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IB 150 All Practice Homework With Complete Solutions Latest Update
- Course
- IB 150
- Institution
- University Of Illinois - Urbana-Champaign
IB 150 All Practice Homework With Complete Solutions Latest Update
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Solution 2024/2025Pepper
IB 150 All Practice Homework With Complete
Solutions Latest Update
What is one reason that organisms have to maintain homeostasis
(maintaining a relatively stable internal environment that differs from the
external environment)? ANS✔✔ Organisms have to perpetually keep
themselves out of equilibrium with the environment.
What can you conclude about an organism that has reached equilibrium
with its external environment? ANS✔✔ The organism is dead.
Which of the cell shapes in the previous question do you expect to make up
the lining of your respiratory system. ANS✔✔ Sheet
Match the following concepts to their appropriate relationships and
functions with respect to diffusion: ANS✔✔ the Fick's Law equation →
models the rate of diffusion
metabolic rate of organism → determines (in part) P1
each of the four variables in Fick's Law → affects the likelihood of
respiratory gas molecules to move from point A to point B via random
motions
Second Law of Thermodynamics → shows that the process of diffusion is
exergonic
surface area to volume ratio (SA/V) → explains the relationship between the
rate of supply to the rate of demand for respiratory gases
, Solution 2024/2025
Pepper
The figure below shows the simplified diagram of the insect respiratory
system that we used to model its supply of oxygen to its cells via diffusion.
Why did we have to divide the entire length that an oxygen molecule has to
traverse via diffusion from the external atmosphere to inside the
mitochondria of a body cell into two distances, and calculate the rate of
diffusion separately for the distance X-Y and Y-Z? ANS✔✔ D differs for the
two distances
In class, we determined that the larger insect was not able to achieve a
sufficient rate of diffusion from point X to point Y in its tracheal satisfy the
oxygen demand of its cells without increasing the cross-sectional area of its
tracheal tubes.
The variables of Fick's Law that we determined for our larger insect with
thin trachea is shown in the table below:
Assuming that the cells of the insect require an oxygen supply of 2.0 * 10-6
mL/min (= 0.000002), use Fick's Law to determine what the cross-sectional
area (A) of this larger insect has to minimally be in µm2 to maintain the
minimal rate of diffusion of oxygen of 2.0 * 10-6 mL/min.
Round your answer to the nearest full µm2. ANS✔✔ 110
Amphibians such as frogs breathe both with their lungs and via gas
exchange through their moist skin. Which is likely to be able to derive a
higher proportion (fraction) of its oxygen demand from gas exchange
through their skin as opposed to via its lungs? Hint: consider which concept
you need to consider to answer this question. ANS✔✔ poison dart frog (one
of the smallest frogs in the world)
Which concept did you have to apply to determine the answer to the
previous question? ANS✔✔ SA/V
, Solution 2024/2025
Pepper
There are amphibians that are even larger than bullfrogs. Which of the
following could explain how such a large amphibium could obtain a
sufficient rate of diffusion of respiratory gases? ANS✔✔ different shape (e.g.
flat or ribbon shaped)
larger internal surface area of the lungs
reduced metabolic rate (reduced rate of cellular respiration)
Respiratory surfaces must always stay moist (be covered by a very thin film
of water). Diffusion across dry surfaces is exceedingly slow.
Which variable of Fick's Law is most likely responsible for this? ANS✔✔ D
In class, we oversimplified the insect respiratory system a bit to make our
lives easier for calculating Fick's Law variables.
For example, as in any respiratory organ, the actual respiratory surfaces
where the tips of the tracheoles make contact with individual cells of the
insect are moist and filled with water.
When the insect becomes active and its muscle cells have a greater
demand for oxygen as a result, this water gradually pulls out of the
tracheoles and into the muscle cells again (see figure above). What might
the benefit of this be to the insect? ANS✔✔ Decreases the part of the
distance filled with a medium that has a lower diffusion coefficient to
increase the diffusion rate at times of high metabolic demand for oxygen.
There are many different species of marine annelid worm. Some are very
small, only a few millimeters in length. Others, such as lugworms, are much
larger. Lugworms live in U-shaped burrows that they build in the sediment
of shallow marine intertidal zones.
Ignoring surface area of gills, which of the following variables DECREASES as
a lugworm grows larger? ANS✔✔ SA/V
, Solution 2024/2025
Pepper
There are many different species of marine annelid worm. Some are very
small, only a few millimeters in length. Others, such as lugworms, are much
larger. Lugworms live in U-shaped burrows that they build in the sediment
of shallow marine intertidal zones.
Which variable does presence of gills most affect in lugworms? ANS✔✔ A
Blue whales are mammals and just like us have lungs with alveoli and
transport oxygen in blood via a closed circulatory system. However, in
contrast to us, blue whales are the biggest animals that have ever lived.
Compared to a human, the total distance that oxygen has to diffuse to
reach cells in blue whales is blank , while the distance of bulk flow for
oxygen in blue whales is blank . ANS✔✔ roughly the same,
larger.
What is a prerequisite (requirement) for counter-current exchange to
function? ANS✔✔ unidirectional flow of the outside medium (air or water)
bulk flow (mass flow) of blood and external medium (air or water)
Mammalian lungs with the respiratory surfaces in the shape of dead-end
alveoli require tidal flow to ventilate. Tidal flow is not conducive to counter-
current exchange. The next two questions ask you to explore why not.
When asked to demonstrate why something cannot work, an effective
strategy is to model the ineffective set-up and explore what the
consequences would be. Below is a diagram of what our alveoli might look
like, if they were set-up to enable counter-current flow during inhalation:
First, identify the concentration gradient for both inhalation and for
exhalation in the hypothetical alveoli above that are plumbed for counter-
current exchange during inhalation. ANS✔✔ blood during exhalation →
Phigh
blood during inhalation → Plow
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