantly and lose their skeleton, while CO₂ removes all the oxygen from the water, making it impossible for any marine life to survive.

Try three questions

Which short explanation correctly describes both how higher water temperature makes corals turn white and how increased carbon dioxide in the ocean hurts their skeletons?

Which paragraph most accurately explains both why a coral reef becomes white during a hot summer and how rising carbon dioxide in the ocean weakens the reef's skeleton?

Which brief statement best explains both why a rise in sea temperature makes corals turn white and how increasing carbon dioxide weakens their calcium‑carbonate skeletons?

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