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Divemaster Knowledge Development > Divemaster Knowledge Development Part 2 > Flashcards

Divemaster Knowledge Development Part 2 Flashcards

1
Q

Water covers approximately how much of the Earth’s surface?

A

Water covers approximately 71% of the Earth’s surface.

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2
Q

Where are crucial habitats for marine species to lay their legs?

A

Crucial habitats for marine species to lay their eggs are coastal wetlands, such as mangrove forests, salt marshes and estuaries.

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3
Q

What are you looking for when identifying a rip current off a beach?

A

When identifying a rip current off a beach you are looking for turbid, foamy water moving away from the shore, disrupting the waves where it rushes out to sea.

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4
Q

What is a thermocline?

A

A thermocline happens when relatively warm, low-density surface water is separated from cool, high-density deep water.

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5
Q

Wind is the most common disturbing force that causes what in the ocean?

A

Wind is the most common disturbing force that causes waves in the ocean.

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6
Q

The gravitational interaction between the sun, moon and earth cause what in the ocean?

A

The gravitational interaction between the sun, moon and earth cause tides in the ocean.

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7
Q

When do waves become unstable and break?

A

Waves become unstable and break when the water depth is 1.3 times the wave height.

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8
Q

How many times faster does the unprotected human body lose heat in water than in air?

A

The unprotected human body loses heat approximately 20times faster in water than in air.

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9
Q

At what depth does the air you breath become four times as dense?

A

At a depth of 30metres / 99 feet, the air you breathe is approximately four times as dense as compared to the surface.

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10
Q

If a balloon is filled to 10litres at the surface and then taken to a depth of 40metres / 99feet, what will be the volume be upon reaching the depth?

A

If a balloon is filled to 10litres at the surface and then taken to a depth of 40metres / 99feet, the volume in the balloon will be 2litres upon reaching the depth.

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11
Q

If I diver breaths from a cylinder that contains .02% carbon monoxide at a depth of 20metres / 60feet, what will the physical effect of the gas be equivalent to?

A

If I diver breaths from a cylinder that contains .02% carbon monoxide at a depth of 20metres / 60feet, the physical effect of the gas will be equivalent to breathing .08% carbon monoxide.

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12
Q

If an object is neutrally buoyant in salt water, what will happen to the object when it’s placed in fresh water?

A

If an object is neutrally buoyant in salt water, it will sink when placed in fresh water.

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13
Q

Approximately how many time faster does sound travel through water than in air?

A

Sound travels approximately four times faster through water than in air. This makes it next to impossible to determine the direction of sound underwater.

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14
Q

The pressure inside a cylinder will increase if exposed to what?

A

The pressure inside a cylinder will increase if exposed to sunlight on a hot day.

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15
Q

If air contains 79% nitrogen and 21% oxygen at sea level, what will the partial pressure of oxygen be if taken to 20metres / 66 feet in seawater?

A

If air contains 79% nitrogen and 21% oxygen at sea level, the partial pressure of oxygen in 20metres / 66feet of seawater will be 0.63 bar/ata.

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16
Q

If a glass of water is placed in a recompression chamber and the pressure surrounding the water is decreased, what will happen to the amount of gas dissolved in the water?

A

If a glass of water is placed in a recompression chamber and the pressure surrounding the water is decreased, the amount of gas dissolved in the water will decrease.

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17
Q

What causes objects to appear larger and closer when viewed underwater?

A

Refraction of light causes objects to appear larger and closer underwater.

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18
Q

If a full cylinder of air lasts a diver 100minutes at the surface, how long would you expect it to last at 30metres / 99feet?

A

If a full cylinder of air lasts a diver 100minutes at the surface, all else being the same you would expect it to last 25minutes at 30metres / 99feet.

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19
Q

How do you avoid problems caused by dead air spaces?

A

Breathing slowly and deeply avoids problems caused by dead air spaces.

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20
Q

What can voluntary hyperventilation decrease the amount of in your lungs?

A

Voluntary hyperventilation decreases the amount of carbon dioxide in your lungs, which can increase breath hold time when skin diving.

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21
Q

What carries blood away from the heart?

A

Arteries carry blood away from the heart.

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22
Q

What carries blood towards the heart?

A

Veins carry blood towards the heart.

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23
Q

What can cause a round window rupture within a divers ear?

A

A round window rupture can be caused by a diver equalizing forcefully against a pinched nose.

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24
Q

Most divers begin to feel the effects of gas narcosis at what depth?

A

Most divers begin to feel the effects of gas narcosis at 30metres / 99feet.

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25
Q

When do squeezes most commonly occur?

A

Squeezes most commonly occur during very rapid descents.

26
Q

What will cause a diver to feel light headed because of a tight neck seal?

A

A carotid sinus reflex or blocked jugular venous return will cause a diver to feel light headed because of a light neck seal.

27
Q

What part of the ear is affected most if a squeeze occurs while descending?

A

The middle ear is most affected if a squeeze occurs while descending.

28
Q

What is the most serious sign of Central Nervous System (CNS) toxicity?

A

The most serious sign of Central Nervous System (CNS) toxicity is convulsion.

29
Q

What is the name for a collapsed lung?

A

The name for a collapsed lung is a pneumothorax, caused when air from a rupture collects between the lung and chest wall.

30
Q

What should a diver do if they have a near drowning incident?

A

If a diver has a near drowning incident they should seek medical care, even when appearing recovered, because in nearly all cases, water enters the lungs.

31
Q

What are the symptoms of heat exhaustion?

A

The symptoms of heat exhaustion are cool clammy skin, nausea and weakness.

32
Q

If a cylinder seems heavier than it should be, what should be done?

A

If a cylinder seems heavier then it should be a visual inspection should be done, because it could have water in it.

33
Q

What part of the regulator reduces the high pressure from a scuba cylinder to an intermediate pressure?

A

The first stage of a regulator reduces the high pressure from a scuba cylinder to an intermediate pressure.

34
Q

What part of the regulator delivers the intermediate pressure from the regulator’s first stage to an ambient pressure?

A

The second stage of a regulator delivers the intermediate pressure from a regulator’s first stage to an ambient pressure.

35
Q

What will happen if a regulator’s second stage valve malfunctions?

A

If a regulator’s second stage valve malfunctions it will free flow due to its fail-safe.

36
Q

What causes most functional problems with a regulator?

A

Poor maintenance or servicing cause most functional problems with a regulator.

37
Q

What is the purpose of a regulator environmental seal?

A

The purpose of a regulator environmental seal is to help keep the regulator from freezing in cold water.

38
Q

What is the most common cylinder valve issue?

A

A worn or missing o-ring is the most common cylinder valve issue.

39
Q

What contents must be analyzed when using an enriched air cylinder?

A

The percentage of oxygen must be analyzed when using an enriched air cylinder.

40
Q

What is the concept of the Haldanean decompression model?

A

The Haldanean decompression model is based on the concept that decompression sickness can be avoided by keeping the pressure gradient between dissolved nitrogen in the tissues and the surrounding pressure within acceptable limits.

41
Q

At what altitude do altitude procedures apply when planning on the RDP table?

A

Altitude procedures apply when planning above 300metres / 1000feet on the RDP table.

42
Q

What is the suggested recommendation for flying after diving after completing a single dive?

A

The suggested recommendation is divers wait 12hours before flying in a commercial jet after diving.

43
Q

What is the ocean’s major source of productivity and the base of the marine food chain?

A

Phytoplankton is the ocean’s major source of productivity and the base of the marine food chain.

44
Q

When an alien species is introduced into an ecosystem, what might happen?

A

When an alien species is introduced into an ecosystem, it may have no natural enemies, which allows it to quickly multiply and possibly overtake and kill off the native species.

45
Q

What type of current generally moves down the coast at an angle, pushed by waves and assisted by prevailing winds?

A

A longshore current generally moves down the coast at an angle, pushed by waves and assisted by prevailing winds.

46
Q

After a day of strong winds drive surface waters offshore, what causes water conditions to become clear and cool.

A

Upwelling is likely to cause water conditions to become clear and cool after a day of strong winds drive surface waters offshore.

47
Q

What will cause the volume inside a sealed balloon filled with air to increase?

A

If a balloon filled with air is taken from a cold place to a hot place, this will cause the volume inside to increase.

48
Q

Approximately how much denser is the air a diver breaths at a depth of 30metres / 99feet?

A

The air a diver breaths is approximately 4 times denser at a depth of 30metres / 99feet.

49
Q

If a balloon is filled to 1 litre at 40metres / 132feet, what will its volume be if taken to the surface?

A

If a balloon is filled to 1 litre at 40metres / 132feet, its volume would be 5litres if taken to the surface due to expansion.

50
Q

If a diver ascends to altitude soon after diving, what is there an increased risk of?

A

If a diver ascends to altitude soon after diving, there is an increased risk decompression sickness because exposure to lower pressure may increase bubble formation.

51
Q

If an object is neutrally buoyant in fresh water, what will happen to the object when placed in salt water?

A

If an object is neutrally buoyant in fresh water, it will float when placed in salt water.

52
Q

If air contains 79% nitrogen at sea level, what will the partial pressure of nitrogen be if it is taken to 20metres / 66feet?

A

If air contains 79% nitrogen at sea level, the partial pressure of nitrogen at 20metres / 66feet is 2.37bar/ata

53
Q

How much faster does water conduct heat away from the body than air?

A

Water conducts heat away from the body 20times faster than air from the body.

54
Q

What are the signs and symptoms of carbon monoxide poisoning?

A

The signs and symptoms of carbon monoxide poisoning are headaches, nausea and lips are redder than normal after a dive.

55
Q

If a diver complains of fatigue and numbness in one shoulder after a deep dive, what may they have?

A

If a diver complains of fatigue and numbness in one shoulder after a deep diver, the diver may have decompression illness and should seek medical attention.

56
Q

What is the most serious lung overexpansion injury?

A

An air embolism is the most serious lung overexpansion injury, which can cause a blood clot and result in a stroke.

57
Q

What is the most efficient way to provide oxygen to a breathing, injured diver?

A

The most efficient way to provide oxygen to a breathing, injured diver is with a nonresuscitator demand valve system.

58
Q

Which cylinder valve allows the regulator first stage to screw into the valve?

A

A DIN cylinder valve allows the regulator to screw into the valve.

59
Q

What may cause a wet breathing regulator?

A

I wet breathing regulator may be caused by the exhaust valve not sealing or a tear in the mouthpiece.

60
Q

What are the recommended procedures for using dive computers while diving in a buddy team?

A

The recommended procedures for using dive computers while diving in a buddy team, are each buddy must have a computer and the buddy team should follow the most conservative computer.

61
Q

Flying after diving recommendations suggest that divers should wait how long after completing multiple dives before flying in a commercial jet airliner?

A

Flying after diving recommendation suggests that divers should wait 18hours after multiple dives before flying in a commercial jet airliner.

Divemaster Knowledge Development (2 decks)

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