Chapter 20 Section 2 Handout Life in the Oceans

1 What two major factors do marine organisms depend on for their survival? essential nutrients in ocean water and sunlight.

2 Describe the chemistry of the ocean. a balance of dissolved gases and solids.

3 How do marine organisms help maintain the chemical balance of ocean water? They remove nutrients and gases and return other nutrients and gasses to the ocean.

4 What are three elements absorbed by marine plants? carbon hydrogen oxygen sulfur nitrogen phosphorus silicon

5 What is one way photosynthetic marine plants return oxygen to the ocean? They remove carbon dioxide and produce oxygen

6 One way nutrients return to the surface is through a process called _______. recycling.

7 How do bacteria help release essential nutrients into the ocean? They digest the remains of dead organisms and release nutrients.

8 Where do organisms in the ocean consume all the elements necessary for life? near the surface of the ocean

9 What happens to elements necessary for life when ocean organisms die? sink and decay and released back into the ocean water.

10 Where are nutrients stored in the ocean? Deep water

11 What must happen to nutrients stored in deep water before they can be used by most organisms in the ocean? they must return to the surface before most organisms can use them

12 What is one way nutrients stored in deep water return to the surface? upwelling

13 What happens when wind blows steadily parallel to a coastline? Surface water moves farther offshore and is replaced by deep cold water.

14 In what part of the ocean do most marine organisms live? The upper 100 meters of water

15 The mass of mosly microscopic organisms that float or drift freely in the waters of aquatic environments are called _______. plankton

16 How do plankton form the base of food webs in the ocean? Plankton are consumed by small organisms which become food for larger organisms.

17 Organisms such as dolphins and squid, that swim actively in open water, are called ________. nekton.

18 Organisms that live at the bottom of oceans or bodies of fresh water are called ________. benthos.

The End