Diving Into Ocean Ecosystems

In aquatic ecosystems, phytoplankton and other photosynthetic organisms appear in the upper layers of the water,but not deeper layers. Which statement explains this distribution?

• The deeper layers are too cold for photosynthesis to occur.

• The deeper layers have too little oxygen for photosynthetic organisms to survive.

• The deeper layers have too much carbon dioxide for photosynthetic organisms to survive.

• The deeper layers do not receive sunlight which is necessary for photosynthesis to occur.

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A team of deep-sea divers and biologists is exploring the open ocean. As team members dive downward from the surface, they observe significant changes to the ocean community at a depth of about 200 meters. What is the main cause of the changes at this depth?

• loss of brightness of the water

• increasing salinity of the water

• increasing temperature of the water

• decreased oxygen concentration of the water

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NGSS.MS-LS2-3

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Carrie is conducting an experiment on a solution. The solution’s initial pH is 3.2. Then, as Carrie gradually adds Compound X into the solution, the pH increases to 9.8. Which is the most likely identity of Compound X?

• a strong acid, such as hydrochloric acid (HCL)

• a strong base, such as sodium hydroxide (NaOH)

• a salt, such as sodium chloride (NaCl)

• a solvent, such as water (H20)

Jill made the table below during her research on aquatic zones and living organisms.

• Organisms in the intertidal zone must be able to withstand very cold water.

• There are no producers in the benthic zone that rely on photosynthesis.

• Organisms in the benthic zone must be able to tolerate large amounts of oxygen.

• The warm water and abundant sunlight in the neritic zone limits the plankton population.

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Ocean acidification begins with 

• pollution from ships
• carbon dioxide released from combustion
• dumping of waste from cities into the ocean

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Marine organisms make their shells from calcium and

• chloride
• carbonate
• seawater

An example of a marine organism that needs calcium carbonate 

• a crab
• a shark
• an octopus

What happens to 1/4 of the greenhouse gases in the atmosphere?

• It is released into space.

• It gets absorbed by the ocean.

As the ocean becomes more acidic, the pH of the water

• increases
• decreases

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What do some marine creatures do with the carbonate ion?

• use it as a food source

• use it as a defense mechanism

• use it to build shells and exoskeletons

• use it to cool body temperatures