PADI Marine Biology & Conservation 5 — Questions and Answers
Question 1: What is the ecological role of apex predators like sharks in a marine food web?
- They primarily consume phytoplankton and zooplankton
- They regulate prey populations and maintain ecosystem balance (Correct answer)
- They compete directly with filter feeders for resources
- They have no measurable impact on lower trophic levels
Correct answer: They regulate prey populations and maintain ecosystem balance
Apex predators control prey populations and prevent overgrazing of critical habitats; their removal triggers trophic cascades that destabilize entire ecosystems.
Question 2: Which structure in a bony fish controls its buoyancy by adjusting the volume of gas inside?
- Liver
- Lateral line
- Swim bladder (Correct answer)
- Gill rakers
Correct answer: Swim bladder
The swim bladder is an internal gas-filled organ that fish inflate or deflate to achieve neutral buoyancy at various depths without constant swimming effort.
Question 3: What is the 'bleaching threshold' of water temperature for most tropical coral reef systems?
- 2°C above average seasonal maximum
- 1°C above the average seasonal maximum sustained for several weeks (Correct answer)
- 5°C above the average seasonal maximum
- Any temperature above 30°C
Correct answer: 1°C above the average seasonal maximum sustained for several weeks
Coral bleaching is typically triggered when water temperatures exceed the seasonal maximum by just 1°C for several weeks, causing corals to expel their symbiotic zooxanthellae.
Question 4: What is meant by the term 'trophic level' in marine biology?
- The depth zone where an organism lives
- The organism's position in a food chain based on its energy source (Correct answer)
- The geographic region where a species is found
- The reproductive rate of a species
Correct answer: The organism's position in a food chain based on its energy source
Trophic level describes an organism's position in a food web; producers are level one, herbivores level two, and predators occupy progressively higher levels.
Question 5: Which global initiative does PADI support that asks divers to report marine life sightings to contribute to scientific databases?
- Project AWARE
- Reef Check
- CITES compliance
- Both Project AWARE and Reef Check (Correct answer)
Correct answer: Both Project AWARE and Reef Check
PADI supports both Project AWARE (ocean protection, debris reporting, shark and ray data) and Reef Check (coral reef monitoring surveys) as citizen science programs for divers.
Question 6: What is the difference between a 'benthic' and a 'pelagic' marine organism?
- Benthic organisms are microscopic; pelagic organisms are large
- Benthic organisms live on or near the seafloor; pelagic organisms live in open water (Correct answer)
- Benthic organisms are carnivores; pelagic organisms are herbivores
- Benthic organisms migrate seasonally; pelagic organisms do not
Correct answer: Benthic organisms live on or near the seafloor; pelagic organisms live in open water
Benthic describes organisms associated with the seafloor (e.g., sea cucumbers, flatfish), while pelagic describes organisms living in the open water column (e.g., tuna, jellyfish).
Question 7: A diver finds a piece of marine debris entangled around a sea turtle's neck. According to PADI's Project AWARE guidelines, what is the recommended action?
- Never intervene; human interaction always causes more harm
- Carefully remove the debris if it can be done safely without further injuring the animal (Correct answer)
- Capture the turtle and bring it to the surface for immediate veterinary care
- Report the sighting only after the dive is complete; do nothing underwater
Correct answer: Carefully remove the debris if it can be done safely without further injuring the animal
Project AWARE and PADI encourage divers to carefully remove marine debris entangling wildlife when it can be done safely, as entanglement is often fatal if left untreated.
PADI Marine Biology & Conservation 5
What is the ecological role of apex predators like sharks in a marine food web?