IB 150 Exam 1 Homework

What is one aspect that most of the six qualities that set life apart share, that make life feel so different from inanimate matter?

Life is associated with a life force, distinct from the other four physical forces, that animates matter.

Living organisms are composed of organic matter, that represents different matter and obeys different physical laws than inorganic matter.

Living organisms are able to use external energy sources to perform work to perpetually keep themselves out of equilibrium with the surrounding environment.

Living organisms manage to break the laws of physics to move through the world with purpose.

Organisms are able to keep themselves in constant equilibrium with their environment.

Living organisms are able to use external energy sources to perform work to perpetually keep themselves out of equilibrium with the surrounding environment.

What is one reason that organisms have to maintain homeostasis (maintaining a relatively stable internal environment that differs from the external environment)?

Organisms have to increase the disorder inside their cells and tissues.

Organisms grow and reproduce.

Organisms have to maintain equilibrium with their environment.

Organisms have to perpetually keep themselves out of equilibrium with the environment.

Organisms have to make ATP

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?

The organism is actively performing work, such as working out its muscles.

The organism is dead.

The organism is using ATP to maintain this state of equilibrium with its environment.

The organism is healthy and actively metabolizing.

The organism is dead.

Which of the following relates the expected Gibbs free energy (G) of products and reactants in an exergonic reaction?

Products will have a lower free energy than reactants.

Products will have a higher free energy than the reactants.

Products and reactants have the same free energy.

Products will have a lower free energy than reactants.

Consider the graphs below which show G (free energy) on the y-axis during the course of a reaction (i.e., time is on the x-axis). Which graph correctly depicts how free energy changes during an endergonic reaction? (Note: R = reactants and P = products)

Graph A

Graph B

Graph C

Graph D

Graph A

What has to happen in order for an organism to undergo endergonic reactions?

Organisms have to change the ΔG of that reaction from positive to negative.

Organisms have to raise the ∆G of the reaction.

Organisms have to couple these endergonic reactions to exergonic reactions.

Organisms have to engage in aerobic cellular respiration.

Organisms have to couple these endergonic reactions to exergonic reactions.

Complete the following concept map by selecting the correct term for each marked empty field below.

field 1 → cell shapes,

field 2 → volume,

field 3 → surface area,

field 4 → diffusion rate,

field 5 → cubed,

field 6 → squared

Calculate the missing values for SA/V ratio for each of the different cell shapes. (Use the dimensions given in each figure).

Field 1 → 0.60,

Field 2 → 0.56,

Field 3 → 0.83,

Field 4 → 2.22

Which of the cell shapes in the previous question do you expect to make up the lining of your respiratory system.

Sheet

Narrow Cylinder

Cube

Cylinder

Sheet

Match the following concepts to their appropriate relationships and functions with respect to diffusion:

metabolic rate of organism → determines (in part) P1

surface area to volume ratio (SA/V) → explains the relationship between the rate of supply to the rate of demand for respiratory gases

the Fick's Law equation → models the rate of diffusion

Second Law of Thermodynamics → shows that the process of diffusion is exergonic

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

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?

D differs for the two distances

the distances X-Y and Y-Z are of very different lengths

(P2-P1) differs between the two distances

A differs between the two distances

oxygen is moved via bulk flow through one, and via diffusion through the other distance

D differs for the two distances

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.

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.

poison dart frog (one of the smallest frogs in the world)

bullfrog (one of the largest frogs in the world)

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?

A

SA/V

L

bulk flow (mass flow)

Second Law of Thermodynamics

D

(P2-P1)

SA/V

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?

a. reduced metabolic rate (reduced rate of cellular respiration)

b. different shape (e.g. flat or ribbon shaped)

c. living in an environment of lower oxygen concentration

d. larger internal surface area of the lungs

e. dry skin

reduced metabolic rate (reduced rate of cellular respiration)

different shape (e.g. flat or ribbon shaped)

larger internal surface area of the lungs

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?

L

A

D

(Phigh-Plow)

D

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?

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.

Increases the distance that oxygen diffuses through to maximize the rate of diffusion during times of increased metabolic demand for oxygen.

Increases the available respiratory surface area for diffusion where the tracheoles contact a muscle cell.

Increases the diffusion coefficient of the water to increase the diffusion rate at times of high metabolic demand for oxygen

It helps to actively ventilate the air in the trachea to move oxygen closer to the respiratory surfaces.

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.

Context for questions 19 and 20

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?

A

SA/V

Phigh-Plow

L

V

SA/V

Which variable does presence of gills most affect in lugworms?

V

Phigh-Plow

A

L

D

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 ----- while the distance of bulk flow for oxygen in blue whales is -----

roughly the same

larger

What is a prerequisite (requirement) for counter-current exchange to function?

concurrent flow of blood in capillary beds and external oxygenated medium (water or air)

bulk flow (mass flow) of blood and external medium (air or water)

unidirectional flow of the outside medium (air or water)

tidal flow of external medium (air or water)

gills

respiratory pigments in blood

bulk flow (mass flow) of blood and external medium (air or water)

unidirectional flow of the outside medium (air or water)

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.

air during exhalation → Plow

blood during exhalation → Phigh

blood during inhalation → Flow,

air during inhalation → Phigh

Based on your answer to the previous question, what problem prevents mammalian lungs from engaging in counter-current design?

If mammalian alveoli had respiratory capillaries directed to engage in counter-current exchange during inhalation

there would no longer be a concentration gradient during exhalation, and oxygen uptake would be impossible.

... the rate of the diffusion would be too slow to optimize oxygen uptake.

... the concentration gradient would reverse during exhalation and cause diffusion of oxygen from blood to the air.

... the concentration gradient would reverse during exhalation and cause diffusion of oxygen from air to the blood.

... there would no longer be a concentration gradient during inhalation, , and oxygen uptake would be impossible.

... the concentration gradient would reverse during exhalation and cause diffusion of oxygen from blood to the air.

Context for 26 and 17

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.

Lugworms create a unidirectional water current that runs through their U-shaped burrows. Why does this allow lugworms to establish a countercurrent oxygen exchange in their gills?

Enhances mixing of oxygenated and stale, deoxygenated water in its burrow that results in a reduced Phigh-Plow across the gill surfaces.

Sets up tidal flow (bidirectional flow) of water in their burrows so that water traverses gills forwards and backwards as necessary for countercurrent exchange.

Capillaries in gills can be consistently directed to run blood in the opposite direction as external water flow

BOTH a) and c)

All of the above

Capillaries in gills can be consistently directed to run blood in the opposite direction as external water flow

How is/are the relevant variable(s) of Fick's Law optimized by the countercurrent oxygen exchange in lugworm gills?

L is minimized

A is maximized

SA/V is maximized

(Phigh-Plow) is re-established

(Phigh-Plow) is maximized

(Phigh-Plow) is re-established

What is the role of each of the following structures in the mammalian respiratory system?

hemoglobin in pulmonary capillaries → supports low Plow in blood serum (liquid)

hemoglobin in systemic capillaries → supports high Phigh in blood serum (liquid)

bulk flow of blood from pulmonary to systemic capillary beds → supports low L

capillaries forming a dense net over the alveoli → supports high A

water film lining inner surface of alveoli (as opposed to dry cell surface) → supports high D

Label the numbered structures of a human heart with the appropriate term:

structure 1 → right atrium,

structure 2 → right ventricle,

structure 3 → left atrium,

structure 4 → left ventricle,

structure 5 → pulmonary artery,

structure 6 → aorta,

structure 7 → superior vena cava,

structure 8 → inferior vena cava,

structure 9 → pulmonary veins,

structure 10 → septum

The circulatory systems of most fish differ in some important ways from ours (mammalian circulatory system). Briefly: Fish have a two-chambered heart that only pumps blood from systemic veins via the ventral aorta towards the gill capillary beds. The blood leaves the gill capillaries via the dorsal aorta which delivers the blood to the systemic capillary beds without passing the heart a second time.

field 1 → high,

field 2 → low,

field 3 → low,

field 4 → low,

field 5 → low,

field 6 → high,

field 7 → low,

field 8 → low,

field 9 → low,

field 10 → low,

field 11 → low,

field 12 → high,

field 13 → high,

field 14 → low,

field 15 → low

Why is the oxygenated blood that reaches the body cells of a fish generally at lower pressure than in a mammal?

The fish's blood is harder to pump because it is typically colder than its environment.

The fish's blood is easier to pump because fish live underwater.

The fish's blood does not return to the heart after acquiring O2 in the capillaries of the gills.

The fish's heart does not have a ventricle.

The fish's blood does not return to the heart after acquiring O2 in the capillaries of the gills.

When calculating the rate of CO2 diffusion in plant leaves using Fick's Law, we have to calculate the rate of diffusion for the distance through the stomatal opening separately from the distance through the air space of the mesophyll layer.

Which variable differs systematically for the two distances that requires us to consider the rate of diffusion for these two layers separately?

D

A

L

(Phigh-Plow)

A

What is a likely explanation for this observation?

Higher CO2 concentration meant the plants had to open their stomata more (increasing its variable 'Area' of Fick's Law) to maintain adequate rates of CO2 diffusion into their leaves.

Increased drought conditions allow plants to take up additional CO2 by allowing plants to increase the variable 'Area' and decreasing the variable 'Distance' in Fick's Law.

Increased drought conditions forced plants to reduce the variable 'Area' in Fick's Law to avoid water loss to a degree that reduced diffusion rates of CO2 below today's values despite the higher atmospheric CO2 concentrations.

High CO2 concentrations force higher water loss due to increases in the variable (Phigh-Plow) in Fick's Law resulting in increased drought damage to the plants.

Increased drought conditions forced plants to reduce the variable 'Area' in Fick's Law to avoid water loss to a degree that reduced diffusion rates of CO2 below today's values despite the higher atmospheric CO2 concentrations.

Context for questions 35-39

When measuring the respiratory surface area of gills in brook trout, Abigail notices that the surface area grows linearly when compared to the volume of the fish as the fish grew:

What relationship do the data in the graph reveal as the trout grow larger?

The ratio of gill respiratory surface area to body volume increases faster than linearly

The ratio of gill respiratory surface area to body volume increases linearly

The ratio of gill respiratory surface area to body volume is constant (stays the same)

The ratio of gill respiratory surface area to body volume decreases linearly

The ratio of gill respiratory surface area to body volume decreases faster than linearly

The ratio of gill respiratory surface area to body volume is constant (stays the same)

In bodies of the same shape, surface area always grows faster than the volume, resulting in no limitations for the oxygen supply.

As a body of the same shape gets larger, its ratio of external surface area to body volume always stays the same, so that when the volume doubles, the external surface area also doubles.

As the body of the fish grows, its gill surface area has to increase more slowly than predicted for the SA/V ratio of a body of the same shape so that its gill surface area doubles when its body volume doubles during growth.

As the body of the fish grows, its gill surface area has to increase much faster than predicted for the SA/V ratio of a body of the same shape so that its gill surface area doubles when its body volume doubles during growth.

As the body of the fish grows, its gill surface area has to increase much faster than predicted for the SA/V ratio of a body of the same shape so that its gill surface area doubles when its body volume doubles during growth.

Knowing the difference in oxygen concentration in their environment, and assuming everything else in carp is equal to the brook trout example, which of the dotted lines shows the predicted relationship of body volume to gill surface area in carp in comparison to the brook trout relationship (thin solid line)?

Line A

After Alessandro collected some data, he finds that the carp data are most similar to Line B in the previous question, i.e. that the relationship of gill surface area and volume in carp is similar to that of trout.

Which of the following hypotheses may be possible explanations that are consistent with the data and that Alessandro can set out to test next in his carp study system?

Carp experience higher oxygen concentrations in their environment than previously assumed.

Carp experience lower oxygen concentrations in their environment than previously assumed.

Carp have a larger distance of diffusion in their gills.

Carp have a higher concentration of hemoglobin in their blood than trout do.

Carp live in oxygen-depleted waters.

Carp habitually are stronger and more active swimmers than trout.

Carp lack hemoglobin in their blood.

Carp have a lower metabolic energy requirement than trout do.

Carp have a higher concentration of hemoglobin in their blood than trout do.

Carp have a lower metabolic energy requirement than trout do.

Carp experience higher oxygen concentrations in their environment than previously assumed.

Below are some additional observations about icefish. Match each of these observations to a relevant parameter (variable) that could help explain how these curious fish can maintain sufficient oxygen supply to satisfy their metabolic demand despite the lack of respiratory pigments.

Cold water can dissolve more oxygen than warm water. → high Phigh (high concentration)

Ice fish have an unusually high volume of blood compared to their body weight. → high rate of O2 transport via bulk flow

Icefish only live in water near the freezing point. → low metabolic demand for oxygen

Ice fish contain a protein in their blood that acts as an antifreeze. → does not explain meeting metabolic demand for oxygen

Some species of icefish are nearly transparent because they also lost the muscle pigment myoglobin. → does not explain meeting metabolic demand for oxygen

Icefish have no scales in their skin, and can hence use their skin as a respiratory surface. → high A (area)

Birds engage in counter-current exchange, mammals do not. Simply based on what you know about counter-current exchange, in which group of animal would you predict to find that respiratory capillaries flow alongside respiratory surfaces over a longer length for?

birds

mammals

birds

Which of the following statements is true?

Density-independent growth is more likely to occur in large than in small populations.

A population that is experiencing density-independent growth levels off at the carrying capacity.

Density-independent growth can continue indefinitely in nature.

Density-independent growth results in exponential population growth.

Density-independent growth results in exponential population growth.

Which of the following statements about a population experiencing logistic growth is true?

If the values for N and K are similar, the amount of available resources is high.

If the values for N and K are far apart, the population will grow very slowly.

If N is less than K, the population will not grow.

If N is greater than K, the population size will decline.

If N is greater than K, the population size will decline.

Based on the figure, which statement correctly interprets the data? (clutch size is the number of eggs in the nest)

Female density is affected by clutch size.

There is sexual selection on clutch size.

There are density-dependent effects on clutch size.

Survival rate is affected by female density.

There are density-dependent effects on clutch size.

Until quite recently, the total human population in the world was less than 1 billion people. Starting with the industrial revolution, the population size dramatically increased, and recently reached 7 billion people worldwide. Although the rate of population growth has slowed since the 1980s, the global population is expected to continue to rise to 9 billion people by 2050, and to finally level off somewhere around 10-13 billion people by 2100.

Use the data in Table 1 to determine the annual population growth rate (r) for the global human population (a) pre-industrial revolution and (b) by mid-20th century:

For the time interval 1800-1801, r = [0.011].

For the time interval 1950-1951, r = [0.024].

Each of the following are true statements about changes that occurred between 1800 and 1950 AD.

Select one or more that could account for the direction of change in the population growth rate you calculated in the previous question

Advances in medicine led to a dramatic reduction in mortality, particularly infant mortality.

Advances in mechanized farming and pest control resulted in rising crop yields per acre (more food grown per farmed acre).

Technological advances, particularly in irrigation technology and industrial production of fertilizers, allowed for expansion of agriculture onto land that was previously unsuitable for growing of crops.

Based on your answer to question 4, the human population grew ----- between 1800 and 1950 AD.

faster than exponentially

The status of black-footed ferrets will be reevaluated and potentially downgraded from "critically endangered" to "endangered" once their population size exceeds 2000 individuals. Assuming no change to their annual growth rate in 2010, in what calendar year (in AD) would this occur?

2014

A population survey of this population of black-footed ferrets in the same year you identified in the previous question found ~1300 individuals in the wild instead of your estimate of over 2000. What can you conclude happened to this population since 2010 based on a comparison of your population size estimate for this year in the previous question and the observed number?

The population growth rate declined since 2010.

The death rate of individuals increased from 0.2 to 0.3 after 2010.

More individuals died per year than before 2010.

The birth rate declined from 0.4 to 0.3 after 2010.

The number of offspring per female declined from 3 to 1 after 2010.

The population growth rate declined since 2010.

What is the growth rate in the year you just identified in question 7 above, given the population size of 1300 in this year and a population size of 1090 individuals as revealed by a census in the previous year?

0.1925

Which of the following hypotheses are consistent with this observed predator-prey relationship between black-footed ferrets and prairie dogs? You may assume that the ferrets are immune to Yersinia pestis and hence not directly affected by this bacterium for this question.

The realized niche of black-footed ferrets is limited by competition with the pathogenic bacterium Yersinia pestis.

The carrying capacity of black-footed ferrets is closely tied to the population size of prairie dogs.

Black-footed ferrets are the only main predator of prairie dogs.

The food web that includes black-footed ferrets is relatively linear, preventing prey-switching of the ferrets.

The realized niche of black-footed ferrets is limited by competition with prairie dogs.

The food web that includes black-footed ferrets is relatively linear, preventing prey-switching of the ferrets.

The carrying capacity of black-footed ferrets is closely tied to the population size of prairie dogs.

In the case of two competing barnacle species, the larger species Semibalanus is able to eliminate individuals of the smaller species Chthamalus through interference competition over its entire fundamental niche by overgrowing or dislodging them as they grow larger. Which of the following could be an explanation (reasonable hypothesis) that is sufficient to fully explain why Chthamalus evades competitive exclusion within the high-tide zone?

Semibalanus is outcompeted by Chthamalus in the high-tide zone.

The fundamental niche of Chthamalus extends over the entire tidal zone (both high and low-tide).

Chthamalus is competitively excluded in the low-tide zone.

The high-tide zone is outside the range of tolerance for Semibalanus.

The fundamental niche of Semibalanus extends over the entire tidal zone (both high and low-tide).

The high-tide zone is outside the range of tolerance for Semibalanus.

Why are populations of both competing species increasing at the time step indicated by the arrow?

Resources are unlimited in this environment.

Their population sizes are well below their carrying capacity.

In the presence of species 2, the carrying capacity for species 1 is lower due to competition for the same resources.

The resource demand of the one species is reducing the carrying capacity of the other in this environment.

Their niches overlap completely.

Their population sizes are well below their carrying capacity.

Which of the following has to be true about the two species shown in the graph in the previous question?

In the absence of the other species, species 1 is more likely to maintain a higher carrying capacity than species 2.

Species 1 is competitively superior to species 2 in some environmental settings, and species 2 is competitively superior to species 1 in other environmental settings in the area these data were collected in.

Species 2 is competitively superior to species 1 across the full range of environmental variation encountered in the observed area.

Species 1 is competitively superior to species 2 across the full range of environmental variation encountered in the observed area where the populations size data in this plot were collected.

The intrinsic rate of growth of species 1 has to be higher than that of species 2.

The niche of species 1 overlaps completely with that of species 2 in the environment th

The niche of species 1 overlaps completely with that of species 2 in the environment these data were collected in.

Species 1 is competitively superior to species 2 across the full range of environmental variation encountered in the observed area where the populations size data in this plot were collected.

In the absence of the other species, species 1 is more likely to maintain a higher carrying capacity than species 2.