©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
PNB 2250 Exam 3 Study Guide with
Complete Solutions
Examples of respiratory structures of terrestrial animals - Ans:✔✔-bulk flow with tracheal system and
spiracles (insects), cutaneous (frog)
Examples of respiratory structures of aquatic animals - Ans:✔✔-bulk flow (sponges, cnidarians), gills,
water vascular system, arborescent respiratory trees (sea cucumber), cutaneous (leech)
Do all aquatic animals necessarily exchange gasses in water? - Ans:✔✔-No, some aquatic animals could
exchange gasses above water using lungs, like aquatic mammals, or cutaneous respiration, like frogs,
which takes advantage of moist skin rather than being in the water
Relationship between a gas's volume and its pressure - Ans:✔✔-Volume and pressure are inversely
related because in a higher volume gas has more room to move, which means it has a lower pressure.
What is a gas's partial pressure? - Ans:✔✔-A partial pressure is the independent gas's exertion of
pressure on the walls of a container via molecular collisions.
How does O2 and CO2 differ in their solubility & concentration in water versus in air? - Ans:✔✔-
Solubility of oxygen is lower in water than air, while CO2 reacts with water to form bicarbonate and
Page 1/43
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FIRST PUBLISH OCTOBER 2024
carbonic acid. Oxygen is in higher concentration than CO2 in both air and water. Warmer water and salt
water holds less oxygen
What happens to air pressure as elevation increases? What happens to water pressure as depth
increases? - Ans:✔✔-As elevation increases, air pressure decreases.
As depth increases in water, pressure increases.
How might water's density and viscosity affect the energy required for ventilation by aquatic animals
compared to that in air-breathers? How does this impact locomotion? - Ans:✔✔-Water has a high
viscosity and density, which means that it is thicker and heavier. This means that water holds less oxygen
than the air does. This means that locomotion is also hard for aquatic mammals.
Name an animal that has neither a circulatory system nor a respiratory system and relies solely on
cutaneous diffusion for gas exchange. How is this adequate for its survival? - Ans:✔✔-Small and thin
animals, like flatworms and horsehair worm parasites, have no respiratory or circulatory systems and
solely rely on cutaneous/cuticle diffusion through water or air.
Name one aquatic and one terrestrial animal that respires cutaneously, but moves the diffused gasses
through a circulatory system - Ans:✔✔-Long animals use cutaneous respiration and moves the gas to the
circulatory system
Aquatic cutaneous: leech
Terrestrial cutaneous: frog
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Name one aquatic and one terrestrial animal that has the opposite physiological setup: one that lacks a
circulatory system (at least one used primarily for gas exchange) and respires using bulk flow of the
medium (water or air) - Ans:✔✔-Bulk flow animals have no circulatory system
Aquatic: sponge, cnidarian
Terrestrial: insect (tracheal system and spiracles)
Name an aquatic and terrestrial animal that utilizes a bulk flow step in both their respiratory and
circulatory systems and identify the two sites of gas diffusion during the transport of O2 and CO2
through the body. - Ans:✔✔-Animals that utilize bulk flow in their respiratory and circulatory systems
Aquatic: mollusks, crustaceans
Terrestrial: vertebrates
It diffuses into respiratory vasculature of the alveoli and respiring cells through the capillaries, where it
enters mitochondria for aerobic respiration.
What are the gills of a mollusk called (which also double as a ciliated, filter-feeding structure in bivalves)?
- Ans:✔✔-Ctenidia are large leaf-like organs that are used partly for respiration and partly for filtering
food from the water in mollusks
How do cephalopods actively move water across their gills? - Ans:✔✔-Cephalopods have paired gills and
muscles that force water through a mantle cavity
Page 3/43
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How do crustaceans, such as crabs, shrimp, and crayfish, breathe? - Ans:✔✔-Crustaceans have gills that
are highly modified and located at the base of each leg under the carapace. The water flow is
unidirectional, entering the ventral side and exiting the bailer (anterior) near the mouth
Describe at least two ways that different echinoderms can respire in water without gills. - Ans:✔✔-Sea
Stars use both external respiratory papulae and a water vascular system.
Sea cucumbers have arborescent respiratory trees stemming from their cloaca (breathing out of anus)
How do hagfish differ from lampreys? (hint: nostril) - Ans:✔✔-Hagfish have a single nostril connected to
the esophagus and ventilate using a muscular velum - moves to propel water unidirectionally through
the mouth, down the pharynx, and into the bilateral atria that exits the body through the atriopore
opening
Lampreys have a single nostril that's not connected to the gut and have a row of gill pouches (7 per side)
that each have an external opening. Can be unidirectional when the fish is swimming and tidal when
attached to a surface (rock/host).
What is ram ventilation and which group of animals uses this? What is their anatomy like? - Ans:✔✔-
Continuous swimming sharks use ram ventilation, which means that they move water over their gills by
swimming and "ramming" the water into their mouths and over their gills.
Sharks and rays have gill septa and unidirectional flow
Page 4/43
FIRST PUBLISH OCTOBER 2024
PNB 2250 Exam 3 Study Guide with
Complete Solutions
Examples of respiratory structures of terrestrial animals - Ans:✔✔-bulk flow with tracheal system and
spiracles (insects), cutaneous (frog)
Examples of respiratory structures of aquatic animals - Ans:✔✔-bulk flow (sponges, cnidarians), gills,
water vascular system, arborescent respiratory trees (sea cucumber), cutaneous (leech)
Do all aquatic animals necessarily exchange gasses in water? - Ans:✔✔-No, some aquatic animals could
exchange gasses above water using lungs, like aquatic mammals, or cutaneous respiration, like frogs,
which takes advantage of moist skin rather than being in the water
Relationship between a gas's volume and its pressure - Ans:✔✔-Volume and pressure are inversely
related because in a higher volume gas has more room to move, which means it has a lower pressure.
What is a gas's partial pressure? - Ans:✔✔-A partial pressure is the independent gas's exertion of
pressure on the walls of a container via molecular collisions.
How does O2 and CO2 differ in their solubility & concentration in water versus in air? - Ans:✔✔-
Solubility of oxygen is lower in water than air, while CO2 reacts with water to form bicarbonate and
Page 1/43
, ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
carbonic acid. Oxygen is in higher concentration than CO2 in both air and water. Warmer water and salt
water holds less oxygen
What happens to air pressure as elevation increases? What happens to water pressure as depth
increases? - Ans:✔✔-As elevation increases, air pressure decreases.
As depth increases in water, pressure increases.
How might water's density and viscosity affect the energy required for ventilation by aquatic animals
compared to that in air-breathers? How does this impact locomotion? - Ans:✔✔-Water has a high
viscosity and density, which means that it is thicker and heavier. This means that water holds less oxygen
than the air does. This means that locomotion is also hard for aquatic mammals.
Name an animal that has neither a circulatory system nor a respiratory system and relies solely on
cutaneous diffusion for gas exchange. How is this adequate for its survival? - Ans:✔✔-Small and thin
animals, like flatworms and horsehair worm parasites, have no respiratory or circulatory systems and
solely rely on cutaneous/cuticle diffusion through water or air.
Name one aquatic and one terrestrial animal that respires cutaneously, but moves the diffused gasses
through a circulatory system - Ans:✔✔-Long animals use cutaneous respiration and moves the gas to the
circulatory system
Aquatic cutaneous: leech
Terrestrial cutaneous: frog
Page 2/43
, ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
Name one aquatic and one terrestrial animal that has the opposite physiological setup: one that lacks a
circulatory system (at least one used primarily for gas exchange) and respires using bulk flow of the
medium (water or air) - Ans:✔✔-Bulk flow animals have no circulatory system
Aquatic: sponge, cnidarian
Terrestrial: insect (tracheal system and spiracles)
Name an aquatic and terrestrial animal that utilizes a bulk flow step in both their respiratory and
circulatory systems and identify the two sites of gas diffusion during the transport of O2 and CO2
through the body. - Ans:✔✔-Animals that utilize bulk flow in their respiratory and circulatory systems
Aquatic: mollusks, crustaceans
Terrestrial: vertebrates
It diffuses into respiratory vasculature of the alveoli and respiring cells through the capillaries, where it
enters mitochondria for aerobic respiration.
What are the gills of a mollusk called (which also double as a ciliated, filter-feeding structure in bivalves)?
- Ans:✔✔-Ctenidia are large leaf-like organs that are used partly for respiration and partly for filtering
food from the water in mollusks
How do cephalopods actively move water across their gills? - Ans:✔✔-Cephalopods have paired gills and
muscles that force water through a mantle cavity
Page 3/43
, ©GRACEAMELIA 2024/2025 ACADEMIC YEAR. ALL RIGHTS RESERVED
FIRST PUBLISH OCTOBER 2024
How do crustaceans, such as crabs, shrimp, and crayfish, breathe? - Ans:✔✔-Crustaceans have gills that
are highly modified and located at the base of each leg under the carapace. The water flow is
unidirectional, entering the ventral side and exiting the bailer (anterior) near the mouth
Describe at least two ways that different echinoderms can respire in water without gills. - Ans:✔✔-Sea
Stars use both external respiratory papulae and a water vascular system.
Sea cucumbers have arborescent respiratory trees stemming from their cloaca (breathing out of anus)
How do hagfish differ from lampreys? (hint: nostril) - Ans:✔✔-Hagfish have a single nostril connected to
the esophagus and ventilate using a muscular velum - moves to propel water unidirectionally through
the mouth, down the pharynx, and into the bilateral atria that exits the body through the atriopore
opening
Lampreys have a single nostril that's not connected to the gut and have a row of gill pouches (7 per side)
that each have an external opening. Can be unidirectional when the fish is swimming and tidal when
attached to a surface (rock/host).
What is ram ventilation and which group of animals uses this? What is their anatomy like? - Ans:✔✔-
Continuous swimming sharks use ram ventilation, which means that they move water over their gills by
swimming and "ramming" the water into their mouths and over their gills.
Sharks and rays have gill septa and unidirectional flow
Page 4/43
