Biology Test Biology Marine Biology & Aquatic Ecosystems 1 — Questions and Answers
Question 1: Which zone of the ocean receives enough sunlight to support photosynthesis?
- Abyssal zone
- Benthic zone
- Aphotic zone
- Photic (euphotic) zone (Correct answer)
Correct answer: Photic (euphotic) zone
The photic (euphotic) zone extends to about 200 meters depth where sufficient light penetrates for photosynthesis.
Question 2: What are the primary producers in most open-ocean (pelagic) ecosystems?
- Kelp forests
- Phytoplankton (Correct answer)
- Zooplankton
- Coral polyps
Correct answer: Phytoplankton
Phytoplankton are microscopic photosynthetic organisms that form the base of the oceanic food web.
Question 3: Coral reefs are built primarily by:
- Calcareous algae alone
- Colonial cnidarians secreting calcium carbonate skeletons (Correct answer)
- Sponges depositing silica
- Mollusks forming limestone beds
Correct answer: Colonial cnidarians secreting calcium carbonate skeletons
Reef-building (hermatypic) corals are colonial cnidarians that secrete calcium carbonate (aragonite) exoskeletons.
Question 4: Coral bleaching occurs when corals expel their symbiotic algae (zooxanthellae) due to:
- Excess nutrients
- Low salinity
- Elevated water temperatures and stress (Correct answer)
- Reduced wave action
Correct answer: Elevated water temperatures and stress
Thermal stress causes corals to expel zooxanthellae, losing their color and primary food source, leading to bleaching and potential death.
Question 5: Which physical factor most strongly stratifies the ocean into distinct layers?
- Water pressure
- Temperature and salinity differences (creating density gradients) (Correct answer)
- Current direction
- Dissolved oxygen levels
Correct answer: Temperature and salinity differences (creating density gradients)
Differences in temperature and salinity create density gradients that stratify the ocean into the epipelagic, mesopelagic, and deeper zones.
Question 6: Estuaries are highly productive ecosystems because they receive nutrients from:
- Deep ocean upwelling only
- Both freshwater runoff (rivers) and tidal marine input (Correct answer)
- Volcanic vents
- Offshore kelp beds
Correct answer: Both freshwater runoff (rivers) and tidal marine input
Estuaries sit at the junction of rivers and the sea, receiving continuous nutrient input from both terrestrial runoff and tidal flushing.
Biology Test Biology Marine Biology & Aquatic Ecosystems 1
Which zone of the ocean receives enough sunlight to support photosynthesis?