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BISC1404 Introductory Biology 2 Spring 2024, Exam 2 Predictor Short answer questions
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BISC1404 Introductory Biology 2 Spring 2024, Exam 2 Predictor Short answer questions
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BISC1404 Introductory Biology 2Spring 2024, Exam 2 Predictor
Short answer questions (24 points Total): Please answer ONLY 2 of the following 4
questions (complete both part a and b for your selections). Diagrams are allowed.
Each Questions has 6 marks/points
Short Answer 1:
Question 1a
Describe what is meant by the apical and basolateral domains of epithelial cells. Describe
one specific example of the apical or basolateral features of an epithelial tissue you are
familiar with in humans.
Epithelial cells are organized into distinct regions known as the apical and basolateral domains.
Apical Domain: This is the top part of the epithelial cell that faces the lumen (the inside
space of a tube or cavity) or the external environment. It is often specialized for functions
such as absorption, secretion, or sensing. Features of the apical domain can include
microvilli (which increase surface area for absorption), cilia (which help in movement),
and specialized transport proteins.
Basolateral Domain: This part of the epithelial cell faces the underlying tissue and the
bloodstream. It is involved in the transport of substances into and out of the epithelial
layer. The basolateral domain typically contains different types of transporters and
channels, and is often connected to the underlying connective tissue by the basement
membrane.
Example: Intestinal Epithelium
In the intestinal epithelium, the apical domain features microvilli, which form the brush border.
These microvilli significantly increase the surface area for nutrient absorption. They contain
various enzymes that aid in the final stages of digestion. On the basolateral side, there are
specialized transporters, such as the sodium-glucose cotransporter, that facilitate the uptake of
glucose and other nutrients into the bloodstream. This specialization ensures efficient nutrient
absorption and transport, highlighting the distinct functions of the apical and basolateral domains
in epithelial tissue.
, Question 1b
Compare large and small animal body sizes with respect to their surface area-to-volume
ratios. Describe one reason why a large animal would use less energy than a small animal
(consider the mass-specific BMR)?
The surface area-to-volume ratio (SA) is a key concept in understanding how body size affects
various physiological processes in animals.
Surface Area-to-Volume Ratio
Small Animals: Small animals have a higher SA ratio. This means that, relative to their
volume, they have more surface area exposed to the environment. For example, a mouse
has a large surface area for its volume, leading to greater heat loss and increased
metabolic demands to maintain body temperature.
Large Animals: Large animals have a lower SA ratio. This means they have less surface
area relative to their volume. For instance, an elephant's large body size results in less
surface area for heat exchange, allowing it to conserve heat more effectively.
Energy Use and BMR
One reason a large animal would use less energy than a small animal is related to mass-specific
basal metabolic rate (BMR).
Mass-specific BMR: Larger animals tend to have a lower mass-specific BMR than
smaller animals. This means that while a larger animal has a higher overall energy
requirement, the energy consumed per unit of body mass is lower. This is partly due to
the metabolic scaling laws, where metabolic rates increase with size, but not in a linear
fashion.
For example, if we compare a small animal like a mouse with a larger animal like an elephant,
the mouse has a high BMR relative to its size due to its high SA
ratio. It loses heat more quickly and needs to consume more energy to maintain its body
temperature. In contrast, the elephant, with its lower SA
ratio, loses heat more slowly, thus requiring less energy per gram of body mass to sustain its
metabolism.
This difference in energy requirements illustrates how larger animals can be more energy-
efficient than smaller ones, despite their higher total energy needs.
Question 2a
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