Bio 109 Study Questions and Correct Answers
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Osmoregulation
A homeostatic process by which animals control solute concentrations and balance water gain
and loss.
Osmosis
The movement of water across a selectively permeable membrane.
Osmolarity
The solute concentration in a solution, which determines the direction of water movement across
a membrane.
Osmoconformers
Animals that are isoosmotic with their surroundings and do not actively regulate their internal
osmolarity.
Osmoregulators
Animals that expend energy to control water uptake and loss in environments that are
hyperosmotic or hypoosmotic to their body fluids.
Stenohaline
Organisms that cannot tolerate substantial changes in external osmolarity.
Euryhaline
,Organisms that can survive large fluctuations in external osmolarity, such as salmon or
barnacles.
How do marine bony fishes maintain water balance?
They drink seawater to replace water lost by osmosis and excrete excess salts through their gills
and kidneys.
How do freshwater animals maintain water balance?
They excrete large amounts of dilute urine to remove excess water taken in by osmosis and
replace lost salts through food and active uptake across the gills.
What are transport epithelia?
Specialized epithelial cells arranged in tubular networks that regulate solute movement and are
essential for osmotic regulation and waste disposal.
Ammonia as a nitrogenous waste
A highly toxic form of nitrogenous waste that requires large amounts of water for dilution and
excretion.
Urea as a nitrogenous waste
A nitrogenous waste product that is less toxic than ammonia and requires less water for
excretion.
Uric acid as a nitrogenous waste
A nitrogenous waste that is relatively non-toxic, does not dissolve easily in water, and is excreted
with minimal water loss, though it requires significant energy to produce.
, Gout
A condition characterized by painful joint inflammation caused by the accumulation of uric acid
crystals.
Filtration
The process in an excretory system where body fluids are pressure-filtered to remove water and
small molecules while retaining cells and large molecules.
Reabsorption
The process of reclaiming valuable solutes and water from the filtrate back into the body fluids.
What factors influence the energy cost of osmoregulation?
The difference between an animal's osmolarity and its surroundings, the permeability of the
animal's surface to water, and the work required to pump solutes across membranes.
How do terrestrial animals minimize water loss?
Through body coverings, behavioral adaptations like a nocturnal lifestyle, and by obtaining water
from food and metabolic processes.
What is metabolic water?
Water produced as a byproduct of cellular respiration, which helps land animals manage their
water budgets.
Why do sharks have an osmolarity close to seawater?
It prevents excessive water loss to the environment; they dispose of the small amount of water
that enters their body through their kidneys.
Guaranteed A+!
Osmoregulation
A homeostatic process by which animals control solute concentrations and balance water gain
and loss.
Osmosis
The movement of water across a selectively permeable membrane.
Osmolarity
The solute concentration in a solution, which determines the direction of water movement across
a membrane.
Osmoconformers
Animals that are isoosmotic with their surroundings and do not actively regulate their internal
osmolarity.
Osmoregulators
Animals that expend energy to control water uptake and loss in environments that are
hyperosmotic or hypoosmotic to their body fluids.
Stenohaline
Organisms that cannot tolerate substantial changes in external osmolarity.
Euryhaline
,Organisms that can survive large fluctuations in external osmolarity, such as salmon or
barnacles.
How do marine bony fishes maintain water balance?
They drink seawater to replace water lost by osmosis and excrete excess salts through their gills
and kidneys.
How do freshwater animals maintain water balance?
They excrete large amounts of dilute urine to remove excess water taken in by osmosis and
replace lost salts through food and active uptake across the gills.
What are transport epithelia?
Specialized epithelial cells arranged in tubular networks that regulate solute movement and are
essential for osmotic regulation and waste disposal.
Ammonia as a nitrogenous waste
A highly toxic form of nitrogenous waste that requires large amounts of water for dilution and
excretion.
Urea as a nitrogenous waste
A nitrogenous waste product that is less toxic than ammonia and requires less water for
excretion.
Uric acid as a nitrogenous waste
A nitrogenous waste that is relatively non-toxic, does not dissolve easily in water, and is excreted
with minimal water loss, though it requires significant energy to produce.
, Gout
A condition characterized by painful joint inflammation caused by the accumulation of uric acid
crystals.
Filtration
The process in an excretory system where body fluids are pressure-filtered to remove water and
small molecules while retaining cells and large molecules.
Reabsorption
The process of reclaiming valuable solutes and water from the filtrate back into the body fluids.
What factors influence the energy cost of osmoregulation?
The difference between an animal's osmolarity and its surroundings, the permeability of the
animal's surface to water, and the work required to pump solutes across membranes.
How do terrestrial animals minimize water loss?
Through body coverings, behavioral adaptations like a nocturnal lifestyle, and by obtaining water
from food and metabolic processes.
What is metabolic water?
Water produced as a byproduct of cellular respiration, which helps land animals manage their
water budgets.
Why do sharks have an osmolarity close to seawater?
It prevents excessive water loss to the environment; they dispose of the small amount of water
that enters their body through their kidneys.
