During the cell cycle, proteins called cyclins bind to enzymes that send signals for the cell to progress through stages of cell replication. At the end of this cycle, the cyclins degrade to prevent further signaling for the cell to divide.

Uncontrolled production of cyclins will most likely result in —

The life cycle of a frog is illustrated in the diagram.

Which statement best explains how the cell cycle is important to the life cycle of the frog?

Students created note cards comparing characteristics of eukaryotic and prokaryotic cells. Which set of note cards most accurately compares these cells?

Which statement describes the process of osmosis in an animal cell?

Environmental factors typically activate genes in a cell by causing the cell to —

Materials are provided to students to build models of a prokaryotic cell, a eukaryotic cell, and a virus. The materials and the structures they represent are listed in the table shown.

Which material will students use in all three models?

Which table correctly identifies how the plasma membrane contributes to the maintenance of cellular homeostasis?

The diagram shows the major stages of the cell cycle and the percentage of time spent in each phase.

Which statement best describes why a cell spends the majority of its time in interphase?

A diagram of an HIV infection is shown.

Which conclusion about the HIV infection of a host cell is best supported by the diagram?

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?

When the skin comes in contact with an irritant, receptors in the skin send signals to the spinal cord. The signal is then sent to the brain for processing, and the individual begins to scratch the affected area. Which two systems are most likely interacting when a person experiences itching caused by a skin irritant?

Which graphic organizer best compares the energy inputs and outputs of cellular respiration and photosynthesis?

Which statements best compare the function of an ATP molecule to a DNA molecule?

For an enzyme to be able to catalyze a reaction, the active site must —

A flower that has both male and female reproductive structures is shown.

Which statement best describes an interaction that will allow a flowering plant to reproduce by self-pollination?An anther is transferred from a filament to another filament within the same flower.

Breaking down food for nutrients involves many body systems. A student made a partial list of the processes that occur.

Which body systems interact most directly in the three listed processes?

A student makes a Venn diagram to compare the functions of carbohydrates and lipids

Which cellular function of carbohydrates and lipids should be placed in the shared section of the Venn diagram?

Students construct a graphic organizer to illustrate the different levels of biological organization.

Which term does the letter X represent in the graphic organizer?

Students set up a controlled experiment by growing the same type of seedlings in two different locations. After a period of time, the students observed the seedlings and recorded their observations in the table shown

What caused the shoots of the seedlings on the windowsill to bend toward the window?

The hormone adrenaline causes blood vessels to contract and send more blood to major muscles.

An illustration of how a particular DNA mutation will most likely affect the polypeptide produced is shown. What type of mutation is illustrated?

Which property is shared by the cells of all living things?

A segment of DNA is shown in the diagram. Which of these identifies the part of the DNA segment labeled X?

Snowshoe hares can be found living in the Rocky Mountains of New Mexico. During the summer months, when there is no snow on the ground, the snowshoe hare’s coat color is typically brown. During the winter months, when the mountains are covered in snow, the snowshoe hare’s coat is typically white. Which statement describes the genetic basis for the seasonal changes in coat color?

A genetic cross involving two unlinked genes is represented. AaGG x aaGg

Which genotype is NOT possible in the offspring produced by the cross?

A partial DNA segment and an mRNA codon chart are shown. 3′ TCATGCATG 5′

What amino acid sequence is encoded in the partial DNA segment?

In Texas Longhorn cattle, coat coloration is an inherited trait. What is the genetic basis of coat-color variation in Texas Longhorn cattle?

7 When a new mutation occurs in a somatic cell of a sexually reproducing organism, what percentage of the individual’s offspring are likely to inherit the mutation?

Some angelfish colors are determined by codominance. Possible phenotypes and genotypes of angelfish colors are shown.

Which table shows the expected phenotypes of offspring resulting from a cross between a black angelfish and a black-lace angelfish?

8 A cellular process is shown. Which statement best describes the significance of this process?

Farmers spray pesticides on their plants to protect the plants from being eaten by insects. Some individual insects have a genetic mutation that makes them resistant to the toxins in the pesticides.

Which statement best describes how only a few resistant individuals resulted in the pesticide becoming ineffective?

A cladogram of five species is shown.

Based on the cladogram, the ancestral species most likely had —

The Mexican long-nosed bat roosts in Big Bend National Park in West Texas. The bat feeds on nectar and pollen and hovers while it feeds. Additionally, its tongue can extend up to eight centimeters. The features of Mexican long-nosed bats are evidence of natural selection because the features are adaptations that —

A researcher determines an organism to be eukaryotic, unicellular, and autotrophic. In which taxonomic group should this organism be classified?

When multiple transitional fossils are found in many rock layers, they provide evidence of —

Students examine images of a certain species of bat commonly found in Texas. Using the bat dichotomous key, they conclude that the bat species is a Mexican free-tailed bat due to its large, round ears.

Based on the dichotomous key, in addition to the shape of the bat’s ears, which other set of features should the students look for to confirm the identity of the bat?

The taxonomic classifications of four species of amphibians are shown.

Based on the information provided, which two species are most closely related?

The giant octopus lays 20,000 to 100,000 fertilized eggs. After hatching, most octopuses become prey to larger marine organisms, and less than 5% will reach adulthood to reproduce. One benefit of the giant octopus laying many eggs is to —

Researchers analyzed a mitochondrial gene of different bat species to determine relatedness. A cladogram of their results is shown.

Based on the cladogram, which set of bat species is the least related?

Two scientists want to compare their research of fireflies. Which information must the two scientists provide to each other to determine if they studied the same type of fireflies?

The survival of a species depends on its ability to adapt to changes in the environment. A species must be capable of surviving and reproducing despite changes to food sources, climate, or threats from predators. Which statement correctly describes a way that mutations increase the likelihood that a species will survive in a changing environment?

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

Four different nucleotides are used as building blocks of DNA. Which of the following can be used to distinguish one nucleotide from another?

The green frog (Lithobates clamitans clamitans) is found in many parts of the United States. The table contains some information about this frog. Why does the ability to lay 1,000 to 5,000 eggs increase the fitness of the species

L. clamitans clamitans?

In the early 1900's a scientist hypothesized a link between DNA and the production of proteins 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 1940's 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 this newly identified

molecule?

During meiosis, homologous chromosomes exchange genetic material. This exchange of

genetic material —

As a fertilized egg divides, the cells differentiate because they —

The photograph shows monarch butterflies landing on plants where there are thousands of other monarch butterflies. These butterflies feed on milkweed plants as they travel south for the winter, covering distances of 5,000 km or more each year. However, the population of these butterflies has been steadily declining over the last 20 years. What is the most likely reason the population of these butterflies has been declining?

Bactrian camels, dromedaries, llamas, and alpacas are all members of the same taxonomic family, Camelidae. Members of this family all have two toes, no hooves, true canine teeth, and a split upper lip. The family Camelidae originated in North America. The physical features

of animals in this family and the family’s geographical origin provide evidence that all these

animals —

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

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?

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?

The diagram shows cells in different phases of mitosis. A student is trying to find a cell in a particular phase of mitosis. The 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 cell is in the phase of mitosis that the student is searching for?

The quiver tree grows in desert areas in southern Africa. In recent decades average temperatures have been rising in southern Africa. Scientists predict that this warming trend will continue. Quiver trees in the hottest parts of their range near the equator are dying, but quiver trees at high elevations or in parts of the range that are farther from the equator are growing and reproducing. Which of these best explains what is happening to the quiver tree population in southern Africa?

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

This diagram shows cellular activity across a cell membrane. Which two processes does this diagram most directly model?

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?

Cells pass through a G₂ checkpoint before entering mitosis. Ideally, if DNA damage is 2 detected, the cells do not enter mitosis until the damage is repaired. Why is DNA damage repaired before cells enter mitosis?

The table shows a DNA sequence and three types of mutations that can change the DNA sequence. Which mutation will cause translation to stop?

People who have Alzheimer’s disease experience an increasing loss of brain function and cognition over time. Alzheimer’s is characterized by a buildup of abnormal protein fragments that damage brain cells. Recently scientists have discovered an enzyme, BACE2, that decreases these abnormal protein fragments in the brain of a person with Alzheimer’s disease. Which statement explains how BACE2 most likely works?

The complex carbohydrates pictured below are made by linking molecules of glucose.

In 2010, scientists excavated a skull fossil that provides evidence of a newly discovered species of big cat. Based on the evidence, scientists hypothesize that big cats branched off from smaller wild cats about 6 million years ago. Which of these resources did the scientists most likely rely on to form their hypothesis?

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? Draw a Punnet Square!!!!

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?

Each strand of a DNA molecule contains nitrogenous bases that pair with other nitrogenous bases in very specific ways. A diagram of a section of DNA is shown. Which DNA strand is complementary to the one shown above?

A prey population consists of individuals with a variety of running speeds. The adaptation that allows some of these animals to run fast would be an example of natural selection if it helps them —

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 amount of energy the producers in this energy pyramid provide the primary consumers is 54,000 joules. From this amount, 540 joules are provided to the tertiary consumers. Based on this model, how much of the energy was provided to secondary consumers?

Food webs such as the one shown were first used in 1927 by the animal ecologist Charles Elton. The food web below represents the feeding relationships among organisms in an Alaskan ecosystem. An environmental change that removed which of these organisms from the ecosystem would cause the most instability in the ecosystem?

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?

The photograph shows monarch butterflies landing on plants where there are thousands of other monarch butterflies. These butterflies feed on milkweed plants as they travel south for the winter, covering distances of 5,000 km or more each year. However, the population of these butterflies has been steadily declining over the last 20 years. What is the most likely reason the population of these butterflies has been declining?

While visiting a national park, a student encounters an unfamiliar organism in a damp area near a body of water. The student notes that the organism is about 10 cm long, has four legs, and has a tail. The organism is black with small white spots on its smooth, moist skin. It also appears to have an internal skeletal system. To which class does the organism most likely belong?

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

Some relationships between different organisms are shown in the table. Which table correctly identifies each type of interaction described?

Cytokinins are a class of plant hormones that help regulate growth by promoting cell division. Cytokinins are produced mainly in meristematic tissue, where most plant growth occurs. Which system carries cytokinins produced in the roots to the rest of the plant?

Scientists studying illnesses caused by chemically contaminated food conduct research to minimize the effects of these diseases on society. These chemicals harm the body through interactions between the digestive system and the immune system. Scientists conducting this research are likely to describe which of these interactions between the digestive and immune systems?

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?

Part of a hydrothermal vent food web is represented in the diagram. Which organisms are both secondary and tertiary consumers in this food web?

Five general characteristics of organisms in kingdoms Plantae or Fungi are listed in the box. Which table correctly lists the characteristics of the organisms in the two kingdoms?

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 picture shows a 3-D model of a virus called a bacteriophage. Bacteriophages can infect bacteria such as E. coli. In what way are the bacteriophage and E. coli alike?

This dichotomous key can be used to identify some conifers. Based on the key, which of these best describes the leaves and cones of the long-leaf pine?

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

The table lists and describes three types of cells from prepared slides that students observed with a microscope. Which of these sets of slides could students have used for their observations? Hint: Red blood cells are also known as erythrocytes.

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

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?

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?

Atmospheric nitrogen has to be combined with other elements, or fixed, in order to be used by plants. Lightning is one way that nitrogen is fixed. When lightning occurs, the extreme heat breaks the bonds in nitrogen molecules, allowing nitrogen to combine with oxygen and form nitrogen oxides. In what way is most of the nitrogen fixed by lightning made available for use by plants?

Plants called sundews have rounded green leaves with many hair-like structures. The ends of these structures contain enzymes in a sticky liquid that looks like nectar or moisture, as shown in the picture. The hairs do not react to dust or nonliving material but will bend inward when insects get caught in the sticky liquid. Sundews digest trapped insects over a period of a few days. Based on this information, what functions do the specialized leaves of sundews perform?

Scientists around the world use a standardized taxonomic system. Why would scientists want to use a taxonomic system that is standardized?

A student performed an investigation in which two ivy plants were planted in two separate containers. One of the containers had earthworms mixed in with the soil, and the other container had soil and no earthworms. The plants were given the same amount of water and exposed to the same amount of sunlight. The student observed that after several weeks of growth, the plant exposed to earthworms appeared to be healthier and exhibited more growth. To conclude that the relationship between the plant and the earthworm is an example of mutualism, the student must perform follow-up investigations that do which of the following?

Nudibranchs are marine gastropods that lack shells. Many of these gastropods retain the foul-tasting poisons of their prey and secrete them when threatened. The bright coloration of the nudibranchs warns predators to avoid them. Based on this information, how has adaptation allowed marine gastropods to be successful

without a shell?

The four butterflies in the illustrations represent the offspring in the F₁ generation. Which statement is best supported by the phenotypes of these offspring?

A new predator of rabbits has been introduced within an ecosystem. This new predator runs faster than the native predators of rabbits.

Which statement describes what will most likely occur in the rabbit population due to the introduction of the predator?

Which answer choice best describes a community?

Eight components present in nucleic acids are listed in the box. Which components bond with adenine in a section of double-stranded DNA?

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

Which four body systems interact to allow a person to sneeze?

Students use a microscope to look for structures present in four different cells. The students placed an X for each structure that was viewed for each cell on the table shown. Which cell that was viewed is most likely a prokaryote?

A dichotomous key for identifying fish is shown. Based on this key, which two fish have eyes located on either side of their head and are not spotted?

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

The karyotype, or chromosomal profile, for humans is shown. A karyotype can be used to investigate genetic disorders.

The chemical colchicine is used in the production of karyotypes. Colchicine prevents spindle fibers from forming during the cell cycle.

What is a result of preventing spindle fibers from forming?

A team of students encounters an unknown organism in a field while conducting a biodiversity study. Some students think the organism is a plant, while others think it is a fungus.

Which question should the students investigate to classify the organism correctly?

The San Marcos salamander, Eurycea nana, is a light reddish-brown translucent salamander about 2–5 cm in length. E. nana is found only in Spring Lake and a portion of the San Marcos River.

Which human activity would most likely decrease the ability of the salamanders to survive?

The diagram shows data on the evolution of horses. The data in the diagram is evidence that —

A student produces a labeled 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?

Enzymes are proteins that have a three-dimensional shape that is specific to a particular substrate. Environmental conditions can change the shape of the protein.

What is the most likely result if the shape of the enzyme changes?

A type of cellular transport is shown. Which description best identifies this type of cellular transport?

The aye-aye lemur is a mammal that feeds mostly on insect larvae that live inside trees. The aye-aye lemur has a specialized middle finger that is long and thin. The aye-aye lemur moves along a tree branch and taps the branch with its specialized finger. When the aye-aye lemur hears a difference in the echo, it will tear open the bark with its teeth until the insect tunnel is exposed. The aye-aye lemur then uses its specialized finger to reach the insect larvae and remove it. Which selective pressure most likely resulted in the development of the aye-aye lemur’s special adaptation?

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?

Gibberellins are hormones produced in the root tips of plants. The plant uses these hormones to stimulate the growth of shoots.

How are gibberellins able to affect other parts of the plant?

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

Which other molecule is a product of this process?

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?

Conservation biologists studying cheetah populations have determined that the lack of genetic diversity among the cheetahs is due to genetic drift.

Which statement explains the most likely consequence of having a low genetic diversity on the cheetah population?

CRISPR-Cas9 is a genetic modification technique that edits parts of the genome of an organism. Using this technique scientists can add, remove, or modify sections of the DNA sequence.

How can scientists use this technique to control gene expression?

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

The fuzzy millipede, Polyxenus fasciculatus, is found in Texas and is preyed upon by most species of ants. To protect itself against the ants, it ejects fibers from a tuft located at the tail end of its body. The tufts have hooks at the tips and barbs along their length that lock and interlink with the ant’s setae, small hairs that cover the body of the ant. When an ant attacks, the millipede flexes its back end toward the ant and wipes the tufts against it. As the ant attempts to remove the tufts, it entangles itself more, becoming immobilized. Which two systems most directly interact in the fuzzy millipede’s defense against ants?

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?

When cells lose their ability to regulate the cell cycle, they can divide at an accelerated rate and form a mass of cells. This mass of cells is referred to as —

The model shows a mutation to a partial sequence of bases in a gene.

Which type of mutation does the model demonstrate?

Many tree frog populations are threatened due to habitat loss. In an effort to promote conservation, tree frogs may be bred in captivity. A zoo acquired male and female tree frogs from two different populations. In the zoo, the tree frogs were able to successfully mate within their own population, but breeding attempts between the two populations were unsuccessful.

Based on this information, which statement correctly describes the relationship between the two populations of tree frogs?

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?

In 1898 Friedrich Loeffler and Paul Frosch found evidence that the cause of the highly contagious hoof-and-mouth disease in livestock was a microscopic infectious particle. It was discovered that this particle requires a host cell to reproduce.

Which pathogen is most likely responsible for causing hoof-and-mouth disease in livestock?

The diagrams show a partial food web containing the Glyptapanteles wasp and the life cycle of this wasp.

Based on the two diagrams, which list correctly identifies the relationships Glyptapanteles wasp larvae have with other organisms?

Male guppies found in areas without predators are more colorful than the ones found in locations with large predator populations. A population of adult guppies originating from an area with a large number of predators is transferred to a nearby area with few predators.

Which of these is most likely to happen over a few generations?

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 chart of some plant systems and functions is shown.

Which system interactions are dependent on the plant’s ability to respond to the direction of light?

Exposure to the building material asbestos has been linked to certain types of cancers. Asbestos causes mutations in the p53 gene, which controls tumor suppression.

Which statement best explains why people with cancer due to asbestos exposure do not pass the mutation on to their offspring?

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

A feedback mechanism in the human body is shown. Based on this diagram, which two systems interact to maintain homeostasis?

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

A table of four types of carbohydrates is shown.

Which list correctly matches the functions to the types of carbohydrates?

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

White-tailed deer are seasonal breeders. Female white-tailed deer begin their reproductive cycle in the fall. Rising testosterone levels in male white-tailed deer cause them to start their breeding season around the same time. Offspring are born the following spring and summer.

What is the most likely explanation for white-tailed deer having a seasonal breeding cycle instead of a monthly breeding cycle like many domesticated animals?

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

The ocean sunfish (Mola mola) is a large, flat fish that spends most of 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 statement accurately describes the energy needs for photosynthesis and cellular respiration?

Which table shows two steps of DNA replication?

This cladogram shows the evolutionary relationships among some mammals based on homologous structures.

Which statement is supported by this cladogram?

Some species of millipedes will roll into a ball when threatened, while other species of millipedes can secrete noxious chemicals from their bodies.

These adaptations allow the millipedes to —

The diagram shows how specialized body cells can develop. Which of the following best explains why cells that contain the same genetic material do not develop into the same types of cells?

Transmembrane proteins span the width of cell membranes. Four types of transmembrane proteins are shown in a section of cell membrane.

Although these proteins have different specific functions, they all —

The results shown in the picture were obtained using a technique known as gel electrophoresis. This technique separates mixtures of DNA. In the picture nine different samples of DNA are compared. Gel electrophoresis can be used to —

The graphs show the reaction rate for an enzyme across a range of temperatures and pH. Based on these data, this enzyme functions best at what temperature and pH?

Scientists can determine relatedness among organisms by comparing partial amino acid sequences. The table shows four partial amino acid sequences from four organisms. Which organism is the LEAST related to the other three organisms?

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?

What is the role of mRNA in expressing specialized structures?

A mutation in which types of cells would only affect the organism and not future generations?

A sequence of a DNA template strand is shown. 3’ TCC AAT GGC TTA TTT GCA 5’ Which of these is the correct amino acid chain produced from the DNA template strand?

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 activities in the cell cycle occur during specific phases. In which phase of the cell cycle is DNA replicated?

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?

An advertisement for a health supplement for dogs claims to build lean muscle and strengthen tendons and ligaments, as well as provide energy. Which two biomolecules must the supplement contain to provide these benefits?

The diagram shows light- and dark-colored beetles that live on a tree. Which result is most likely to occur to the beetle population due to predation over time?

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

Adaptations that result from natural selection are expected to increase the fitness of an organism. In terms of natural selection, which of the following best describes fitness?

In the early 1900s, Thomas Hunt Morgan was among the first scientists to contribute to the chromosome theory of heredity. Morgan’s investigations into heredity in fruit flies led him to propose that the event represented in the diagram sometimes occurs. Which statement about the event represented in the diagram is valid?

Niles Eldredge and Stephen Jay Gould researched the lenses of the eyes of fossil trilobites of different species. In 1972 they published a paper in which they described the tendency of a species to remain the same until a sudden change in the environment causes a new related species to appear. Which hypothesis was most challenged by the work of Eldredge and Gould?

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

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?

The relationships among different orders of millipedes are shown in the cladogram. Based on this cladogram, which statement best describes relationships among millipede orders?

Which of the following best describes these biomolecules?

This model of the cell cycle includes two arrows that each represent a process in the cycle. What do the two arrows represent?

The image shows part of the humerus bone in different genera of primates. Which statement is best supported by the observable structures of the different humerus

bones?

A certain mutation in the gene for hemoglobin results in the red blood cells becoming sticky, rigid, and irregularly shaped. These irregularly shaped red blood cells block the flow of blood throughout the body. A single base mutation is responsible for these irregularly shaped blood cells. Which of these mutations most likely results in the mutated hemoglobin gene?

The diagram illustrates the activity of vesicles during a cellular process. Which statement best explains the function of the vesicles?

The Indian leaf butterfly has traits that allow it to resemble a leaf. The bright colors of the monarch butterfly indicate that the butterfly tastes bad and can be poisonous.

The female reproductive and endocrine systems work interactively for which main purpose?

In the 1880s, Louis Pasteur developed a method of weakening viruses. The weakened viruses could be injected into healthy individuals. How is this method effective in fighting viral diseases?

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

A student used a microscope to study four members of the phylum Ciliophora. Members of this phylum move when propelled by hundreds of tiny cilia. Although these organisms belong to the same phylum, they are classified as different —

In the mid-1980s an aggressive strain of algae known as Caulerpa was accidentally introduced into the Mediterranean Sea when a seaside aquarium cleaned out its tanks. The algae contains a toxin that prevents native herbivores from consuming it. Caulerpa quickly spread over the sea floor, crowding out many species including sponges, corals, sea fans, and lobsters. Which statement explains the most likely impact Caulerpa has had on the biodiversity in the Mediterranean Sea?

Plant roots have extensions called root hairs. These root hairs are important in the homeostasis of the plant. Which statement best explains the importance of the root hairs to the stems and leaves of the plant?

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?

Which list correctly identifies characteristics that protists share with animals?

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?

The white cattail is a hybrid species of plant that is a result of the cross between the broad-leaved cattail and the narrow-leaved cattail. Over time, the white cattail has established itself in the wetlands of Midwestern states.

An individual who participates in a long-distance run on a hot day will produce large quantities of sweat. As a result of the excessive sweating, the amount of urine produced by the kidneys will change. How will the kidneys respond to help the individual’s body maintain homeostasis?

The gray squirrel, Eastern fox squirrel, and red squirrel are all different species of squirrels. Why is having a scientific name for each species of an organism important?

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?

Scientists have observed many types of tropical fish moving beyond their traditional ocean ranges into waters that have historically been more temperate. These fish compete for food with native fish, consuming much from the kelp forests and beds of sea grass. The expansion of the ranges of tropical fish was most likely caused by —

A corn plant produces both male and female flowers. The male flower forms the tassel and the female flower forms the ear of corn. The silks that emerge from the ear are the stigma of the female flower. Each silk leads to an ovule that can become a corn seed. Which of these must happen for corn seeds to develop on the ear?

The human body is composed of organ systems. Which list represents a system organized from least to most complex?

Some components of cells are listed. Which of the components could be observed using a microscope in a prepared slide of leaf epidermal cells but not in a prepared slide of human cheek cells?

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 —

How do the circulatory system and immune system work together to respond to an injury?

A student groups different types of cells as shown. Which table headings should the student use for the two groups?

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?

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

Fruits grown in hot climates are usually less sweet than those grown in cooler temperatures. The high temperatures increase the rate of respiration in the plants, thus reducing the sugar content in some fruits. Why does increased respiration in the leaves and stems reduce the sugar content in the fruits of a plant?

Which statement explains how producers are dependent upon consumers for their survival?

Which of these describes a difference between viruses and cells?

As part of the nitrogen cycle, animals acquire some amino acids by doing which of the following?

Which two body systems must directly interact for vertebrate organisms to exchange gases?

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

The diagrams show some of the levels of biological organization. In what order are the levels in the diagrams?

Early-onset Alzheimer’s disease affects people under the age of 65. Less than five percent of people who are diagnosed with Alzheimer’s disease have this type. Many cases of early-onset Alzheimer’s disease are inherited, a type known as familial Alzheimer’s disease (FAD). Which statement is best supported by this information?

The cladogram shows the evolution of land plants as indicated by fossil records. Which discovery would challenge the validity of this cladogram?

Atherosclerosis is a disease that obstructs blood flow and, therefore, oxygen supply to target organs. A major component of atherosclerosis is the excessive reproduction of smooth muscle cells of the blood vessels. Certain drugs may have the potential to reverse or prevent the unregulated reproduction of the diseased blood-vessel cells. Which of these processes is the most likely target of these drugs?

Carbohydrates are more easily metabolized than lipids. However, on a gram-for-gram basis lipids provide cells with more —

Lord Howe Island is a volcanic island in the Tasman Sea that is about 11 km long and 2.8 km wide. The island has two species of palm trees, Howea forsteriana and the more abundant Howea belmoreana. The two species do not interbreed even when they grow very close to each other. Which evolutionary process fails to occur?

Using a light microscope, a student identified the following characteristics of four organisms found in a sample of pond water. Based on the observations of the student, which organisms most likely belong to the taxonomic group for bacteria?

Sexual reproduction in animals depends on the production of gametes. Which of these processes produces gametes in animals?

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?

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

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

Checkpoints occur between the stages of the cell cycle. If a cell does not meet certain criteria at the end of a stage, it will not move to the next stage. Which of these occurs just before the cell enters the G stage of the cell cycle?

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?

Which group of organelles is directly responsible for the production of new molecules within a cell?

In 1917 the biologist Thomas Hunt Morgan conducted studies in which he kept some caterpillars in the dark and placed some others under red, green, or blue lights. Exposure to red light produced butterflies with brightly colored wings. Exposure to green light resulted in dark-colored wings. Exposure to blue light or no light resulted in pale-colored wings. What was the most likely conclusion of Morgan’s research?

Severe acute respiratory syndrome (SARS) is an illness caused by a coronavirus. Symptoms including a high fever, headaches, and body aches typically occur two to seven days after infection by the virus. SARS is more serious in elderly patients. This information suggests that the reproductive cycle of the SARS virus is —

Lactose is found in milk products. It is converted by the body into a usable form in a series of chemical reactions. The diagram shows the series of reactions that convert lactose into a usable form. If Enzyme 2 is denatured, the levels of which substance will increase?

The picture below shows a person’s karyotype. Which of the following can best be determined by examining this karyotype?

The cellular process known as the sodium-potassium pump was discovered in the 1950s by Jens Christian Skou, a Danish scientist. This process is a form of active transport that moves three sodium ions to the outside of a cell for every two potassium ions that it moves into the cell. Which of these best explains why energy is needed for active transport?

Researchers Robert Briggs and Thomas King used ultraviolet radiation to destroy the nuclear DNA of frog eggs. Nuclei from adult skin cells and from tadpole-gut epithelial cells were cultured and then injected into eggs that had their nuclei destroyed. The results were tadpoles. Which conclusion is supported by the data from this investigation?

The Linnaean taxonomic system classifies organisms into divisions called taxa. If two organisms belong to the same taxonomic group, they are related. Similarity at which of these levels indicates the closest relationship?

Sickle-shaped red blood cells result from a mutation in the gene that codes for hemoglobin. This mutation results in sickle-cell anemia. A partial sequence of bases from a normal hemoglobin gene and a sequence that results in sickle-cell anemia are shown below. What type of mutation is depicted in this sequence?

In Madagascar scientists have discovered a moth, Xanthopan morganii praedicta, that has a 30.5 cm proboscis and feeds from and pollinates Darwin’s orchid, Angraecum sesquipedale. The orchid has a nectar-producing tube that is 27.9 cm long. How is the moth’s proboscis size an adaptation for its environment?

Genome maps provide the DNA sequences of chromosomes. Some scientists have compared the genome maps of a hedgehog and a sloth. What do these genome maps allow the scientists to determine?

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 by a single gene, what is the expected outcome of crossing two tomato plants that are heterozygous for hairy stems?

Which of the following biomolecules typically contains both nitrogen and phosphate?

Most plant leaves take in more carbon dioxide as light increases. They give off carbon dioxide if light intensity is too low. The graph shows a plant’s carbon dioxide levels at different light intensities. At point X, the rate of which process is equal to the rate of photosynthesis?

Telophase is a stage of a cellular process that begins after the chromosomes have moved to opposite poles of the cell. During which cellular process does telophase occur?

Which of the following polypeptides is coded for by the mRNA sequence ′ ′ 5 AUGGUUAAACGACAAUCC3?

Which condition is essential for natural selection to result in a new species?

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 —

The diagram shows a dichotomous key and a picture of a fruit. According to the key, the fruit comes from which species of tree?

The opossum, which is native to North America, and the kangaroo, which is native to Australia, are marsupials. The fact that both these mammals incubate their immature offspring in a pouch provides

evidence that they —

Some students are instructed to put a celery stalk in a red dye solution for a lab activity. First the students carefully cut the bottom of the stalk with a scalpel. Then they put the stalk in the beaker with the solution and place the beaker on a shelf in the lab room. The next day they check the stalk and make observations. The students note that the leaves at the end of the stalk have changed color from green to red. The students cut across the celery stalk and use a hand lens to see that the small tube openings along the edge of the celery stalk are also red. The cross section is shown below. How do the plant systems work together to make this movement of liquid possible?

The table below provides some information about the feeding methods of the five rhinoceros

species. Which rhinoceros species is best adapted for feeding in the large open grasslands of Africa’s Serengeti ecosystem?

The cladogram shows the evolution of land plants as indicated by fossil records. Which discovery would challenge the validity of this cladogram?

The outermost layer of plant stems in dicotyledons consists of epidermal cells and guard cells that surround openings called stomata. The epidermal cells are usually covered with

a waterproof layer that provides protection from injury and water loss. The stomata allow gas exchange. The epidermal cells and stomata have functions similar to those of which two human body systems?

Dead zones are low-oxygen areas that develop on the seafloor. Scientists hypothesize that phytoplankton blooms cause these dead zones. Phytoplankton blooms occur when excess nutrients are introduced by pollution from fertilizers, sewage plants, and the burning of fossil fuels. Which of the following would most likely cause an increase in these contributors to dead zones?

What two human systems work together to provide body cells with a constant supply of oxygen while removing carbon dioxide waste products?

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?

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?

A marine ecosystem is represented below. What is lost to the environment at each of the trophic levels of this ecosystem?

Which of the following functions at the same organizational level as the kidney in the human excretory system?

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 —

The osmoregulation process is shown below. This process is an example of which of the following?

In any environment or ecosystem, organisms can have several different types of relationships.Three types of relationships are described below. Which of these correctly describes the relationships between the organisms?

Hydrothermal vents form deep in the ocean when iron-rich magma is released from openings on the seafloor. These vents spew extremely hot water (400°C) mixed with methane and sulfur. Bacteria that thrive in this hostile environment form the base of a food chain that leads to colonization by tube worms, mussels, and many other life-forms. When a hydrothermal vent becomes inactive and cold, the bacterial community that lives in the hot fluid methane and sulfur dies out. Which organisms most likely succeed the original community in this ecosystem?

When a person is suddenly cut by a sharp object, a nervous impulse is sent along a sensory neuron to the spinal cord. The impulse is immediately transmitted through motor neurons to produce a response. Which of the following correctly identifies and describes this response?

Toxoplasmosis is an infection producing brain lesions caused by the parasitic protozoan Toxoplasma gondii. Mice with their gonads removed are more resistant to T. gondii and develop very few lesions on their brain tissue. The graph shows the results of a scientific study of normal adult mice infected with T. gondii. Which systems most likely interact and cause the severity of infections to vary?

Brazil nuts (Bertholletia excelsa) are tall canopy trees that make up a large portion of the Amazon rain forest. They produce large grapefruit-sized seedpods. The agouti, a ground-dwelling rodent, has teeth strong enough to open the tough seedpods. While the agouti eats some of the tree’s seeds, it also buries caches in various spots on the rain forest floor. Why is the agouti important to the rain forest ecosystem?

A terrestrial food web is shown below. Which of the following lists only organisms that are secondary consumers in this food web?

The Linnaean taxonomic system classifies organisms into divisions called taxa. If two organisms belong to the same taxonomic group, they are related. Similarity at which of these levels indicates the closest relationship?

The diagram below represents the nitrogen cycle in a student’s aquarium. Ammonia, nitrites, and, to a lesser degree, nitrates can be harmful to fish. The student wants to keep the nitrogen in this aquarium cycling normally without having to continually change the water. Which of the following should the student add more of to help remove nitrates and improve the natural cycling of nitrogen in this aquarium?

The graph below 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?