Deck 14: Benthic Communities

Question 1

Desiccation is a threat to organisms living in ____.

A)seafloor vent communities
B)the pelagic zone
C)the intertidal zone
D)the disphotic zone

Answer 1

C

Question 2

____ are vascular plants that are successful in low, muddy coasts in tropical and semitropical areas.

A)Mangroves
B)Ahermatypic corals
C)Kelp
D)Diatoms

Answer 2

A

Question 3

Because seaweeds don't need to transport water up from their base, ____.

A)they lack many of the structures common in terrestrial vascular plants
B)vessels circulate water around the rest of the organism instead
C)the roots are instead dedicated to gathering nutrients and carbon dioxide
D)they actually grow upside down

Answer 3

A

Question 4

Which of these statements is FALSE concerning estuaries?

A)Larvae are often abundant there.
B)Estuaries are in danger of development and pollution.
C)Very few autotrophs live in estuaries, but many animals can be found there.
D)Estuaries are places where saltwater and fresh water meet.

Question 5

A ring-shaped island of coral reefs and coral debris enclosing, or almost enclosing, a shallow lagoon from which no land protrudes is known as a(n)____.

A)open reef
B)barrier reef
C)fringing reef
D)atoll

Question 6

The most common pattern for benthic organism distributions is ____.

A)clumped distribution
B)linear distribution
C)random distribution
D)uniform distribution

Question 7

Why can red algae grow at greater depths than most other photosynthetic organisms?

A)Their accessory pigments absorb enough light to thrive in dim light.
B)They are adapted to live at greater pressures.
C)They grow to be extremely long, and can reach into the euphotic zone.
D)They are partly heterotrophic, obtaining energy from captured zooplankton.

Question 8

Ahermatypic corals ____.

A)are found in shallow waters in the tropics
B)have symbiotic algae
C)are found in deep water
D)are actually plants

Question 9

Animals that are attached to the bottom are called ____.

A)sessile
B)benthic motile
C)infaunal
D)interstitial

Question 10

Why are organisms in rocky intertidal zones sorted into horizontal bands?

A)crashing waves remove weaker ones close to the water line
B)some float and are carried upward at high tide
C)some can better tolerate drying out between high tides
D)some need to stay out of the water to breathe

Question 11

Primary productivity in estuaries is high because ____.

A)light is seasonal and dim
B)nutrients are abundant
C)there is no saltwater
D)there are no primary consumers

Question 12

The most important physical factor for intertidal communities is ____.

A)lack of light
B)high salinity
C)lack of nutrients
D)the rise and fall of the tides

Question 13

Algae are classified by ____.

A)how they photosynthesize
B)their location in the intertidal zone
C)the color of their accessory pigments
D)what they feed on

Question 14

A fringing reef ____.

A)forms near the coastline of an island
B)has a deep lagoon that separates the reef from the island
C)is ring-shaped and is not associated with an island
D)is composed of a series of linear segments extending radially from an island

Question 15

Perhaps the most difficult oceanic habitat is/are ____.

A)the abyssal zone
B)intertidal coarse sand and cobble beaches
C)intertidal rocky shores
D)the epipelagic zone

Question 16

Seaweeds are ____.

A)vascular plants
B)unicellular algae
C)muticellular algae
D)phytoplankton

Question 17

Benthic organisms live ____.

A)on or associated with the bottom
B)suspended in the water column
C)by drifting through the water, unable to swim against currents
D)near the water's surface

Question 18

The root-shaped jumble at the base of a seaweed is called a(n)____.

A)holdfast
B)blade
C)stamen
D)aerenchyma

Question 19

Nutrients in coral reefs are ____.

A)extremely limited, which is why productivity lower than the deep ocean
B)so plentiful that there is no limit to phytoplankton growth
C)largely trapped below the pycnocline
D)recycled efficiently because the water is shallow

Question 20

An individual coral animal is called a ____.

A)polyp
B)rhodophyte
C)phaeophyte
D)stipe

Question 21

The rising concentration of carbon dioxide in the atmosphere threatens corals because it lowers ocean pH and decreases the availability of carbonate ions.

Question 22

Which list provides the stages of evolution of coral reefs around volcanic islands in the correct order?

A)atoll, fringing reef, barrier reef
B)fringing reef, barrier reef, atoll
C)barrier reef, fringing reef, atoll
D)fringing reef, atoll, barrier reef

Question 23

Hermatypic corals live in warm, well-lit water.

Question 24

Coral reefs are typically home to ____.

A)a large number of species
B)mostly one dominant species
C)autotrophs only
D)chemosynthetic microbes

Question 25

Hydrothermal vents that support biological communities exist because of primary productivity in the form of chemosynthesis.

Question 26

Mangrove trees have distinctive roots that trap and hold sediment.

Question 27

An estuary is where rivers meet the ocean and where freshwater and seawater mix.

Question 28

Which organism forms colonies of individuals living within a connected framework of skeletons?

A)kelp
B)diatoms
C)corals
D)krill

Question 29

Because of the harsh contrast in salinity, estuaries are among the last productive of marine habitats.

Question 30

What do scientists think might form the "stepping stones" that would enable organisms to disperse from one seafloor vent to another?

A)high spots on the seafloor that extend into the photic zone
B)whale carcasses
C)coral reefs
D)large fish that swim from vent to vent

Question 31

Tube worms at seafloor vents get their energy by ____.

A)catching small organisms for food
B)absorbing the thermal energy of the heated water from the vent
C)hosting chemosynthetic bacteria
D)performing photosynthesis

Question 32

Deep sea vent communities depend on specialized photoautotrophs that extract the exceedingly dim light that filters down to that depth.

Question 33

Which of the following statements is FALSE concerning hydrothermal vents?

A)They are typically found in shallow waters near subduction zones.
B)Certain animals are found at hydrothermal vents such as tube worms.
C)Hydrothermal vents are typically found associated with spreading centers.
D)Vent waters cool as they are released from the vent.

Question 34

Life in productive tropical reefs is best characterized by ____.

A)extreme competition for food, living space, and mates
B)very few species, but large numbers of each species
C)very little competition due to the abundance of resources
D)mostly symbiotic relationships

Question 35

Which of the following is FALSE with regard to seafloor communities?

A)Many deep sea organisms have fragile bodies.
B)Phytoplankton thrive.
C)Chemoautotropic bacteria are common at hydrothermal vents.
D)Gigantism is a common characteristic of deep sea organisms.

Question 36

Species abundance and diversity is generally higher on the deep ocean floor than in the part of the water column immediately above it.

Question 37

The coral reef community ____.

A)is made up exclusively of various species of coral polyps
B)is limited to carnivorous animals
C)lies only within the kelp forest habitat of the tropics
D)is a highly productive and diverse collection of organisms in shallow water environments

Question 38

Individuals of representative families in deep water often tend to be much smaller than related individuals in the shallow ocean.

Question 39

The symbiotic dinoflagellates that live in the tissues of coral polyps ____.

A)provide carbon dioxide and phosphates for the polyps
B)feed on the tissues of the polyps and are dangerous parasites
C)are the main cause of coral bleaching, and are threatening the reefs of the world
D)provide additional nourishment and oxygen to the polyps through photosynthesis

Question 40

Tropical coral reefs typically form in areas of high wave energy.

Question 41

Hydrothermal vents support a community of organisms including pogonophorans, clams, crabs, and worms, just to name a few. But hydrothermal vents are found in the deep-sea far from the photic zone. If no light reaches hydrothermal vents, what is the basis of the primary productivity that supports the community?

Question 42

Describe Darwin's hypothesis for atoll formation around volcanic islands.

Question 43

What are some factors that make life difficult on the deep ocean floor?

Question 44

The intertidal zone represents one of the most stressful environments in terms of changing environmental conditions. Explain this comment using specific examples of stresses and how organisms are able to survive in the intertidal zone.

Question 45

Explain why salt marshes and estuaries are among the most productive of marine habitats.