BIO 311D Exam 4

Which of these is the largest terrestrial biome on Earth? tundra coniferous forest temperate broadleaf forest temperate grassland desert

coniferous forest Coniferous forests are the largest terrestrial biome on Earth. However, as a result of logging, they are disappearing at a very rapid rate.

The leaves at the top of a tree's canopy are exposed to direct sunlight during the day, and their phytochromes will occur in a high _____ ratio. Meanwhile, the leaves of the same tree at the bottom of the canopy are highly shaded during the day and will likely have a higher proportion of the _____ form of phytochrome present due to exposure to a higher proportion of _____ light.

Pfr/Pr Pr far-red

Show the sequence of events that occurs once the membrane potential reaches threshold.

(1) membrane potential reaches threshold -> (2) many voltage-gated Na+ channels open -> (3) Na+ ions rush into the cell -> (4) membrane potential rises (depolarizes) rapidly

10,000 kcal of producer could support approximately _____ kcal of tertiary consumer. 1,000 100 10 1 0

10

At location __, the axon membrane reaches threshold and the voltage gated Na+ channels open.

F

Cell-mediated response

cytotoxic T cells

In the caterpillar, 100 J are lost in feces, or __% of the energy it consumes.

50%

Humoral response

B cells antibodies plasma cells

Which equation represents the logistic growth rate of a population?

ΔN/Δt = (r max)N(K-N)/K

Age (years) 0-1 1-2 2-3 Number Alive at Start of Year 80 64 40 Proportion Alive at Start of Year 1.000 0.800 blank Death Rate ? blank blank Average Number of Female Offspring 0.00 1.20 2.40 Which equation determines the death rate in year 0-1? (This value is marked with a "?" in the table.)

(80-64)/80 = 0.200 To calculate the death rate in year 0-1, divide the number of squirrels that died that year by the number alive at the start of the 0-1 year. To determine the number of squirrels that died in year 0-1, subtract the number of squirrels alive at the start of year 1-2 from the number of squirrels alive at the start of year 0-1. That is (80-64)/80 = 0.200.

There are two properties that affect the conduction speed of an action potential along an axon: the axon's diameter and whether or not the axon is myelinated. Rank the axons from slowest to fastest conduction speed. If two axons have the same conduction speed, place one on top of the other.

(slowest) non-myelinated invertebrate axon 20 um diameter non-myelinated invertebrate axon 30 um diameter non-myelinated invertebrate axon 40 um diameter myelinated vertebrate axon 30 um diameter (fastest) For non-myelinated axons, the larger the diameter of the axon, the faster the conduction speed of an action potential. However, even the smallest myelinated axons are much faster than the largest non-myelinated axons (the squid axon, for example).

Which size forest fragment would be most affected by habitat fragmentation over a given period of time? 1000 hectares. 100 hectares. 10 hectares. 1 hectare.

1 hectare The smallest fragments would be most affected by habitat fragmentation due to disturbances flowing into the fragment from the exterior.

What are rain shadows? -Dry regions on the leeward side of mountain ranges. -Wet regions on the windward side of mountain ranges. -Wet regions on the leeward side of mountain ranges. -Dry regions on the windward side of mountain ranges.

Dry regions on the leeward side of mountain ranges.

Assume there are 200 MendAliens living on an island in my back yard. If my island has an area of 20 hectares, what is the population density of MendAliens in terms of MendAliens per hectare?

10 MendAliens per hectare Population density is calculated as population size divided by area: 200 MendAliens / 20 hectares = 10 MendAliens per hectare.

This graph represents a person's level of Antibodies to antigen A (exposed at day 0 and again at day 28) and Antibodies to antigen B (exposed at day 28). Using the patterns/information presented, if you expose this individual to antigen C on day 56, what are you likely to see? Give a brief explanation of your reasoning. a) 103 antibodies to B on day 61 b) 104 antibodies to A on day 61 c) 10 antibodies to C on day 61 d) 10 antibodies to C on day 67 e) 10 antibodies to A on day 67

10 antibodies to C on day 67 Explanation: According to the graphs of exposure to antigens A & B, the initial antibody concentrations are around 10^1, which is between 10-14 days after exposure. So, antigen C should give a similar response in which around 11 days after exposure, you should see approximately 10^1 antibodies.

What is the correct sequence in which these events in systemic acquired resistance occur? 1. Phloem transports chemical signal to plant parts distant from the site of attack. 2. Damaged tissues secrete methyl-salicylic acid. 3. Salicylic acid induces production of P R proteins. 4. Methyl-salicylic acid is converted to salicylic acid in healthy cells.

2, 1, 4, 3 damaged tissues secrete methyl-salicylic acid -> phloem transports chemical signal to plant parts distant from the site of attack -> methyl-salicylic acid is converted to salicylic acid in healthy cells -> salicylic acid induces production of P R proteins

If an action potential lasts from the beginning of the rising phase to the point of maximal undershoot, what is the maximum frequency at which a neuron could fire action potentials? Assume that the neuron can fire only one action potential at a time and that the refractory period following the action potential is equal in length to the action potential. a) 0.0023 events per second (Hz) b) 0.0046 events per second (Hz) c) 220 events per second (Hz) d)430 events per second (Hz)

220 events per second

Predict how the coleoptile will grow (or not grow) under each treatment. Cut coleoptile (tip removed)

24 hour dark: short and straight 24 hour light: short and straight

Predict how the coleoptile will grow (or not grow) under each treatment. Cut coleoptile with mica insert

24 hour dark: short and straight 24 hour light: short and straight

Predict how the coleoptile will grow (or not grow) under each treatment. Cut coleoptile with agar insert

24 hour dark: tall and straight 24 hour light: tall and bent

Predict how the coleoptile will grow (or not grow) under each treatment. Intact coleoptile (control)

24-hour dark: tall and straight 24 hour light: tall and bent

In the caterpillar, 33 J are used for biosynthesis, or __% of the assimilated energy.

33%

Approximately _____% of the energy at one trophic level is passed on to the next highest trophic level. 0-5 5-10 10-15 15-20 90-100

5-10

You are doing a mark-recapture experiment to determine the population size of the MendAliens living on an island in my back yard. Initially, you catch and mark 130 MendAliens, which you then release. Next, you capture 90 MendAliens, of which 20 are marked. What is your estimate of the population size of MendAliens living on the island in my back yard?

585 To get the population size N, multiply the number marked in the first catch, M1, by the total number caught in the second catch, C, and divide that by the number of marked recaptures in the second catch, M2: N = (M1 x C) / M2 Or: (130 x 90) / 20 = 585.

Suppose that scientists also studied a second population of Belding's ground squirrels from a different habitat. Life table data for the first three years of this hypothetical population are shown below. (Note that the table is not completely filled in because you will be calculating some of these values.) Age (years) 0-1 1-2 2-3 Number Alive at Start of Year 80 64 40 Proportion Alive at Start of Year 1.000 ? blank Death Rate blank blank blank Average Number of Female Offspring 0.00 1.20 2.40 Which equation determines the proportion of ground squirrels alive at the start of year 1-2? (This value is marked with a "?" in the table.)

64/80 = 0.800 To calculate the proportion alive at the start of year 1-2, divide the number alive at the start of year 1-2 by the number alive at the start of year 0-1. That is 64/80 = 0.800.

In the caterpillar, 67 J are used in cellular respiration, or __% of the assimilated energy.

67%

If a short-day plant has a critical night length of 15 hours, then which of the following 24-hour cycles will prevent flowering? A) 8 hours light/16 hours dark B) 4 hours light/20 hours dark C) 6 hours light/2 hours dark/light flash/16 hours dark D) 8 hours light/8 hours dark/light flash/8 hours dark

8 hours light/8 hours dark/light flash/8 hours dark

At location __, the voltage gated Na+ channels reactivate.

A

Suppose you laid a seedling on its side so that the root was parallel to the ground as shown in the figure. Several hours after the change in position, where in the root cells, position A, B, or C in the figure, would you find the amyloplasts?

A

Each muscle cell is in contact with a single motor neuron that controls the contraction of that cell. The diagram below shows a single muscle fiber and its motor neuron. Understanding the unique structural components of a muscle cell and its interaction with its motor neuron is a prerequisite for understanding muscle contraction and how it is regulated. Drag the labels to their appropriate locations on the diagram below

A skeletal muscle cell is composed of a large number of contractile fibrils called myofibrils. The basic unit of contraction in a myofibril is a sarcomere. The sarcomeres are arranged end to end along the entire length of each myofibril. Each myofibril is partially surrounded by a specialized form of endoplasmic reticulum, called the sarcoplasmic reticulum. An action potential traveling along the motor neuron initiates an action potential in the muscle cell, which leads to muscle contraction. At the synaptic terminal of the motor neuron, an action potential causes the release of neurotransmitters, which subsequently trigger an action potential on the plasma membrane of the muscle cell. This action potential is propagated deep into the muscle cell via the T (transverse) tubules. In the interior of the cell, the action potential initiates changes in the sarcoplasmic reticulum.

Which of the following is most likely to survive a changing climate? A species with low genetic diversity. A species in which all members are genetic clones. A species with a large amount of genetic diversity. A species with all genetically identical members.

A species with a large amount of genetic diversity.

Which statement correctly describes what causes the second voltage-gated Na+ channel to open? - As Na+ ions enter the cell through the first channel, they spread out from the channel. When these Na+ ions reach the second channel, it opens. - As Na+ ions enter the cell through the first channel, Na+ ions outside the cell move toward the open Na+ channel. When the concentration of Na+ ions near the second channel becomes low enough, the second channel opens. - After the first channel opens, the movement of Na+ ions (both inside and outside the cell) alters the Na+ ion distribution across the membrane near the second channel, causing it to open. - After the first channel opens, the movement of many types of ions (both inside and outside the cell) alters the distribution of charges near the second channel, causing it to open.

After the first channel opens, the movement of many types of ions (both inside and outside the cell) alters the distribution of charges near the second channel, causing it to open. When Na+ ions enter the cell through the first channel, the charge distribution across the membrane changes. Inside the cell, the increase in Na+ ions near the first channel makes that region more positive; as a result, negative ions are attracted to the region, while positive ions are repelled. Conversely, outside of the cell, the loss of Na+ ions makes the region near the first channel more negative; as a result, positive ions are attracted to that region, while negative ions are repelled. Together, all of these ion movements alter the charge (and thus the membrane potential) at the neighboring channel, allowing it to reach threshold.

Calculate NEP after the outbreak, and identify the most appropriate conclusion about whether the forest was a carbon sink or a carbon source. a) After the outbreak, the forest was a carbon source because NEP was less than 0. b) After the outbreak, the forest was a carbon source because NEP was greater than 0. c) After the outbreak, the forest was a carbon sink because NEP was greater than 0. d) After the outbreak, the forest was a carbon sink because NEP was less than 0.

After the outbreak, the forest was a carbon source because NEP was less than 0. NEP = NPP - Rh NEP = 400 - 424 = -24 NEP of -24 < 0...so a carbon source.

Which of the following statements are true of logistic growth? -As the population approaches carrying capacity, it grows more slowly. -As the population approaches carrying capacity, it grows more rapidly. -When the population reaches carrying capacity, it stops growing. -The population grows at a steady rate.

As the population approaches carrying capacity, it grows more slowly. When the population reaches carrying capacity, it stops growing.

Which of the following statements about Hadley cells is true? -Warm air expands and rises from the surface of the atmosphere around the poles. -As warm air rises, air at the top of the atmosphere is pushed poleward and cools. -The moisture in cool air condenses into clouds and precipitates because cool air holds more moisture than warm air. -Warm air begins to cool as it starts to sink at about 30° North and South latitude.

As warm air rises, air at the top of the atmosphere is pushed poleward and cools.

The diagram below shows the five main transport proteins that control the distribution of Na+ and K+ ions across the plasma membrane of an axon. Assume that the membrane is at resting potential---the membrane potential of the axon remains constant at about -70 mV. Drag the arrows onto the diagram to show the direction of Na+ (gray arrows) and K+ (red arrows) movement through each transport protein at resting potential. If no ions move through a transport protein at resting potential, leave that target blank.

At resting potential, the membrane potential remains constant at about -70 mV. This means that there is no net movement of ions across the membrane. Assuming that Na+ and K+ are the only ions that move at resting potential, Na+ movement out of the cell through the sodium-potassium pump is balanced by an influx of Na+ through the non-gated Na+ channels. Conversely, K+ movement into the cell through the sodium-potassium pump is balanced by an outward movement of K+ through the non-gated K+ channels.

At location __, the voltage gated K+ channels are closing.

B

Calculate NEP before the outbreak and identify the most appropriate conclusion about whether the forest was a carbon sink or a carbon source. a) Before the outbreak, the forest was a carbon sink because NEP was greater than 0. b) Before the outbreak, the forest was a carbon source because NEP was greater than 0. c) Before the outbreak, the forest was a carbon source because NEP was less than 0. d) Before the outbreak, the forest was a carbon sink because NEP was less than 0.

Before the outbreak, the forest was a carbon sink because NEP was greater than 0. NEP = NPP - Rh NEP = 440 - 408 = 32 NEP of 32 > 0...so a carbon sink.

Which processes increase a population's size? -Deaths and emigration -Deaths and immigration -Births and immigration -Births and deaths

Births and immigration

Drag the labels onto the graph to indicate which presynaptic neuron produced each change in the axon hillock's membrane potential. Assume that the same number of ligand-gated ion channels opens at each synapse.

By analyzing each change in the membrane potential at the axon hillock of the postsynaptic neuron, you can tell which presynaptic neuron produced the change. For example, when the membrane potential at the axon hillock becomes more negative (hyperpolarizes), you know that an inhibitory postsynaptic potential (IPSP) was produced at the synapse. Conversely, when the membrane potential at the axon hillock becomes less negative (depolarizes), you know that an excitatory postsynaptic potential (EPSP) was produced at the synapse. Because postsynaptic potentials decrease in magnitude with distance from the synapse, a smaller change in the axon hillock's membrane potential indicates that the presynaptic neuron that produced that potential is farther away. Conversely, a presynaptic neuron nearer the axon hillock will produce a larger change in the axon hillock's membrane potential. Finally, an action potential is generated in the postsynaptic cell only when the membrane potential at the axon hillock reaches threshold. In this example, both presynaptic neurons that produce EPSPs must produce potentials nearly simultaneously in order to bring the membrane potential at the axon hillock to threshold. This effect is called summation.

Match the letter of each location along the axon with the correct description of what is occurring at that position. At location __, the membrane potential changes sign (from a positive to negative value) and the voltage gated K+ channels are open.

C

_____ are secondary consumers. Producers Herbivores Plants Cows Carnivores

Carnivores Secondary consumers are animals that eat other animals; thus, they are carnivores.

What are population dynamics? -Regular fluctuations in the population size of some animals. -Proportion of individuals at each possible age. -Number of individuals born each year in a population. -Changes in populations through time.

Changes in populations through time

At location __, the voltage gated Na+ channels are inactivating and the voltage gated K+ channels are opening.

D

Which of the following statements about density-independent growth is true? -A population that is experiencing density-independent growth levels off at the environment's carrying capacity. -Density-independent growth can continue indefinitely in nature. -Density-independent growth is also known as exponential growth. -The per-capita rate of increase may exceed rmax during density-independent growth.

Density-independent growth is also known as exponential growth.

The fixed pattern of changes in membrane potential during an action potential is coordinated by the sequential opening and closing of voltage-gated ion channels. Can you identify the status (open/closed) of the voltage-gated Na+ and K+ channels during each phase of an action potential? Drag the appropriate labels onto the graph to indicate the status (open or closed) of the voltage-gated Na+ and K+ channels during each phase of an action potential. Labels may be used once, more than once, or not at all.

During the rising phase, the membrane potential becomes less negative because voltage-gated Na+ channels are open and Na+ ions enter the cell. During the falling and undershoot phases, the membrane potential becomes more negative because voltage-gated K+ channels are open (while voltage-gated Na+ channels are closed) and K+ ions leave the cell. At resting potential, both types of voltage-gated channels are closed and no ions move through the voltage-gated channels.

At location __, the membrane potential changes sign (from a negative to positive value) and the voltage gated Na+ channels are open.

E

Which of the following statements about energy flow are true? Energy spent on cellular respiration is available to higher trophic levels. Energy used in the production of offspring is available to higher trophic levels. Autotrophs typically capture about 90% of the available energy from the sun through photosynthesis. In a trophic pyramid, biomass represents chemical energy. If the lowest trophic level of an ecosystem--the primary producers--contains 1,200 grams of biomass per square meter, it is reasonable to expect the secondary consumer level to contain about 12 grams of biomass per square meter. Energy contained in feces is available to higher trophic levels. Animals that produce their own body heat and maintain a high body temperature are likely to be less efficient at converting food into biomass than are animals that do not regulate their body temperature.

Energy used in the production of offspring is available to higher trophic levels. In a trophic pyramid, biomass represents chemical energy. If the lowest trophic level of an ecosystem--the primary producers--contains 1,200 grams of biomass per square meter, it is reasonable to expect the secondary consumer level to contain about 12 grams of biomass per square meter. Animals that produce their own body heat and maintain a high body temperature are likely to be less efficient at converting food into biomass than are animals that do not regulate their body temperature.

Which location on Earth receives the most solar radiation per unit area? -Equator -30° North and South latitude. -South Pole. -North Pole.

Equator The equator receives the most solar radiation per unit area because sunlight arrives almost perpendicular to Earth's surface there.

Exotic species

Exotic, or non-native, species often disrupt the ecosystem where they are introduced. Exotic species may prey on native species, outcompete native species for resources, or infect native species with new diseases. Sometimes, exotic species can change the environment to such an extent that it is no longer habitable by native species. The European starling was introduced to New York over a century ago, and since then has spread across North America, displacing many native songbirds.

True or false? Weather is defined as the prevailing long-term atmospheric conditions in a particular region.

False Climate is defined as the prevailing long-term weather conditions in a particular region; weather is defined as the short-term atmospheric conditions of temperature, sunlight, moisture, and wind.

At location __, the axon membrane is at resting potential.

G

Habitat loss and fragmentation

Habitat loss and fragmentation are the greatest threats to biodiversity. Fragmentation can lead to genetic isolation of smaller populations and increased probability of local extinction of some species, especially large mammals. Draining wetlands, clearing tropical forests, and destroying ocean bottom structures are examples of habitat loss.

Which of the following statements about a population experiencing logistic growth is true? -If the K and N values are similar, the amount of available resources is high. -If the K and N values 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 will shrink.

If N is greater than K, the population will shrink. This statement is true, since K is the maximum number of individuals that can be supported in a particular habitat over a sustained period of time.

The cycle diagram below shows the sequence of events that affect Ca2+ levels in a muscle cell, beginning with the propagation of an action potential down a T tubule (top of the diagram). Drag the labels to their appropriate locations on the cycle diagram below. Note that SR stands for sarcoplasmic reticulum.

In muscle cells, the cytosolic Ca2+ concentration is kept low by active transport of Ca2+ from the cytosol into the sarcoplasmic reticulum. When an action potential moves down the T tubules, it triggers Ca2+ channels in the sarcoplasmic reticulum to open. As a result, Ca2+ ions rush into the cytosol. Once in the cytosol, the Ca2+ ions diffuse into the myofibrils, where they enable muscle contraction to begin. When the action potential is completed, the Ca2+ channels in the sarcoplasmic reticulum close, and Ca2+ ions are again pumped back into the sarcoplasmic reticulum. As the cytosolic level of Ca2+ drops, Ca2+ ions diffuse out of the myofibrils, stopping muscle contraction.

Which of the following statements correctly describe(s) the relationship between Ca2+ concentration in the cytosol and the response in the sarcomere? -Increasing Ca2+ concentration causes movement of tropomyosin, exposing myosin-binding sites on actin. -Increasing Ca2+ concentration causes troponin to bind to tropomyosin. -Decreasing Ca2+ concentration causes dissociation of Ca2+ from troponin. -Decreasing Ca2+ concentration promotes interactions between actin and myosin. -Increasing Ca2+ concentration causes troponin and tropomyosin to bind to actin.

Increasing Ca2+ concentration causes movement of tropomyosin, exposing myosin-binding sites on actin. Decreasing Ca2+ concentration causes dissociation of Ca2+ from troponin.

The average age of childbearing in country A is 26, whereas the average age in country B is 30. In each country, the average number of offspring per woman is 3. Which of the following statements about the population growth rate in each country must be true? -The population growth rate in country A is lower than in country B. -The population growth rate in country A is higher than in country B. -It is not possible to compare the population growth rates of countries A and B. -The population growth rates in countries A and B are the same.

It is not possible to compare the population growth rates of countries A and B. because the death rates in each country are unknown.

Which of the following is true? Lengthy droughts lead to an increase in mountain pine beetles. Weather has no impact on mountain pine beetle populations. Heavy floods lead to an increase in mountain pine beetles. Lengthy droughts lead to a decrease in mountain pine beetles.

Lengthy droughts lead to an increase in mountain pine beetles.

Cytotoxic T cells are the effector cells in the cell-mediated immune response. The diagram below summarizes the interaction of a cytotoxic T cell and its target cell. Drag the labels to their appropriate locations on the diagram below using the following steps.

Multiple molecules are involved in the activation and action of cytotoxic T cells. A cytotoxic T cell is activated through interaction with antigen-presenting cells and signals from helper T cells. Once a cytotoxic T cell has been activated, it can recognize an infected cell presenting a specific antigen fragment on its surface. The T cell receptor (TCR) recognizes the class I MHC-antigen fragment complex, and the CD8 protein on the cytotoxic T cell binds to the MHC molecule. To kill the infected cell, the cytotoxic T cell secretes perforin and granzymes. Perforin perforates the cell by forming pores, allowing granzymes to enter the cell and break down proteins. This leads to apoptosis, or programmed cell death. Once a cytotoxic T cell has induced apoptosis in a cell, it moves on to attack other infected cells or cancer cells.

NEP = _____ - Rh

NPP

NEP = GPP - (Rh + Ra) where GPP =

NPP + Ra

NEP = ( ___ + Ra) - (Rh + ___)

NPP; Ra

Overexploitation

Overexploitation is the harvesting of organisms faster than they can reproduce. For example, some scientists estimate that there may have been 3 to 5 billion passenger pigeons in North America when Europeans first arrived. Hunters began overharvesting these pigeons in the 1800s, leading to a notable decrease in numbers and contributing to the extinction of the species.

Consider a plant that grows best in bright sunlight in which seed germination is controlled by phytochromes. Which of the following statements describe(s) the structure and function of phytochromes in this plant?

Phytochromes absorb red light maximally when the phytochrome is in the Pr configuration. When a phytochrome in the Pfr configuration absorbs far-red light, the phytochrome converts to the Pr configuration. The plant seeds are more likely to germinate after exposure to red light than after exposure to far-red light. Phytochromes contain photoreceptors.

Which of the following statements about age pyramids is true? -Populations in developed countries grow more quickly than populations in less-developed countries. -Predictions of a population's future take into account such factors as increasing survivorship and fecundity levels that remain the same. -Age distribution in developed countries shows an hourglass pattern, with the greatest numbers of people being either very young or very old. -Age distribution in less-developed countries is bottom-heavy, indicating that these populations are dominated by the very old.

Predictions of a population's future take into account such factors as increasing survivorship and fecundity levels that remain the same.

NEP = GPP - RT where RT =

Ra + Rh

Which desert is caused by a Hadley cell? -Patagonian Desert in Argentina. -Desert next to the Rockies. -Atacama Desert in Chile. -Sahara Desert in Africa.

Sahara desert in Africa

Which of the following statements about systemic acquired resistance (SAR) in plants is false? Hormones produced by an attacked leaf carry a signal to the rest of the plant. Salicylic acid is the only compound involved in SAR signaling. A suite of genes called the pathogenesis-related loci is expressed in response to a signal from an attacked leaf. SAR results in the production of protective compounds distant from the site of initial infection.

Salicylic acid is the only compound involved in SAR signaling. This statement is false; salicylic acid is involved in the SAR response, but its function is unclear and there may be other molecules involved in SAR signaling.

Which of the following statements correctly describe(s) T tubules and their role in conducting action potentials in muscle cells? - T tubules have receptor proteins that bind neurotransmitters released from the synaptic terminal of the motor neuron. - T tubules are extensions of the sarcoplasmic reticulum that are in contact with the plasma membrane. - T tubules carry action potentials into the interior of the muscle cell via voltage-gated Na+ and K+ channels. - T tubules lack the voltage-gated Na+ and K+ channels that are present in the plasma membrane. - Without T tubules, the muscle cell would not be able to contract. - T tubules are infoldings of the plasma membrane that encircle the myofibrils and are in contact with the sarcoplasmic reticulum.

T tubules carry action potentials into the interior of the muscle cell via voltage-gated Na+ and K+ channels. Without T tubules, the muscle cell would not be able to contract. T tubules are infoldings of the plasma membrane that encircle the myofibrils and are in contact with the sarcoplasmic reticulum.

How does a plant defend against herbivores? Plant cells at the site of attack are killed to starve the herbivore of nutrients. The hormone systemin is produced at the site of injury and signals the plant to produce proteinase inhibitors. The plant produces molecules that stimulate the herbivore's digestive enzymes. Plant cells produce salicylic acid to warn the rest of the plant about the attack.

The hormone systemin is produced at the site of injury and signals the plant to produce proteinase inhibitors.

What does a pyramid of net production look like in a real ecosystem, and what are the trophic efficiencies? The pyramid below represents the data collected from H. T. Odum's work on the Silver Springs ecosystem in north-central Florida. (Note that Odum used the units kilocalories [kcal] instead of joules [J].) Drag the labels to the pyramid to indicate the trophic efficiency from each trophic level to the next.

The idealized pyramid of net production uses the typical values of 1% for the conversion of sunlight energy to net primary production and 10% for trophic efficiency. In real ecosystems, trophic efficiencies usually vary from about 5% to about 20%. The numbers for the Silver Springs ecosystem fall within this range.

Which of the following statements about the effects of forest fragmentation on plant biomass and species diversity is true? The loss of plant biomass has a domino effect on other species that live in the forest fragment. Small forest fragments lose their species diversity at the same rate as large forest fragments. The loss of plant biomass correlates mostly with the death of understory plants. Large forest fragments (>1000 hectares) are not affected by edge effects and their species diversity is expected to be stable over a long period of time.

The loss of plant biomass has a domino effect on other species that live in the forest fragment. This phenomenon exacerbates the edge effects seen in forest fragments and causes a more rapid loss of species diversity in the fragment.

In 1970, the average age of childbearing was 28, and the average number of offspring per woman was 3 in a certain country. In 1980, the average age of childbearing was still 28, but the average number of offspring per woman was 2 in that country. If the death rate in the country remained constant during those years, how did the population growth rate change from 1970 to 1980?

The population growth decreased. Reducing the average number of offspring per woman decreases the population growth rate.

Which of the following statements are true of a population at carrying capacity? -The rate at which resources are used is equal to the rate at which they are supplied. -The population growth rate equals zero. -The population continues to grow at a constant rate. -The birth rate equals the death rate.

The rate at which resources are used is equal to the rate at which they are supplied. The population growth rate equals zero. The birth rate equals the death rate.

Drag the labels to their appropriate locations on the diagram below, indicating the function of each structure during muscle contraction.

The thin filaments and thick filaments in a sarcomere interact with each other when an action potential triggers the muscle to contract. The thin filament is composed of actin and regulatory proteins that respond to changes in the Ca2+ concentration in the sarcomere. The thick filament is composed of myosin proteins, whose heads bind to actin and pull the thin filament toward the center of the sarcomere.

Based on these data alone, identify the most appropriate statement about the impact mountain pine beetle outbreaks may have on climate regulation. a) These data demonstrate that mountain pine beetle outbreaks can convert forest ecosystems from carbon sources to carbon sinks. A forest that is a carbon sink absorbs more CO2 from the atmosphere than it releases, contributing to a diminished greenhouse gas effect and less warming. b) These data demonstrate that mountain pine beetle outbreaks can convert forest ecosystems from carbon sinks to carbon sources. A forest that is a carbon source releases more CO2 to the atmosphere than it absorbs, contributing to higher atmospheric CO2 concentrations and an enhanced greenhouse gas effect. c) These data demonstrate that mountain pine beetle outbreaks can convert forest ecosystems from carbon sinks to carbon sources. A forest that is a carbon source absorbs more CO2 from the atmosphere than it releases, contributing to a diminished greenhouse gas effect and less warming. d) These data demonstrate that mountain pine beetle outbreaks can convert forest ecosystems from carbon sources to carbon sinks. A forest that is a carbon sink releases more CO2 to the atmosphere than it absorbs, contributing to higher atmospheric CO2 concentrations and an enhanced greenhouse gas effect.

These data demonstrate that mountain pine beetle outbreaks can convert forest ecosystems from carbon sinks to carbon sources. A forest that is a carbon source releases more CO2 to the atmosphere than it absorbs, contributing to higher atmospheric CO2 concentrations and an enhanced greenhouse gas effect.

True or false? Factors that determine the per capita rate of increase of a population include the age of breeding and the number of offspring produced each year.

True The per capita rate of increase of a population is the difference between the per capita birth rate and the per capita death rate, and is determined by factors that include the age of breeding and the number of offspring produced each year.

True or false? Biologists studied the effects of forest fragmentation by calculating the difference between the amount of plant biomass in the edges of forest fragments and the interiors of unfragmented forest.

True Through these studies, biologists found that the edge plots lost about 14 percent of their biomass every two years, starting at two years after the fragmentation occurred.

True or false? The growth rate of a certain population increases very quickly for a time and then levels off to zero. The most likely reason that the growth rate leveled off to zero is that the population reached the carrying capacity of that environment.

True.

B cells are involved in the humoral immune response. The flowchart below summarizes the steps involved in B cell activation. Drag the labels to their appropriate locations on the flowchart below. (Note that TCR stands for T cell receptor.)

When a B cell encounters an antigen it recognizes via its antigen receptors, it internalizes part of that antigen and presents a fragment of the antigen with a class II MHC molecule. An activated helper T cell (activated after an encounter with an antigen-presenting cell) can then recognize this class II MHC-antigen fragment complex on the surface of the B cell and bind to it. This interaction, along with cytokines the helper T cell releases, activates the B cell. The B cell then proliferates and differentiates into plasma cells and memory cells. Plasma cells secrete antibodies that neutralize the pathogen or mark it for destruction. Memory B cells aid in the secondary immune response, should the body encounter the same pathogen again.

Which of the following statements correctly describes why a series of closely spaced action potentials causes a sustained contraction rather than a series of closely spaced twitches? -Ca2+ ions are released quickly from troponin, keeping the Ca2+ concentration in the cytosol high between closely spaced action potentials. -Fewer Ca2+ ions are released from the sarcoplasmic reticulum as a result of several closely spaced action potentials than as a result of a single action potential. -When a series of action potentials is closely spaced, there is not sufficient time for Ca2+ uptake into the sarcoplasmic reticulum between action potentials, and Ca2+ remains bound to troponin throughout the series. -Release of Ca2+ from the sarcoplasmic reticulum through channels is slow compared to the uptake of Ca2+ into the SR via ATP-dependent pumps, resulting in Ca2+ slowly trickling into the sarcomeres between closely spaced action potentials.

When a series of action potentials is closely spaced, there is not sufficient time for Ca2+ uptake into the sarcoplasmic reticulum between action potentials, and Ca2+ remains bound to troponin throughout the series.

Contraction of the sarcomere: the sliding-filament model Drag the labels to their appropriate locations on the cycle diagram below.

When an action potential causes the Ca2+ level to rise in the sarcomere, the cycle of myosin-actin interactions begins with binding of the myosin heads to actin. Binding of actin is followed by the power stroke, which pulls the thin filament toward the center of the sarcomere. When the myosin head binds ATP, it detaches from actin. Then, the myosin head hydrolyzes ATP to ADP and Pi, which extends the myosin head and puts it in position to bind actin once again. The cycle continues as long as Ca2+ is present in the sarcomere. The result of repeated cycles is the shortening of the sarcomere, and ultimately, contraction of the muscle.

Under which of the following conditions would a population most likely experience exponential growth? -Large number of individuals in the starting population. -Young populations with few individuals. -Environment with a low carrying capacity. -Habitat with limited resources.

Young populations with few individuals

Calculate the trophic efficiency from each trophic level to the next for the pyramid of productivity (biomass pyramid) shown below.

a = 14.9% b = 10.6% c = 12.0% In most ecosystems, total biomass declines from lower to higher trophic levels. The low efficiency of energy transfer---between 11% and 15%, in this example---means that most of the energy in biomass at one trophic level is lost when that biomass is consumed. This loss of energy explains why most food webs have only four or five trophic levels.

Assuming similar conditions, which of the following shorelines will likely be most protected from tidal flooding as climate change intensifies? A shoreline with a thriving coral reef. A shoreline with a bleached coral reef. A shoreline without a coral reef. A shoreline with a decaying coral reef.

a shoreline with a thriving coral reef

The percentage of intermediate muscle fibers plus fast muscle fibers in world-class sprinters is approximately the same as the percentage of slow muscle fibers in ____________. a) a world-class marathon runner b) an average active person c) an extreme endurance athlete d) a middle-distance runner

a world-class marathon runner

Aquatic nitrate pollution can result in _____. algal bloom oxygen depletion fish kills hypoxia an algal bloom that, when the algae die and are decomposed by bacteria, leads to hypoxia and the death of fish

an algal bloom that, when the algae die and are decomposed by bacteria, leads to hypoxia and the death of fish

Which of these are the two major sources of nitrate pollution in rivers? the burning of fossil fuels by factories and cars animal wastes and the burning of fossil fuels by cars animal wastes and fertilizers fertilizer runoff and the burning of fossil fuels by cars animal wastes and the burning of fossil fuels by factories

animal wastes and fertilizers

Plants often use changes in day length (photoperiod) to trigger events such as dormancy and flowering. It is logical that plants have evolved this mechanism because photoperiod changes... A) are more predictable than air temperature changes. B) alter the amount of energy available to the plant. C) are modified by soil temperature changes. D) can reset the biological clock.

are more predictable than air temperature changes

Molecules that are eaten and not eliminated in feces are said to be ________ by the animal.

assimilated

A large fraction of assimilated energy is used for ______________, during which ATP is made for cellular work.

cellular respiration

The rest of the assimilated energy is used for biosynthesis--the building of new ________.

biomass

Only the energy used for ___________ can be transferred to the next trophic level.

biosynthesis

Which of the following factors does not contribute to environmental resistance? -environmental toxins -competition for space -birth rate -weather conditions -competition for food

birth rate

When an arborist prunes a limb off a valuable tree, he or she usually paints the cut surface. The primary purpose of the paint is to... A) minimize water loss by evaporation from the cut surface. B) improve the appearance of the cut surface. C) stimulate growth of the cork cambium to "heal" the wound. D) block entry of pathogens through the wound.

block entry of pathogens through the wound

excitatory postsynaptic potential (EPSP)

brings the postsynaptic membrane potential closer to threshold depolarizes the postsynaptic membrane results from the movement of Na+ ions into the postsynaptic cell is a graded potential

Is this statement supported or not supported by the graph? "World-class sprinters are born with a higher percentage of fast and intermediate muscle fibers than other people have." a) supported b) not supported c) cannot be determined from the graph

cannot be determined

What element is found in all organic compounds? carbon oxygen helium iron nitrogen

carbon

Where do plants get the carbon they use to make organic molecules? glucose oxygen water starch carbon dioxide

carbon dioxide

Suppose that an artificial non-gated K+ channel could be inserted into the plasma membrane of an axon at resting potential (membrane potential = -70 mV). Assume that the axon has not recently produced an action potential. What would happen when an artificial K+ channel is inserted into an axon membrane at resting potential? How does the movement of K+ ions through the artificial channel affect the membrane potential?

causes a hyperpolarization

Which are detritus?

dead animal rotting log

A human activity such as draining a wetland _______ ecosystem diversity.

decreases

Extinction ___ species diversity.

decreases

Which of these biomes is characterized by little rainfall? temperate broadleaf forest coniferous forest desert temperate grassland tropical rain forest

desert Deserts are characterized by levels of rainfall less than 30 cm per year.

Which are secondary consumers?

earthworm millipede

Which of these provides your body with energy? minerals fats oxygen vitamins light

fats

Molecules that are eaten but not absorbed by the animal leave the animal's body in _____ and are ____________.

feces not assimilated

Which are primary consumers of decomposer?

fungus cricket maggots

Which factor does not affect a habitat's carrying capacity? -Availability of food -Number of nesting sites -Genetic variation in the population -Intensity of predation

genetic variation in the population

Which of the following is Maloney most likely to recommend to private landowners in order to best protect sugar pines from mountain pine beetles? Give them lots of fertilizer. Use pesticides. Give them plenty of water. Remove the bark from the bottom half of the trees.

give them plenty of water

During cellular respiration, cellular work, and biosynthesis, a significant amount of energy is lost as ____.

heat

Both humoral and cell-mediated response

helper T cells and cytokines memory cells antigen-presenting cells

Which organism does not cause disease in plants? bacteria herbivore fungus virus

herbivore An herbivore consumes plants.

The strength of a stimulus (for example, whether you feel a slight pain versus an intense pain) determines the number of action potentials sent along an axon. As the graphs show, a strong stimulus produces more action potentials spaced more closely together than a weak stimulus. The time between when a first action potential ends and a second action potential can be triggered is determined by the axon's refractory period. A second action potential cannot be triggered until the end of the refractory period. Which of the following characteristics determines when the refractory period ends? - how long it takes for the voltage-gated K+ channels to close during the undershoot phase - how low the membrane potential drops below resting potential during the undershoot phase - how long it takes for the voltage-gated Na+ channels to reactivate at the end of an action potential - how long it takes for the voltage-gated Na+ channels to close at the end of an action potential - how long it takes for the membrane potential to return to resting potential after the undershoot phase

how long it takes for the voltage-gated Na+ channels to reactivate at the end of an action potential During the refractory period, an action potential cannot be triggered even if the membrane potential reaches threshold because the voltage-gated Na+ channels are inactive. The Na+ channels must reactivate before Na+ ions can move into the cell again, and the rising phase of the second action potential can begin. In this way, the refractory period determines how closely one action potential can follow another.

What is the initial localized response of a resistant plant to pathogen invasion? hypersensitive response plant death systemic acquired resistance systemin production

hypersensitive response The hypersensitive response causes the infected plant cells to die and sends a signal to the rest of the plant to prepare its defenses.

Suppose that an artificial non-gated K+ channel could be inserted into the plasma membrane of an axon at resting potential (membrane potential = -70 mV). Assume that the axon has not recently produced an action potential. What would happen when an artificial K+ channel is inserted into an axon membrane at resting potential? Does the membrane potential promote or impede the movement of K+ ions through the artificial channel?

impede

Which factors have permitted the human population to continue increasing despite using nonrenewable resources at an unsustainable rate? -disease outbreaks -improvements in medical care -expansion of high-density urban areas -famines

improvements in medical care expansion of high-density urban areas

As a population approaches carrying capacity, environmental resistance __________. -increases -cannot be determined from the graph -decreases -remains constant

increases

High genetic diversity within a species ___ the likelihood that the species can adapt to new environmental conditions.

increases

Low genetic diversity within a species ___ the likelihood that the species may go extinct.

increases

The number of habitat types ___ when ecosystem diversity increases.

increases

indicate which type(s) of gated ion channels are found in each membrane associated with a chemical synapse. postsynaptic cell postsynaptic membrane

ligand gated

Plants use _____ as a source of energy. minerals fats oxygen vitamins light

light

Where do plants get the energy to make organic molecules? minerals glucose vitamins light water

light

Which are primary producers?

living maple leaves

Upon exposure to blue light, plants not only begin to grow toward the light, but move their chloroplasts to the sunny side of each cell. The adaptive advantage of moving chloroplasts to the sunny side of each cell ________. A) maximizes light absorption by the chloroplasts for photosynthesis B) increases production of phototropic hormones C) maximizes heat absorption by the chloroplasts for cellular respiration D) increases adenosine triphosphate (ATP) production during the light-independent reactions

maximizes light absorption by the chloroplasts for photosynthesis

Which of these is NOT an organic molecule? carbohydrates minerals proteins glucose lipids

minerals

inhibitory postsynaptic potential (IPSP)

moves the postsynaptic membrane potential farther away from threshold hyperpolarizes the postsynaptic membrane results from the movement of K+ ions out of the postsynaptic cell is a graded potential

Which are tertiary consumers?

none

indicate which type(s) of gated ion channels are found in each membrane associated with a chemical synapse. postsynaptic cell plasma membrane of cell body

none

Suppose that an artificial non-gated K+ channel could be inserted into the plasma membrane of an axon at resting potential (membrane potential = -70 mV). Assume that the axon has not recently produced an action potential. What would happen when an artificial K+ channel is inserted into an axon membrane at resting potential? In what direction will the K+ ions move through the artificial channel?

out of the cell

Which of these would NOT contribute to a global increase in temperature? deforestation increasing the use of gasoline-burning vehicles increasing the industrial release of carbon dioxide planting trees increasing the amount of animal life on Earth

planting trees Trees remove more carbon dioxide from the atmosphere than they release into the atmosphere. By removing carbon dioxide, they reduce the greenhouse effect and this would contribute to a reduction in global temperature.

Drag the labels onto the flowchart to indicate the sequence of events that occurs in the presynaptic cell (orange background) and the postsynaptic cell (blue background) after an action potential reaches a chemical synapse.

presynaptic cell: 1. action potential enters the presynaptic membrane -> 2. Ca2+ channels in presynaptic membrane open briefly-> 3. Ca2+ ions enter presynaptic cell-> 4. neurotransmitter containing vesicles fuse with presynaptic membrane-> 5. neurotransmitter released into presynaptic cleft-> post synaptic cell: 6. neurotransmitter binds to ligand-gated ion channels in postsynaptic membrane; channels open -> 7. neurotransmitter degraded or removed from cleft; ligand-gated ion channels close

Suppose that an artificial non-gated K+ channel could be inserted into the plasma membrane of an axon at resting potential (membrane potential = -70 mV). Assume that the axon has not recently produced an action potential. What would happen when an artificial K+ channel is inserted into an axon membrane at resting potential? Does the K+ concentration gradient promote or impede the movement of K+ ions through the artificial channel?

promote

Which are both secondary and tertiary consumers?

robin alligator lizard Primary producers (autotrophs) and detritus, such as decaying plant material, are at the lowest trophic level in a food web. Primary consumers and decomposers (detritivores) rely on primary producers and detritus, respectively, for energy and organic compounds. Secondary consumers eat primary consumers and decomposers, and tertiary consumers eat secondary consumers. When an organism dies, its chemical elements are recycled, becoming available to the food web at low trophic levels once again.

Which compound is not used in the localized response to pathogen invasion? Salicylic acid. Phytoalexins. Nitric oxide. Proteinase inhibitors.

salicylic acid Salicylic acid is a phytochemical involved in the systemic acquired resistance response in plants.

The biology department of your college decides to employ Maloney's strategy to help a local coniferous species. Which of the following will students need to collect? roots seeds male and female cones needles

seeds

Seed packets give a recommended planting depth for the enclosed seeds. The most likely reason some seeds are to be covered with only 1/4 inch of soil is that the... A) seedlings do not produce a hypocotyl. B) seedlings do not have an etiolation response. C) seeds require light to germinate. D) seeds require a higher temperature to germinate.

seeds require light to germinate

Ecosystem in which... Every animal has 3% of its energy from food going into biosynthesis. What is the shape of net production pyramid? And the height of net production pyramid?

shape = less steep height = fewer trophic levels

Ecosystem in which... Plants have better defenses against herbivores, and animals have better defenses against predators. What is the shape of net production pyramid? And the height of net production pyramid?

shape = less steep height = fewer trophic levels

Ecosystem in which... A greater percentage of organisms at each trophic level are eaten by the trophic level above. What is the shape of net production pyramid? And the height of net production pyramid?

shape = more steep height = more trophic levels

Ecosystem in which... Every animal has 50% of its energy from food going into biosynthesis. What is the shape of net production pyramid? And the height of net production pyramid?

shape = more steep height = more trophic levels

The mark-recapture method would be best for sampling a population of _____. -sharks -rose bushes -maple trees -oysters -wheat

sharks The mark-recapture method works best for active species whose individuals tend to be highly mobile.

According to the graph, which type of muscle fiber predominates in endurance athletes (marathon runners and extreme endurance athletes)? a) fast b) intermediate c) slow d) a combination of intermediate and fast muscle fibers

slow

Switching from fossil fuels to _____ energy would significantly decrease the release of carbon dioxide into the atmosphere. solar nuclear geothermal solar and geothermal solar, nuclear, and geothermal

solar, nuclear, and geothermal All of these energy sources would decrease the release of carbon dioxide into the atmosphere. However, the use of nuclear reactors is associated with other problems.

Which structure does not protect stems and leaves from damage by herbivores? thorns spines trichomes stomata

stomata Stomata are openings that allow gases to diffuse in and out of leaves.

Is this statement supported or not supported by the graph? "To train as a middle-distance runner, an average person should increase the percentage of slow fibers at the expense of fast fibers." a) supported b) not supported c) cannot be determined from the graph

supported

Which aspects of a region's climate have the most impact on plants and animals? Sunlight and wind. Temperature and moisture. Moisture and wind. Soil composition and temperature.

temperature and moisture

What are the two major factors determining the distribution of terrestrial biomes? temperature and light temperature and rainfall light and rainfall plants and animals temperature and plants

temperature and rainfall

Which biome is characterized by an extensive canopy that allows little light to penetrate to the ground and by the presence of epiphytes? temperate grassland coniferous forest tropical rain forest desert tundra

tropical rain forest

True or false? Plants do not produce many defenses against pathogens unless they are threatened because defensive structures and compounds require much energy and materials to produce and maintain.

true The production and maintenance of defensive structures and compounds requires more energy than a plant may have at all times.

Which biome is characterized by the presence of permafrost? taiga tropical forest tundra coniferous forest desert

tundra Permafrost, permanently frozen subsoil, is a characteristic of tundra.

indicate which type(s) of gated ion channels are found in each membrane associated with a chemical synapse. postsynaptic cell axon hillock

voltage gated Na+ voltage gated K+

indicate which type(s) of gated ion channels are found in each membrane associated with a chemical synapse. presynaptic cell synaptic terminal

voltage gated Na+ voltage gated K+

indicate which type(s) of gated ion channels are found in each membrane associated with a chemical synapse. presynaptic cell presynaptic membrane

voltage gated Na+ voltage gated K+ voltage gated Ca2+

Which action influences the abiotic components of an organism's environment? Extinction of predators. Introduction of exotics. Water pollution. Interactions with offspring.

water pollution