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PNB 2250 Exam 4 UCONN Questions And Answers With Latest Set
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PNB 2250 Exam 4 UCONN Questions And Answers With Latest Set
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PNB 2250 Exam 4 UCONN Questions And AnswersWith Latest Set
Allen's Rule ANS Animal shapes minimizes heat loss in cold climates and heat gain in warm
climates
Related to surface/volume
Arm length in tropical climates longer than
arm length in
cold climates
Might be related to cartilage growth
Effects of temperature
Isometric growth ANS ◦ A change in size w/o a change in proportion
◦ E.g., as an animal doubles in size, the length of the legs also changes in proportion
◦ Relationship between length, surface area and volume (mass)
Ex) Fish keep same shape with varying size
Bergmann's Rule ANS Larger species are found in colder climates
Largest mammals are found in colder
climates, while smaller mammals are found in
warm climates
Inuits (Culturally similiar people of Canada, Alaska, Greenland, etc that eat raw meat) who live at the
pole are heavier than Inuits who live closer to the equator
NO LONGER ACCEPTED and many people feel that energy availability, escape from predation
accounts for the differences
,Lenth, SA, Volume Relationship (Isometric) ANS For every doubling in length (2x), surface area
increases four-fold (4x) and volume increases eight- fold (8x)
L=S2 =V3(21 =22 =23)or2-4-8
Consider the implications
As an animal double in length, the surface
area of the lungs increases 4-fold, but there
are 8-fold more cells*****
An animal would have to double the flow of
blood to keep up - hypoxia becomes an
issue
Allometric scaling (Length, SA, Volume) ANS •Not isometric
Increase in L by 33%, results in an increase in
surface area by 66% and an increase in
volume by 100%
A relationship of 1-2-3, instead of 2-4-8.
L=2S=3V
•So a doubling in length will only produce 6x as many new cells, instead of 8x as many new cells in
isometric scaling
As an animal double in length, the surface
area of the lungs increases 4-fold, but there
are 6-fold more cells
Animals scale allometrically not isometrically ANS ◦ Likely due to the constraints on nutrient
delivery
◦ So a baby's head is a larger percentage of the whole body size than a young adult.
◦ The body mass grew but the limbs did not grow proportionately
,Kleiber's Law ANS Animals metabolic rate scales allometrically with volume with a coefficient
<1.0
Mr = c(M^0.75)
c - constant, M - mass, Mr - metabolic rate
Assuming cell size doesn't change, in larger species of animals, cells consume O2 at a much lower
rate
Kleiber's law is only valid if you express metabolic rate per gram animal mass
E.g., O2 ml/min/g
If expressed as redox coupling efficiency or metabolic efficiency then the exponent is not the same.
E.g., amount of energy released by ATP directly resulting in work
Scientist argue that the exponent falls between 2/3 and 3/4
Why a coefficient <1.0? (Kleiber's Law) ANS Symmorphosis
Biological structures are formed so as to
meet but not exceed maximal requirement
No over-engineering
If the most you increase respiration is 10-fold,
there is no sense in making a heart that can
increase blood flow 20-fold
Keep in mind that all changes in size are subject to physical constraints
Diffusion, diffusion, diffusion
Diffusion becomes harder as you get bigger
, Just as its harder to deliver packages to 100
homes compared to 10 homes
Symmorphosis ANS Biological structures are formed so as to
meet but not exceed maximal requirement
No over-engineering
If the most you increase respiration is 10-fold,
there is no sense in making a heart that can
increase blood flow 20-fold
Diffusion ANS •Effective over small distances only
◦ O2 as a gas moves 4.2 x 10-3 m/sec
◦ O2 in solution moves 2.5 x 10-5 m/sec
◦ In blood, it would take O2 11 hours to move
1 m if there was no circulation
•Animal size is predicated on a deliver system that overcomes the limitations of diffusion
◦ O2 takes 0.25 sec to cross the respiratory
membrane by diffusion
◦ Fractal geometry
Fractals ANS •Circulation or lung structure, a repeating structural pattern at smaller and smaller
scales - fractals
•Fractals are redundant and robust, ensuring the most optimal way to deliver nutrients to all cells
•Fractal geometry is commonly seen in animal AND plant structure
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