PNB 2250 Exam 4 (UConn) Questions
and Answers 100% Pass
Allen's Rule - ✔✔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 - ✔✔◦ 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
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,Bergmann's Rule - ✔✔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) - ✔✔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*****
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,An animal would have to double the flow of
blood to keep up - hypoxia becomes an
issue
Allometric scaling (Length, SA, Volume) - ✔✔•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 - ✔✔◦ Likely due to the constraints on
nutrient delivery
Katelyn Whitman, All Rights Reserved © 2025 3
, ◦ 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 - ✔✔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
Katelyn Whitman, All Rights Reserved © 2025 4
and Answers 100% Pass
Allen's Rule - ✔✔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 - ✔✔◦ 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
Katelyn Whitman, All Rights Reserved © 2025 1
,Bergmann's Rule - ✔✔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) - ✔✔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*****
Katelyn Whitman, All Rights Reserved © 2025 2
,An animal would have to double the flow of
blood to keep up - hypoxia becomes an
issue
Allometric scaling (Length, SA, Volume) - ✔✔•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 - ✔✔◦ Likely due to the constraints on
nutrient delivery
Katelyn Whitman, All Rights Reserved © 2025 3
, ◦ 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 - ✔✔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
Katelyn Whitman, All Rights Reserved © 2025 4
