Biology 224 Final Exam
Why is there a constant urgent need of O2 in animals? - Answer-Most animal cells need a constant
supply of ATP. They have a constant need of breathing (absorb oxygen and excrete carbon dioxide) in
order to survive. O2 is required as the terminal electron aceptor of respiratory electron transport.
External respiration - Answer-Between the environment and lungs. the transport of O2 into and CO2 out
of the body. Gas exchanges occur through diffusion.
This involves a gas exchange membrane:
A gas-exchange membrane is a thin layer of one or two simple epithelia.
It separates internal tissues from the environmental medium (air or water).
External respiration is the process by which:
environmental O2 --> membrane --> tissues
dissolved CO2 --> membrane --> environment ( in the opposite direction).
Internal respiration - Answer-Between the blood and the cell. Transports O2 into and CO2 out of cells
Cellular respiration - Answer-Intracellular catabolic reactions that convert stored energy to ATP
Diffusion Rate: (Fick's Law) - Answer-J= D.A C1 - C2 divided by x.
C1 & C2 = Regions of high and low concentrations of solutes
A = Diffusion Area
X = Distance separating the concentration regions
D = Diffusion co-efficient, influenced by Physico-chemical properties of the solute, & temperature
,Application of Fick's Law to the diffusion of respiratory gases - Answer-J= D.A P1 - P2 divided by x.
1 & P2 = Regions of high and low partial pressure,
respectively
A = Diffusion Area
X = Distance separating the concentration regions
D = Diffusion co-efficient, influenced by Physico-chemical properties of the gas, & temperature
How small does an animal needs to be to rely on diffusion of O2 alone? - Answer-Using Fick's law•
Vertebrate muscle requires O2 partial pressure ~ 40 mmHg • Atmospheric O2 partial pressure = 160
mmHg
The distance inside the tissue where O2 partial pressure
reaches a minimum of 40 mmHg is ~ 1mm
What happens when organisms get larger? - Answer-Oxygen requirement increases with mass.
However, diffusion distance also increases and the surface area to volume ratio decreases. Bacteria's
surface area to volume ratio is 6,000,000: 1 and a whale's surface area to volume ratio is 0.06 to 1.
Therefore, larger organisms need organs like lungs and gills to help with gas exchange.
Respiration in larger animals requires multiple steps: - Answer-Most vertebrate's gas-transfer system
involves: 1) ventilation: to move gas into and out of the lungs. 2) diffusion of oxygen into the blood. 3)
perfusion or transport of blood by the heart to the tissues. 4) diffusion of oxygen from the blood in the
capillaries in the tissues into the mitochondria in the cells. The steps for the transport of CO2 from the
cells to the environment are the reverse of this.
The structure of the gas-exchange system in animals is influenced by: - Answer-Properties of the
medium- Air vs. water
Requirements of the animal
Anything that increases the diffusion coefficient, increases the surface area of the exchange surface,
enhances the partial pressure gradient, or reduces the thickness of the diffusion path will speed the rate
of diffusion.
,Properties of Gases- Dalton's Law: - Answer-total pressure exerted by a gas mixture (e.g., atmosphere) is
the sum of individual pressures exerted by each gas in the mixture.
What is partial pressure? - Answer-The individual pressure exerted by each gas within a mixture of gases
is the partial pressure (Pg).
Partial pressure is calculated by multiplying the fractional composition of that gas by the atmospheric
pressure.
The rate of diffusion of a gas is proportional to its partial pressure
within the total gas mixture.O2 and CO2 will flow based on their pressure gradient (high to low).
Partial pressure at sea level vs. atmospheric air: - Answer-The fractional composition of air at sea level
and at the top of mount Everest is the same, but the partial pressure of each of the major gasses in air
are reduced to 1/3 at sea level.
Diffusion of gasses- water vs. air- - Answer-There is 30 times the amount of O2 in air than in water for
the same partial pressure. This requires aquatic animals to breathe much more in order to obtain the
same volume of O2 as other animals. Density of water is 1000 time more than air and viscosity is about
50 times more than air. It takes more energy to move water than air over a respiratory surface.
Advantages of breathing in water than in air - Answer-CO2 is 20 times more soluble in water than air, so
excretion is much easier during ventilation. Land animals must lose water by evaporation during
ventilation, which can cause their respiratory surface to dry. Therefore, they must consume water.
Solubility of gas - Answer-Gases are not equally soluble in different fluids or the same fluid at different
temperatures. Oxygen is far more soluble in lipids than in water, and is more soluble in cold
temperatures than warm. Gas will move down a partial pressure gradient from a region of high partial
pressure to an area of low partial pressure. When oxygen is in equilibrium between two gases, the
concentrations may be different, but the partial pressures will be the same.
, Water Breathers: - Answer-Gills are invaginations of the body - Respiratory surfaces- Branched and
folded- Increase diffusion area
Water moves over the gills
- Beating of cilia; and contractions of body muscles pump water over gills.
External gills - Answer-Extend out from the body and do not have protective coverings
Internal Gills - Answer-Located within the body;
- Protected by chambers of the body
-provides protection for delicate structures
- Currents of water to be directed over the gills.
Double pumping mechanism in bony and cartilaginous fish: - Answer-+ and - indicate pressure gradient
across the gills and pressure relative to surrounding water
Ram ventilation - Answer-Pelagic fish like some sharks and mackerel.
Mackerel can't fully oxygenate their blood if prevented from active swimming
Tracheal system of insects for gas exchange - Answer-Trachea = windpipe- Invaginations of the outer
epidermis that branch repeatedly
Air enters and leaves at openings in the insects chitinous exoskeleton through spiracles
each spiricle incorporates a muscle that allows the spiracles to open and close. O2 is consumed by
tissues and CO2 is taken up by the bicarbonate buffering system, resulting in a small negative pressure in
the tracheal system. The small inward current of air moving in through the spiracle prevents water
vapour from escaping. As the bicarbonate buffering system becomes saturated, Free Co2 builds up
inside the insect causing the spiracles to open, allowing CO2 to move out.
Trachea branches into tracheoles
O2 - ECF - Cells
Why is there a constant urgent need of O2 in animals? - Answer-Most animal cells need a constant
supply of ATP. They have a constant need of breathing (absorb oxygen and excrete carbon dioxide) in
order to survive. O2 is required as the terminal electron aceptor of respiratory electron transport.
External respiration - Answer-Between the environment and lungs. the transport of O2 into and CO2 out
of the body. Gas exchanges occur through diffusion.
This involves a gas exchange membrane:
A gas-exchange membrane is a thin layer of one or two simple epithelia.
It separates internal tissues from the environmental medium (air or water).
External respiration is the process by which:
environmental O2 --> membrane --> tissues
dissolved CO2 --> membrane --> environment ( in the opposite direction).
Internal respiration - Answer-Between the blood and the cell. Transports O2 into and CO2 out of cells
Cellular respiration - Answer-Intracellular catabolic reactions that convert stored energy to ATP
Diffusion Rate: (Fick's Law) - Answer-J= D.A C1 - C2 divided by x.
C1 & C2 = Regions of high and low concentrations of solutes
A = Diffusion Area
X = Distance separating the concentration regions
D = Diffusion co-efficient, influenced by Physico-chemical properties of the solute, & temperature
,Application of Fick's Law to the diffusion of respiratory gases - Answer-J= D.A P1 - P2 divided by x.
1 & P2 = Regions of high and low partial pressure,
respectively
A = Diffusion Area
X = Distance separating the concentration regions
D = Diffusion co-efficient, influenced by Physico-chemical properties of the gas, & temperature
How small does an animal needs to be to rely on diffusion of O2 alone? - Answer-Using Fick's law•
Vertebrate muscle requires O2 partial pressure ~ 40 mmHg • Atmospheric O2 partial pressure = 160
mmHg
The distance inside the tissue where O2 partial pressure
reaches a minimum of 40 mmHg is ~ 1mm
What happens when organisms get larger? - Answer-Oxygen requirement increases with mass.
However, diffusion distance also increases and the surface area to volume ratio decreases. Bacteria's
surface area to volume ratio is 6,000,000: 1 and a whale's surface area to volume ratio is 0.06 to 1.
Therefore, larger organisms need organs like lungs and gills to help with gas exchange.
Respiration in larger animals requires multiple steps: - Answer-Most vertebrate's gas-transfer system
involves: 1) ventilation: to move gas into and out of the lungs. 2) diffusion of oxygen into the blood. 3)
perfusion or transport of blood by the heart to the tissues. 4) diffusion of oxygen from the blood in the
capillaries in the tissues into the mitochondria in the cells. The steps for the transport of CO2 from the
cells to the environment are the reverse of this.
The structure of the gas-exchange system in animals is influenced by: - Answer-Properties of the
medium- Air vs. water
Requirements of the animal
Anything that increases the diffusion coefficient, increases the surface area of the exchange surface,
enhances the partial pressure gradient, or reduces the thickness of the diffusion path will speed the rate
of diffusion.
,Properties of Gases- Dalton's Law: - Answer-total pressure exerted by a gas mixture (e.g., atmosphere) is
the sum of individual pressures exerted by each gas in the mixture.
What is partial pressure? - Answer-The individual pressure exerted by each gas within a mixture of gases
is the partial pressure (Pg).
Partial pressure is calculated by multiplying the fractional composition of that gas by the atmospheric
pressure.
The rate of diffusion of a gas is proportional to its partial pressure
within the total gas mixture.O2 and CO2 will flow based on their pressure gradient (high to low).
Partial pressure at sea level vs. atmospheric air: - Answer-The fractional composition of air at sea level
and at the top of mount Everest is the same, but the partial pressure of each of the major gasses in air
are reduced to 1/3 at sea level.
Diffusion of gasses- water vs. air- - Answer-There is 30 times the amount of O2 in air than in water for
the same partial pressure. This requires aquatic animals to breathe much more in order to obtain the
same volume of O2 as other animals. Density of water is 1000 time more than air and viscosity is about
50 times more than air. It takes more energy to move water than air over a respiratory surface.
Advantages of breathing in water than in air - Answer-CO2 is 20 times more soluble in water than air, so
excretion is much easier during ventilation. Land animals must lose water by evaporation during
ventilation, which can cause their respiratory surface to dry. Therefore, they must consume water.
Solubility of gas - Answer-Gases are not equally soluble in different fluids or the same fluid at different
temperatures. Oxygen is far more soluble in lipids than in water, and is more soluble in cold
temperatures than warm. Gas will move down a partial pressure gradient from a region of high partial
pressure to an area of low partial pressure. When oxygen is in equilibrium between two gases, the
concentrations may be different, but the partial pressures will be the same.
, Water Breathers: - Answer-Gills are invaginations of the body - Respiratory surfaces- Branched and
folded- Increase diffusion area
Water moves over the gills
- Beating of cilia; and contractions of body muscles pump water over gills.
External gills - Answer-Extend out from the body and do not have protective coverings
Internal Gills - Answer-Located within the body;
- Protected by chambers of the body
-provides protection for delicate structures
- Currents of water to be directed over the gills.
Double pumping mechanism in bony and cartilaginous fish: - Answer-+ and - indicate pressure gradient
across the gills and pressure relative to surrounding water
Ram ventilation - Answer-Pelagic fish like some sharks and mackerel.
Mackerel can't fully oxygenate their blood if prevented from active swimming
Tracheal system of insects for gas exchange - Answer-Trachea = windpipe- Invaginations of the outer
epidermis that branch repeatedly
Air enters and leaves at openings in the insects chitinous exoskeleton through spiracles
each spiricle incorporates a muscle that allows the spiracles to open and close. O2 is consumed by
tissues and CO2 is taken up by the bicarbonate buffering system, resulting in a small negative pressure in
the tracheal system. The small inward current of air moving in through the spiracle prevents water
vapour from escaping. As the bicarbonate buffering system becomes saturated, Free Co2 builds up
inside the insect causing the spiracles to open, allowing CO2 to move out.
Trachea branches into tracheoles
O2 - ECF - Cells
