Bio final

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The carbon, hydrogen, and oxygen in a plant body come from _____, whereas the majority of other elements come from _____. Please choose the correct answer from the following choices, and then select the submit answer button. CO2 and water; the soil CO2 and water; the air other organisms; CO2 and water the air; CO2 and water the soil; CO2 and water

CO2 and water; the soil

Which of the statements is true? Please choose the correct answer from the following choices, and then select the submit answer button. Pectins are found in plant and animal tissues. Cadherins and pectins are both transmembrane proteins. Cadherins and integrins allow for adhesion in animal and plant cells. Cadherins cause adjacent epithelial cells to adhere to one another. Integrins bind epithelial cells to cadherins of other epithelial cells.

Cadherins cause adjacent epithelial cells to adhere to one another.

Which of the statements is true? Please choose the correct answer from the following choices, and then select the submit answer button. Integrins on one cell attach to cadherins on another cell to promote cell adhesion. Cadherins on the surface of animal cells permit cells to adhere to other cells. Integrins and cadherins facilitate cell adhesion to extracellular substrates. Cadherins are used in plant cells to attach the plasma membrane to the cell wall.

Cadherins on the surface of animal cells permit cells to adhere to other cells.

How is a carrier protein different from a channel protein? Please choose the correct answer from the following choices, and then select the submit answer button. Carrier proteins undergo conformational change so that they are open alternately to one side of the membrane or the other. Transport through a carrier protein does not depend on the random motion of molecules. Carrier proteins use ATP, but channel proteins do not. Transport through carrier proteins depends on concentration gradients, but transport through channel proteins does not.

Carrier proteins undergo conformational change so that they are open alternately to one side of the membrane or the other.

A thin band of hydrophobic material that prevents water passage between cells is associated with the endodermis. This band is called the: Please choose the correct answer from the following choices, and then select the submit answer button. Casparian strip. cortex. medulla. plasmodesmata. parenchyma.

Casparian strip.

A student notices two bacteria cells of the same species in close association with one another, with a thin projection running between them. He assumes that these two cells are fusing, forming a new individual. His instructor informs him that this is not the case. Why? Please choose the correct answer from the following choices, and then select the submit answer button. Cell fusion does not occur with bacterial cells, and these cells are likely undergoing conjugation. These cells are likely undergoing transformation. These cells are actually daughter cells resulting from meiosis. Cell fusion does not occur with bacterial cells, and these cells are likely undergoing transformation. Cell fusion does not occur with bacterial cells.

Cell fusion does not occur with bacterial cells, and these cells are likely undergoing conjugation.

Prokaryotes absorb their nutrients from the environment. However, many prokaryotes have cell walls. What can you conclude from this information? Please choose the correct answer from the following choices, and then select the submit answer button. Cell walls are permeable, allowing nutrients to pass through. Prokaryotes produce all their own nutrients with enzymes in the cell wall. Prokaryotes live in hypertonic environments. Prokaryotic cell walls do not need to allow nutrients to pass through them, because prokaryotes produce their own nutrients.

Cell walls are permeable, allowing nutrients to pass through.

Which statement is true regarding chloroplasts? Please choose the correct answer from the following choices, and then select the submit answer button. Chloroplasts utilize carbon dioxide as a reactant. Unlike mitochondria, chloroplasts only contain an outer (and not an inner) membrane. Chloroplasts release carbon dioxide as a waste product. Chloroplasts are sites of cellular respiration.

Chloroplasts utilize carbon dioxide as a reactant.

Some lipid rafts are characterized by an accumulation of cholesterol. What does this mean for the fluidity of the lipid raft? Please choose the correct answer from the following choices, and then select the submit answer button. Cholesterol has no effect on the fluidity of the membrane at normal temperatures. Cholesterol decreases the fluidity of the membrane at normal temperatures. Cholesterol increases the fluidity of the membrane at normal temperatures. Cholesterol is too polar to become part of the phospholipid bilayer.

Cholesterol decreases the fluidity of the membrane at normal temperatures.

Which of the statements is an accurate statement about multicellularity? Please choose the correct answer from the following choices, and then select the submit answer button. Complex multicellularity does not involve the differentiation of cells with distinct shapes and functions. Distinct cell fates are achieved by switching off all genes that may be expressed in a different cell type. Complex multicellularity involves differentiation in space instead of time. Unicellular organisms cannot have life cycles in which different cell types alternate in time.

Complex multicellularity involves differentiation in space instead of time.

Consider the image. In this image of a sunflower, which letter indicates an organ whose epidermis does not have a waxy cuticle? Please choose the correct answer from the following choices, and then select the submit answer button. E A B C D F

How can two cells in the same complex multicellular organism have different fates? Please choose the correct answer from the following choices, and then select the submit answer button. Different amounts of DNA are found in the nuclei of the two cells. Different types of transcription and translation machinery are found in the two cells. Different genes are activated and repressed in the two cells. All of these choices are correct. Different DNA sequences are found in the nuclei of the two cells.

Different genes are activated and repressed in the two cells.

What is the fundamental concept that causes gel electrophoresis of proteins to work? Please choose the correct answer from the following choices, and then select the submit answer button. Different proteins have different charges and sizes. Different proteins respond in the same way to dyes in a gel. Some proteins are enzymes and will react with molecules in the gel. All proteins will react with a dye to produce a band. All proteins have the same charge and will move through the gel at the same speed.

Different proteins have different charges and sizes.

A zookeeper is very upset because one of the lions jumped the fence of his enclosure and mated with a neighboring tigress. This mating produced a "liger." Which of the statements is likely true of this liger cub? Please choose the correct answer from the following choices, and then select the submit answer button. Due to genetic incompatibility between the lion and tiger, the liger cub will likely be sterile. The liger cub was born because it is genetically identical to one of the parents. Because of the similarities in chromosome number of the lion and tiger, the liger cub will likely be fertile and bear offspring. The cub is the result of an incompatible lock-and-key mechanism between its parents.

Due to genetic incompatibility between the lion and tiger, the liger cub will likely be sterile.

Imagine a cell that has a membrane composed mostly of lipids with saturated fatty acid tails, and that this membrane also has low cholesterol content. What are the characteristics of this cell membrane? Please choose the correct answer from the following choices, and then select the submit answer button. Due to its low cholesterol content, the cell membrane would lose its fluidity at cold temperatures. The lipids contained in such a membrane would be highly mobile and in nearly constant flux. The lipids would be able to easily transition between the inner and outer layers of the bilayer constituting the cell membrane. The characteristics of this cell membrane will closely mirror those of a membrane composed of only unsaturated fatty acids.

Due to its low cholesterol content, the cell membrane would lose its fluidity at cold temperatures.

Eukaryotes have the ability to take in nutrients by phagocytosis, whereas prokaryotes do not. Which of the statements explains an advantage this ability brings to eukaryotes? Please choose the correct answer from the following choices, and then select the submit answer button. Eukaryotes are able to exploit complex materials, including other cells, for food that prokaryotes cannot. Phagocytosis provides eukaryotes with a way of obtaining more RNA for translation, which allows them to become more complex. Phagocytosis provides eukaryotes with a way of obtaining more DNA for their genome, which allows them to become more complex. Eukaryotes are able to get bigger because they can now ingest larger materials. None of the answer options is correct.

Eukaryotes are able to exploit complex materials, including other cells, for food that prokaryotes cannot.

Which of the statements is a key advantage of eukaryotic cells over prokaryotic cells? Please choose the correct answer from the following choices, and then select the submit answer button. Eukaryotic cells have a rigid cytoskeleton, which allows them to withstand greater stress. Eukaryotic cells have a cell membrane, which allows them to ship materials into and out of the cell. None of the other answer options is correct. Eukaryotic cells have ribosomes, which allow them to make more complex proteins. Eukaryotic cells have a flexible cytoskeleton, which allows them to change shape and gives them the ability to engulf other materials.

Eukaryotic cells have a flexible cytoskeleton, which allows them to change shape and gives them the ability to engulf other materials.

The fossil record is often used to infer phylogenetic history. Which of the statements accurately supports this assumption? Please choose the correct answer from the following choices, and then select the submit answer button. Events that occur early in the fossil record are represented by branching events nearer to the tips of a phylogenetic tree. Events that occur early in the fossil record are represented by branching events nearer to the root of a phylogenetic tree. There is a one-to-one correlation between each branch of the phylogenetic tree and fossil specimens. There are fossil representatives of every organism in the tree of life. Fossil record events are too old to be represented on phylogenetic trees, which reconstruct the more recent past.

Events that occur early in the fossil record are represented by branching events nearer to the root of a phylogenetic tree.

All bacteria are unicellular. True False

False

How do fossils provide evidence of evolutionary history? Please choose the correct answer from the following choices, and then select the submit answer button. Fossils provide complete information on extinct species. Fossils provide a record of extinct species. Older fossils are an excellent source of DNA from which we can construct molecular phylogenies. Fossils provide an accurate account of the number of species that exist at any particular time.

Fossils provide a record of extinct species.

A young student is trying to reproduce an experiment discussed in the textbook. She introduces single-celled green algae into a petri dish containing predatory protists. After several generations, what will she observe if she is able to reproduce the results of the experiment? Please choose the correct answer from the following choices, and then select the submit answer button. The protists will produce multicellular colonies. None of the other answer options is correct. Both protists and green algae will remain unicellular. Green algae will form multicellular colonies. Green algae will remain unicellular; there is no benefit to forming multicellular structures.

Green algae will form multicellular colonies.

Which of the activities in the roots does not require energy? Please choose the correct answer from the following choices, and then select the submit answer button. transport of solutes into the cytoplasm of root cells absorbing water into the root hair All root activities require energy. making specific nutrients in the soil available to the root supporting symbiotic relationships with soil microorganisms

absorbing water into the root hair

Photosynthetic protists are informally referred to as: Please choose the correct answer from the following choices, and then select the submit answer button. fungi. plants. algae. protozoa.

algae

To which group do most simple multicellular species belong? Please choose the correct answer from the following choices, and then select the submit answer button. protozoans algae fungi slime molds bacteria

algae

You are a biologist on a trip to an island in the South Pacific. While there, you are allowed to collect DNA samples from a local species of rat that resembles a species seen on a nearby continent. If your DNA analysis also indicates the two species are closely related, you might conclude that the evolution of the two separate species was an example of _____ through _____. Please choose the correct answer from the following choices, and then select the submit answer button. sympatric speciation; vicariance sympatric speciation; dispersal allopatric speciation; vicariance allopatric speciation; dispersal

allopatric speciation; vicariance

Which of the groups contains vessels as their primary form of water transport? Please choose the correct answer from the following choices, and then select the submit answer button. ferns and horsetails gymnosperms angiosperms mosses lycophytes

angiosperms

Sieve plates: Please choose the correct answer from the following choices, and then select the submit answer button. are modified cell walls that connect sieve elements. do not contain plasmodesmata. have solid, impermeable surfaces. contain mitochondria and chloroplasts. dissolve at sieve tube maturity.

are modified cell walls that connect sieve elements.

You are in a lab studying a newly discovered cell type. You observe a rigid cytoskeleton in this cell, along with a nucleus and a compartmentalized interior. How would you classify this cell? Please choose the correct answer from the following choices, and then select the submit answer button. as an advanced prokaryotic cell, because it has a rigid cytoskeleton as a primitive prokaryotic cell as a possible transitional cell changing from prokaryotic to eukaryotic as a eukaryotic cell that has to be heterotrophic None of the answer options is correct.

as a possible transitional cell changing from prokaryotic to eukaryotic

When plants reduce SO4 to form H2S during _____, SO4 _____ electrons. Please choose the correct answer from the following choices, and then select the submit answer button. anaerobic respiration; loses anaerobic respiration; gains anammox; gains assimilation; loses assimilation; gains anammox; loses

assimilation; gains

When reduction of SO4 to form H2S occurs during _____, SO4 _____ electrons. Please choose the correct answer from the following choices, and then select the submit answer button. anaerobic respiration; gains anammox; loses anaerobic respiration; loses assimilation; loses assimilation; gains anammox; gains

assimilation; gains

In the Sierra Nevada mountains of California, there are many populations of the checkerspot butterfly Euphydryas editha. Females of each population lay their eggs on different regions of their host plants. The young hatch as caterpillars, and they live on the host plant and eat its leaves. Consider two of the populations, population A and population B. The host plant used by population A grows over a single season, with new leaves, which are the most nutritious, appearing at the tip of the stem. The host plant of population B lives for many seasons, with new leaves appearing at the base of the stem. Where do you expect females from population B to lay their eggs? Please choose the correct answer from the following choices, and then select the submit answer button. at the base of the plant stem at the tip of the plant stem anywhere along the plant stem in the middle of the plant stem

at the base of the plant stem

Imagine you are talking to your friend who is very excited because he has just transduced his first batch of bacteria in the laboratory. What does this mean? Please choose the correct answer from the following choices, and then select the submit answer button. He introduced a gene of interest into his bacteria using other bacterial species that can form pili. He introduced a gene of interest into his bacteria by lysing other bacterial cells and exposing his bacteria to this mixture. He produced a strain of antibiotic-resistant bacteria by exposing his bacterial cultures to antibiotics. Through periodic selection, he was able to isolate a gene of interest in his bacteria. He introduced a gene of interest into his bacteria using viruses.

He introduced a gene of interest into his bacteria using viruses.

A commercial tuna fisherman is very concerned that overfishing will result in a decrease in tuna population size, thus affecting his catches in future years. What strategy can he employ to make sure that the tuna population can be sustained in the long term? Please choose the correct answer from the following choices, and then select the submit answer button. He should only catch fish at the reproductive age. He should only catch old fish. He should only catch young, non-reproducing fish.

He should only catch young, non-reproducing fish.

The common mud turtle experiences relatively uniform mortality rates throughout its life. It exhibits Type _____ survivorship. Please choose the correct answer from the following choices, and then select the submit answer button. I II III

Which of the statements regarding a simple multicellular organism is true? Please choose the correct answer from the following choices, and then select the submit answer button. Simple multicellular organisms only include algae. If an individual cell from a single multicellular organism is damaged or dies, the whole organism will likely die. Certain cells of a simple multicellular organism, typically referred to as inner mass cells, are isolated from the external environment. All simple multicellular organisms are only multicellular at one stage of their life cycles, which is the larval or embryonic stage. If a single cell is removed from a simple multicellular organism, the cell may be able to reproduce on its own.

If a single cell is removed from a simple multicellular organism, the cell may be able to reproduce on its own.

Imagine that a scientist discovers a new flying species of mammal that resembles a winged rabbit. What can the scientist say about this organism? Please choose the correct answer from the following choices, and then select the submit answer button. Without any further information, the scientist can say that bat wings and the wings of this new species are homologous. If molecular sequence data show that bats and this new species share a common ancestor not shared by other mammals, the wings of these two species would be considered homologous. If molecular sequence data show that bats and this new species do not share a common ancestor not shared by other mammals, the wings of bats and this new species would be considered homologous. If molecular sequence data show that bats and this new species share a common ancestor not shared by other mammals, the wings of these two species would be considered analogous. No data could support or reject the hypothesis that the wings of bats and the new species are homologous.

If molecular sequence data show that bats and this new species share a common ancestor not shared by other mammals, the wings of these two species would be considered homologous.

Which of the options is not a general requirement for complex multicellular life? Please choose the correct answer from the following choices, and then select the submit answer button. Cells must stick together. Cells must participate in a network of genetic interactions that regulate cell division. Cells must communicate with one another. All of these choices are correct. Individual cells must retain a full range of functions, including reproduction.

Individual cells must retain a full range of functions, including reproduction.

When we say "populations evolve, not individuals," what does this mean? Please choose the correct answer from the following choices, and then select the submit answer button. Only genotype frequencies change over time, not allele frequencies. Individuals cannot change their genetic makeup, but genotype frequencies in a population can change. Evolution is a change in the genetic make-up of individuals over time. Only alleles change over time, not genotype frequencies.

Individuals cannot change their genetic makeup, but genotype frequencies in a population can change.

Why is Hardy-Weinberg such a valuable tool when examining populations? Please choose the correct answer from the following choices, and then select the submit answer button. It enables researchers to identify beneficial mutations. It always enables us to predict phenotype frequencies. It enables researchers to determine whether an allele is dominant or recessive. It enables us to identify whether a population is evolving.

It enables us to identify whether a population is evolving.

Which statement is true regarding anammox? Please choose the correct answer from the following choices, and then select the submit answer button. All of these choices are correct. It is identical to nitrogen fixation. It is performed in oxygen-rich environments. It can be carried out by both eukaryotes and archaeons. It generates less energy than respiration.

It generates less energy than respiration.

Which of the statements is true of transport in phloem? Please choose the correct answer from the following choices, and then select the submit answer button. It moves materials down the plant body. It only occurs from leaves to roots. It is driven by turgor pressure. It is usually a passive process. It occurs from sink to source.

It is driven by turgor pressure.

Refer to the figure shown. The human age-structure histogram of India is shaped like a pyramid. What does this tell you about India's population? Please choose the correct answer from the following choices, and then select the submit answer button. It is currently shrinking but will increase over the next few years. It is relatively constant. It is growing. It is shrinking. It is currently growing but will decrease over the next few years.

It is growing.

Why is the energy from a molecule of ATP required by the sodium-potassium pump? Please choose the correct answer from the following choices, and then select the submit answer button. It provides the energy required to ionize sodium and potassium. It helps the sodium and potassium ions bind to the pump binding sites. It helps prevent other molecules from being transported by the pump. It provides the energy required to move sodium and potassium ions against their concentration gradients.

It provides the energy required to move sodium and potassium ions against their concentration gradients.

If animals were unable to produce pectin, what effect would this have on their epithelial tissues? Please choose the correct answer from the following choices, and then select the submit answer button. Epithelial cells would be unable to form organized sheets of cells. Epithelial cells would be unable to adhere to the extracellular matrix. Epithelial cells would be unable to communicate with one another. Epithelial cells would be unable to adhere to one another. It would have no effect on epithelial tissue structure or function.

It would have no effect on epithelial tissue structure or function.

The current theory is that chloroplasts are descendants of symbiotic cyanobacteria that lived within eukaryotic cells. If we look at their respective genomes, however, we see that the cyanobacteria have many more genes than do chloroplasts. Where did cyanobacteria genes go? Please choose the correct answer from the following choices, and then select the submit answer button. Nowhere; cyanobacteria and chloroplasts actually have the same number of genes. Many of the genes were transported to the nucleus, and others were lost. Endosymbiosis requires a reduction in genetic material in order to be successful. Restriction enzymes removed them. None of the answer options is correct.

Many of the genes were transported to the nucleus, and others were lost.

Which statement about mitochondria is true? Please choose the correct answer from the following choices, and then select the submit answer button. Mitochondria are rich in pigments and rely on peptide gradients to function correctly. Mitochondria rely on peptide gradients to function correctly. Mitochondria are subdivided into compartments known as thylakoids. Mitochondria are rich in pigments. Mitochondria generate ATP.

Mitochondria generate ATP.

A jellyfish relies on diffusion to provide oxygen to its body cells, and yet it is much larger than the 1-centimeter limit imposed by diffusion. How can it be so thick and still meet its metabolic demands by diffusion alone? Please choose the correct answer from the following choices, and then select the submit answer button. Much of the thickness of a jellyfish consists of metabolically inert materials that do not require oxygen. Jellyfish have specialized tubular cells that facilitate the movement of oxygen throughout the body. The layers of metabolically active tissue are very thick and highly folded, which provides a large surface area for diffusion. Jellyfish maintain a very large concentration gradient for oxygen across their body tissues. Water makes up most of the body of a jellyfish, and oxygen diffuses more rapidly in water than in tissues.

Much of the thickness of a jellyfish consists of metabolically inert materials that do not require oxygen.

A jellyfish relies on diffusion to provide oxygen to its body cells, and yet it is much larger than the 1-centimeter limit imposed by diffusion. How can it be so thick and still meet its metabolic demands by diffusion alone? Please choose the correct answer from the following choices, and then select the submit answer button. Water makes up most of the body of a jellyfish, and oxygen diffuses more rapidly in water than in tissues. Jellyfish maintain a very large concentration gradient for oxygen across their body tissues. The layers of metabolically active tissue are very thick and highly folded, which provides a large surface area for diffusion. Jellyfish have specialized tubular cells that facilitate the movement of oxygen throughout the body. Much of the thickness of a jellyfish consists of metabolically inert materials that do not require oxygen.

Much of the thickness of a jellyfish consists of metabolically inert materials that do not require oxygen.

Which equation represents anammox? Please choose the correct answer from the following choices, and then select the submit answer button. N2 + 2H2O %u2192 NH4+ + NO2- NO2- + 4H2%u2192 NH4- + 2H2O 2H2O + 2NO3- %u2192 2NH2- + 4O2 NH4+ + NO2- %u2192 N2 + 2H2O NH4+ + 2H2O %u2192 NO2 + 4H2

NH4+ + NO2- %u2192 N2 + 2H2O

_____ allows populations to adapt to the abiotic and biotic conditions where they live. Please choose the correct answer from the following choices, and then select the submit answer button. Competition Reproduction Natural selection Predation

Natural selection

_____ results in the oxidation of NH3 to form NO3-, and _____ results in the reduction of NO3- to form N2. Please choose the correct answer from the following choices, and then select the submit answer button. Denitrification; nitrogen fixation Nitrogen fixation; anammox Nitrification; denitrification Anammox; nitrogen fixation Nitrification; nitrogen fixation Denitrification; nitrification

Nitrification; denitrification

_____ is an element that is abundant in Earth's atmosphere; however, usable forms of this element, such as ammonia, are comparatively rare in certain soils. Symbiotic relationships between plants like soybeans and bacteria have formed to circumvent this problem. Please choose the correct answer from the following choices, and then select the submit answer button. Nitrogen Oxygen Carbon Sulfur

Nitrogen

Why are some single-celled eukaryotes only found as haploid cells for the majority of their lifespan, whereas others are only found as diploid cells for the majority of their lifespan? Please choose the correct answer from the following choices, and then select the submit answer button. Only the eukaryotes that reproduce asexually will occur as diploid cells. Only the eukaryotes that reproduce sexually will occur as haploid cells. Only the eukaryotes that reproduce asexually will occur as haploid cells. None of the answer options is correct. Only the eukaryotes that reproduce sexually will occur as diploid cells.

None of the answer options is correct.

Which of the cell adhesion molecules can be found in all complex multicellular organisms? Please choose the correct answer from the following choices, and then select the submit answer button. cadherins integrins pectins None of the other answer options is correct. cadherins and integrins

None of the other answer options is correct.

To which of the superkingdoms does a jellyfish belong? Please choose the correct answer from the following choices, and then select the submit answer button. Amoebozoa Opisthokonta Stramenopila Archaeplastida Excavata

Opisthokonta

Multiple lines of evidence indicate that complex multicellularity evolved at least six different times. Which of the superkingdoms includes organisms that exhibit complex multicellularity? Please choose the correct answer from the following choices, and then select the submit answer button. plants, animals, fungi, slime molds, red algae, green algae, brown algae Opisthokonta, Amoebozoa, Archaeplastida, Stramenopila Opisthokonta, Archaeplastida, Stramenopila plants, animals, fungi, slime molds green algae (and land plants), red algae, brown algae, animals, fungi, slime molds

Opisthokonta, Archaeplastida, Stramenopila

The largest mass extinction occurred at the end of which period? Please choose the correct answer from the following choices, and then select the submit answer button. Triassic Ordovician Devonian Cretaceous Permian

Permian

Which of the statements is true regarding a phylogenetic tree? Please choose the correct answer from the following choices, and then select the submit answer button. Phylogenetic trees are constructed based solely on the morphological characteristics of species; sequence similarities among different organisms are evaluated only by taxonomists. Given the sheer number of prokaryotic and eukaryotic species on Earth, it is impossible to create a phylogenetic tree encompassing all of these organisms. Phylogenetic trees depict only the evolutionary relationships between different classes; relationships among different species within the same genus are not illustrated in such trees. Phylogenetic trees could be considered physical representations of hypotheses that seek to establish the evolutionary relationships between different organisms. Within a phylogenetic tree, the order of groups located at the tree tips—not the nodes within a tree—determines sister-group relationships.

Phylogenetic trees could be considered physical representations of hypotheses that seek to establish the evolutionary relationships between different organisms.

You are an experienced naturalist and biologist and you observe two birds mating that you do not believe are members of the same species. The eggs from this breeding do not hatch, and when you obtain one of the eggs, you find embryonic development stopped not long after fertilization. Which of the following conclusions is supported by these observations? Please choose the correct answer from the following choices, and then select the submit answer button. This evidence suggests the two types of birds are a single species. Temporal isolation prevented successful production of offspring. Behavioral isolation prevented successful production of offspring. Post-zygotic factors prevented successful production of offspring. Pre-zygotic isolation prevented successful production of offspring.

Post-zygotic factors prevented successful production of offspring.

Reproductive isolating mechanisms are divided into categories based on when they act. _____ isolating factors prevent fertilization from taking place; _____ isolating factors result in failure of the fertilized egg to develop into a fertile individual. Please choose the correct answer from the following choices, and then select the submit answer button. Post-zygotic; pre-zygotic Pre-zygotic; pre-zygotic Pre-zygotic; post-zygotic Post-zygotic; post-zygotic

Pre-zygotic; post-zygotic

Researchers seldom find prokaryotic cells that are greater than 100 micrometers in diameter. Why would the size of prokaryotic cells be restricted? Please choose the correct answer from the following choices, and then select the submit answer button. Prokaryotic cells have multifunctional genes that can encode several proteins on a single mRNA. Prokaryotic cells must absorb all of their nutrients from their environment and therefore require a high surface area to volume ratio. Prokaryotic cells do not have a phospholipid bilayer for a membrane. Prokaryotic cells can exchange genetic information through pili, which are connections to nearby cells. All of the answer choices are correct.

Prokaryotic cells must absorb all of their nutrients from their environment and therefore require a high surface area to volume ratio.

You have learned that having linear DNA has consequences, the major one being that the DNA is shortened every time it replicates. This does not happen with the circular DNA found in prokaryotes. What, then, is the advantage of having linear DNA? Please choose the correct answer from the following choices, and then select the submit answer button. Linear DNA is easier to package than circular DNA. Replication can begin from multiple sites on linear DNA, allowing rapid replication and relieving the evolutionary pressure for a streamlined genome. Linear DNA is less susceptible to viruses than circular DNA. Since mitochondria and chloroplasts have circular DNA, nuclear DNA had to be linear. All of these choices are correct.

Replication can begin from multiple sites on linear DNA, allowing rapid replication and relieving the evolutionary pressure for a streamlined genome.

What is a possible explanation for why a population may not be in Hardy-Weinberg equilibrium? One allele for a trait is fixed in the population. There are more than two alleles for a trait. The Hardy-Weinberg equilibrium cannot be achieved by all types of traits. The alleles for a trait being examined exhibit incomplete dominance. Selection is favoring a particular trait in the population.

Selection is favoring a particular trait in the population.

Which of the statements helps explain why there are abundant air spaces between mesophyll cells in leaves? Please choose the correct answer from the following choices, and then select the submit answer button. to make leaves lighter and less dense because O2 diffusion is faster in air than in water because CO2 diffusion is faster in air than in water to ensure evaporation can pull nutrients from the soil via the vascular tissues

because CO2 diffusion is faster in air than in water

The bioluminescence characteristic of certain squid species is the result of a co-evolutionary relationship between: Please choose the correct answer from the following choices, and then select the submit answer button. bioluminescent archaeons and squid. bioluminescent bacteria and squid. Wolbachia and squid. thaumarchaeotes and squid.

bioluminescent bacteria and squid.

Which of the answer choices are "usable" forms of nitrogen (N) and sulfur (S) that plants and animals can assimilate to build proteins? Please choose the correct answer from the following choices, and then select the submit answer button. both S2 and S3 both SO4 and NO3 both N2 and S2 both N2 and NO3 both NH3 and S2

both SO4 and NO3

The last common ancestor of fungi, mammals, and archaeons likely had which characteristics? Please choose the correct answer from the following choices, and then select the submit answer button. both a distinct nucleus and a plasma membrane both a circular chromosome and membrane-bound organelles both a plasma membrane and a circular chromosome both membrane-bound organelles and a circular chromosome both free-floating genetic material (DNA) and a distinct nucleus

both a plasma membrane and a circular chromosome

Nitrogen gas (N2) in the atmosphere can be directly utilized by which organisms? Please choose the correct answer from the following choices, and then select the submit answer button. archaeons both bacteria and archaeons algae bacteria eukaryotes

both bacteria and archaeons

When two species compete for resources the fitness of: Please choose the correct answer from the following choices, and then select the submit answer button. only the poor competitor will decrease. both competitors will remain the same. only the better competitor will increase. both species will decline.

both species will decline.

A phospholipid molecule in a membrane can: Please choose the correct answer from the following choices, and then select the submit answer button. flip (rotate between the two halves of the bilayer), spin (rotate around its vertical axis), and move side-to-side (lateral movement). both spin (rotate around its vertical axis) and move side-to-side (lateral movement). only move side-to-side (lateral movement). only flip (rotate between the two halves of the bilayer). only spin (rotate around its vertical axis).

both spin (rotate around its vertical axis) and move side-to-side (lateral movement).

Which of the statements about cell signaling is correct? Please choose the correct answer from the following choices, and then select the submit answer button. Signaling molecules are generally polysaccharides that activate receptors on target cells and activate or repress gene expression. All animals have gap junctions to allow targeted signaling between cells. Molecular mechanisms for signaling between cells exist in complex multicellular organisms, but not in single-celled eukaryotes. Only cells on the exterior surface of an organism have receptors to detect environmental signals. Signaling pathways and the molecules involved (e.g. kinases) evolved before the evolutionary split between plants and animals, and thus are similar in the two groups.

Signaling pathways and the molecules involved (e.g. kinases) evolved before the evolutionary split between plants and animals, and thus are similar in the two groups.

You may know that scientists are able to synthesize new strands of DNA through a process known as PCR, which utilizes a DNA polymerase derived from bacteria. By repeatedly heating the reaction products to 70˚C, researchers can create new DNA from a template DNA strand. What does this tell you about bacteria compared to archaeons? Please choose the correct answer from the following choices, and then select the submit answer button. Some bacteria can survive at high temperatures, although archaeons can survive in much hotter environments. Some bacteria can survive at higher temperatures compared to archaeons. Archaeons prefer colder environments compared to bacteria. Bacteria and archaeons can likely both survive at temperatures of 122˚C.

Some bacteria can survive at high temperatures, although archaeons can survive in much hotter environments.

To which of the superkingdoms do diatoms belong? Please choose the correct answer from the following choices, and then select the submit answer button. Excavata Opisthokonta Stramenopila Archaeplastida Amoebozoa

Stramenopila

Sulfur is an integral part of which molecules? Please choose the correct answer from the following choices, and then select the submit answer button. enzymes cofactors vitamins Sulfur can be an integral component of any of these molecules. amino acids

Sulfur can be an integral component of any of these molecules.

Which is a function of the signal-recognition particle (SRP)? Please choose the correct answer from the following choices, and then select the submit answer button. The SRP binds to the SRP receptor on the rough endoplasmic reticulum. The SRP directs proteins to the nuclear pores of the nuclear envelope. The SRP binds to sugars added to proteins in the Golgi apparatus. The SRP halts translation.

The SRP binds to the SRP receptor on the rough endoplasmic reticulum.

A gardener treats his plants with pesticides, killing all the aphids that are on the plants. Once the aphids die, what likely happens to the mutualistic bacteria inhabiting their digestive tracts? Please choose the correct answer from the following choices, and then select the submit answer button. The bacteria would contribute to the decomposition of dead aphids. The bacteria would migrate outside of the digestive tract and survive on the leaves of garden plants. The bacteria would likely die without their mutualistic aphids, as this is an example of a facultative relationship. The bacteria would likely die without their mutualistic aphids, as this is an example of an obligate relationship.

The bacteria would likely die without their mutualistic aphids, as this is an example of an obligate relationship.

A doctor is treating a patient for an apparent bacterial infection. She prescribes antibiotics that target either the peptidoglycan in bacterial cell walls or the bacterial translational machinery. To her surprise, this treatment does not work. Why might this treatment be ineffective? Please choose the correct answer from the following choices, and then select the submit answer button. All of these choices are correct. The patient may be infected with bacteria that have cell walls composed of chitin. The patient may be infected with bacteria that have cell walls composed of cellulose. The bacterium may have developed resistance to these treatments.

The bacterium may have developed resistance to these treatments.

A doctor is treating a patient for an apparent bacterial infection. She prescribes antibiotics that target either the peptidoglycan in bacterial cell walls or the bacterial translational machinery. To her surprise, this treatment does not work. Why might this treatment be ineffective? Please choose the correct answer from the following choices, and then select the submit answer button. The bacterium may have developed resistance to these treatments. The patient may be infected with bacteria that have cell walls composed of chitin. The patient may be infected with bacteria that have cell walls composed of cellulose. All of these choices are correct.

The bacterium may have developed resistance to these treatments.

A scientist is studying a population of feral cats in his city. After ten years, he notes the growth of the population of feral cats as (K-N)/K = 0. Based on this information, what can he deduce about the logistic growth curve for the population at this point in time? Please choose the correct answer from the following choices, and then select the submit answer button. The curve is at its inflection point (that is, the rate of growth has started to slow). The curve resembles an exponential growth curve. The curve has plateaued at K. The curve is at its steepest point.

The curve has plateaued at K.

Which statement is true regarding the cytoplasm in eukaryotic cells? Please choose the correct answer from the following choices, and then select the submit answer button. The cytoplasm is a homogenous jelly-like substance. The cytoplasm is the location of the genetic material. The cytoplasm is a single compartment in the cell uninterrupted by membrane barriers. The cytoplasm contains organelles and cytosol and refers to cellular contents outside the nucleus but inside the plasma membrane.

The cytoplasm contains organelles and cytosol and refers to cellular contents outside the nucleus but inside the plasma membrane.

Imagine that you have two blades of grass. One is from a normal plant, and the other is from a mutant plant that cannot absorb water into its vacuoles. How will the structures of these two blades of grass compare? Please choose the correct answer from the following choices, and then select the submit answer button. The grass blade from the mutant plant will appear taller than that from the normal plant. The grass blade from the mutant plant will appear limp compared to that from the normal plant. The grass blades from the mutant and normal plant will appear identical. The grass blade from the mutant plant will be sturdier compared to that from the normal plant.

The grass blade from the mutant plant will appear limp compared to that from the normal plant.

Imagine that a population of meerkats exhibits exponential growth. What does this tell you about the intrinsic growth rate (r) of the meerkat population? Please choose the correct answer from the following choices, and then select the submit answer button. The growth rate is steadily increasing. The growth rate increased at first, but then decreased. The growth rate is steadily decreasing. The growth rate has remained constant. The growth rate is fluctuating.

The growth rate has remained constant.

In the example of secondary active transport, what would happen if ATP suddenly became unavailable for Step 1 in Panel a. of the figure shown? Click to view full size. Please choose the correct answer from the following choices, and then select the submit answer button. The movement of the molecules through the antiporter would continue for a while until the proton gradient was depleted. All processes in this system would stop immediately. The proton gradient would remain strong and unchanged. The protons would simply diffuse through the membrane back into the cytoplasm.

The movement of the molecules through the antiporter would continue for a while until the proton gradient was depleted.

Which component is part of the endomembrane system of a eukaryotic cell? Please choose the correct answer from the following choices, and then select the submit answer button. The nuclear envelope, the Golgi apparatus, and the endoplasmic reticulum all make up the endomembrane system. the plasma membrane the chromosomes the ribosomes

The nuclear envelope, the Golgi apparatus, and the endoplasmic reticulum all make up the endomembrane system.

Most eukaryotic cells contain mitochondria, but a few single-celled eukaryotic organisms found in oxygen-free environments do not. Which of the observations led biologists to reject the hypothesis that these mitochondria-free eukaryotes evolved before the endosymbiotic event that established mitochondria in other eukaryotes? Please choose the correct answer from the following choices, and then select the submit answer button. All eukaryotes exhibit some sort of energy utilization. Some eukaryotes have chloroplasts instead of mitochondria. The nuclear genome of these mitochondria-free eukaryotes contains relics of mitochondrial genes. All eukaryotes have remnant chloroplast genes.

The nuclear genome of these mitochondria-free eukaryotes contains relics of mitochondrial genes.

You are asked to determine whether an unknown tissue specimen comes from a plant or an animal. Closer inspection with an electron microscope reveals that the cells are connected by small openings lined by extensions of the cell membrane and containing tubules connecting the endomembrane systems of adjacent cells. Which conclusion can you draw from your observations? Please choose the correct answer from the following choices, and then select the submit answer button. The openings are gap junctions, so the tissue must come from a plant. The openings are plasmodesmata, so the tissue must come from an animal. The openings are gap junctions, so the tissue must come from an animal. The openings could be either gap junctions or plasmodesmata, so it cannot be determined whether the tissue came from a plant or an animal. The openings are plasmodesmata, so the tissue must come from a plant.

The openings are plasmodesmata, so the tissue must come from a plant.

A researcher is studying a population with a unique age structure. An age-structured histogram he has developed over the course of several decades has undergone transformations in shape, from a pyramid shape to a roughly rectangular shape to an inverted pyramid shape (where the base is narrower than the top). How has this population changed over time? Please choose the correct answer from the following choices, and then select the submit answer button. The population increases and then rapidly declines. The population first grows, then stabilizes, and then declines. The population is first stable, then increases, and then declines. The population at first declines, then stabilizes, and then increases.

The population first grows, then stabilizes, and then declines.

A doctor takes two different cheek swabs from one of his patients. He cultures the microorganisms from one swab and derives microorganism sequence information from the other. What do you expect his results will be? Please choose the correct answer from the following choices, and then select the submit answer button. The sequencing data will identify more microorganisms compared to the culture data. The culture results will identify more microorganisms compared to the sequencing data. His culture results will match his sequence results; all of the microorganisms identified via sequencing will be found in the swab cultures.

The sequencing data will identify more microorganisms compared to the culture data.

In the kidney, glucose transport across the cell membrane is the result of a combination of two steps of active transport. Refer to the figures shown. The first step involves a primary active transport system performed by the sodium-potassium pump. It uses the energy from ATP hydrolysis to move sodium ions out of the cell and potassium ions into the cell. The second step involves a secondary active transport symporter that uses the energy in the sodium gradient created by the first step. This second step moves glucose, as well as sodium ions that move down their concentration gradient, into the cell. Step 1 Step 2 Based on the two-step model of glucose transport, what would happen if the rate of function of the sodium-potassium pump increased? Please choose the correct answer from the following choices, and then select the submit answer button. The sodium-potassium pump would make a stronger sodium gradient, so more glucose could be transported across the membrane. The sodium-potassium pump would be unaffected, and therefore, there would be no effect on glucose transport. The sodium-potassium pump would make a weaker sodium gradient, but it would have no effect on glucose transport. The sodium-potassium pump would be unaffected, but the rate of glucose transport would increase.

The sodium-potassium pump would make a stronger sodium gradient, so more glucose could be transported across the membrane.

In the kidney, glucose transport across the cell membrane is the result of a combination of two steps of active transport. Refer to the figures shown. The first step involves a primary active transport system performed by the sodium-potassium pump. It uses the energy from ATP hydrolysis to move sodium ions out of the cell and potassium ions into the cell. The second step involves a secondary active transport symporter that uses the energy in the sodium gradient created by the first step. This second step moves glucose, as well as sodium ions that move down their concentration gradient, into the cell. Step 1 Step 2 Based on the two-step model of glucose transport, what would happen if the supply of ATP was depleted from the cell? Please choose the correct answer from the following choices, and then select the submit answer button. The sodium-potassium pump would be unaffected, and therefore, there would be no effect on glucose transport. The sodium-potassium pump would be unaffected, but the rate of glucose transport would increase. The sodium-potassium pump would make less of a sodium gradient, but it would have no effect on the glucose transport. The sodium-potassium pump would make less of a sodium gradient, so less glucose could be transported across the membrane.

The sodium-potassium pump would make less of a sodium gradient, so less glucose could be transported across the membrane.

In a particular layer of rock, a number of fossilized ferns are found, but no fossilized mosses. What conclusions can be drawn from this finding? Please choose the correct answer from the following choices, and then select the submit answer button. Mosses and ferns did not coexist in the same environment. The soft tissues of mosses may not have fossilized as readily as the more decay-resistant tissues of ferns, so it is difficult to draw any conclusions from this limited sample. Ferns evolved earlier than mosses, so it is not surprising to find a layer with only ferns and no mosses. There are fewer species of moss than ferns. Ferns decompose more rapidly than mosses and thus are more likely to fossilize.

The soft tissues of mosses may not have fossilized as readily as the more decay-resistant tissues of ferns, so it is difficult to draw any conclusions from this limited sample.

In the system depicted in the figure, the structure labeled "w" is permeable to water, but not to the solute. Based on this, and on what you see in the figure, and the assumption that some time will be allowed to pass, which of the following predictions would you make? Click to view full size. Please choose the correct answer from the following choices, and then select the submit answer button. Some of the solute from side A would diffuse to side B. The solution level on side A would go up, and that on side B would go down. The solution level on side A would go down, and that on side B would go up. Some of the solute from side B would diffuse to side A.

The solution level on side A would go down, and that on side B would go up.

Which statement is true regarding archaeons? Please choose the correct answer from the following choices, and then select the submit answer button. They do not include organisms that can undergo methanogenesis. They have cell walls composed of chitin. Like bacteria, they are killed by peptidoglycan-targeting antibiotics. Their transcriptional machinery is similar to the machinery used by eukaryotes. Unlike bacteria, their cell size and cell shape are not determined by diffusion.

Their transcriptional machinery is similar to the machinery used by eukaryotes.

As a population geneticist, you find a species of snails with more genetic diversity than humans. What does this mean? Please choose the correct answer from the following choices, and then select the submit answer button. There is more variation in the gene pool of snails than humans. The snails have more mutations occurring than humans. The snails have more genes on their chromosomes than humans. The snails have a larger population size than humans. The snails have more DNA than humans.

There is more variation in the gene pool of snails than humans.

A researcher is comparing the sequences of genes encoding cell wall proteins in archaeons with those coding cell wall proteins in bacteria. How similar do you expect these sequences will be? Please choose the correct answer from the following choices, and then select the submit answer button. These sequences will be dissimilar, as archaeons have chitin-based cell walls and bacteria primarily have peptidoglycan-based cell walls. These sequences will be similar, as bacteria and archaeons belong to the same prokaryotic domain. These sequences will be dissimilar, as archaeon cell walls are not composed of peptidoglycan. These sequences will be similar, as both archaeons and bacteria have cell walls composed of peptidoglycan variants.

These sequences will be dissimilar, as archaeon cell walls are not composed of peptidoglycan.

In the system depicted in the figure, the structure labeled "w" is permeable to water, but not to the solute. Based on this , and on what you see in the figure, which statement is correct? Click to view full size. Please choose the correct answer from the following choices, and then select the submit answer button. Over time, a net movement of water will occur from side B to side A. Over time, the solvent will become evenly distributed on both sides. This image is not a real possibility, because the solute will diffuse. This image represents the equilibrium conditions. This image represents the starting conditions.

This image represents the starting conditions.

Imagine that a zoo in Sri Lanka has started an elephant-breeding program. Zookeepers have introduced an Indian and Sri Lankan elephant into the same enclosure. What will be the result of this mating? Please choose the correct answer from the following choices, and then select the submit answer button. This mating will demonstrate that these elephants are members of the same species and will produce fertile offspring. This mating will produce infertile offspring (i.e., like a mule). This mating will fail to produce fertile offspring.

This mating will demonstrate that these elephants are members of the same species and will produce fertile offspring.

A young boy is staring at the tropical fish tank in his mother's office. He reaches in and pulls out a fern-like plant. When he closely examines this plant, he notices it has very large cells with several dark spots. What is likely true of this plant? Please choose the correct answer from the following choices, and then select the submit answer button. This is an example of a terrestrial tree-fern in the aquatic phase. This plant is coenocytic; the dark spots are actually nuclei. This plant is coenocytic; the dark spots are symbiotic organisms. Given the tropical environment, this plant is likely a fungus.

This plant is coenocytic; the dark spots are actually nuclei.

A young boy is staring at the tropical fish tank in his mother's office. He reaches in and pulls out a fern-like plant. When he closely examines this plant, he notices it has very large cells with several dark spots. What is likely true of this plant? Please choose the correct answer from the following choices, and then select the submit answer button. This plant is coenocytic; the dark spots are symbiotic organisms. This plant is coenocytic; the dark spots are actually nuclei. Given the tropical environment, this plant is likely a fungus. This is an example of a terrestrial tree-fern in the aquatic phase.

This plant is coenocytic; the dark spots are actually nuclei.

_____ are shorter and typically narrower than _____. Please choose the correct answer from the following choices, and then select the submit answer button. Tracheids; vessels Vessels; tracheids Sieve tube elements; companion cells Xylem; phloem

Tracheids; vessels

_____ is a type of horizontal gene transfer where genetic information is transferred from one bacterium to another by a virus. Please choose the correct answer from the following choices, and then select the submit answer button. Transduction Conjugation Transformation Transferation Conduction

Transduction

Which of the scenarios represents genetic incompatibility? Please choose the correct answer from the following choices, and then select the submit answer button. Two groups of birds do not reproduce because of incompatible courtship behaviors. Two groups of snakes do not produce fertile offspring because they have a different number of chromosomes. Two groups of beetles do not produce offspring because they feed on the same plants in different parts of the world. Two groups of ladybugs do not produce offspring because they feed on different species of plants.

Two groups of snakes do not produce fertile offspring because they have a different number of chromosomes.

Which of the statements best describes a symbiotic relationship between two organisms? Please choose the correct answer from the following choices, and then select the submit answer button. Two organisms live in close, long-term, physical association with each other. Two organisms live in close, physical association with each other, and both organisms benefit from the relationship. Two organisms live in close, physical association with each other, and both organisms thrive, but one is the primary provider and the other is the primary beneficiary. Two organisms live in close, physical association with each other, and one organism benefits to the detriment of the other.

Two organisms live in close, long-term, physical association with each other.

As human mortality is greatest during later life stages and most children survive into adulthood, humans demonstrate a _____ survivorship curve. Please choose the correct answer from the following choices, and then select the submit answer button. Type I Type II Type III

Type I

Which type of survivorship curve can be depicted as a straight line, where mortality rates are roughly equivalent at all life stages? Please choose the correct answer from the following choices, and then select the submit answer button. Type II Type I Type III

Type II

Mice produce several offspring that do not normally survive into adulthood, and mortality rates are highest during the first few months of life. These animals exhibit a: Please choose the correct answer from the following choices, and then select the submit answer button. Type I survivorship curve. Type II survivorship curve. Type III survivorship curve.

Type III survivorship curve.

Which of the statements accounts for why eukaryotic cells are typically much larger than prokaryotic cells? Please choose the correct answer from the following choices, and then select the submit answer button. A eukaryotic nucleus is so large that the cell has to be bigger to allow space for other organelles. Using molecular motors, eukaryotic cells can transport materials throughout their cytoplasm much faster than prokaryotic cells can; prokaryotic cells have to rely on simple diffusion. None of the answer options is correct. Because eukaryotic cells have more DNA, their cell volume has to be larger. Reproducing sexually requires the cells to be larger so that everything in the cell can be evenly distributed to the daughter cells.

Using molecular motors, eukaryotic cells can transport materials throughout their cytoplasm much faster than prokaryotic cells can; prokaryotic cells have to rely on simple diffusion.

During osmosis, water moves down its own concentration gradient. How is it possible to reduce the concentration of a solvent? Please choose the correct answer from the following choices, and then select the submit answer button. When solvents dissolve solutes, the solvent concentration increases. Solvents are repelled by solutes and tend to move away from them. Only solutes can change concentration; solvents never change. When more solutes are dissolved in solvents, the concentration of the solute increases, but per unit volume, the concentration of the solvent decreases.

When more solutes are dissolved in solvents, the concentration of the solute increases, but per unit volume, the concentration of the solvent decreases.

Which of the results from a mark-recapture study done on mice would reflect a larger population size? Please choose the correct answer from the following choices, and then select the submit answer button. When taking the second sample, 100 individuals are caught and 80 are marked from the first sample. When taking the second sample, 100 individuals are caught and 20 are marked from the first sample. When taking the second sample, 200 individuals are caught and 80 are marked from the first sample. When taking the second sample, 200 individuals are caught and 20 are marked from the first sample. All of these scenarios would result in the same population estimate.

When taking the second sample, 200 individuals are caught and 20 are marked from the first sample.

How does current theory explain the origin of a nucleus in eukaryotic cells? Please choose the correct answer from the following choices, and then select the submit answer button. None of the other answer options is correct. A prokaryotic cell was engulfed by another cell and became specialized in DNA replication. While there are some competing theories on the origin of the nucleus, neither theory discussed in the text really explains the origin of the nucleus. A prokaryotic cell was engulfed by another cell and became specialized in DNA transcription. A prokaryotic cell was engulfed by another cell and became specialized in translation.

While there are some competing theories on the origin of the nucleus, neither theory discussed in the text really explains the origin of the nucleus.

Which of the answer choices is most likely to fossilize? Please choose the correct answer from the following choices, and then select the submit answer button. a snail that died on a rock a lizard that died on a mountainside a leaf that fell from a tree and landed on the forest floor a jellyfish that died and sunk to the bottom of the ocean a crayfish that died in its muddy burrow by a creek

a crayfish that died in its muddy burrow by a creek

Chloroplasts are thought to have originated from a symbiotic relationship between an ancient eukaryotic cell and: Please choose the correct answer from the following choices, and then select the submit answer button. algae. a proteobacterium. a cyanobacterium. an archaeal cell.

a cyanobacterium.

Which of the answer choices is the best description of a protozoan? Please choose the correct answer from the following choices, and then select the submit answer button. a chemotrophic prokaryote a heterotrophic protist a photosynthetic protist a chemotrophic protist a heterotrophic prokaryote

a heterotrophic protist

Consider the image. The phylogeny shown illustrates: Please choose the correct answer from the following choices, and then select the submit answer button. that chimps gave rise to humans. proof of the evolutionary relationships between humans and chimps. a hypothesis about the evolutionary relationships of the apes.

a hypothesis about the evolutionary relationships of the apes.

All of the answer choices are properties of at least some prokaryotic cells except: Please choose the correct answer from the following choices, and then select the submit answer button. a nucleus. plasmids. pili. small size.

a nucleus.

Which of the answer choices is the best description of algae? Please choose the correct answer from the following choices, and then select the submit answer button. a photosynthetic protist a chemotrophic prokaryote a heterotrophic prokaryote a chemotrophic protist a heterotrophic protist

a photosynthetic protist

The mathematic expression ΔN/ ∆t/N1, where N denotes the size of a population and t represents time, is used to calculate: Please choose the correct answer from the following choices, and then select the submit answer button. a population's density. a habitat's carrying capacity. the "available" percentage of a habitat's carrying capacity. a population's growth rate. Euler's number.

a population's growth rate.

Which factors contribute most to intraspecific competition? Please choose the correct answer from the following choices, and then select the submit answer button. predator population size a species' fundamental niche and abiotic surroundings mutualistic relationships predation and parasitism a species' rate of reproduction and the carrying capacity of the environment

a species' rate of reproduction and the carrying capacity of the environment

If the frequency of allele A is 0.7 in a population that is in Hardy-Weinberg equilibrium, what would the frequency of the heterozygous Aa genotype be? Please choose the correct answer from the following choices, and then select the submit answer button. 0.42 The genotype frequency cannot be calculated from the information provided. 0.3 0.09 0.49

0.42

A researcher is studying the color of grasshopper exoskeletons. Assume that this phenotype is caused by the action of two alleles. Green grasshoppers have the genotype AA and brown grasshoppers have the genotype aa. If the frequency of the A allele in this population is 0.2, what is the frequency of the a allele? Please choose the correct answer from the following choices, and then select the submit answer button. 0.1 0.6 0.8 0.4 0.2

0.8

The half-life of 14C is 5,730 years. Archaeologists dig up a seed that contains 0.25 parts per trillion 14C. If it originally contained 1 part per trillion 14C, how old is the archaeological specimen? Please choose the correct answer from the following choices, and then select the submit answer button. 5,730 years 11,460 years 17,190 years 22,920 years 28,650 years

11,460 years

If a gene has two alleles, and allele A has a frequency of 83 percent, then allele a has a frequency of: Please choose the correct answer from the following choices, and then select the submit answer button. 41.5 percent. 17 percent. 166 percent. 117 percent. 7 percent.

17 percent.

A marine ecologist counts the number of crabs in three different intertidal regions that are each two hectares. The crab counts are 7, 2, and 6, respectively. What is the best estimate of population density per hectare for this particular species of crab? Please choose the correct answer from the following choices, and then select the submit answer button. 7 6 More sampling would have to be done until two areas have the same count. 5 2

If there are 100 diploid individuals in a population and 20 are homozygous for B, 60 are heterozygous, and 20 are homozygous for b, what is the allele frequency of B? Please choose the correct answer from the following choices, and then select the submit answer button. The frequency of B cannot be calculated with the provided information. 80 percent 20 percent 40 percent 50 percent

50 percent

Which of the statements is a hypothesis to explain the origin of the modern eukaryotic cell? Please choose the correct answer from the following choices, and then select the submit answer button. A cell evolved a nucleus first, then incorporated a proteobacterial cell that became a mitochondrion. None of the answer options is correct. A cyanobacterial cell became incorporated into an archaeon at the same time that eukaryotes developed. A cell evolved a nucleus first, then incorporated a cyanobacterial cell that became a lysosome. A cell evolved a nucleus first, then incorporated a cyanobacterial cell that became a mitochondrion.

A cell evolved a nucleus first, then incorporated a proteobacterial cell that became a mitochondrion.

Consider the image. Select the best set of data for constructing the type of diagram shown. Please choose the correct answer from the following choices, and then select the submit answer button. anatomical, physiological, and developmental studies of extant species in the fossil record morphological data of extant species A combination of all of the other answer options would yield the best data set. molecular data

A combination of all of the other answer options would yield the best data set.

A researcher is studying a specific strain of bacteria. In one of her cultures, she notices that the bacteria are antibiotic-resistant. As there are no genes in the chromosome that could confer antibiotic-resistance in these bacteria, the researcher assumes this is the result of a spontaneous mutation. What is another possible explanation? Please choose the correct answer from the following choices, and then select the submit answer button. A gene conferring antibiotic resistance is present on ribosomes. A gene conferring antibiotic resistance is present on peptidoglycans. A gene conferring antibiotic resistance is present on plasmids. A gene conferring antibiotic resistance is present on mitochondria.

A gene conferring antibiotic resistance is present on plasmids.

_____ is a special case of explosive speciation in which new species form rapidly in response to numerous "open" ecological niches. Please choose the correct answer from the following choices, and then select the submit answer button. Allopatric speciation Peripatric speciation Adaptive radiation Co-speciation Sympatric speciation

Adaptive radiation

Which of the statements is true regarding adaptive radiation? Please choose the correct answer from the following choices, and then select the submit answer button. Adaptive radiation tends to occur at a slower pace than genetic drift between two similar populations on the mainland. Adaptive radiation is more likely to occur in a population produced by a dispersal event than in a long-established population on a continent. Adaptive radiation is more likely to occur when there are a variety of similar and competing species. Adaptive radiation is more likely to occur within a mainland population than in a smaller population that underwent dispersal.

Adaptive radiation is more likely to occur in a population produced by a dispersal event than in a long-established population on a continent.

Imagine that a researcher discovers a new type of organelle in single-celled eukaryotes. She suspects that this new organelle is the result of endosymbiosis. How could she support this theory? Please choose the correct answer from the following choices, and then select the submit answer button. She could use electron microscopy to determine if any structural similarities exist between this new organelle and prokaryotic cells (such as whether it is similar to proteobacteria or cyanobacteria). She could determine whether this organelle has both an inner and outer membrane. All of these answer options represent ways to test this theory. If this organelle has its own DNA, she could compare its genetic sequence to those of certain prokaryotes.

All of these answer options represent ways to test this theory.

A population can decrease in size as a result of which of the processes? Please choose the correct answer from the following choices, and then select the submit answer button. an increase in emigration an increase in death rate an increase in predation All of these choices are correct.