A segments of a DNA strand is shown.

3' AGGTCAGGT 5'

Which of these is the correct complementary DNA strand for the segment shown?

Students are given data from an investigation that identified some of the chemical elements present in four different samples. Which sample was most likely DNA?

Which part of a DNA molecule is responsible for the direct coding of specific traits in an organism?

Differences in traits such as hair texture are determined by differences in -

A student used poster board to construct this model of a section of DNA. Which statement describes this model of DNA?

Nitrogenous bases are located on both strands of the DNA double helix. What is the significance of the nitrogenous base?

How is information for a specific protein carried on a DNA molecule?

The sequence of nitrogenous bases in DNA varies widely. The sequence of the bases in DNA is most important for which of the following?

A model of a DNA molecule is shown below. The arrow indicates -

Characteristics such as a widow's peak or attached earlobes are determined by the genetic code. Which components of DNA are referred to as the genetic code?

How does DNA in cells determine an organism's traits?

Which of these components are found in the cells of all living organisms?

Scientists use zebra fish to study human genetic diseases because zebra fish and humans share many of the same genetic diseases. Which statement describes why zebra fish experience similar genetic diseases as humans?

In the early 1980s scientists were able to produce two biomolecules by splicing a human gene into the bacterium E. coli to make recombinant human insulin and growth hormone. Which statement best explains why this experiment was successful?

Organisms can be classified based on homology, which is shared characteristics inherited from a common ancestor. In the past, homologies were based on studies of anatomical structures and patterns of embryonic development. In more recent years, the use of molecular biology techniques has allowed homologies to be compared at the level of nucleotide sequences. Nucleotide sequence comparisons are possible because all organisms share which of the following?

Four different types of cells are shown below. Which characteristic is shared by all four cells?

The fact that a strain of yeast with a certain defective gene can use the human version of the gene to repair itself is evidence that yeast and humans -

Students are modeling mRNA during the process of protein synthesis. Which answer choice correctly describes the model of the mRNA strand being transcribed?

A sequence of a DNA template strand is shown. Which of these is the correct amino acid chain produced from the DNA template strand?

A model of a biological process is shown. What is the purpose of this process?

The initial steps in gene expression are modeled below. Double-stranded DNA first unwinds into two strands. Which process and product are represented in Diagram 2?

Which of the following polypeptides is coded for by the mRNA sequence 5' AUGGUUAAACGACAAUCC 3'

The Himalayan rabbit's habitat has cold, snowy winters and mild summers. The body is typically covered in white fur except for the nose, feet, tail, and ears, which are covered in black fur.

A scientist shaved an area of white fur on the back of a Himalayan rabbit and placed an ice pack over the shaved area. The shaved area grew black fur.

Which of these best explains why the hair that grew back where the ice pack was placed was black and not white?

The arctic fox inhabits northern areas of North America. The same arctic fox is shown in the drawing at different times of the year. What causes this change in fur color?

Human bone, muscle, and nerve cells all contain the same number of chromosomes with the same complement of genes. What enables these cells to perform specialized activities?

Mice have two unlinked allele pairs that affect fur color. The table shows how allele pairs affect fur color. The term "agouti" describes fur with pigmentation that changes in each hair from the shaft to the tip, giving the fur a banded appearance. Mice with the aa allele pair are albino, regardless of the second allele-pair combination.

What is the probability of albinism in the offspring of a cross between two mice with AaBb alleles?

The inheritance pattern for an autosomal dominant trait is shown in the pedigree. Shaded symbols represent individuals that express the dominant trait.

Based on this pedigree, what are the most likely genotypes of individuals I-1 and I-2?

In humans blood type is determined by the A, B, and O alleles. The A and B alleles are codominant to each other and dominant over the O allele. An individual with the AO genotype and an individual with the BO genotype can produce offspring with which of the following phenotypes?

In cattle the allele for cloven hooves (H) is dominant over the allele for mule-foot hooves (h). The phenotype for each trait is shown in the picture.

What is the probability of cloven hooves in the offspring of parents that are heterozygous for the trait?

Albinism is an autosomal recessive condition. Which circle graph shows the genotype probability when an albino female mates with a male that is heterozygous for the albinism trait?

The four butterflies in the illustrations represent the offspring in the F1 generation.

Which statement is best supported by the phenotypes of these offspring?

Chickens can have different types of feathers. Frizzled feathers curl toward a chicken's head. Assume that feather type is determined by a single gene and that the allele for frizzled feathers is dominant over the allele for straight feathers. In a cross between two chickens with straight feathers, what percentage of the offspring can be expected to have frizzled feathers?

Facial dimples and free earlobes are both considered dominant human traits. What are the expected phenotypes of the offspring of a female with dimples and free earlobes (DDFf) and a male with dimples and attached earlobes (ddff)?

Normal fruit flies have brownish-yellow bodies, and this body color is dominant. A mutation in the gene for body color can produce flies with an ebony body color. A homozygous normal fruit fly (e+e+) is crossed with a homozygous ebony fruit fly (ee). What is the predicted outcome of this genetic cross?

In the 1860s Gregor Mendel performed numerous dihybrid crosses between pea plants. Dihybrid crosses involve the study of the inheritance patterns related to two different traits. In guinea pigs, the allele for black fur (B) is dominant over the allele for brown fur (b), and the allele for short fur (F) is dominant over the allele for long fur (f). What percentage of the offspring from a BbFf x bbff cross would be expected to be heterozygous for both traits?

Tomato plants usually have hairy stems. Hairless stems are present in tomato plants that are homozygous recessive for this trait. If the stem characteristics are determined be a single gene, what is the expected outcome of crossing two tomato plants that are heterozygous for hairy stems?

If several pea plants with the genotype TTYy are crossed with the pea plants with the genotype Ttyy, what percentage of the offspring will be expected to have the TTYy allele combination?

Gametes produced by an organism contain a combination of genes from that organism. In every gamete, this combination is -

What are the three main parts of a nucleotide?

Use the chart to find to amino acid that corresponds to the codon GGA:

What is the process shown in the diagram?

In cocker spaniels the allele for a black coat color (B) is dominant over the allele for a brown coat color (b). If a brown cocker spaniel is crossed with a heterozygous black cocker spaniel, which of the following genotypic ratios can be expected?

In 1952 Rosalind Franklin took the x-ray photograph shown below, which gave the world its first look at DNA.

By studying this photograph, scientists gained knowledge about the -

A segment of DNA is represented in the illustration.

How is information for a specific protein carried on the DNA molecule?

What are the offspring's possible phenotypes?

Brown fur is dominant. White fur is recessive.

One parent is homozygous for brown fur as the other is heterozygous.

Cross Two Homozygous plants

(RRYY x rryy)

R = round seeds, r = wrinkled seeds Y = yellow seeds, y = green seeds

What percent will have Round and Yellow seeds?

What process is occurring in the diagram?

Which role of protists has the most positive effect on maintaining the plant population in an ecosystem?

Saprophytes are fungi that feed on dead and decomposing organisms. They secrete enzymes that digest components of cell walls, such as cellulose and lignin.

Which statement explains why these fungi are an important part of the biogeochemical cycle?

A student researching bacteria concluded a report with the claim in the box.

Which statement correctly addresses the validity of the claim?

Health professionals sometimes recommend nutritional supplements that contain a variety of species of bacteria to promote good digestive health. The product label for one of these supplements is shown.

Why does this type of bacteria-filled supplement benefit human health instead of causing illness?

Some fungi secrete substances that are toxic to bacteria that compete with them for food. Scientists have used their knowledge of this ability of fungi in order to produce which of the following substances?

During secondary succession, which of these best describes why decomposing pioneer plants give way to larger, more complex plant species, such as hardwood trees?

Grassland ecosystems in Texas have evolved to depend on periodic fires to return nutrients to the soil and encourage plant reproduction. Humans have prevented fires in many of these grassland areas, resulting in plant and animal communities with little diversity. Wildlife biologists often recommend purposefully starting fires called prescribed burns, which are monitored and controlled, in grassland ecosystems every 3 to 4 years. These biologists observe greater diversity in plant and animal life in the years following a prescribed burn. What natural processes are the biologists attempting to imitate?

A small town in the piney woods of East Texas has a soccer field composed of native grasses. The soccer field is mowed once a week. What effect does continual mowing have on the ecology of the field?

Enchanted Rock State Natural Area is located in Central Texas. Enchanted Rock is a dome of granite. The area contains four easily identifiable communities. The table describes characteristics of each type of community in the area.

A student studying primary succession should focus on which of these communities?

An estuary collects sediments from teh ocean and rivers that feed into it. The sediments swirl around and then settle to form a medflat. Eel grass is then established on the mudflat. The ecosystem changes over time and ultimately develops into a salt marsh that contains mangrove trees. Which of the following is likely NOT involved in this example of ecological succession?

The rocky material left behind by a retreating glacier forms what is called a moraine. When primary succession occurs on a moraine, which life-forms will help create the soil by breaking down bare rock?

During ecological succession, how does the growth of young hardwoods affect the organisms living in an ecosystem?

Which statement describes the differences in species diversity between an ecosystem beginning the process of primary succession and one beginning the process of secondary succession?

As ecosystems move through the stages of succession, the populations of organisms in them change. Which of the following describes the stage of succession likely to have the most species diversity?

How do an increase in the organic matter in soil and an increase in soil depth affect the population of plants in an area?

The graph shows the changes in the number of species in an ecosystem. Which event was most likely the cause of the changes in species diversity in this ecosystem?

Surtsey is an island located south of Iceland. The island was formed by a volcanic eruption and first appeared in 1963. The table contains descriptions of changes in the population and diversity of species on Surtsey. Which of these lists the descriptions in the correct order of ecological succession on Surtsey?

The graph shows the basic changes in a forest community after a disturbance occurred. The information shown in the graph suggests that the changes in the forest community were caused by -

The ocean sunfish is a large, flat fish that spends most if its time in deep water feeding mainly on jellyfish. Sunfish often have many species of copepods, small crustaceans, that bury their heads into the soft tissue of the sunfish. Sunfish will swim to the surface of the water and lie sideways, allowing seabirds to eat the copepods from their skin. Which list describes the types of relationships the sunfish has with other marine organisms?

Which of these best demonstrates mutualism between certain types of bacteria and humans?

In North American forests, two species of birds, nuthatchers and brown creepers, forage on the same trees for insects. Brown creepers feed on insects found near the bottom of the tree trunk, while nuthatchers feed on insects in the top part of the tree. The difference in foraging behavior most likely affects the nuthatchers and brown creepers by -

A partial Texas food web is shown. The populations of which organisms will most likely increase as a result of a disease that suddenly reduced the population of Texas horned lizards?

A biomass pyramid of an ecosystem is shown. Which statement provides the best explanation for the difference in biomass of organisms found at each trophic level?

The table lists some organisms found in a swamp ecosystem and their sources of energy. When constructing an energy pyramid of the swamp ecosystem, which of these would be placed at the top of the pyramid?

A partial meadow food web is shown. Based on this food web, which organisms are direct sources of energy for secondary consumers?

The energy pyramid below shows the energy made available by producers. Based on the energy flow between trophic levels in an energy pyramid, how much energy would be expected to be found at the secondary consumer level in this pyramid?

The Texas blind salamander lives in the Edwards Aquifer region around San Marcos. The table lists some of the organisms that live with the salamander in this environment and their food sources. In an energy pyramid for these aquifer cave dwellers, which of the following would be placed at the bottom?

What would be the most likely effect of a wildfire that burned a large area of a forest?

Which of the following is most likely to cause the greatest disruption to an ecosystem?

The diagram shows molecules that a mitochondrion uses and produces during a cellular process.

Which other molecule is a product of this process?

In a study of physical endurance, researchers observed significant increases in the heart rates and breathing rates of participants immediately after they engaged in strenuous exercise.

Which statement best explains the increase in the heart rate and the breathing rate during exercise?

When mammals get an infection, their internal body temperature often rises 2 to 3 degrees Celsius. The body gets the energy it needs to react to an infection by -

Which molecule synthesized by plants is a major source of energy for cellular processes in both plants and animals?

Cells can generate as many as 36 to 38 molecules of adenosine triphosphate (ATP) from the metabolism of one molecule of glucose. Which cellular process results in this amount of ATP production?

Parrotfish are herbivores that are found in coral reefs. To escape predation, a parrotfish will graze with a rabbitfish, which has venomous spines at the end of its pelvic fins. The rabbitfish does not benefit from this relationship. Which type of relationship do the parrotfish and the rabbitfish have in the coral-reef environment?

A segment of DNA produces methionine, threonine, histidine, aspartate, and glycine when translated. A substitution mutation occurs and causes the synthesis of the segment as shown. Which is the new peptide chain when the new DNA segment is translated?

Frogs and toads belong to the order Anura. The smallest organism in this order is about 7 millimeters long, while the largest is about 30 centimeters long. Which of these lists best describes this order?

On March 24, 1989, an oil tanker ran aground on Bligh Reef in Prince William Sound, Alaska, and spilled millions of liters of crude oil. The graph shows pink salmon populations in Prince William Sound from 1970 to 1999. What do these data suggest about the effect the oil spill had on pink salmon?

Cells typically respond to DNA damage in three ways: by ceasing to grow and divide until the damage is repaired, by permanently ceasing to grow and divide, or by dying. In 2010 a group of scientists reported that a certain kind of immune reaction can cause DNA damage that leads to a fourth response. DNA damage can turn off genes involved in cell-signaling pathways. Turning off these genes can cause less-mature cells to divide too rapidly, often leading to the development of

In recent years humans have interfered with the natural balance within deer populations in various ecosystems. The interference includes eliminating predators of the deer. Which of the following statements correctly describes the long-term outcome of this interference?

A student wants to use the Venn diagram to show the characteristics of two kingdoms of organisms. The characteristics that the two kingdoms share will be listed in the shaded area where the circles intersect. Which of these is a characteristic that the student should list in the shaded part of the diagram?

A student preparing for a hike wants to pack a snack that has biomolecules that provide quickly available energy but few excess calories. Which nutrition label lists the best combination of biomolecules that provide quickly available energy while providing the fewest calories from other types of biomolecules?

An informational pamphlet in a health clinic describes an interaction between body systems. Which statement identifies the body systems that are directly involved in the interaction described and explains how they accomplish the interaction?

Diatoms are one of the most common types of phytoplankton in marine habitats. Like plants, diatoms contain chlorophyll and produce glucose from which of the following?

A genome-wide association study involves searching the genomes of many people in order to find genetic variations associated with common diseases such as cancer, asthma, and diabetes. These studies are possible because of computer databases that allow researchers to compare the genomes of people who do not have a particular condition with the genomes of people who do have this condition. In order to do this type of testing, researchers need blood samples or cheek swabs from people. Obtaining these samples is necessary because blood and cheek cells contain

When the level of carbon dioxide in the blood is too high, the excess carbon dioxide reacts with water and produces carbonic acid. The carbonic acid causes the blood pH to become more acidic. When the blood pH becomes too acidic, chemoreceptors in the brain instruct the body to react and maintain homeostasis in blood pH. Which of these responses by the body would eliminate the excess carbon dioxide and help maintain homeostasis in blood pH?

Two populations of mice living in the same forest are separated by a large water-filled ditch. After a rainstorm, flooding brings several mice from one population to the other population. When the mice from the first population reproduce with members of the second population, which of the following will likely occur?

The model represents the change in DNA content of a cell during the cell cycle. Which part of the model represents the S phase?

Coradas garrulus is a blue bird with an orange-brown back. The offspring of this bird have an effective defense mechanism. The young birds vomit and cover themselves in a foul-smelling orange liquid when they sense a threat by predators. Which two systems alert the young bird to the danger and help produce the vomit it uses as a defense?

Structures represented in the illustration below are found in the lower epidermis of a plant leaf. The illustration at right shows the response to a certain environmental condition. The response represented in the illustration would most likely be caused by

How is information for a specific protein carried on the DNA molecule?

The food web shows the flow of energy through a sagebrush-steppe ecosystem. Which of these organisms are in a trophic level that receives a larger percentage of the energy captured by the producers than the percentage received at the bats’ trophic level?

Fireflies emit light. The production of light by an organism is called bioluminescence. To generate visible light, cells in a firefly’s tail produce thousands of luciferase enzymes. Luciferase binds to a chemical called luceferin. Once bound, the luciferase enzyme speeds up a chemical reaction that combines an oxygen molecule and luciferin to produce oxyluceferin. This reaction requires energy and releases light. Which of the following best describes how the luciferase enzyme speeds up the chemical reaction?

An analysis of DNA and RNA sequences can be used to classify organisms. A dendrogram, such as the one shown, is based on molecular data. It can be used to represent evolutionary relationships within a group of organisms that are hypothesized to have descended from a common ancestor. Which statement is best supported by the information in this dendrogram?

Adult mountain lions (Puma concolor) are almost 2 meters long. They have a black spot over each eye. The common names used throughout the United States for this species are listed. Why is it best for scientists to use the name from the standardized taxonomic system?

The internal transport of water and minerals in plants requires that two systems work together. Which diagram correctly describes how the two systems accomplish this?

At birth, Himalayan rabbits are usually white over their entire bodies. But when parts of their bodies reach temperatures below 35°C, a pigment that causes these parts to turn black is produced. Which of the following is most likely the cause of this phenomenon?

All the animals to the right of the hagfish would have the common characteristic of

The differences between two molecules include the type of sugar that forms a section of the molecules and the identity of one of the four nitrogenous bases that make up another section of the molecules. These two molecules are

Plants have developed many methods of seed dispersal. The table below shows seeds to two different species. How has the seed dispersal method developed by these plants given them a reproductive advantage?

The table lists the types of white blood cells found in humans, indicates how abundant they are, and describes their functions. The two most abundant types of white blood cells may both be involved in a response to which of these?

Some students used vinegar to dissolve a way the shells of three eggs and used these eggs as models of human red blood cells. The students observed the changes in the eggs when they were placed in different solutions. Which statement best describes the role of the cell membrane in this model?

Animal body systems often coordinate their actions to carry out specific functions for the whole animal. Which of these correctly describes the interaction of two biological systems for a specific purpose in the human body?

A student is asked to draw a food web in which the same organism is a primary consumer as well as a secondary consumer. How should the organism be represented in the food web?

Which of these models of a DNA strand (below) shows bases that are complementary to the ones on the student’s DNA model (above)?

Three species of lizards of the genus Gallotia are found on the Canary Islands, a chain of seven volcanic islands off the west coast of Africa. The easternmost island, Lanzarote, is the oldest, while the westernmost island, El Hierro, is the youngest. The distribution of lizard species is shown on the map below. Which statement about the ancestry of the lizards from the genus Gallotia is best supported by this information?

In the European roe deer (Capreolus capreolus), implantation of embryos after breeding is delayed. The deer breed in July or August but do not give birth until the following May or June. From summer to late December, the embryo rests in a state of dormancy as a 30-cell blastocyst. In late December or early January, the embryo sends a signal that causes the female to release hormones, allowing the embryo to continue to develop normally. Why is delayed implantation an advantageous adaptation for the European roe deer?

This diagram of the fossil record represents changes in mollusks over millions of years. How can the pattern of change in the fossil record best be explained?

Human body cells each have 46 chromosomes in their nuclei. Meiosis is necessary in order to ensure that each gamete produced in the human body has —

In the 1960s the molecular biologist George Streisinger developed the strand-slippage hypothesis. Streisinger noticed that mutations occurred in areas of DNA that contained many repeated sequences. When a strand-slippage error occurs, an insertion mutation can result. How does the insertion mutation affect the DNA?

The technique known as chromosome painting is the result of scientific research. Scientists use chromosome painting to mark the locations of genes on human chromosomes with fluorescent tags. It is also possible to apply this technique to the chromosomes of many different species. Chromosome painting allows for which of the following?

Which of these statements best explains the process of energy conversion that takes place in the mitochondria?

Some organisms have genes that improve their ability to survive and reproduce. If the genes also help their offspring survive and reproduce, then which of the following will most likely increase?

Enzymes are proteins that help increase the rate of chemical reactions inside cells. These proteins are composed of many simpler molecules called amino acids. Which of the following suggests that the shape of an enzyme determines the enzyme’s function?

A photomicrograph of onion root tip cells during mitosis is shown below. Which phase of mitosis is occurring in the cell indicated by the arrow?

Which of these must occur during S phase of the cell cycle so that two daughter cells can be produced during M phase?

Cell differentiation is critical during embryonic development. The process of cell differentiation results in the production of many types of cells, including germ, somatic, and stem cells. Cell differentiation is most directly regulated by —

The limbs of several organisms are shown in the illustrations below. Scientists sometimes compare the limbs of these organisms to look for evidence of common ancestry. These limbs provide evidence of common ancestry because they —

How does an enzyme speed up chemical reactions?

Which of the following correctly describes a viral reproductive cycle?

Diffusion is the movement of ______ from ________.

Which of the following does a plant need in order to make glucose?

What is the ability for an organism to survive and reproduce?

Evidence of evolution shows that all organisms

Bat wings and bird wings have similar structure. What type of evidence is this?

Who is most related to the hamster?

The 1918 influenza epidemic killed between 50 million and 100 million people worldwide. THis epidemic happened near the end of World War I. More people died from the influenza epidemic than were killed in the war. Which of the following explains why this virus was so deadly worldwide?

The diagram represents one way an enzyme can be inhibited. Which statement explains the effect of an inhibitor on an enzyme?

During the final stages of human gestation, receptors for the hormone oxytocin increase on the smooth muscle cells of the uterus. The release of oxytocin during labor stimulates the smooth muscle tissue in the wall of the uterus. The vigorous contraction of the uterine smooth muscle helps push the baby through the birth canal so that delivery can occur. This process involves the interaction of which organ systems?

In the early 1900s a scientist hypothesized a link between DNA and the production of protein in the cytoplasm. However, the fact that DNA could not be found outside the nucleus led scientists to believe that another substance was also involved in the synthesis of protein in the cytoplasm. In the 1940s scientists performed an experiment that ultimately identified the site of protein synthesis. They also identified the molecule responsible for transporting information from the nucleus to the site of protein synthesis. What was the newly identified molecule?

Which statement best describes the relationship between the products of photosynthesis and the reactants in cellular respiration?

In the early 1980s scientists were able to produce two biomolecules by splicing a human gene into the bacterium E. coli to make recombinant human insulin and growth hormone. Which statement best explains why this experiment was successful?

Kidneys are part of the excretory system in a human body. They purify the impure blood and send it back to the rest of the body. Which system is mainly responsible for the transport of plasma to the kidneys?

Several structures work together to allow flowering plants to reproduce. The diagram shows a typical flower. Which table correctly identifies the function of each structure or group of structures in the reproduction of the plant?

The complex carbohydrates pictured below are made by linking molecules of glucose. In all three complex carbohydrates, the subunits of glucose are bonded together differently. Because they have different structures, they most likely —

Some organisms have genes that improve their ability to survive and reproduce. If the genes also help their offspring survive and reproduce, then which of the following will most likely increase?

What term matches the following? ( pg 34)

Geese survive by flying north for the summer and south for the winter. This way they can find abundant food year round.

Which organisms can be found at the first, or lowest, trophic level?

A scientist observes a single-celled organism with several long, whip-like tails. Which function do the whip-like tails most likely perform for the organism?

Which process best describes the assembly of proteins from amino acids?

Which biological molecules are most likely represented by molecules 1 and 2?

Which statement best describes a relationship between enzymes and a simple biological reaction?

Which of the following is most involved in providing structure for a plasma membrane?

During strenuous exercise, body temperature increases. The body responds to the increase in temperature by sweating, which helps to reduce the body temperature.

Which is demonstrated in this situation?

Which statement best describes the relationship that exists among proteins, DNA, and cells?

A freshwater plant is placed in a container of saltwater. What will most likely happen to the cells of the plant?

A student is looking for evidence that spindle fibers are separating the chromosomes to ensure that each new nucleus has one copy of each chromosome. Which diagram is the student looking for?

The photograph shows a laboratory investigator examining samples of DNA in a procedure called PCR, or polymerase chain reaction. Using PCR, the investigator can create thousands or even millions of copies of a fragment of DNA for closer investigation. In which of these situations would PCR be most useful?

Which statement about enzyme activity is best supported by this graph?

Which table correctly identifies the four most-abundant elements in biomolecules?

What is the purpose of this process this process?

The graph models core body temperature during a rapid change in environmental conditions. Which statement explains the pattern in the graph?

The table shows some observations made by four students during a field trip to a nature area. Which student made observations of a community of organisms?

Oncogenes are mutated forms of genes. Oncogenes can transform a cell into a tumor cell. Some tumor cells are benign, while others are malignant. How does the presence of an oncogene lead to the formation of a tumor?

Scientists estimate that there are more than 20,000 species of ants. The species range in size from 1 mm long to 38 mm long and live in most environments. The diets of ants range from flowers and seeds to fluids from their own larvae. Ants have been able to successfully inhabit so many different environments because their populations have been able to --

Some students used vinegar to dissolve away the shells of three eggs and used the eggs as models of human red blood cells. The students observed the changes in the eggs when they were placed in different solutions. (View Image)

Which statement best describes the role of the cell membrane in this model?

Viruses can be transmitted through air, water, food, insect bites, and direct skin contact. Once a virus gains entry to the body, it invades a host cell in order to --

What is the role of mRNA in expressing specialized structures?

From a single fertilized ovum undergoing a series of rapid cell divisions, a human infant develops. The embryonic cells become specialized for a variety of functions. Which of these statements best describes how different cell types develop?

An illness caused by a certain virus includes fever, rash, joint pain, red eyes, and headache. The virus is transmitted to people by infected mosquitoes. Symptoms quickly occur within three to twelve days after contracting the virus. There is no vaccine for this virus.

Which description best explains the reproductive cycle of this virus?

A student produces a drawing of a virus for a presentation. The student states that the capsid has a function similar to the nuclear membrane found in animal cells.

Which of these describes the similar functions of capsids and nuclear membranes?

The human immunodeficiency virus (HIV) often infects and destroys CD4 T cells. These cells are one of many kinds of white blood cells that are an important part of the immune system.

The most common danger related tot eh destruction of CD4 T cells is -

Bacteriophages can infect bacteria such as E. coli. In what way are the bacteriophage and E. coli alike?

A person infected with the human immunodeficiency virus (HIV) may not have any symptoms for a period of time. During this period the virus affects the body by doing which of the following?