PADI Marine Biology & Conservation 3 — Questions and Answers
Question 1: What is the function of the lateral line system found in most bony fish?
- It regulates buoyancy by sensing water pressure
- It detects vibrations and water movement changes (Correct answer)
- It filters oxygen from water
- It controls coloration for camouflage
Correct answer: It detects vibrations and water movement changes
The lateral line is a sensory system of hair cells that detects low-frequency vibrations and pressure changes in surrounding water, aiding navigation and predator/prey detection.
Question 2: Sea turtles are known to return to the same beach where they were born to nest. What is this behavior called?
- Migration
- Natal homing (Correct answer)
- Philopatry
- Imprinting
Correct answer: Natal homing
Natal homing is the instinctive behavior of sea turtles returning to their birth beach to lay eggs, guided by Earth's magnetic field imprinted at hatching.
Question 3: Which process describes how nutrients cycle from dead organic matter back into the marine food web?
- Photosynthesis
- Decomposition by bacteria and fungi (Correct answer)
- Predation
- Upwelling
Correct answer: Decomposition by bacteria and fungi
Decomposition by bacteria and fungi breaks down dead organic matter, releasing nutrients such as nitrogen and phosphorus back into the water for use by phytoplankton.
Question 4: What term describes zones in the ocean that receive no sunlight and rely on chemosynthesis rather than photosynthesis for energy?
- Photic zones
- Mesopelagic zones
- Hydrothermal vent communities (Correct answer)
- Abyssopelagic zones
Correct answer: Hydrothermal vent communities
Hydrothermal vent communities thrive in total darkness using chemosynthetic bacteria that convert hydrogen sulfide from vents into organic compounds as an energy source.
Question 5: Which factor most directly causes seasonal 'dead zones' in coastal waters?
- Overfishing of apex predators
- Nutrient runoff causing algal blooms and hypoxia (Correct answer)
- Coral bleaching events
- Ocean acidification lowering pH
Correct answer: Nutrient runoff causing algal blooms and hypoxia
Agricultural nutrient runoff triggers massive algal blooms; when the algae decompose, bacteria consume oxygen, creating hypoxic dead zones where most marine life cannot survive.
Question 6: A diver encounters a school of fish that suddenly all turn in the same direction simultaneously. What is this coordinated behavior called?
- Herding
- Flocking
- Shoaling and schooling (Correct answer)
- Swarming
Correct answer: Shoaling and schooling
Shoaling refers to fish grouping together socially, while schooling describes synchronized, polarized movement, both offering predator confusion and hydrodynamic benefits.
Question 7: What is the primary purpose of a Marine Protected Area (MPA)?
- To provide exclusive fishing rights to local communities
- To conserve marine biodiversity by restricting human activities in designated areas (Correct answer)
- To create underwater tourism destinations
- To test new fishing technologies
Correct answer: To conserve marine biodiversity by restricting human activities in designated areas
MPAs are designated ocean areas where human activities are regulated or restricted to protect marine biodiversity, habitats, and ecosystem services.
PADI Marine Biology & Conservation 3
What is the function of the lateral line system found in most bony fish?